UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF

PREVENTION, PESTICIDES, AND

TOXIC SUBSTANCES

TXR No.:	0051445

MEMORANDUM

DATE:		October 22, 2003

SUBJECT:	PYRACLOSTROBIN: Report of the Cancer Assessment Review
Committee (Second Evaluation); PC Code: 099100

FROM:	Jessica Kidwell, Executive Secretary

Cancer Assessment Review Committee

Health Effects Division (7509C)

TO:		Ghazi Dannan, Toxicologist

Barry O’Keefe, Risk Assessor/Biologist

Registration Action Branch 3

Health Effects Division (7509C)

John Bazuin/Cynthia Giles-Parker, PM Team 22

Fungicide Branch

Registration Division (7505C)

The Cancer Assessment Review Committee met on September 10, 2003 to
re-evaluate the carcinogenic potential of Pyraclostrobin.  Attached
please find the Final Cancer Assessment Document.

cc:	J. Pletcher

Y. Woo



CANCER ASSESSMENT DOCUMENT

SECOND EVALUATION OF THE CARCINOGENIC POTENTIAL OF

PYRACLOSTROBIN

PC Code:   099100

FINAL REPORT

October 22, 2003

CANCER ASSESSMENT REVIEW COMMITTEE

HEALTH EFFECTS DIVISION

OFFICE OF PESTICIDE PROGRAMS

COMMITTEE MEMBERS PRESENT AT THE SEPTEMBER 10, 2003 CARC MEETING

DATA PRESENTATION:		_________________________________________

Ghazi Dannan, Toxicologist

DOCUMENT PREPARATION:	                                                  
                    

Jessica Kidwell, Executive Secretary

COMMITTEE MEMBERS IN ATTENDANCE:	(Signature indicates concurrence with
the assessment unless otherwise stated).	

Karl Baetcke				                                                        
              

William Burnam			                                                       
              

Abdallah Khasawinah			                                                  
                   

Nancy McCarroll	             	                                          
                           

Tim McMahon			                                                          
           

Esther Rinde				                                                        
             

Jess Rowland				                                                        
             

Linda Taylor				                                                        
             

NON-COMMITTEE MEMBERS IN ATTENDANCE 	(Signature indicates concurrence
with the pathology report and statistical analysis of data,
respectively)

John M. Pletcher	Pathology Consultant		                                 
                         

Lori Brunsman	Statistical Analysis		                                    
                      

OTHER ATTENDEES:  The meeting was also attended by Paula Deschamp
(HED/RAB3), Stephen Dapson (HED/RAB3), Leung Cheng (HED/RAB3), John
Bazuin (RD), Jr., and Kelly O’Rourke (HED/RAB3). The toxicologists at
Pesticide Management Regulatory Agency (PMRA), Health Canada, Canada
(Diana Somers, Brenda McDonald, and Tom Morris) attended the meeting by
teleconference.

COMMITTEE MEMBERS PRESENT AT THE OCTOBER 21, 2001 CARC MEETING

DATA PRESENTATION:  William Greear and Ghazi Dannan, Toxicologists

DOCUMENT PREPARATION:  Sanjivani Diwan, Executive Secretary

COMMITTEE MEMBERS IN ATTENDANCE:  Karl Baetcke, William Burnam, Kerry
Dearfield

Vicki Dellarco, Virginia Dobozy,Yiannakis Ioannou, Nancy McCarroll,
Esther Rinde, Joycelyn Stewart, Clark Swentzel, Linda Taylor

NON-COMMITTEE MEMBERS IN ATTENDANCE John M. Pletcher (Pathology
Consultant),    Lori Brunsman (Statistical Analysis)

OTHER ATTENDEES:  The meeting was also attended by Ghazi Dannan and
Waheeda Tehseen from OPP/HED and John Benjamin from OPP/RD. The
toxicologists at Pesticide Management Regulatory Agency (PMRA), Health
Canada, Canada and California/Environmental Protection Agency (CAL/EPA)
attended the meeting by teleconference.

TABLE OF CONTENTS

 TOC \f 

EXECUTIVE SUMMARY	1

I.  BACKGROUND INFORMATION	4

II. INTRODUCTION	6

III.  EVALUATION OF CARCINOGENICITY STUDIES	6

1. Carcinogenicity Study with Pyraclostrobin in Wistar Rats	6

A. Experimental Design	6

B. Discussion of Tumor Data	6

C. Non-neoplastic Lesions	11

2. Chronic Toxicity Study in Wistar Rats	12

A. Experimental Design	12

B. Discussion of Tumor Data	12

C. Non-neoplastic Lesions	15

3.  Tumor Analyses: Rat Studies Combined	16

A. Discussion of Tumor Data	16

B. Adequacy of the Dosing - Rats	21

4. Carcinogenicity Study in Mice	24

A. Experimental Design	24

B. Discussion of Tumor Data	24

C. Non-neoplastic Lesions	24

D. Adequacy of Dosing - Mice	25

IV.	TOXICOLOGY	26

1. Metabolism	26

2. Mutagenicity	27

3. Structure-Activity Relationship	29

4. Subchronic, and Chronic Toxicity	31

5. Mode of Action Studies	34

V.  COMMITTEE’S ASSESSMENT OF THE WEIGHT-OF-THE-EVIDENCE	34

1.  Carcinogenicity 	34

2.  Mutagenicity	36

3.  Structure Activity Relationship	36

4.  Mode of Action Studies	36

VI.  CLASSIFICATION OF CARCINOGENIC POTENTIAL	36

VII.  QUANTIFICATION OF CARCINOGENIC POTENTIAL	36

VIII.  BIBLIOGRAPHY	37

 

EXECUTIVE SUMMARY tc \l1 "EXECUTIVE SUMMARY 

On September 10, 2003, the CARC re-evaluated the cancer classification
of pyraclostrobin.  This CARC revisit focused on the three issues: 1)
reassessment of hemolymphoreticular tumors from all rats of all groups
(Section III, 3, A); 2) adequacy of dosing in female rats (Section III,
3, B); 3) adequacy of dosing in female mice (Section III, 4, D).  This
CARC report supercedes the 12/26/01 CARC report (TXR No. 0050363).

Pyraclostrobin was administered in the diet to: 1) 50 male and 50 female
Wistar  Chbb: THOM (SPF) rats at 0, 25, 75 or 200 ppm (0, 1.2, 3.4, and
9.2 mg/kg/day for males and 0, 1.5, 4.7, and 12.6 mg/kg/day for females,
respectively) for 24 months in a carcinogenicity study; 2) 20 Wistar
Chbb:THOM (SPF) rats/sex/group at nominal dose levels of 0, 25, 75, or
200 ppm (0, 1.1, 3.4, and 9.0  mg/kg/day for males and  0, 1.5, 4.6,
12.3 mg/kg/day for females, respectively) for 2 years in a chronic
toxicity study, and 3) 50 male and 50 female B6C3F1 mice at 0, 10, 30 or
120 ppm in males and 0, 10, 30, 120, or 180 ppm in females (0, 1.4, 4.1,
and 17.2  mg/kg/day for males and  0, 1.6, 4.8, 20.5, and 32.8 mg/kg/day
for females, respectively) for 18 months in a carcinogenicity study.

The CARC concluded that the available data were inadequate to make the
determination of the carcinogenic potential of pyraclostrobin in B6C3F1
mice.  The Committee

recommended that the study in female mice be repeated at adequate dose
levels based on the following findings:

Upon reevaluation, the CARC concluded that dosing at the high dose of
180 ppm for female mice was not adequate.  This conclusion was based on
the fact that, because of the variability in the data, there was no
consistent pattern (between cumulative and discrete intervals) of
changes in body weight, body weight gain, food consumption, and food
efficiency to support that an adequate dose had been reached for female
mice.  Although there were statistically significant decreases in body
weight gain (-15%, Day 0-119; -21%, Day 0-259; -26% , Day 0-546) and
food efficiency (-17%, Day 0-119; -21%, Day 0-259; -23%, Day 0-546) at
180 ppm during cumulative periods, the data are inconsistent when
compared to discrete intervals for body weight gain and food efficiency,
where no consistent pattern was seen.  For example, the variability of
the pattern can be seen in the increases and/or decreases in body weight
gain/food efficiency at 180 ppm for the following discrete intervals
(-22%/-22%, Day 92-175; -41%/-40%, Day 176-259; +193%/+187%, Day
260-343; -223%/-235%, Day 428-511).   In addition, the magnitude of
these effects was not clearly dose-related.  For example, the cumulative
decreases in body weight gain at 10 ppm (-8.25% from Day 0-119; -17%
from Day 0-546) were more pronounced than those occurring at 30 ppm (+8%
from Day 0-119; -12% from Day 0-546).  In addition, the effects
occurring in the 90-day study do not support selection of the top dose
of 180 ppm.  Only very minor changes in clinical chemistry and pathology
were seen in females in the 90-day study at 150 ppm.  More pronounced
effects on body weight (-6-13%), body weight gain (-39-74%), and changes
in clinical chemistry and pathology occurred at 500 ppm in the
subchronic study, indicating that the doses in the main study could have
been higher.

The CARC further concluded the following: 

The statistical analyses of the tumor data from the combined results of
carcinogenicity and chronic toxicity studies showed neither a
significant increasing trend nor a significant difference in the
pair-wise comparison of the dosed groups with the controls, for liver  
tumors in male rats and  mammary gland tumors in female rats.  In male
rats, there was only a statistically significant increasing trend
(p<0.05) for hemangiomas; the incidences of hemangiomas,
hemangiosarcomas and combined hemangiomas/hemangiosarcomas in the 200
ppm dose group were within their respective historical control ranges.
The CARC determined that the hemangiomas do not progress to
hemangiosarcomas in rats and concluded that these vascular tumors were
not treatment-related.  The CARC also concluded that the mammary gland
tumors were not treatment-related.

Although there was an increase in Leydig cell tumors of the testes in
all dose groups compared to control, no dose-response was evident and
the tumor incidence at the highest dose tested (200 ppm) was within the
historical control range.  The CARC noted that testicular tumors were
not seen in male rats in the chronic study.  The CARC determined that
these tumors were not treatment-related.

Reassessment of the hemolymphoreticular (HLR) tumors in rats: The
statistical analyses of the tumor data from the combined results of
carcinogenicity and chronic toxicity studies showed neither a
significant increasing trend nor a significant difference in the
pair-wise comparison of the dosed groups with the controls, for all
combined histiocytic sarcoma/lymphoma from both the chronic and
carcinogenicity studies.  In addition, the HLR tumor incidence was
within the historical control range.  Therefore, the CARC did not
consider these tumors to be treatment related.

Adequacy of Dosing in Rats: Males:  The CARC considered that the dosing
in males at 200 ppm approached the adequate level because in males there
were some toxicological changes including a minimal decrease of 10% body
weight gain in addition to increased incidence of liver necrosis. 
Females: Upon reevaluation, the CARC concluded that female rats were
tested adequately at the top dose of 200 ppm.  Based on the more severe
decreases in body weight gain (-21-24%) and food efficiency (-16-17%)
seen during Day 0-399 at 400 and 600 ppm in the main study, which are
supported by the effects seen at 500 ppm in the subchronic study, it is
evident that the female rats may not have tolerated a dose higher than
200 ppm.  Therefore, the CARC concluded that the dose of 200 ppm chosen
for the chronic toxicity and carcinogenicity studies was reasonable and
adequate.

