	

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C.  20460

OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES

January 9, 2006

MEMORANDUM

SUBJECT:	Updated Review of Rodenticide Incident Reports Primarily
Concerning Children, DP Barcode D332563, Chemical#112701, 112001,
128967, 086002, 067707, 067701, 088601, 802901,112802

FROM:	Monica Hawkins, M.P.H., Environmental Health Scientist

	Chemistry and Exposure Branch

	Health Effects Division (7509P)

	Hans D. Allender, Ph.D., Statistician

	Chemistry and Exposure Branch

	Health Effects Division (7509P)

THRU:	David J. Miller, Chief

	Chemistry and Exposure Branch

	Health Effects Division (7509P)

TO:	Laura Parsons, Team Leader

	Special Review and Re-registration Division (7508P)

	Kelly Sherman, Team Leader 

	Special Review and Re-registration Division (7508P)

RODENTICIDE REVIEW

This review addresses the incidents of a group of the following nine
rodenticides:

1- Brodifacoum (PC Code 112701), 

2- Bromadiolone (PC Code 112001), 

3- Difethialone (PC Code 128967),

4- Warfarin (PC Code 086002), 

5- Chlorophacinone (PC Code 067707), 

6- Diphacinone (PC Code 067701), 

7- Zinc Phosphide (PC Code 088601), 

8- Cholecalciferol (PC Code 802901), and 

9- Bromethalin (PC Code 112802). 

The purpose of this review is to update poisoning incident data received
since completion of 1999 incident review by Dr. Blondell. The Poison
Control Center (PCC) data includes rodenticides that are not currently
under evaluation by EPA. A summary of the various rodenticides in each
analysis time period is given in Attachment 1.

The report is divided in two sections: (i) cases reported in the
Incident Data System from 1999 to the present; and (ii) cases reported
in the Poison Control Center Database from 1999 to 2003. For this later
database, SRRD indicated that cases involving young children (6 years
old or less) were the primary interest and the database search was
limited to cases meeting this criterion.

 

Incident Data System

1) OPP Incident Data System (IDS) - reports of incidents from various
sources, including registrants, other federal and state health and
environmental agencies and individual consumers, submitted to OPP since
1992.  Reports submitted to the Incident Data System represent anecdotal
reports or allegations only, unless otherwise stated.  Typically no
conclusions can be drawn implicating the pesticide as a cause of any of
the reported health effects.  Nevertheless, sometimes with enough cases
and/or documentation risk mitigation measures may be suggested.

According to the Incident Data System, it appears that the majority of
cases in children occurred from exposure to Brodifacoum (30 cases out of
43 or 68%) and the most common symptoms reported were diarrhea,
vomiting, and skin rash. Specifics relating to these incidents are
detailed and fully described in Attachment 2, where they are identified
by Incident Number and sorted by rodenticide name.

2.	  SEQ CHAPTER \h \r 1 Poison Control Center Data - 1999 through 2003
for a combination of 9-Rodenticides

This section discusses results from the Poison Control Center’s Toxic
Exposure Surveillance System (TESS) from the years 1999 through 2003 and
reflects only data collected for children six years of age or less.
Cases involving exposures to multiple products and cases with unrelated
medical outcome are excluded.  The tables included in this section
transmit acute pesticide poisoning incidence resulting from exposure to
the following 9 rodenticides:

1- Brodifacoum (PC Code 112701), 

2- Bromadiolone (PC Code 112001), 

3- Difethialone (PC Code 128967),

4- Warfarin (PC Code 086002), 

5- Chlorophacinone (PC Code 067707), 

6- Diphacinone (PC Code 067701), 

7- Zinc Phosphide (PC Code 088601), 

8- Cholecalciferol (PC Code 802901), and 

9- Bromethalin (PC Code 112802) 

Table 1 below compares the frequency of poisoning incidents among all 9
rodenticides in the EPA group with the composite of all pesticides for
which the PCC received an incident report.  The frequency of events is
reported by health effect severity category (all symptoms, moderate, and
major) and by level of health care received.  This ratio provides a
simple measure of the relative frequency of reported health effects by
severity category.  Knowledge of the ratios of symptoms for a class of
chemical (or a single chemical) provides a relative measure of the
public health impact of the acute pesticide events.  In addition, a
Likelihood Ratio test shows whether the compounds under study are
significantly different from the average of all other pesticides.  An
(s) indicates the proportions are significantly different.   