In the mouse carcinogenicity study with pyraclostrobin, no tumors were
seen in either male or female mice.  

Adequacy of Dosing in Mice: Males: The CARC determined that the highest
dose tested was adequate for male mice based on decrease in body weight
gain (20%) at 13 weeks of  80 week study which was supported by the
results of a 90-day range-finding study. Females: As stated above, upon
reevaluation, the CARC concluded that dosing at the high dose of 180 ppm
for female mice was not adequate.

Pyraclostrobin has been tested in an adequate battery of mutagenicity
tests.  All the in vitro and in vivo mutagenicity studies were negative.

Pyraclostrobin is structurally related to two other strobirulin
pesticides, azoxystrobin and trifloxystrobin.  Both azoxystrobin and
trifloxystrobin were classified  (in 1996 and 1999, respectively) as
“not likely to be carcinogenic to humans”.  Azoxystrobin was
mutagenic in vitro  but not in the  in vivo assay.  Trifloxystrobin was
only mutagenic in the Chinese hamster V79 fibroblasts assay.

In accordance with the EPA Draft Guidelines for Carcinogen Risk
Assessment (July, 1999), the CARC classified pyraclostrobin into the
category “Data are inadequate for an assessment of human carcinogenic
potential” because of inadequate testing of female mice.  The
Committee recommended that the registrant should conduct a new study in
female mice at adequate dose levels.

I.  BACKGROUND INFORMATION tc \l1 "I.  BACKGROUND INFORMATION 

Pyraclostrobin, PC. Code: 099100,  CAS NO.  175013-18-0;
[Methyl-N-[[[1-(4-chlorophenyl)pyrazol-3-yl]oxy]-o-tolyl]-N-methoxycarba
mate; BAS 500F; Reg. No. 304 428; is a new active ingredient fungicide,
of the strobilurin class of active ingredients, for use on 30 RACs.  The
biochemical mode of action is the inhibition of electron transport in
pathogenic fungi.   The structure is provided below:

	

Occupational exposure to pyraclostrobin is expected to occur. Turf use
can result in residential/recreational exposure
[postapplication-incidental oral (children), and dermal (adults and
children)].  The primary routes of concern are dermal and inhalation,
with exposure time varying from days to many months.  

On October 24, 2001, Pyraclostrobin was evaluated for its carcinogenic
potential by the Cancer Assessment Review Committee of the Health
Effects Division jointly with Pest Management Regulatory Agency (PMRA),
Health Canada, Canada, along with participation of California/EPA. The
CARC concluded that the available data were inadequate to make the
determination of the carcinogenic potential of pyraclostrobin in Wistar
rats and B6C3F mice. The Committee further recommended that the studies
in female rats and female mice be repeated at adequate dose levels.  The
findings and rationale for this decision may be found in the CARC report
dated December 26, 2001 (TXR No. 0050363). 

The following is an outline of the outstanding deficiencies that were
identified by CARC:

 ADVANCE \d0 

•	The Committee concluded that the data for histiocytic sarcomas were
inadequate due to incomplete histopathological examination of tissues.
The incidence of histiocytic sarcomas seen in the carcinogenicity study
could not be determined because only male rats with lesions (and not
all) were examined histopathologically.

 ADVANCE \d0 •	The Committee concluded that the dosing in female rats
was inadequate since no significant toxicity was noted at the highest
dose. In the carcinogenicity study in rats, although the body weight
gain decreased in males (10%) and females (22%) at the end of 104 weeks,
the body weight gains were variable throughout the study. The CARC
considered that the dosing in males at 200 ppm approached the adequate
level because in males there were some toxicological changes including a
minimal decrease of 10% body weight gain in addition to increased
incidence of liver necrosis. Although high-dose females gained 23% less
weight, they had no non-neoplastic histopathological findings.

 ADVANCE \d0 

•	In the mouse carcinogenicity study with pyraclostrobin, dosing at
the highest dose was not adequate for female mice because of the absence
of significant toxicological effects. The CARC determined that the
highest dose tested was adequate for male mice based on decrease in body
weight gain (20%) at 13 weeks of 80 week study which was supported by
the results of a 90-day range-finding study.

 ADVANCE \d0 

Subsequently, the registrant visited the Agency to present their
rebuttal arguments and submitted additional materials in an effort to
address the CARC's determinations that several key studies were dosed
inadequately. 		

II. INTRODUCTION tc \l1 "II. INTRODUCTION 

On September 10, 2003, the Cancer Assessment Review Committee (CARC) of
the Health Effects Division of the Office of Pesticide Programs met to
re-evaluate the carcinogenic potential of pyraclostrobin.  

Ghazi Dannan of Registration Action Branch 3 presented the new
information submitted by BASF regarding 1) reassessment of
hemolymphoreticular tumors from all rats of all groups; 2) adequacy of
dosing in female rats; 3) adequacy of dosing in female mice.

III.  EVALUATION OF CARCINOGENICITY STUDIES tc \l1 "III.  EVALUATION OF
CARCINOGENICITY STUDIES 

1. Carcinogenicity Study with Pyraclostrobin in Wistar Rats tc \l2 "1.
Carcinogenicity Study with Pyraclostrobin in Wistar Rats  

Reference:  Mellert, W., Deckardt, K., Gembardt, Chr., et.al (1999) BAS
500 F - Carcinogenicity Study in Wistar Rats Administration in Diet for
24 Months.  BASF Aktiengesellschaft, Department of Toxicology,
Ludwigshafen, Germany.  Laboratory Project Id.: 82S0494/96086, November
22, 1999.  MRID 45118331.  Unpublished.

A. Experimental Design tc \l3 "A. Experimental Design 

Pyraclostrobin  (97.09% a.i.,  Lot/Batch # J.-Nr. 27882/191/c) was
administered in the diet to Wistar rats (50/sex/group) for up to 104
weeks at nominal doses of 0, 25, 75, or 200 ppm, equivalent to 0/0,
1.2/1.5, 3.4/4.7, and 9.2/12.6 mg/kg/day [M/F], respectively. 

B. Discussion of Tumor Data tc \l3 "B. Discussion of Tumor Data 

Male rats had a significant increasing trend, and  a significant
difference in the pair-wise comparison of the 200 ppm dose group with
the controls, for liver adenomas, both at p < 0.05.  There was a
significant increasing trend in combined liver adenomas/carcinomas at p
< 0.05 (see Table 1).  There was also a significant trend at p < 0.01
and a significant difference in the pair-wise comparison of the 200 ppm
dose group with the controls at p < 0.05 for hemangiomas at all sites
(see Table 2).  

 There was no increase in liver and vascular tumors in female rats.

	Table 1. Pyraclostrobin - Wistar Rat Carcinogenicity Study

	

      Male Liver Tumor Rates+ and Peto’s Prevalence Test Results (p
values)- Brunsman, 2001. 

     0 ppm          25 ppm	  75 ppm	 200 ppm	Historical Controlsd

Adenomas	  4/50	 7/49	 5/50	11a/49	   10/160

   (%)	   (8)	  (14)	 (10)	 (22)		(6.4)

p =       0.0135*	0.1564	0.2524	0.0177*	Range:4-10%

Carcinomas  4/50	 3/49	 5b/49	  3/47	    10/160

   (%)	  (8)	  (6)	  (10)	   (6)		 (5.8)

p =       0.5515	0.6827	0.3905	0.6150 	Range:4-10%

Combined	  8/50	 10/49	 9c/50	  14/49		20/160

   (%)	  (16)      (20)	  (18)	   (29)		 (12.2)

p =       0.0395*	0.3562	0.3340	 0.0526     Range:5-20%

+Number of tumor bearing animals/Number of animals examined, excluding
those that died before observation of the first tumor.

aFirst adenoma observed at week 68, dose 200 ppm.

bFirst carcinoma observed at week 78, dose 75 ppm.

cOne animal in the 75 ppm dose group had both an adenoma and a
carcinoma.

d Historical control data based on five studies from 4/93 through 8/97;
MRID 45429902

Note:	Significance of trend denoted at control.

Significance of pair-wise comparison with control denoted at dose level.

If *, then p < 0.05.  If **, then p < 0.01.

Table 2. Pyraclostrobin - Wistar Rat Carcinogenicity Study

Male Vascular Tumor Rates+ (All Sites) and Peto’s Prevalence Test

 Results (p values)-Brunsman, 2001

                              0 ppm 	   25 ppm	 75 ppm	200 ppm	 
Historical                                             Controlsd	

Hemangiomas  3/50	  0/49	 2/50	10a/49	  27/330

   (%)	   (6)	  (0)	  (4)	 (20)	   (8)

p =        0.0002**	   -	        -	     0.0164*	Range:2-20%

Hemangio-

 sarcomas	   6/49	  7/48	  6/47	2b/47	  	  20/330

   (%)	   (12)	   (15)	  (13)	  (4)	   (6)

p =         0.9483	  0.2926	 0.3961	   -   	Range:0-15%

Combined	   9/50     7/49	  8/50	12/49	  47/330

   (%)	   (18)      (14)	  (16)	  (24)	   (14)

p =         0.1202	    -	   -	     0.2029    Range:2-25%

+Number of tumor bearing animals/Number of animals examined, excluding
those that died before observation of the first tumor.

aFirst adenoma observed at week 68, dose 200 ppm.

bFirst carcinoma observed at week 84, dose 200 ppm.

d Historical control data based on nine studies from 4/93 through 7/00,
MRID 45429902 

Note:	Significance of trend denoted at control.

Significance of pair-wise comparison with control denoted at dose level.

If *, then p < 0.05.  If **, then p < 0.01.

Table 3.  Pyraclostrobin- Wistar rat Carcinogenicity Study

Male Testicular Tumor Rates

Fisher's Exact Test/Exact trend Test Results (p values)

(Cancer Assessment Document, 2001)

Finding	

Dose (ppm)





	

0	

25	

75	

200	

Historical Control



Males  (percent incidence)



Testes

    Leydig cell tumor

    p=	

19/50 (38)

0.2113

	

25/50 (50)

0.1569

	

24/50 (48)

0.2096

	

25/50 (50)

0.1569

	

143/330 (43)

range-30-60%





Testicular Leydig cell tumors were observed in all male groups, but were
slightly higher in each of the three treated groups (48-50%) when
compared to the control group (38%).  Historical control data for this
tumor were submitted separately (MRID 45443001).  The incidence of
benign testicular Leydig cell tumors in male Wistar rats in studies
performed from 4/95- 7/00 at the testing laboratory is 43% (mean) with a
range of 30-60%; 9 studies were included in the analysis.