For a more detailed explanation of  Table 1 see Attachment 3.

Table 1. Relative Frequency of Acute Poisoning Incidents by Symptom
Severity: Non-Occupational Cases Involving Children Six Years of Age or
Less.

	Severity of outcome

(outcome determined)	Total

exposed	Health care 

provided

Denominator numbers

	25,549	68,005	18,084

Measures	SYM1	MOD2	MAJ3	HCF4	HOSP5	ICU6

Numerator numbers	578	83	9	18,084	302	219

9 Rodenticides percents	2.26%	0.32%	0.03%	26.59%	1.67%	1.21%

All Pesticides percents	21.72%	1.42%	0.12%	15.68%	4.34%	1.75%

Ratio of  9 Rodenticides 

/All pesticides	0.10(S)

P =0.00	0.23 (S)

P = 0.00	0.25

P = 0.94*	1.69 (S)

P = 0.00	0.38 (S)

P = 0.00	0.69 

P =0.51

*Proportions and sample size too small for a valid significance test.

1) percent with ANY symptom in relation to the total of cases followed, 

2) percent with moderate symptoms in relation to the total of cases
followed, 

3) percent with major or fatal outcome in relation to the total of cases
followed,

4) percent of case seen in a Health Care Facility (HCF) in relation to
total exposures 

5) percent of cases seen in a Hospital in relation to cases seen in a
HCF

6) percent of cases taken to an Intensive Care Unit (ICU) in relation to
cases seen in a HCF.

Analysis of Results

The ratio of children seen at a HCF is higher than the proportion seen
among all pesticides exposure – approximately 27% v. 16%.  This may be
due to increased concern for children’s safety; difficulty in
determining exposure in children (cannot communicate exposure
experience) and therefore require additional testing; knowledge or fear
concerning rodenticides; or other unknown factors.  Importantly, the
proportion of children admitted to hospital or ICU is less than or equal
to that seen among the ALL pesticide composite.  This suggests that
while visits to HCF is high, effects seen are treatable and do not
require hospitalization. However for severity of outcome, (SYM, MOD, and
MAJ) rodenticide incidents are significantly lower compared to all
pesticides.

Table 2 provides additional detail by year and Figure 1 shows this same
information in a graphical form.  No trend is apparent for the 5
year-span for the 9-rodenticides group for the total exposure. There is
no apparent trend in the cases that were symptomatic through the years;
the numbers show a steady average of about 115 symptomatic cases per
year. 

Table 2. Number of Rodenticides Cases by Year

Year	Symptomatic

Cases	Moderate

Cases	Major

Cases	Cases Followed	Total

Exposures	HCF

Cases	Hospital

Cases	ICU

Cases

1999	117	14	4	5845	13647	3939	62	53

2000	129	21	3	5206	13650	3643	59	44

2001	96	19	2	4845	13642	3624	63	43

2002	124	11	0	4997	13842	3551	59	42

2003	112	18	0	4656	13224	3327	59	37

Total	578	83	9	25549	68005	18084	302	219

 

No apparent trend is noted on the 5 year-span for the 9-rodenticides
group for the total exposure. However, there is a reduction of cases
followed in relation to annual total exposure. This is, in 1999, 5,845
cases out of 13,367 (42.8%) were followed; at the other extreme, in 2003
only 4,656 cases out of 13,224 (35.2%) were followed. There is no
apparent trend in the cases that were symptomatic through the years; the
numbers show a steady average of about 115 symptomatic cases per year.



Figure 1. Total Cases and Symptomatic Cases by Year. 