Table 4.  Pyraclostrobin - Wistar Rat Carcinogenicity Study

Female Mammary Gland Tumor Rates+ and Exact Trend Test 

and Fisher’s Exact Test Results (p values)- Brunsman, 2001

   0ppm         25 ppm	         75 ppm	         200 ppm	             
Historical                                                        
Controlsd	

Adenomas	 0/49	0/50	    2a/50		1/49		 1/330

   (%)	 (0)		(0)		(4)		 (2)		 (0.3)

Adenocarcinomas

 2/49	6b/50		2/50	     8/49		 28/330

   (%)	  (4)	(12)		 (4)		 (16)	 (8)

p =      0.0453*	0.1409	0.6837	0.0456*	 Range:0-14%

Combined	  2/49	 6/50     4/50       9/49	 29/330

   (%)	  (4)	(12)		 (8)		 (18)	 (9)

p =      0.0260*	0.1409	0.3485	 0.0254*	 Range:0-16%

Fibroadenomas

            10/49	 10/50	8/50		  10c/49	 43/330

   (%)	  (20)	 (20)	(16)		   (20)p	 (13)

P=        0.4969	0.5787	0.3792	  0.5987    Range:0-20%

+Number of tumor bearing animals/Number of animals examined, excluding
those that died before week 53.

aFirst adenoma observed at week 105, dose 75 ppm.

bFirst carcinoma observed at week 87, dose 25 ppm.

cFirst fibroadenoma observed at week 68, dose 200 ppm.

d Historical control data based on nine studies from 4/93 through 7/00,
MRID 45429902 

Note:	Significance of trend denoted at control.

Significance of pair-wise comparison with control denoted at dose level.

If *, then p < 0.05.  If **, then p < 0.01. 

There was an increased incidence of mammary gland adenocarcinoma in the
females at 200 ppm (16% vs 4% controls; Table 4).  Historical data
showed an incidence of female mammary gland adenocarcinoma in Wistar
rats from 4/95- 7/00 to be 8% (mean) and 0-14% (range); 9 studies were
included in the analysis (MRID 45429902). 

C. Non-neoplastic Lesions tc \l3 "C. Non-neoplastic Lesions 

Table 5 lists the non-neoplastic microscopic findings in male rats.  The
target organs were liver, and kidneys.  The changes in forestomach, and
glandular stomach were seen late at necropsy and were considered by the
CARC to be age related.  There were no treatment related non-neoplastic
lesions in the female mammary glands.

Table 5.  Selected Non-neoplastic Microscopic Findings in
Carcinogenicity Study 

Observed in Male Rats Treated with Pyraclostrobin for up to 104 Weeksa

(MRID 45118331)

Finding	

Dose (ppm)

	

0	

25	

75	

200



Number of animals examined	

50	

50	

50	

50



Forestomach-male	





       Acanthosis	

0	

1	

1	

6



       Ulcers	

2	

1	

0	

4



Glandular stomach-male	





       Erosions

       Ulcers	

2

2	

5

2	

7

2	

10

7



Liver-male

       Congestion

        Vacuolated foci

        Clear cell foci

        Necrosis (focal,                 grade 3) b	

9

3

13

1	

5

10

20

2	

7

10

16

2	

12

9

17

10



 Kidney-male

       Tubular casts

       Tubular atrophy	

5

5	

3

3	

4

4	

15

16

a	Data were obtained from MRID 45118331

b	The incidence was outside the range for the historical controls; no
grading was reported for the historical controls  (2%-16%; BASF, 2001)

D. Adequacy of Dosing

See Section III, 3, B for adequacy of dosing for the chronic toxicity
and carcinogenicity studies.

2. Chronic Toxicity Study in Wistar Rats tc \l2 "2. Chronic Toxicity
Study in Wistar Rats 

Reference:  Mellert, W., Deckardt, K., Gembardt, Chr., et.al. (1999) BAS
500 F- Chronic Toxicity Study in Wistar Rats Administration in the Diet
for 24 Months.  BASF Aktiengesellschaft, Department of Toxicology,
Ludwigshafen, Germany.  Laboratory Project Id.: 82S0494/96085, November
9, 1999.  MRID 45118329.  Unpublished.

A. Experimental Design tc \l3 "A. Experimental Design 

Pyraclostrobin (97.09% a.i., Lot/Batch# J.-Nr.  27882/191/c) was
administered continuously in the diet  to 20 Wistar Chbb:THOM (SPF)
rats/sex/group at nominal dose levels of 0, 25, 75, or 200 ppm
(equivalent to [M/F] 0/0, 1.1/1.5, 3.4/4.6, and 9.0/12.3  mg/kg/day) for
2  years.					

B. Discussion of Tumor Data tc \l3 "B. Discussion of Tumor Data 

Contrary to the findings in the carcinogenicity study, there was no
increase in liver tumors in male rats and  mammary tumors in female rats
in the chronic study (Table 6 and 8, respectively).  However, among male
rats there were significant differences only in the pair-wise
comparisons of the 75 ppm dose group with the controls for
hemangiosarcomas at all sites at p < 0.05 and for hemangiomas and/or
hemangiosarcomas combined at all sites at p < 0.01 (Table 7).		

Table 6. Pyraclostrobin - Wistar Rat Chronic Study

Male Liver Tumor Rates+- Brunsman, 2001

    0 ppm              25 ppm	       75 ppm	         200 ppm    
Historical                                             Controls	

Adenomas	 4/20	  2/20	   2/20	    1a/20      10/160

   (%)	                 (20)		      (10)	         (10)	            (5)		
     (6)

                               Range: 4-10%

Carcinomas 0/20	  2b/20	   2/20	     0/20      10/160

   (%)	                 (0)		        (10)	         (10)	             
(0)		       (6)

              									       Range: 4-10%	

Combined	    4/20		       3c/20	         4/20	             1/20 	       
      20/160

   (%)	               (20)		        (15)	         (20)	              (5)
	      (13)                                               Range: 5-20%

+Number of tumor bearing animals/Number of animals examined, excluding
those that died before week 53.

aFirst adenoma observed at week 105, dose 200 ppm.			

bFirst carcinoma observed at week 92, dose 25 ppm.

cOne animal in the 25 ppm dose group had both an adenoma and a
carcinoma.

Note:	Significance of trend denoted at control; Significance of
pair-wise comparison with control denoted at dose level; If *, then p <
0.05.  If **, then p < 0.01.			

Table 7. Pyraclostrobin - Wistar Rat Chronic Study

Male Vascular Tumor Rates+ (All Sites) and Exact Trend Test 

  and Fisher’s Exact Test Results (p values)- Brunsman, 2001

           0ppm             25 ppm	          75 ppm	          200 ppm   
Historical Controls

Hemangiomas   1a/20    	2/20		 4/20	  0/20	   27/330

   (%)	     (5)		(10)		  (20)	  (0)	    (8)

p =          0.2142	   0.5000		0.1708	 0.5000  range=2-20%	

Hemangio-

 sarcomas	         0/20		2/20		    5b/20	      1/20	        20 / 330

   (%)	   (0)		(10)	       (25)	   (5)	    (6)

p =          0.4570	   0.2436		0.0236*	 0.5000  range=0-15%

Combined     1/20		4/20	       9/20	   1/20	   47/330

   (%)	   (5)		(20)	       (45)	   (5)	    (14)

p =          0.3142	    0.1708	0.0042**	 0.7564  range=2-25%

+Number of tumor bearing animals/Number of animals examined, excluding
those that died before week 53.

aFirst adenoma observed at week 86, dose 0 ppm.

bFirst carcinoma observed at week 81, dose 75 ppm.

Note: Significance of trend denoted at control.

Significance of pair-wise comparison with control denoted at dose level.

If *, then p < 0.05.  If **, then p < 0.01.						

Table 8.   Pyraclostrobin - Wistar Rat Chronic Study

Female Mammary Gland Tumor Rates+ and Exact Trend Test and 

Fisher’s Exact Test Results (p values)-Brunsman, 2001

  0ppm     25 ppm	  75 ppm	 200 ppm		Historical Controls

Adeno-

 carcinomas#      3a/19	    2/20		      5/19	     0/19		28/330

   (%)	  (16)	 (10)	  (26)	  (0)		 (8)

p =       0.0871	0.4746	0.3464	0.1149	 range:0-14%

Fibro-

  adenomas         5b/19	     5/20	       3/19	       8/19		  45/330

   (%)	  (26)	  (25)	   (16)	   (42)

p =       0.1089	0.6063	 0.3464	 0.2475     range:0-20%

+Number of tumor bearing animals/Number of animals examined, excluding
those that died before week 53.

aFirst adenocarcinoma observed at week 85, dose 0 ppm.

bFirst fibroadenoma observed at week 96, dose 0 ppm.

#No adenomas were observed.

Note:	Significance of trend denoted at control.					

Significance of pair-wise comparison with control denoted at dose level.

If *, then p < 0.05.  If **, then p < 0.01. 

C. Non-neoplastic Lesions tc \l3 "C. Non-neoplastic Lesions 

No treatment-related non-neoplastic changes were observed.

D. Adequacy of Dosing for the Assessment of Carcinogenicity

See Section III, 3, B for adequacy of dosing for chronic toxicity and
carcinogenicity studies.

3.  Tumor Analyses: Rat Studies Combined tc \l2 "3.  Tumor Analyses:
Rat Studies Combined 

A. Discussion of Tumor Data tc \l3 "A. Discussion of Tumor Data 

Both the carcinogenicity and chronic toxicity studies were conducted
during the same study period.  Therefore, the results of these studies
were combined and analyzed statistically by HED (Brunsman, 2001).  The
statistical analyses of the combined tumor data for male and female rats
from the carcinogenicity and chronic toxicity studies are presented
below in Tables 9-12.  

There was neither a significant increasing trend nor a significant
difference in the pair-wise comparison of the dosed groups with the
controls, for liver tumors in male rats.  Male rats had a significant
increasing trend in hemangiomas at all sites at p < 0.05.   There were
no significant pair-wise comparisons of the dosed groups with the
controls.  

Neither the hemolymphoreticular tumors nor the testicular tumors were
seen in male rats in the chronic study.

Reassessment of Hemolymphoreticular Tumors from All Rats of All Groups

 ADVANCE \d0 	In response to 2001 CARC's conclusion that the data for
histiocytic sarcomas were inadequate due to incomplete histopathological
examination of tissues, BASF evaluated all animals from all groups 
ADVANCE \d0 and submitted amendments to the original chronic toxicity
and carcinogenicity studies (MRIDs 45118329 and 45118331, respectively).
The two amendments are:

 ADVANCE \d0 		Mellert, W. (2002) BAS 500F - Chronic Toxicity Study in
Wistar Rats; Administration in the Diet for 24 Months; Amendment to MR1D
No. 45508601 (which was the first amendment of original study, namely
MRID 45118329). BASF Reg. Doc. No. 2002/1005113, March 25, 2002. MRID
No. 45661703, 440 pages.

 ADVANCE \d0 		Mellert, W. (2002) BAS 500F - Carcinogenicity Study in
Wistar Rats; Administration in the Diet for 24 Months; Amendment to MRID
No. 455118331 (should be 45118331). BASF Reg. Doc. No. 2022 (should be
2002)/1005114, March 25, 2002. MRID No.   45661704, 1144 pages.

 ADVANCE \d0 	After evaluating all males in the low and mid dose groups,
only one additional low dose animal from the carcinogenicity study was
found to have a lymphoma; no additional animals with histiocytic sarcoma
were found. Updated hemolymphoreticular tumor findings are summarized in
Table 10.			