The relative contribution of each individual rodenticide to the total
number of persons exposed to rodenticides over the 5 year period of
interest is presented in Figure 2.  This figure indicates that
Brodifacoum contributes almost 80% of the total exposure cases of the
group; the combination of Bromadiolone, Difethialone, and Diphacinone
produce about 16% of the exposures.  In contrast, Chlorophacinone, Zinc
Phosphide, and Cholecalciferol make a combined contribution of less than
1%. The percentages are taken against the total exposure for the
five-year period of 68,005.

Figure 2. Individual Contribution of Each Rodenticide to the
9-rodenticides Group.



A similar proportion is observed in relation to the number of cases that
were symptomatic, as shown in Figure 3.  The percentages are calculated
against the total of 578 symptomatic cases. Brodifacoum contributes more
than 72% of the total of symptoms, which may be a function of market
share. Chlorophacinone, Zinc Phosphide, and Cholecalciferol make a
combined contribution of less than 2.5%.

Figure 3. Symptomatic Cases of Rodenticides from the 9-rodenticides
Group.

Figure 4 shows a relatively flat pattern with no decrease of exposures.
There is an increase of 2,024 exposures or 22%. (from 9,128 in 1999 to
11,152 in 2003). This is equivalent to an annual average increase of
exposures to Brodifacoum of 4.4%. Symptomatic cases remain relatively
small proportion of total exposure.

Figure 4. Annual Distribution of Brodifacoum for Cases with Exposure and
Symptoms.

Summary

According to PCC data, there are no significant changes in cases per
year or proportions of rodenticides when compared to the previous report
“Updated Review of Rodenticides Incident Reports Primarily Concerning
Children DP Barcode D256673” dated June 3, 1999.  

The summary findings for the period 1999 to 2003 for children are as
follow:

The combination of 9-rodenticides is statistically well below the
composite of all pesticides in the production of symptoms, in the
production of moderate symptoms and (although not statistically
significant) in the production of major symptoms.

The ratio of children seen in a Health Care Facility as a result of a
potential exposure to the 9-rodenticides group is almost 70% higher than
the composite of all pesticides, and statistically significant.

The ratio of children seen in a hospital is statistically significant
and lower than the composite; the fraction sent to ICU, although also
lower, shows no statistical difference to the composite.

Only 37% of exposure cases are followed.

There is an annual reduction of cases followed of about 7% in the
five-year span. 

About 1.18% of cases followed and 0.44% of the total children exposed
warrant a visit to a Hospital.

No apparent annual trend is noticed in the 5 year-span for the
9-rodenticides group.

Brodifacoum contributes almost 80% of the total exposure cases of the
group; this may be due to market share.

Brodifacoum contributes more than 72% of the total of symptoms produce
by the 9-rodenticides group.

Recommendations

Given the total number of rodenticide exposures for children under 6
years of age, risk mitigation measures to reduce exposure to this
rodenticide should be considered.  This could include public education
and outreach, product substitution and/or use of bait stations. 

  

 

Attachment 1.

Summary of the Various Rodenticides Groups in Each Analysis Time Period

Rodenticides	Superwarfarin*	Incident Memo (2006)**	Incident Memo (1999)
RED 1998***

Diphacinone	X	X	X	X

Pindoe	X

X

	Chlorophacinone	X	X	X	X

Brodifacoum	X	X	X	X

Difenacoum	X



	Bromadiolone	X	X	X	X

Bromethalin

X

X

Cholecalciferol

X



Zinc phosphide

X	X

	Difethialone

X



Warfarin

X	X

	Pival and sodium salt



X

Other/Unknown

	X

	

*Internet source; should check how PCC defines “superwarfarin”

** Includes 9 subject of Comprehensive Ecological Risk Assessment

***Separate RED for Zinc Phosphide



Attachment 2.

Cases from the Incident Data System

Brodifacoum reports

Incident#11098-10

	A pesticide incident occurred in 2000, when a girl, who is less than
six years old, reported stomach pain and frequent urination.  The
girl’s mother found some of the products pellets under their couch
cushions and in one of her child’s room.  The mother stated that she
was certain that her daughter did not ingest any of the pellets.  No
further information on the disposition of the case was reported.