Table 9. Pyraclostrobin - Wistar Rat Carcinogenicity and Chronic Studies
Combined

Male Liver Tumor Rates+ and Exact Trend Test and

 		        Fisher’s Exact Test Results (p values)-Brunsman, 2001

            0 ppm                      25 ppm	                     75
ppm	                200 ppm

Adenomas	   8/70		    9/70		    7/70		  12a/70

   (%)	   (11)		    (13)		    (10)		    (17)

p =        0.1567		   0.5000		   0.5000		  0.2347

Carcinomas   4/70		    5/70		    7b/70		    3/70

   (%)	    (6)		     (7)		    (10)		     (4)

p =        0.3174		   0.5000		   0.2659		  0.5000 

Combined	  12/70		   13/70		   13c/70		   15/70

   (%)	   (17)            (19)		    (19)		    (21)

p =        0.2666		   0.5000		   0.5000		  0.3345 

+Number of tumor bearing animals/Number of animals examined.  The
analysis took into consideration the males that died before week 53. 
However, no deaths occurred during the first year.

aFirst adenoma observed at week 68, dose 200 ppm.

bFirst carcinoma observed at week 78, dose 75 ppm.

cOne animal in the 75 ppm dose group had both an adenoma and a
carcinoma.

Note:	Significance of trend denoted at control; Significance of
pair-wise comparison with control denoted at dose level; If *, then p <
0.05.  If **, then p < 0.01.

 ADVANCE \d0 

Table 10. Combined Incidences of Hemolymphoreticular Tumor Rates from
Carcinogenicity and Chronic Toxicity Studies in Male Wistar Rats

Hemolymphoreticular (HLR) Tumor Rates			Dose (ppm)

0		25		75		200

Males

Carcinogenicity Study (page 37 of MRID# 45661704)

Histiocytic sarcoma				1/50		1/50		2/50		5/50

Lymphoma					0/50		2/50		0/50		1/50

Combined histiocytic sarcoma/lymphoma	1/50		3/50		2/50		6/50

Chronic Toxicity Study (page 50 of MRID# 45661703)

Histiocytic sarcoma				1/20		0/20		1/20		0/20

Lymphoma					1/20		0/20		0/20		0/20

Combined histiocytic sarcoma/lymphoma	2/20		0/20		1/20		0/20

All HLR Tumors from both studies		3/70		3/70		3/70		6/70



Neither trend nor pair-wise tests were significant.

Historical control data submitted showed that the incidence of
hemolymphoreticular tumors in male Wistar rats from 4/93- 7/00 at the
testing laboratory ranged from 0%-10% with a mean of  4%; 9 studies were
included in the analysis (MRID 45429902). 

  Table 11. Pyraclostrobin - Wistar Rat Carcinogenicity and Chronic
Studies Combined

 	       Male Vascular Tumor Rates+ (All Sites) and Exact Trend Test and

 		Fisher’s Exact Test Results (p values)- Brunsman, 2001

            0 ppm                      25 ppm	                     75
ppm	                200 ppm

Hemangiomas  4/70		    2/70		    6/70		   10a/70

   (%)	    (6)		     (3)		     (9)		    (14)

p =        0.0101*		  0.3403		  0.3723		   0.0786

Hemangiosarcomas

 		        6/70		          9/70		         11b/70		           3/70

   (%)	    (9)		    (13)		    (16)		     (4)

p =        0.0946		  0.2930		   0.1504		   0.2466   

Combined	       10/70		          11/70		           17/70		         
13/70

   (%)	   (14)            (16)		    (24)		    (19)

p =        0.2635		  0.5000		   0.0991		   0.3245 

+Number of tumor bearing animals/Number of animals examined.  The
analysis took into consideration the males that died before week 53. 
However, no deaths occurred during the first year.

aFirst adenoma observed at week 68, dose 200 ppm.

bFirst carcinoma observed at week 81, dose 75 ppm.

Note:	Significance of trend denoted at control.

Significance of pair-wise comparison with control denoted at dose level.

If *, then p < 0.05.  If **, then p < 0.01.

Table 12. Pyraclostrobin - Wistar Chbb:THOM(SPF) Rat

Carcinogenicity and Chronic Studies Combined		

Female Mammary Gland Tumor Rates+ and Exact Trend Test

and Fisher’s Exact Test Results (p values)

                                  Dose (ppm)

      0			 25		      75		     200

Adenomas	   0/68		    0/70		    2a/69		     1/68

   (%)	    (0)		     (0)		     (3)		      (1)

p =            0.1987            1.0000            0.2518           
0.5000

Adeno-

 carcinomas    5b/68		    8/70		    7/69		     8/68

   (%)	    (7)		    (11)		    (10)		     (12)

p =            0.2784            0.2999            0.3922           
0.2807

Combined	   5/68		    8/70		    9/69		     9/68

   (%)	    (7)		    (11)		    (13)		     (13)

p =            0.1933            0.2999            0.2074           
0.1991 

Fibro-

 adenomas      15/68		   15/70		   11/69		    18c/68

   (%)	   (22)		    (21)		    (16)		     (26)

p =            0.2307            0.5461            0.2437           
0.3448 



+Number of tumor bearing animals/Number of animals examined, excluding
those that died before week 53.

aFirst adenoma observed at week 105, dose 75 ppm.

bFirst carcinoma observed at week 85, dose 0 ppm.

cFirst fibroadenoma observed at week 68, dose 200 ppm.

Note:	Significance of trend denoted at control.

Significance of pair-wise comparison with control denoted at dose level.

If *, then p < 0.05.  If **, then p < 0.01.

B. Adequacy of the Dosing - Rats tc \l3 "B. Adequacy of the Dosing -
Rats 

A 3-month feeding study was used as the basis for dose selection in both
the carcinogenicity and chronic toxicity rat studies.  In this
subchronic oral study (MRID 45118321), pyraclostrobin (BAS 500F; 98.5%
a.i) was administered in the diet to 10 Wistar rats/sex/group at doses
of 0, 50, 150, 500, 1000, or 1500 ppm (equivalent to 0, 3.5/4.2,
10.7/12.6, 34.7/40.8, 68.8/79.7, and 105.8/118.9 mg/kg/day for
males/females) for 3 months.

There were no treatment-related findings at 50 ppm, and the only
findings noted at 150 ppm was extramedullary hematopoiesis in the spleen
of females (3/10 vs 0/10 controls).  However, because the finding in the
spleen was not corroborated by hematology changes at the same dose, they
are not considered to be of toxicological relevance.

Terminal body weights (-7%) and overall (day 91) body weight gains
(-11%) were decreased in males in the 500 ppm group.  At 1000 and 1500
ppm, body weights (-12-26%) and body weight gains (-23-75%) were
decreased throughout treatment in males.  Additionally at 1500 ppm, body
weights (-8-9%) and body weight gains (-16-65%) were decreased in
females. Body weights were decreased in the 1500 ppm females (-8-9%) on
study days 7, 14, and 91.  Food consumption was decreased intermittently
throughout treatment in both sexes (-6-17%) in the 500 ppm group.  In
the 1000 and 1500 ppm groups, food consumption was decreased (-9-46%) in
both sexes throughout the study.  Several clinical chemistry parameters
differed from controls and reflected the continual catabolic state
associated with the reduced nutritional status in these animals.  For
example, in the 500 ppm group, cholesterol was decreased (-19%) in
males, and alkaline phosphatase was decreased  (-14%) in females.  In
the 1000 and 1500 ppm groups, alkaline phosphatase (-14-23%) and
globulins (-8-13%) were decreased in both sexes.   Triglycerides
(-50-61%) and cholesterol (-26-29%) were decreased in males and total
bilirubin was increased (+58-95%) in males.  Serum cholinesterase was
decreased in the 1000 (-41%) and 1500 (-49%) females.  [In addition, at
1500 ppm total bilirubin was increased (+35%) in females.]  

The liver, spleen, and duodenum were the target organs of toxicity.  
Absolute (+16-58%) and relative (+22-74%) spleen weights were increased
in the females and/or males at doses of 500 ppm and greater.  Relative
liver weight was increased in the females 1000 and 1500 ppm groups 
(+14-34%).  Absolute weights of the liver in females in the 1500 ppm
group were increased (+22%).  

Several hematological findings corroborated these effects on the spleen,
including mild hemolytic anemia which was evidenced by increased
reticulocytes in the 1000 ppm males and in the 1500 ppm animals
(+41-94%), and decreased erythrocytes in the 1000 and 1500 ppm females
(-7-11%).  Likewise, gross and microscopic spleen changes, including
spleen discoloration       (2-11/20 vs 0/20 controls), sinus distension
(18/20 vs 0/20 controls), extramedullary hematopoiesis (9/10 females vs
0/10 controls), and histiocytosis (13-17/20 vs 0/20 controls)
corroborated a toxic effect on the spleen, consistent with the
hematology.

Dose-related increases in minimal to slight hepatocyte hypertrophy, 
predominantly in zone 3, were observed in the 500 (3/10 vs 0/10
controls) and 1000 ppm males (6/10 vs 0/10 controls) and in the 1500 ppm
animals (4-10/20 vs 0/20 controls).  Dose-related thickening of the
duodenal wall was observed macroscopically in the 1000 ppm females (2/10
vs 0/10 controls) and in the 1500 ppm animals (20/20 vs 0/20 controls). 
Microscopically, dose-related increases were observed in the incidences
of hyperplasia in the duodenal mucosa in the 500 (4/10 vs 2/10 controls)
and 1000 ppm males (5/10 vs 2/10 controls) and in the 1500 ppm animals
(20/20 vs 4/20 controls).

The LOAEL is 500 ppm (equivalent to 34.7/40.8 mg/kg/day for
males/females) based on decreased body weights/body weight gains
(males), decreased food consumption, increased relative liver weight and
absolute and relative spleen weight in females, and histopathology of
the duodenum, spleen and liver.  The NOAEL for this study is 150 ppm
(equivalent to 10.7/12.6 mg/kg/day for males/females). 

Based upon the results of this 3-month study, the doses of 25, 75 and
200 ppm were selected for the chronic toxicity/carcinogenicity study.
The high dose for the carcinogenicity and chronic toxicity studies was
set at 200 ppm both for males and females. In the rat carcinogenicity
study, there was no adverse effect on survival observed for either sex.
All dose groups and controls had (65% survival at study termination.

Males:  At the October 2001 meeting, the CARC concluded that the dosing
in males at 200 ppm approached the adequate level because in males there
were some toxicological changes including a minimal decrease of 10% body
weight gain in addition to increased incidence of liver necrosis.  The
top dose of 200 ppm seems to yield some toxicological changes including
a minimal body weight decrement in males of up to 7% and a minimal
decrease of up to 10% body weight gain in addition to non-neoplastic
pathology changes (Table 5).  The increased incidence of hepatocyte
necrosis was noted in males at 200 ppm (20%) and the increased incidence
exceeded the historical control range (2%-16%) provided by the
Registrant (BASF, 2001).  

Re-evaluation of the Adequacy of Dosing in Female Rats

 ADVANCE \d0 

At the October 2001 meeting, the CARC concluded that the dosing in
female rats was “inadequate” since no significant toxicity was noted
at the highest dose.  In their rebuttal of dosing adequacy, the
Registrant disclosed (and provided data) that rats were also
concurrently tested at higher doses, namely, 400 ppm in males and at 400
and 600 ppm in females with their own control groups.  However, all
groups in this study were terminated after one year into the study
because these doses were considered excessive based on >10% decrease in
body weight gain (BWG); i.e., an MTD was exceeded from BASF's
perspective. No other findings of toxicity/mortality were seen.

 ADVANCE \d0 The Registrant also submitted several documents in which
data on BWG and food efficiency (FE) from the guideline chronic and
carcinogenicity studies were re-analyzed after pooling the animals from
the two rat studies to "enhance the statistical power" and pooling the
data across selected study intervals to "smooth out fluctuations at any
time period."

 ADVANCE \d0 In order to independently verify the findings of the new
studies including statistical manipulations and BWG/FE findings, RAB3
initiated a contract review with Oak ridge to examine the statistical
methods, the validity of combining the rat carcinogenicity and chronic
toxicity studies, and the findings of the supplementary studies with the
higher dose groups of 400 and 600 ppm.  The results of these evaluations
are summarized in the report entitled “ ADVANCE \d0 Statistical
Analysis of Body weight and Food Consumption Data from Chronic Toxicity
and Carcinogenicity Feeding Studies in Rats” (prepared by Oak Ridge
National Laboratory) (TXR No. 0051615).

Upon reevaluation at the September 10, 2003 meeting, the CARC concluded
that female rats were tested adequately at the top dose of 200 ppm. 
There was a statistically significant decrease in cumulative body weight
gain compared to controls across study intervals from Day 147 to study
termination in the 200 ppm group females.  No effects on body weight
gain were seen prior to Day 147. Cumulative body weight gain was
decreased 6% at Day 0-147 and 19% at the end of the study (Day 0-728). 
For females in the 400 ppm and 600 ppm dose groups, more consistent
decreases in cumulative body weight gain were observed early in the
study, from 0-91 days (-8%, 400 ppm; -10%, 600 ppm) and throughout the
whole study, from 0-399 days (-21%, 400 ppm; -24%,600 ppm). 
Statistically significant decreases in cumulative food efficiency values
(up to -16-17%) across these study intervals were consistent with
decreases in cumulative body weight gain at 200 ppm, 400 ppm, and 600
ppm.  The decreases in food efficiency showed that the deficits in body
weight gain in females were due to the toxicity of the test material and
not reductions in food consumption.

In the subchronic rat study, effects in males and females at 500 ppm
included decreased body weight gain in males (-11%), decreased food
consumption (-6-17%) in both sexes, decreased cholesterol (-19%) in
males and alkaline phosphatase in females (-14%), increased absolute and
relative spleen weights, increased relative liver weight, and
histopathology of the duodenum, spleen and liver. It is reasonable to
assume that the toxicity seen in the subchronic study at 500 ppm would
be more adverse in a chronic study.  Thus, based on the more severe
decreases in body weight gain (-21-24%) and food efficiency (-16-17%)
seen during Day 0-399 at 400 and 600 ppm in the main study which are
supported by the effects seen at 500 ppm in the subchronic study, it is
evident that the female rats may not have tolerated a dose higher than
200 ppm.  Therefore, the CARC concluded that the dose of 200 ppm chosen
for the chronic toxicity and carcinogenicity studies was reasonable and
adequate.

4. Carcinogenicity Study in Mice tc \l2 "4. Carcinogenicity Study in
Mice 

Reference:  Mellert, W., Deckardt, K., Küttler, et.al. (1999) BAS 500F
- Carcinogenicity Study in B6C3F1 Mice Administration in the Diet for 18
Months.  BASF Aktiengesellschaft, Department of Toxicology,
Ludwigshafen, Germany.  Laboratory Project Id.: 76C0494/96101, November
22, 1999.  MRID 45118330.  Unpublished.

A. Experimental Design tc \l3 "A. Experimental Design 

Pyraclostrobin  (97.09% a.i.,  Lot/Batch # J.-Nr. 27882/191/c) was
administered in the diet to B6C3F1/CrlBR mice (50/sex/group) for up to
80 weeks at nominal doses of 0, 10, 30 or 120 ppm in males and 0, 10,
30, 120, or 180 ppm in females, equivalent to 0/0, 1.4/1.6, 4.1/4.8,
17.2/20.5, and 32.8 (females only) mg/kg/day [M/F], respectively).  

B. Discussion of Tumor Data tc \l3 "B. Discussion of Tumor Data 

No treatment-related neoplastic changes were observed.

C. Non-neoplastic Lesions tc \l3 "C. Non-neoplastic Lesions 

No treatment-related non-neoplastic changes were observed.

D. Adequacy of Dosing - Mice tc \l3 "D. Adequacy of Dosing - Mice 

The doses chosen for the current study were based on the results of a
3-month study (MRID 45118320) in which pyraclostrobin was administered
in the diet to 10 B6C3F1 Crl BR mice/sex/group at nominal doses of 0,
50, 150, 500, 1000, or 1500 (equivalent to 0, 9.2/12.9, 30.4/40.4,
119.4/162.0, 274.4/374.1, 475.5/634.8 mg/kg/day for the males/females)
for 3 months.  No treatment-related differences were observed in
mortality, clinical signs, or organ weight data.  At 150 ppm, body
weights and body weight gains were decreased (p(0.05 or 0.01) in the
males throughout treatment.  Body weights gains were decreased in the
females at study day 77.  Urea was increased (p(0.02 or 0.002) and
triglycerides were decreased ( p(0.05 or 0.02) in both males and
females.  Ulcer/erosion of the glandular stomach was observed in the
males and females.  Increased apoptosis was observed in the mesenteric
lymph nodes in the females (2/10 treated vs 0/10 controls).  At doses
(500 ppm, body weights and body weight gains were decreased (p(0.05 or
0.01) throughout treatment.  Food efficiency was decreased (p(0.01)
throughout treatment in the males and during the first three weeks in
the females.  Decreases (p(0.05) were observed in mean corpuscular
volume in the males and mean corpuscular hemoglobin in the females. 
Increased urea (p(0.002) and decreased triglycerides ( p(0.002) were
observed in both sexes. Decreased globulin (p(0.02 or 0.002) and
increased cholesterol (p(0.02) were observed in the females. 
Ulcer/erosion of the glandular stomach was observed both macroscopically
in the males and microscopically in the males and females.  Thickening
of the duodenal wall was observed both macroscopically and
microscopically in the males and females.  Increased apoptosis was
observed in the mesenteric lymph nodes in the males and females (5-16/20
treated vs 0/20 controls).  Atrophy of the thymus was observed in the
males (3-8/10 treated vs 0/10 controls).  At doses (1000, food
consumption was intermittently increased (p(0.05 or 0.01) throughout
treatment in the males and females.  Leukocytes and mean corpuscular
hemoglobin were decreased (p(0.05 or 0.002) in the males, and creatinine
and hemoglobin were decreased (p(0.05 or 0.02) in the females.  At 1500
ppm, hemoglobin was decreased (p(0.002) in the males, and platelets were
increased (p(0.02) in both sexes.  Discoloration of the jejunum (2/10
treated) and colon (1/10 treated) were observed in the males (vs 0/10
controls each), and focal necrosis of the liver was observed in the
females (1/10 treated vs 0/10 controls).  The LOAEL for this study was
150 ppm for both sexes and the NOAEL was 50 ppm.

Based upon the results of this 3-month study, the doses for the
carcinogenicity study were set at 10, 30, 120 (males and females) and
180 ppm in females.

Males:  At the October 2001 meeting, the CARC determined that the
highest dose tested was adequate for male mice based on decrease in body
weight gain (20%) at 13 weeks of the 80 week study  which was supported
by the results of a 90-day range-finding study.

Re-evaluation of the Adequacy of Dosing in Female Mice:  At the October
2001 meeting, the CARC decided that “in the mouse carcinogenicity
study with pyraclostrobin, dosing at the highest dose was not adequate
for female mice because of the absence of significant toxicological
effects”.  Subsequently, the Registrant, in their rebuttal to the 2001
CARC report, presented further evaluation of the body weight, food
consumption, and food efficiency data (MRID 45661702) which were
reviewed at the present CARC meeting.

Upon reevaluation at the September 2003 meeting, the CARC concluded that
dosing at the high dose of 180 ppm for female mice was not adequate. 
This conclusion was based on the fact that, because of the variability
in the data, there was no consistent pattern (between cumulative and
discrete intervals) of changes in body weight, body weight gain, food
consumption, and food efficiency to support that an adequate dose had
been reached for female mice.  Although there were statistically
significant decreases in body weight gain (-15%, Day 0-119; -21%, Day
0-259; -26% , Day 0-546) and food efficiency (-17%, Day 0-119; -21%, Day
0-259; -23%, Day 0-546) at 180 ppm during cumulative periods, the data
are inconsistent when compared to discrete intervals for body weight
gain and food efficiency, where no consistent pattern was seen.  For
example, the variability of the pattern can be seen in the increases
and/or decreases in body weight gain/food efficiency at 180 ppm for the
following discrete intervals (-22%/-22%, Day 92-175; -41%/-40%, Day
176-259; +193%/+187%, Day 260-343; -223%/-235%, Day 428-511).   In
addition, the magnitude of these effects was not clearly dose-related. 
For example, the cumulative decreases in body weight gain at 10 ppm
(-8.25% from Day 0-119; -17% from Day 0-546) were more pronounced than
those occurring at 30 ppm (+8% from Day 0-119; -12% from Day 0-546).  In
addition, the effects occurring in the 90-day study do not support
selection of the top dose of 180 ppm.  Only very minor changes in
clinical chemistry and pathology were seen in females in the 90-day
study at 150 ppm.  More pronounced effects on body weight (-6-13%), body
weight gain (-39-74%), and changes in clinical chemistry and pathology
occurred at 500 ppm in the subchronic study, indicating that the doses
in the main study could have been higher.

IV.	TOXICOLOGY tc \l1 "IV.	TOXICOLOGY 

1. Metabolism tc \l2 "1. Metabolism  

Based on pharmacokinetics/metabolism studies in the rat, at least
34.5-37.7% of an orally administered low- or high-dose (5 or 50 mg/kg)
or repeated doses of pyraclostrobin was absorbed.  Regardless of sex,
dose, radiolabel (14C-tolyl or 14C-chlorophenyl) or pretreatment,
urinary excretion accounted for 10.8-16.0% of the administered dose,
with the majority of urinary excretion occurring within 24 hours.  Fecal
excretion accounted for nearly 85% of an administered dose of which
nearly 30% was from biliary excretion.   Plasma concentrations were
highest in all groups at 0.5-1 hours and 8 hours (two peaks); males had
lower plasma concentrations than females ((16-38%) during the earlier
time points.  Elimination was biphasic at the low dose with plasma half
lives of nearly10/35 hours and monophasic at the high dose with a half
life of nearly 20 hours.  The distribution pattern of radioactivity in
tissues was similar between sexes (typically higher among females)
reaching peak levels at 0.5 hours post-dosing; some of the highest
concentrations were found in the liver, thyroid, kidney, lung, adrenal
glands, and pancreas. There was no evidence of tissue accumulation since
levels at 42-72 hours dropped greater than 20-fold relative to the
earliest measurement at 0.5 hour.  Nearly  33 metabolites were isolated
and identified in the urine, feces, and bile; there were no sex- or
dose-related differences in the metabolite profile in urine or feces but
the position of the label seemed to alter the profile, particularly in
the urine.  The metabolic pathway included phase-I reactions such as
N-demethoxylation, various hydroxylations, and cleavage of the ether
bond with subsequent oxidation; these were followed by the phase II
glucuronidation and sulfation reactions. 