Incident#12587-11

	A pesticide incident occurred in 2002, when a fifteen month old girl
reported spots that spread across her face.  The girl’s grandmother
reported that her granddaughter ingested two or three of the product’s
pellets.  No further information on the disposition of the case was
reported.

Incident#13052-12

	A pesticide incident occurred in 2002, when a fifteen month old girl
grabbed the product’s pellets out of the cupboard.  The girl’s
mother took five or six pellets out of her mouth and was not sure if she
swallowed any of them.  The girl was taken to the emergency room and was
diagnosed with a parasite.  No further information on the disposition of
the case was reported.

Incident#13338-15

	A pesticide incident occurred in 2002, when a four year old girl
reported fever, throat irritation, and drowsiness after she was found
playing with the product.  She was treated by a physician and the
results for her mono and strep test were negative.  No further
information on the disposition of the case was reported.

Incident#13639-11

	A pesticide incident occurred in 2002, when a two year old boy walked
into a room in his house carrying the product.  The boy reported
blisters.  He was taken to the emergency room and hooked up to a cardiac
monitor for several hours.  No changes in the rhythm were detected.  No
further information on the disposition of the case was reported. 

Incident#14934-13

	A pesticide incident occurred in 2004, when a one year old boy reported
vomiting and diarrhea after the product’s container was found ripped
up behind the television and in a closet in his house.  The boy’s
father vacuumed the floor and was not sure if his son ingested the
product or not.  No further information on the disposition of the case
was reported.  

Incident#14983-5

	A pesticide incident occurred in 2004, when a five year old boy, who
denies ingesting the product, was hospitalized for a week for possible
ingestion of the product.  His father works in a restaurant that uses
the product.  One day, the boy’s father left him alone while he was at
work and the boy could have eaten the product.  The boy was released to
foster care until the situation is resolved.  No further information on
the disposition of the case was reported. 

Incident#15104-15

	A pesticide incident occurred in 2004, when a two year old boy reported
diarrhea, vomiting, and a fever.  The boy’s mother placed a few of the
traps in her home.  She checked the traps and noticed that ¾ of one of
them was missing.  The boy said that he ate some of the product.  No
further information on the disposition of the case was reported.  

Incident#15180-5

	A pesticide incident occurred in 2004, when a three year old boy, who
has a history of nose bleeds, went behind a sofa to ingest the product. 
The boy was treated at a health care facility by a physician for a
prolonged prothrombin time.  No further information on the disposition
of the case was reported.

Incident#15417-3

	A pesticide incident occurred in 2004, when a twenty-two month old girl
may have ingested the product that was placed behind a coach and in
several other open areas.  The girl’s grandmother was not absolutely
certain that she ingested the product during the previous few days. 
There was no evidence of the product in her mouth.  The girl reported
diarrhea for two days and was treated by a physician.  No further
information on the disposition of the case was reported.

Incident#15529-2

	A pesticide incident occurred in 2004, when a nineteen month old girl
reported hives and welts.  The girl’s mother is not absolutely certain
that she ingested the product.  There was no evidence of the product in
her mouth but she may have been able to rinse her mouth out with the
contents in her sippy cup.  The girl’s mother stated that she would
take her daughter to the doctor.  No further information on the
disposition of the case was reported.  

Incident#15610-2

	A pesticide incident occurred in 2004, when two children licked the
product.  Both children were asymptomatic.  A three year old boy
reported a rash that was due to exposure to something else.  No further
information on the disposition of the case was reported.

Incident#15619-2

	A pesticide incident occurred in 2004, when a one year old girl
ingested less than 10 pellets of the product that were detectable in her
teeth and on her tongue.  The mother reported that her daughter’s
stool was hard and contained blood and the color of the pellets was in
it.  No further information on the disposition of the case was reported.


Incident#15732-4

	A pesticide incident occurred in 2004, when a two year old girl
reported a rash on her stomach after being at a cabin earlier in the
day.  Several boxes of the product were placed in the cabin.  No further
information on the disposition of the case was reported.