2. Mutagenicity tc \l2 "2. Mutagenicity 

According to several FIFRA guideline tests, pyraclostrobin has no
mutagenic or clastogenic properties and no effect on DNA repair in in
vitro bacterial or mammalian cells or in vivo in whole animals.  The
submitted test battery satisfies the new mutagenicity initial testing
battery guidelines.  No other genetic toxicology data requirements have
been identified at this time.

(i)  In a  reverse gene mutation assay in bacteria (MRID 45118332),
strains, TA98, TA100, TA1535 and TA1537 of  S. typhimurium and strain
WP2 uvrA of  E. coli were exposed to BAS 500F (Batch No. 026063, 98.2%
a.i.)  dissolved in dimethylsulfoxide (DMSO), at concentrations of  0,
20, 100, 500, 2500 and 5000 µg/plate in the presence and absence of an
Aroclor 1254-stimulated rat liver metabolic activation system using the
standard plate test.   A second assay was conducted at the same
concentrations using the preincubation test.  

BAS 500F was tested up to precipitating concentrations (> 2500 µ
g/plate, + S9).  The positive controls induced the appropriate responses
in the corresponding strains.   There was no evidence of 
treatment-induced mutant colonies above background levels.

(ii)  In a mammalian cell gene mutation assay (MRID 45118335), Chinese
hamster ovary (CHO) cells cultured in vitro were exposed to BAS 500 F
[Batch No. CP026063], purity 98.2%  a.i., dissolved in DMSO, at
concentrations of  0.625, 1.25, 2.5, 5.0, 10.0 and 20.0  µg/mL in the
presence and absence of an Aroclor 1254-stimulated rat liver metabolic
activation system .  A second experiment was conducted in the absence of
an Aroclor 1254-stimulated rat liver metabolic activation system
metabolic activation only at concentrations of  3, 4, 5, 6, 7 and 8
µg/mL.  A third experiment tested concentrations of  1.25, 2.5, 5.0,
10.0 and 20.0 µg/mL, both in the presence and absence of metabolic
activation.  

BAS 500 F was tested up to cytotoxic and solubility limit (> 5 µ
g/mL-S9; >50  µ g/mL +S9).  The positive controls induced the
appropriate response.  There was no evidence of induced mutant colonies
over background. 

(iii) In a mammalian cell cytogenetics chromosomal aberration assay
(MRID 45118333), V79 cell cultures were exposed to BAS 500 F [Batch No.
026063], purity 98.2%, dissolved in dimethylsulfoxide (DMSO), at
concentrations of  0.0, 6.25, 12.5 and 25.0 µg/mL in the presence and
absence of an Aroclor 1254-stimulated rat liver metabolic activation
system.   A second assay was conducted at concentrations of  0, 3.125,
6.25 and 12.5 µg/mL in the presence of metabolic activation, and
concentrations of  0, 0.005, 0.010, 0.050 and 0.100 µg/mL in the
absence of metabolic activation.  

BAS 500 F was tested up to precipitating concentrations (> 50 µg/mL).  
Positive controls induced the appropriate response.  There was no
evidence of an increase in the number of  structural or numerical
chromosomal aberrations induced over background.   It is, therefore,
concluded that BAS 500 F is not a clastogenic agent under the conditions
of this study.       

(iv)  In a mouse bone marrow micronucleus assay (MRID 45118334), NMRI
mice were dosed once by oral gavage with BAS 500 F [Batch No. CP026063],
purity 98.2% at doses of  0 (vehicle control) and 300 mg/kg bw, 10 per
sex per group  and 75 and 150 mg/kg bw, 5 per sex per group.  Bone
marrow cells were harvested at 24 hours post-treatment, 5 per sex per
group, at all dose levels, and at 48 hours post-treatment, 5 per sex 
per group in the 0 and 300 mg/kg bw groups.   The vehicle was olive oil.
 Preliminary dose selection assay showed that the levels  >  400 mg/kg
were lethal.  

One male in the 300 mg/kg bw group died on study day 2.  Clinical signs
of  toxicity included piloerection and squatting posture in all dose
group ~ 30 minutes post-dosing, with complete recovery within 24 hours. 
There was no evidence of  target cell cytotoxicity.  The positive
controls induced the appropriate responses.  There was no significant
increase in the frequency of micronucleated polychromatic erythrocytes
in bone marrow at any dose level tested, at any time after  treatment. 
It is therefore concluded that BAS 500 F did not induce a clastogenic or
aneugenic effect in either sex at any sacrifice time.

(v)  In an unscheduled DNA synthesis assay (MRID 45118336), primary rat
hepatocyte cultures were exposed to BAS 500 F (Batch No. CP026063),
purity 98.2% a.i., dissolved and diluted in DMSO [dimethylsulfoxide] at
concentrations of  0.01, 0.03, 0.1, 0.3 and 1.0 µg/mL for 18 hours.  A
second experiment was conducted at concentrations of  0.004, 0.02, and
0.5 µg/mL.  

BAS 500 F was tested up to cytotoxic concentrations (> 0.3  µ g/ML). 
The positive controls induced the appropriate response.   There was no
evidence that BAS 500 F induced unscheduled DNA synthesis, as determined
by net nuclear silver grain counts.

3. Structure-Activity Relationship tc \l2 "3. Structure-Activity
Relationship  

Azoxystrobin (CAS No. 131860-33-8, PC Code 128810):

		

In accordance with the 1996 Cancer Risk Assessment Guidelines, the
HED-RfD/Peer Review Committee classified azoxystrobin as “not
likely” to be carcinogenic to humans via relevant routes of exposure
based on the lack of evidence of carcinogenicity in mice or rats
(RfD/Peer Review Report dated 1/14/97, HED Doc. No. 012133). 
Treatment-related increases in tumor incidence were not seen after 104
weeks of dietary feeding in mice at 0, 50, 300, or 2000 ppm (MRID
43678141) or in rats at 0, 60, 300, or 750/1500 ppm (males/females)
(MRID 43678139).  

Azoxystrobin was negative in an Ames reverse-mutation assay (MRID
43678146), in a bone marrow micronucleus assay in C57BL/6JfBL10/Alpk
mice (MRID No. 43678148), and in an in vivo/in vitro unscheduled DNA
synthesis assay in Alderley Park rat hepatocytes (MRID No. 43678149). 
However, azoxystrobin was positive in a mouse lymphoma L5178Y TK+/-
forward gene mutation assay (MRID 43678145) and in an in vitro
chromosome aberrations test in human lymphocytes (MRID 43678147).  The
following assessment is from the RfD/Peer Review Report (dated 1/14/97,
HED Doc. No. 012133). 

“The [RfD/Peer Review] Committee overall concluded that Azoxystrobin
in the presence and absence of exogenous metabolic activation induced a
weak mutagenic response in the mouse lymphoma assay.  Although colony
sizing was not performed in the mouse lymphoma assay, it is likely that
the increased MFs seen in this study were associated with a chromosomal
rather than point mutational event.  This interpretation is based on the
similarity of the response uncovered in the mouse lymphoma assay to the
clastogenic response seen with and without S9 activation in human
lymphocytes. However, the negative genotoxicity associated with bone
marrow cytotoxicity in the micronucleus assay provides confidence that
Azoxystrobin is not an in vivo clastogen and aneugen.  This assumption
is further supported by the negative findings of the UDS assay, the lack
of an oncogenic effect in rat or mouse long-term feeding studies and the
absence of significant reproductive or developmental toxicity
attributable to a mutagenic mode of action (i.e., decreased total
implants, increased resorptions).  Hence, it can be concluded that
Azoxystrobin is active in vitro but this genotoxicity is not expressed
in whole animals.

The submitted test battery satisfies the new  mutagenicity initial
testing battery guidelines.  No other genetic toxicology data
requirements have been identified at this time.”	

Trifloxystrobin (CAS No. 141517-21-7, PC Code 128810):

 

Trifloxystrobin was classified by an ad hoc subcommittee of the Cancer
Assessment Review Committee on May 27, 1999 (CARC Report, 6/15/99, TXR
No. 0013433).  The Committee determined that trifloxystrobin should be
classified as a  “Not Likely to be Carcinogenic to Humans.”  The ad
hoc subcommittee concluded that:	

1.	The rat chronic/carcinogenicity study was negative.

2.	Trifloxystrobin was not structurally related to any class of known
carcinogens.

3. 	Trifloxystrobin was positive in one mutagenicity study (Chinese
hamster V79 		fibroblasts), but negative in 7 other mutagenicity
studies.

4.	In the mouse carcinogenicity study, malignant lymphoma was not
statistically significantly increased in males or females at any dose
level. The incidence of malignant lymphoma in the trifloxystrobin
treated groups (2%, 6%, 4%, 8% and 8% in males and 10%, 18%, 18%, 8%,
and 22% in females, at 0, 30, 300, 1000 and 2000 ppm, respectively) was
well within the range for malignant lymphoma in the historical control
groups (range: 2%-9.4% for males and 10%-36.5% for females) and no
dose-response was evident.  In addition, the concurrent control group
had incidence of malignant lymphoma (2% in males and 10% in females)
which was closer to the lower end of the historical control range (Refer
to attachment for details).  Dosing was considered to be adequate based
on decreases in body weight gain and liver pathology in both sexes.

4.  Subchronic, and Chronic Toxicity tc \l2 "4.  Subchronic, and Chronic
Toxicity 

a) Subchronic Toxicity	

Based on findings in repeated dosing oral studies in more than one
species, the main target organs for pyraclostrobin are the upper
gastrointestinal tract (mainly the duodenum and stomach), the
spleen/hematopoiesis, the immune system, and the liver.  In the 90-day
dietary rat, mouse, and dog studies, one or more of the following GI
changes were noted: thickening of the duodenal wall, duodenum mucosal
hypertrophy or hyperplasia, as well as gross and microscopic
ulceration/erosion in the glandular stomach.  Mucosal hyperplasia in the
duodenum was also observed in rats of both sexes after 28-day
administration of 500 and 1500 ppm Pyraclostrobin. 

Rat

 	In the subchronic oral study (MRIDs 45118321 & 45118322), 
pyraclostrobin (BAS 500F; 98.5% a.i.; Lot/Batch # CP 025394) was
administered in the diet to 10 Wistar rats/sex/group at doses of 0, 50,
150, 500, 1000, or 1500 ppm (equivalent to 0, 3.5/4.2, 10.7/12.6,
34.7/40.8, 68.8/79.7, and 105.8/118.9 mg/kg/day for males/females) for 3
months.

The results are summarized on p. 7-9.  The LOAEL is 500 ppm (equivalent
to 34.7/40.8 mg/kg/day for males/females) based on decreased body
weights/body weight gains (males), decreased food consumption, increased
relative liver weight and absolute and relative spleen weight in
females, and histopathology of the duodenum, spleen and liver.  The
NOAEL is 150 ppm (equivalent to 10.7/12.6 mg/kg/day for males/females). 

Mouse

In the subchronic oral study (MRID 45118320), pyraclostrobin (BAS 500F;
98.5% a.i.; Lot/Batch # CP 025394) was administered in the diet to 10
B6C3F1 Crl BR mice/sex/group at nominal doses of 0, 50, 150, 500, 1000,
or 1500 ppm (equivalent to 0, 9.2/12.9, 30.4/40.4, 119.4/162.0,
274.4/374.1, 475.5/634.8 mg/kg/day for the males/females) for 3 months. 