Incident#15783-10

	A pesticide incident occurred in 2004, when a two year old boy reported
vomiting, diarrhea, tremor, and hitting himself on the head.  The boy
may have picked up his pacifier off the floor.  No further information
on the disposition of the case was reported.

Incident#15865-1

	A pesticide incident occurred in 2004, when a two year old boy may have
ingested as much as one half of the product.  Half of the product was
missing but the pellets were not detectable in his teeth or mouth.  The
boy reported hives and welts all over his entire body.  No further
information on the disposition of the case was reported.    

Incident#16032-3

	A pesticide incident occurred in 2005, when a two year old boy was
found with a box of the product but very little was missing.  The boy
reported melena.  No further information on the disposition of the case
was reported.

Incident#16032-6

	A pesticide incident occurred in 2005, when a nine month old boy
ingested an unknown amount of the product.  The boy reported a rash.  No
further information on the disposition of the case was reported.

Incident#16136-15

	A pesticide incident occurred in 2005, when a one year old boy ate one
pellet of the product.  The boy found it under his aunt’s refrigerator
and ate it before she could remove it from his hands or mouth.  The boy
reported a fever and a throat infection and was treated by a physician. 
No further information on the disposition of the case was reported.     
                     

Incident#16583-5

	A pesticide incident occurred in 2005, when a six year old girl
reported vomiting, edema, and a rash.  The girl’s parent was unsure if
she ingested the entire box of the product or not but the girl denied
eating the product.  The girl was treated by a physician.  No further
information on the disposition of the case was reported. 

Incident#16807-4

	A pesticide incident occurred in 2005, when a two year old boy’s
mother found three pellets in his mouth.  The boy reported blood on his
behind and was treated by a physician at an emergency room.  No further
information on the disposition of the case was reported.

Incident#16944-6

	A pesticide incident occurred in 2005, when a two year old girl played
with the product and almost ¾ of it is present.  The girl reported
hematuria.  No further information on the disposition of the case was
reported.

Incident#16988-2

	A pesticide incident occurred in 2005, when a fifteen month old boy
found a container of the product in the kitchen with his mother present.
 His mother did not see the product in his mouth or in his hands.  The
boy reported not having a good appetite for three days and ataxia.  No
further information on the disposition of the case was reported.

Incident#17044-5

	A pesticide incident occurred in 2005, when a two year old boy reported
a small amount of blood in his stool.  The boy’s mother placed the
product in her home.  The box appeared undisturbed but she was concerned
about poisoning.  No further information on the disposition of the case
was reported.

Incident#17230-7

	A pesticide incident occurred in 2006, when a two year old girl may
have ingested some of the product.  The girl reported vomiting and was
taken to the emergency room by her grandparent.  No further information
on the disposition of the case was reported.

Incident#17265-2

	A pesticide incident occurred in 2006, when an eight year old boy
reported difficulty breathing and lethargy.  His parents placed three
packets of the product out and one of the three remaining packets was
left in the box.  The boy’s teacher sent a note home and stated that
the boy fell asleep three times in her class. No further information on
the disposition of the case was reported.

Incident#17464-15

	A pesticide incident occurred in 2006, when a boy, who is less than six
years old, was taken to the emergency room by his grandparent after
possibly ingesting the product.  The boy reported edema and blood was
dripping from his nose and ears.  No further information on the
disposition of the case was reported.

Incident#17510-4

	A pesticide incident occurred in 2006, when a two year old girl was
found with an open product.  The product was not detected in her mouth
or on her hands.  A small amount was missing from the product.  The
girl’s mother gave her something to drink.  The girl passed black
stool and blood was found around her anal area.  No further information
on the disposition of the case was reported.

Incident#17221-1

	A pesticide incident occurred in 2006, when a two year old girl was
found by her uncle with the product in her hands and the product was
wet.  The girl reported melena and was being taken to the hospital.  No
further information on the disposition of the case was reported.