 

The results of these are summarized on p. 7-9.  The LOAEL is 150 ppm
(equivalent to 30.4 and 40.4 mg/kg/day for males and females,
respectively) based on changes in body weight and body weight gains in
the males and changes in clinical chemistry and microscopic pathology in
both sexes.  The NOAEL is 50 ppm (equivalent to 9.2 and 12.9 mg/kg/day
for males and females, respectively). 

Dog

In a subchronic toxicity study in dogs (MRID 45118323), BAS 500 F
(97.09%), was administered to 5 beagles/sex/dose in the diet at dose
levels of 0, 100, 200 and 450 ppm (equal to 0, 2.8, 5.8 and 12.9 mg/kg
bw/day for males, and 0, 3.0, 6.2 and 13.6 mg/kg bw/day for females) for
a 90-day period. 

No treatment-related deaths were observed at any dose level.  All
animals in the 450 ppm group vomited for the first 1 to 3 weeks, which
was considered to be a transient aversion to the test material.  In
addition, all animals in the high dose group had diarrhea throughout the
study period. A slight increase in the incidence of diarrhea (males: 2/5
during week 5; 4/5 females from week  4-11) noted in the 200 ppm group
was not considered to be toxicologically significant because of its
scattered/isolated occurrence. Decreased food intake (-9%), a net loss
in body weight (-12%) and decreased food efficiency (-110%) were seen 
in the 450 ppm group, females only. Clinical chemistry findings included
a slight decrease in total protein, albumin, globulin (all three
parameters in both sexes ranged from -7% to -12%) and glucose (only in
females it ranged from -9.4 % to -13%) at 450 ppm. These findings are
considered to reflect a trend towards lower values indicative of a
marginal treatment-related effect. Gross and histopathological
examination revealed mucosal hypertrophy (males: 2/5 and females: 1/5)
of the duodenum in the 450 ppm group, both sexes.  The digestive system
is the main target of pyraclostrobin toxicity.  Microscopically, the
target site was the duodenum.  Females seem to be more sensitive than
males. 

The LOAEL is 450 ppm (equal to 12.9 mg/kg bw/day for males and 13.6
mg/kg bw/day for females), based on an increased incidence of diarrhea,
clinical chemistry changes and mucosal hypertrophy of the duodenum (both
sexes) and body weight loss, decreased food intake and decreased food
efficiency (females only). The NOAEL is 200 ppm (equal to 5.8 mg/kg
bw/day for males and 6.2 mg/kg bw/day for females).

b) Chronic Toxicity

Rat

Details of the study design, including dosing regimens, and findings are
covered above under section III-1, 2 (MRIDs 45118331, 45118329). 

Rat Carcinogenicity

When all animals were combined, including those sacrificed on schedule
and those found dead or sacrificed in extremis, increased incidences (#
animals/50) of the following findings were observed:  (i) vascular
mineralization of the lungs in the 75 and 200 ppm females (11 and 13
treated, respectively vs 8 controls); (ii) in the kidney of the 200 ppm
males, tubular casts (15 treated vs 5 controls) and tubular atrophy (16
treated vs 5 controls) and in the females tubular casts (10,13,14 and 14
in control, 25, 75, and 200 ppm groups, respectively) and tubular
atrophy (19 in the 200 ppm group and 12 in control and other two treated
groups); (iii) in the 200 ppm males, testicular tubular necrosis (2
treated vs 0 controls), tubular mineralization (13 treated vs 5
controls) and oligospermia in the epididymides (16 treated vs 8
controls); and (iv) in the 200 ppm females, sciatic nerve
radiculoneuropathy (25 treated vs 18 controls). 

When all animals were combined (n=50), an increased incidence of
acanthosis (6 treated vs 0 controls) and ulcers (4 treated vs 2
controls) of the forestomach was observed in the 200 ppm males (Table
5).  The majority of these findings occurred in those found dead or
sacrificed in extremis (acanthosis; 5 treated vs 0 controls, ulcers; 3
treated vs 2 controls).  Also observed in the 200 ppm males were erosion
of the glandular stomach (10 treated vs 2 controls) and stomach ulcers
(7 treated vs 2 controls).  In the decedents, erosion (8 treated vs 1
control) and ulcers (6 treated vs 2 controls) were observed. 
Additionally, the following lesions were observed in the liver of the
control, 25, 75 and 200 ppm males (n=50):(i) congestion (9, 5, 7, and
12, respectively); (ii) vacuolated foci (3,10, 10 and 9, respectively);
(iii) clear cell foci (13, 20, 16 and 17, respectively); and (iv)
necrosis (1, 2, 2 and 10 in control, 25, 75, and 200 ppm groups,
respectively).

Rat Chronic

No treatment related effects were seen in any of the measured
parameters.

Mouse

Details of the study design, including dosing regimens, and findings are
covered above under section III-4 (MRID 45118330). 

In the mouse carcinogenicity study, among all treated male and female
groups, there were statistically significant decreased mean body weights
((4-13%) and body weight gains (4-28%, excluding week 1).  However, the
magnitude of these effects was not clearly dose-related despite the fact
that, during the study period, these effects were more consistently
observed among the high dose animals than among the mid- or low dose
mice.  The CARC determined that the highest dose tested was adequate for
male mice based on decrease in body weight gain (20%) at 13 weeks of  80
week study  which was supported by the results of a 90-day range-finding
study.  The CARC, however, concluded that  the dosing for female mice
was  inadequate based on the absence of pharmacological or toxicological
effects even at the highest dose tested.

5. Mode of Action Studies tc \l2 "5. Mode of Action Studies 

No studies were available.

V.  COMMITTEE’S ASSESSMENT OF THE WEIGHT-OF-THE-EVIDENCE tc \l1 "V. 
COMMITTEE’S ASSESSMENT OF THE WEIGHT-OF-THE-EVIDENCE  

Carcinogenicity  tc \l2 "Carcinogenicity  

The CARC concluded that the available data were inadequate to make the
determination of the carcinogenic potential of pyraclostrobin in B6C3F1
mice. The Committee recommended that the study in female mice be
repeated at adequate dose levels based on the following findings:

Upon reevaluation at the September 2003 meeting, the CARC concluded that
dosing at the high dose of 180 ppm for female mice was not adequate. 
This conclusion was based on the fact that, because of the variability
in the data, there was no consistent pattern (between cumulative and
discrete intervals) of changes in body weight, body weight gain, food
consumption, and food efficiency to support that an adequate dose had
been reached for female mice.  Although there were statistically
significant decreases in body weight gain (-15%, Day 0-119; -21%, Day
0-259; -26% , Day 0-546) and food efficiency (-17%, Day 0-119; -21%, Day
0-259; -23%, Day 0-546) at 180 ppm during cumulative periods, the data
are inconsistent when compared to discrete intervals for body weight
gain and food efficiency, where no consistent pattern was seen.  For
example, the variability of the pattern can be seen in the increases
and/or decreases in body weight gain/food efficiency at 180 ppm for the
following discrete intervals (-22%/   -22%, Day 92-175; -41%/-40%, Day
176-259; +193%/+187%, Day 260-343; -223%/       -235%, Day 428-511).  
In addition, the magnitude of these effects was not clearly
dose-related.  For example, the cumulative decreases in body weight gain
at 10 ppm (-8.25% from Day 0-119; -17% from Day 0-546) were more
pronounced than those occurring at 30 ppm (+8% from Day 0-119; -12% from
Day 0-546).  In addition, the effects occurring in the 90-day study do
not support selection of the top dose of 180 ppm.  Only very minor
changes in clinical chemistry and pathology were seen in females in the
90-day study at 150 ppm.  More pronounced effects on body weight
(-6-13%), body weight gain (-39-74%), and changes in clinical chemistry
and pathology occurred at 500 ppm in the subchronic study, indicating
that the doses in the main study could have been higher.

The CARC further concluded the following: 

The combined results of carcinogenicity and chronic toxicity studies
showed that there was no statistically significant increase in liver
tumors in male rats and mammary tumors  in female rats.  No
dose-response was evident for either liver or mammary tumors and
progression to malignancy was not noted for liver tumors. For males,
there was only a statistically significant increasing trend (p<0.05) for
hemangiomas.  However the incidences of hemangiomas (10/70, 14%),
hemangiosarcomas (3/70, 4%) and combined hemangiomas/hemangiosarcomas
(13/70, 19%) at 200 ppm were within their respective historical control
ranges (2%-20%, 0%-15% and 2%-25%, respectively).  The CARC determined
that the hemangiomas do not progress to hemangiosarcomas in rats and 
concluded that these vascular tumors were not treatment-related.  The
CARC also concluded that the mammary gland tumors were not
treatment-related.

In the carcinogenicity study, there was no statistically significant or
dose-related increase in Leydig cell tumors of the testes in male rats. 
Although the incidences in all dose groups (25/50, 50%; 24/50, 48%;
35/50, 50% at 25, 75 and 200 ppm, respectively) were higher than the
control (9/50, 38%), no dose-response was evident and the tumors
incidence at the highest dose (25/50, 50%)  was within the historical
control range (30%-60%).  The CARC noted that testicular tumors were not
seen in male rats in the chronic study.  The CARC determined that these
tumors were not treatment-related. 

Reassessment of the hemolymphoreticular (HLR) tumors in rats: The
statistical analyses of the tumor data from the combined results of
carcinogenicity and chronic toxicity studies showed neither a
significant increasing trend nor a significant difference in the
pair-wise comparison of the dosed groups with the controls, for all
combined histiocytic sarcoma/lymphoma from both the chronic and
carcinogenicity studies.  In addition, the HLR tumor incidence was
within the historical control range.  Therefore, the CARC did not
consider these tumors to be treatment related.

Adequacy of Dosing in Rats: Males:  The CARC considered that the dosing
in males at 200 ppm approached the adequate level because in males there
were some toxicological changes including a minimal decrease of 10% body
weight gain in addition to increased incidence of liver necrosis.  In
the carcinogenicity study (MRID 45118331), the incidence of liver
necrosis in males at 200 ppm (20%) was outside the historical control
range (2%-16%; BASF, 2001).  Females: Upon reevaluation, the CARC
concluded that female rats were tested adequately at the top dose of 200
ppm.  Based on a 19% decrease in cumulative body weight gain (Day 0-728)
in the females of the 200 ppm group and the more severe decreases in
body weight gain (-21-24%) and food efficiency (-16-17%) seen during Day
0-399 at 400 and 600 ppm in the supplementary study, which are supported
by the effects seen at 500 ppm in the subchronic study, it is evident
that the female rats may not have tolerated a dose higher than 200 ppm. 
Therefore, the CARC concluded that the dose of 200 ppm chosen for the
chronic toxicity and carcinogenicity studies was reasonable and
adequate.

(	In B6C3F1 mice, there were no treatment related increases in tumors.  

(	Adequacy of Dosing in Mice: Males: The CARC determined that the dose
levels tested were adequate for male mice based on decrease in body
weight gain (20%) at 13 weeks which was supported by the results of a
range-finding study.  Females: As stated above, upon reevaluation, the
CARC concluded that dosing at the high dose of 180 ppm for female mice
was not adequate.