Incident#17226-14

	A pesticide incident occurred in 2006, when a nine year old boy’s
father had an empty pail from the product that he was storing bolts in. 
There is some residue in the pails.  The boy’s father wasn’t sure if
his son touched the bolts and the product was absorbed through the skin
or not.  The boy reported diarrhea for three to four days.  No further
information on the disposition of the case was reported. 

Bromadiolone reports

Incident#12563-1

	A pesticide incident occurred in 2000, when a two year old girl
reported vomiting.  The product was discovered open and under the
bathroom sink by her parent.  The girl may have ingested the product. 
No further information on the disposition of the case was reported.

Incident#12690-1

	A pesticide incident occurred in 2002, when a sixteen month old girl
reported hematuria and was treated by a physician.  The girl may have
ingested the product but her symptoms may be due to living in an
extremely unsanitary home.  No further information on the disposition of
the case was reported. 

Incident#13542-1

	A pesticide incident occurred in 2002, when a fifteen month old girl
reported vomiting that contained blood, discolored stool, and diarrhea. 
The girl was treated by a physician at an emergency room.  No further
information on the disposition of the case was reported.

Incident#15242-1

	A pesticide incident occurred in 2004, when a five year old boy
reported a prolonged prothrombin time and was treated by a physician. 
The boy was playing with the product at a neighbor’s house.  Some of
the pellets were found in his mouth.  No further information on the
disposition of the case was reported. 

Incident#15508-2

	A pesticide incident occurred in 2004, when a two year old boy reported
discolored stool (bright green like the product) and a fever.  His
mother placed two one-ounce blocks of the product in her home that
disappeared.  No further information on the disposition of the case was
reported.

Incident#15644-1

	A pesticide incident occurred in 2004, when a twenty month old boy
reported a fever and chills.  The boy’s mother caught him and his dog
playing with one bait block.  The dog ate about ¼ of the 28 gram block
and the boy may have been chewing on it.  The boy was treated by a
physician and diagnosed with a viral illness.  No further information on
the disposition of the case was reported.

Incident#16204-1

	A pesticide incident occurred in 2005, when a two year old boy reported
a fever and hallucination.  His father thinks he may have ingested the
product.  No further information on the disposition of the case was
reported.

Difethialone reports

Incident#16807-20

Missing Incident.

Warfarin reports

There were no incident reports involving children exposed to warfarin in
the Incident Data System.

Chlorophacinone reports

	There were no incident reports involving children exposed to
chlorophacinone in the Incident Data System.

Diphacinone reports

Incident#11808-1

	A pesticide incident occurred in 2001, when a nineteen month old girl
was taken to the emergency room after it was not certain whether she
ingested the product or not.  The girl’s coagulation study was normal
so the attending physician did not administer any type of treatment.  No
further information on the disposition of the case was reported.

Incident#16363-1

	A pesticide incident occurred in 2005, when a thirteen month old girl
tasted one pellet of the product as witnessed by her father.  The girl
reported a rash over her entire body and swollen eyes.  No further
information on the disposition of the case was reported. 

Incident#17324-1

	A pesticide incident occurred in 2006, when a one year old girl
ingested one pellet of the product as witnessed by her mother.  The girl
reported vomiting for a few days.  No further information on the
disposition of the case was reported.

Zinc Phosphide reports

Incident#17470-1

	A pesticide incident occurred in 2006, when a seven year old boy and
his brother swept their shed with the product that spread across the
floor.  The boy reported abdominal pain, conjunctivitis, and shortness
of breath.  The boy was treated by a physician.  No further information
on the disposition of the case was reported.

Cholecalciferol reports

There were no incident reports involving children exposed to
cholecalciferol in the Incident Data System.

Bromethalin reports

Incident#11593-10

	A pesticide incident occurred in 2001, when a fourteen month old boy
ingested the product.  The boy reported agitation, irritability, and
vomiting and was treated by a physician at an emergency room.  No
further information on the disposition of the case was reported.  

Incident#13273-1

	A pesticide incident occurred in 2002, when an eighteen month old
girl’s mother was not watching her daughter while she cleaned her
house.  Her mother was not sure if she ingested some of the product that
she had placed behind her couch.  She gave her daughter some milk and
she vomited and also reported a fever.  The girl was treated by a
physician for a virus.  No further information on the disposition of the
case was reported.