2.  Mutagenicity tc \l2 "2.  Mutagenicity 

Pyraclostrobin has been tested in an adequate battery of mutagenicity
tests that satisfy FIFRA test guidelines.  All the in vitro and in vivo
mutagenicity studies were negative, including the Ames test, a CHO
mammalian cell gene mutation assay,  mammalian cell chromosomal
aberration assay, mouse micronucleus assay, and a UDS assay.

3. Structure Activity Relationship tc \l2 "3. Structure Activity
Relationship 

Pyraclostrobin is structurally related to two other strobulin
pesticides, azoxystrobin and trifloxystrobin.  In 1996, the CARC
classified azoxystrobin as  “not likely to be carcinogenic to humans
.”  It was concluded that azoxystrobin is active as an  in vitro
mutagen, but is not mutagenic in  in vivo assays.  Trifloxystrobin was
classified as “not likely to be carcinogenic to humans ” in 1999. 
Trifloxystrobin was mutagenic in Chinese hamster V79 fibroblasts assay
out of 7 genotoxicity studies conducted.

4. Mode of Action Studies tc \l2 "4. Mode of Action Studies 

No studies were available. 

VI.  CLASSIFICATION OF CARCINOGENIC POTENTIAL tc \l1 "VI. 
CLASSIFICATION OF CARCINOGENIC POTENTIAL 

In accordance with the EPA Draft Guidelines for Carcinogen Risk
Assessment (July, 1999), the CARC classified pyraclostrobin into the
category “Data are inadequate for an assessment of  human carcinogenic
potential” because of inadequate testing of female mice.  The
Committee recommended that the registrant should conduct a new study in
female mice at adequate dose levels. 

VII.  QUANTIFICATION OF CARCINOGENIC POTENTIAL tc \l1 "VII. 
QUANTIFICATION OF CARCINOGENIC POTENTIAL 

Not  required

VIII.  BIBLIOGRAPHY tc \l1 "VIII.  BIBLIOGRAPHY 

MRID No.					CITATION

45118304	Wiemann, C.; Hellwig, J. (1999) BAS 500 02 F: Acute Oral
Toxicity in Rats: Lab Project Number: 18A0236/991082: 1999/12023. 
Unpublished study prepared by BASF Aktiengesellschaft.  22 p. {OPPTS
870.1100}

45118305	Wiemann, C. (1998) Study on the Acute Dermal Toxicity of BAS
500 F in Rats: Lab Project Number: 11A0308/961120: 1998/10966.
Unpublished study prepared by BASF Aktiengesellschaft.  23 p. {OPPTS
870.1200}

45118308	Gamer, A. (1999) BAS 500 F--Acute Inhalation Toxicity Study in
Wistar Rats: Lab Project Number: 1997/11472: 13I0308/967028. Unpublished
study prepared by BASF Aktiengesellschaft.  33 p. {OPPTS 870.1300}

45118314	Wiemann, C. (1998) BAS 500 F--Acute Dermal Irritation/Corrosion
in Rabbits: Lab Project Number: 13H0308/962190: 1998/10959. Unpublished
study prepared by BASF Aktiengesellschaft.  17 p. {OPPTS 870.2500}

45118315	Wiemann, C.; Hellwig, J. (1998) BAS 500 00 F: Acute Dermal
Irritation/ Corrosion in Rabbits: Lab Project Number: 14H0185/972188:
1998/10644.  Unpublished study prepared by BASF Aktiengesellschaft.  17
p. {OPPTS 870.2500}

45118317	Wiemann, C. (1998) BAS 500 F--Maximisation Test in Guinea Pigs:
Lab Project Number: 30H0494/962329: 1998/10964. Unpublished study
prepared by BASF Aktiengesellschaft.  50 p. {OPPTS 870.2600}

45118320	Mellert, W.; Deckardt, K.; Hildebrand, B. et al. (1999) BAS 500
F--Subchronic Oral Toxicity Study in B6C3F1 crl BR Mice Administration
in the Diet for 3 Months: Lab Project Number: 60C0183/96016: 1998/11345.
 Unpublished study prepared by BASF Aktiengesellschaft.  369 p. {OPPTS
870.3100}

45118321	Mellert, W.; Deckardt, K.; Hildebrand, B. et al. (1999) BAS 500
F--Subchronic Oral Toxicity Study in Wistar Rats Administration in the
Diet for 3 Months: Lab Project Number: 50C0183/96015: 1999/10195. 
Unpublished study prepared by BASF Aktiengesellschaft.  363 p. {OPPTS
870.3100}

45118323	Menges, S.; Deckardt, K.; Hildebrand, B. et al. (1999) BAS 500
F--Subchronic Oral Toxicity Study in Beagle Dogs Administration in the
Diet for 3 Months: Lab Project Number: 31D0494/96089: 1999/11678. 
Unpublished study prepared by BASF Aktiengesellschaft.  443 p. {OPPTS
870.4100}

45118328	Schilling, K.; Gembardt, C.; Hildebrand, B. (1999) BAS 500
F--Chronic Oral Toxicity Study in Beagle Dogs Administration in the Diet
for 12 Months: Lab Project Number: 33D0494/96144: 1999/11677. 
Unpublished study prepared by BASF Aktiengesellschaft.  770 p. {OPPTS
870.4100}

45118329	Mellert, W.; Gembardt, C.; Hildebrand, B. et al. (1999) BAS 500
F--Chronic Toxicity Study in Wistar Rats Administration in the Diet for
24 Months: Lab Project Number: 82S0494/96085: 1999/11672.  Unpublished
study prepared by BASF Aktiengesellschaft.  1139 p. {OPPTS 870.4100}

45118330	Mellert, W.; Deckardt, K.; Hildebrand, B. et al. (1999) BAS
500 F--Carcinogenicity Study in B6C3F1 Mice Administration in the Diet
for 18 Months: Lab Project Number: 76C0494/96101: 1999/11871. 
Unpublished study prepared by BASF Aktiengesellschaft.  846 p. {OPPTS
870.4200}

45118331	Mellert, W.; Deckardt, K.; Hildebrand, B. et al. (1999) BAS 500
F--Carcinogenicity Study in Wistar Rats Administration in the Diet for
24 Months: Lab Project Number: 1999/11868: 82S0494/96086.  Unpublished
study prepared by BASF Aktiengesellschaft.  1524 p. {OPPTS 870.4200}

45118332	Engelhardt, G. (1997) BAS 500 F--(Reg. No. 304 428) (ZHT Test
Substance No.: 96/308) in the Ames Salmonella/Mammalian-Microsome
Mutagenicity Test and Escherichia coli/Mammalian-Microsome Reverse
Mutation Assay (Standard Plate Test and Preincubation Test): Lab Project
Number: 40M0308/964244: 1997/10973.  Unpublished study prepared by BASF
Aktiengesellschaft.  36 p. {OPPTS 870.5100}

45118333	Engelhardt, G. (1999) In Vitro Chromosome Aberration Assay with
BAS 500 F in V79 Cells: Lab Project Number: 1999/11403: 32M0308/964304. 
Unpublished study prepared by BASF Aktiengesellschaft.  88 p. {OPPTS
870.5375}

45118334	Engelhardt, G. (1998) Cytogenetic Study in Vivo with BAS 500 F
in the Mouse Micronucleus Test Single Oral Administration: Lab Project
Number: 26M0308/964204: 1998/10460.  Unpublished study prepared by BASF
Aktiengesellschaft.  53 p. {OPPTS 870.5395}

45118335	Engelhardt, G. (1998) In Vitro Gene Mutation Test with BAS 500
F in CHO Cells (HPRT Locus Assay): Lab Project Number: 50M0308/964303:
1998/11422.  Unpublished study prepared by BASF Aktiengesellschaft.  59
p. {OPPTS 870.5300}

45118336	Engelhardt, G. (1998) In Vitro Unscheduled DNA Synthesis (UDS)
Assay with BAS 500 F in Primary Hepatocytes: Lab Project Number:
81M0308/964306: 1998/11421.  Unpublished study prepared by BASF
Aktiengesellschaft.  47 p. {OPPTS 870.5550}

45118403	Leibold, E.; Hoffmann, H.; Hildebrand, B. (1998)
(Carbon-14)-BAS 500 F-Study of the Biokinetics in Rats: Lab Project
Number: 02B0364/966007: 1998/10997.  Unpublished study prepared by BASF
Aktiengesellschaft.  83 p. {OPPTS 870.7485}

45118404	Velic, I. (1999) Metabolism of (carbon-14)-BAS
((carbon-14)-304428) in Rats: Lab Project Number: 38773: 1999/11781. 
Unpublished study prepared by BASF Aktiengesellschaft.  212 p. {OPPTS
870.7485}

45429902	Hastings, C.E. (2001) Pyraclostrobin (BAS 500F): Historical
Control Tumor Data. BASF Reg. Document No. 2001/5001490.

45443001	Hastings, C.E. (2001) Pyraclostrobin (BAS 500F): Historical
Control Tumor Data, Second Submission. Leydig Cell Tumors and Adrenal
Cortical Tumors. BASF Reg. Doc. 2001/5001571.

45661702	Lawrence, G. et al. (2002) Chronic and Oncogenicity Studies
with BAS 500F: Further Evaluation of Body Weight, Food Consumption, and
Food Efficiency. Prepared by ENVIRON International Corporation for
Hastings, C. E. at BASF Corporation; BASF Registration Document No.
2002/5002875.

45661703	Mellert, W. (2002) BAS 500F - Chronic Toxicity Study in Wistar
Rats; Administration in the Diet for 24 Months; Amendment to MR1D No.
45508601 (which was the first amendment of original study, namely MRID
45118329). BASF Reg. Doc. No. 2002/1005113, March 25, 2002. MRID No.
45661703, 440 pages.

 ADVANCE \d0 45661704	Mellert, W. (2002) BAS 500F - Carcinogenicity
Study in Wistar Rats; Administration in the Diet for 24 Months;
Amendment to MRID No. 455118331 (should be 45118331). BASF Reg. Doc. No.
2022 (should be 2002)/1005114, March 25, 2002. MRID No.   45661704, 1144
pages.

------------	BASF. (2001). Amended Report: Pyraclostrobin (BAS 500F):
Historical control data on non-neoplastic lesions in chronic rat
studies.  Data submitted by BASF Corporation ,Research Triangle Park, 
NC 27709. BASF Registration Document # 2001/5001601; Amendment #
2001/5001597.  Dated July, 10, 2001. 

------------	Brunsman, L. (2001). Pyraclostrobin Qualitative Risk
Assessment Based on Wistar Chbb:THOM (SPF) Rat Dietary Studies: 
Memorandum from L. Brunsman to W. Greear, September 25, 2001. TXR No.
014680.

------------	Cancer Assessment Document. 2001.  Evaluation of the
Carcinogenic Potential of Pyraclostrobin.  Final Report. December 26,
2001.  TXR No. 0050363.

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PYRACLOSTROBIN			CANCER ASSESSMENT DOCUMENT 			FINAL

PYRACLOSTROBIN			CANCER ASSESSMENT DOCUMENT 			FINAL

PYRACLOSTROBIN			CANCER ASSESSMENT DOCUMENT 			FINAL

PYRACLOSTROBIN			CANCER ASSESSMENT DOCUMENT 			FINAL

PYRACLOSTROBIN			CANCER ASSESSMENT DOCUMENT 			FINAL

PYRACLOSTROBIN			CANCER ASSESSMENT DOCUMENT 			FINAL