Attachment 3.

Table Description

Table 1.

	Severity of outcome

(outcome determined)	Total

exposed	Health care 

provided

Denominator numbers	25,549	68,005	18,084

Measures	SYM	MOD	MAJ	HCF	HOSP	ICU

Numerator numbers	578	83	9	18,084	302	219

9 Rodenticides percents	2.26%	0.32%	0.03%	26.59%	1.67%	1.21%

All Pesticides percents	21.72%	1.42%	0.12%	15.68%	4.34%	1.75%

Ratio of  9 Rodenticides 

/All pesticides	0.10(S)

P =0.00	0.23 (S)

P = 0.00	0.25

P = 0.94*	1.69 (S)

P = 0.00	0.38 (S)

P = 0.00	0.69 

P =0.51



The following is a brief description of the table components:

The first row “Denominator numbers” presents all the numbers that
will serve as denominators in the calculation of the percents, and they
are:

In the center column, total amount of individuals exposed to group of 9
rodenticides (n = 68,005) Total Exposed. 

In the left, amount of cases followed, (n = 25,546) these cases have an
outcome determined (Outcome determined)

At the right of the table, cases that visited a Health Care Facility (n
= 18084) Health care provided 

B) The row “Measures” describes the outcomes for the cases: SYM
cases that were symptomatic; MOD cases that were classified as moderate;
MAJ cases that were classified as major or fatal; HCF cases of exposure
that went to a Health Care Facility; HOSP cases that went to a hospital;
and ICU cases that went to an Intensive Care Unit.

C) The row “Numerator numbers” are actually the number of cases that
presented the outcome describe in the Measures row.

D) The row “9 Rodenticides percents” gives the percentages on each
measure. These percentages are calculated by dividing the numerator
number by the denominator number (from each major section of the Table
1) and multiplying by 100. For example 578, 83, and 9 are divided by
25,549 producing the respective percents 2.26, 0.32, and 0.03, for SYM,
MOD, and MAJ. In a similar fashion 18,084 is divided by 68,005 for the
percentage of cases seen in a HCF of 26.59; and for the last section of
the Table 1, 302 and 219 are divided by 18,084 to find the percentages
of cases that went to a hospital and ICU. 

The row “All Pesticides Percents” are percentages that were
calculated using all cases available in the PCC database. These
percentages serve as the baseline for the comparison with the given
pesticide, or grouping, in this case a group of 9 rodenticides. 

The “Ratio of 9 Rodenticides/All pesticides” row is obtained by
dividing the percentages of the given compound by the “all
pesticides” percentages, to obtain a dimensionless number or ratio.
This ratio provides an idea of the relative importance of the given
compound (in this case a group of nine). For example, a ratio of 1 (one)
indicates that the percentages are the same for the compound (or group)
under study and the composite of all pesticides; a ratio, say of 2 (two)
indicates that the chemical under study (in this case the average of 9
rodenticides) produces twice the effect; and a ratio of 0.5 indicates
that the compound has half of the activity of the “composite.” The
advantage of these ratios is that they provide a quick overview of the
relative importance of the chemical or grouping.

Also, the “p” value that results from a Likelihood ratio test is
entered in the ratio cell and when significant (p < 0.05) then an (S) is
entered next to the ratio to mark statistical significance. A cell
marked with (S) means that the percentages that produce the ratios are
“statistically” significant and not due to chance. The percentage of
the given compound could be higher or lower than the percentage produce
by the composite as indicated by the ratio. For example, a ratio = 1.6
(S) means the effect produced by the compound is higher that the effect
produced by the composite and statistically different; a ratio = 0.7 (S)
signifies that the chemical has a lower effect than the composite and is
statistically different. On the other hand, a ratio = 1.2, with no (S),
means that the percentage, although higher, is not statistically
different from the composite.

 The chemicals of regulatory interest that comprise this “Rodenticide
Group” have changed
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