	UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

	WASHINGTON D.C., 20460

	OFFICE  OF 

	PREVENTION, PESTICIDES AND 

	TOXIC SUBSTANCES

INTERNAL DELIBERATIVE

MEMORANDUM	PC Code No. 056801

	DP #: 337058

	Date: March 9 2007

Subject: Carbaryl refined drinking water time-series simulations using
regional PCAs

To: 	Chistina Scheltema, Chemical Review Manager, SRRD

	Michael Goodis, Chief, SRRD

	Felicia Fort, Risk Assesor, HED

	Michael Metzger, Chief, HED

From:	Dirk Young, Ph.D., Environmental Engineer, EFED

	

Thru:  Elizabeth Behl, Chief

	Environmental Risk Branch IV, EFED

Please find in an accompanying email the electronic copies of refined
time series of PRZM/EXAMS simulations for carbaryl.  As requested, these
simulations include the regional PCA adjustments to the simulations
previously sent.   Such PCA adjustments have important implications
regarding the spatial representativeness of these simulations.  In this
regard, Table 1 below gives the file names that were sent along with the
relevance of each simulation with respect to its ability to represent
particular areas.  Table 1 also gives the application information for
each simulation. Table 2 gives the model inputs for carbaryl that were
used for these simulations.

As also discussed in our meeting last week, additional simulations have
been performed with the apple scenarios.  These additional simulations
include single applications of carbaryl at both 3 lb/acre (the labeled
rate) as well as at 2 lb/acre (BEAD determined that 90% of acreage is
treated at less than this value).  Also as discussed, a California
strawberry surrogate scenario has been added to the simulations. An
additional simulation to represent Michigan blueberries may be forwarded
to you after EFED reviews the vulnerability of the Michigan blueberry
region and reviews the availability of an appropriate scenario.

 

Table 1.  Decsription of the simulations that have been sent
electronically.

File Name	Description and Relevance	Regional PCA	Application type	App
Dates

ga peach with dormant regional PCA.csv	Georgia Peaches with regional PCA
should be protective of USA	0.38	Aerial Foliar Application; 3 in season
at 3 lb and 1 dormant at 3 lb (Note that last application is 2 lb short
of allowable)	July 1, 8, 15; Oct 15

ga peach No dormant regional PCA.csv	Georgia Peaches without the
optional Dormant Spray along with regional PCA should be protective of
USA	0.38	Aerial Foliar Application; 3 in season at 3 lb 	July 1, 8, 15

CA peach with dormant regional PCA.csv	California Peaches with regional
PCA should be protective of California	0.56	ground Foliar Application; 3
in season at 3 lb and 1 dormant at 3 lb (Note that last application is 1
lb in excess of max seasonal)	July 1, 8, 15; Oct 15

CA peach NO dormant regional PCA.csv	California Peaches without the
optional dormant spray along with regional PCA should be protective of
California	0.56	Aerial Foliar Application; 3 in season at 3 lb 	July 1,
8, 15

FL citrus regional PCA.csv	Florida Citrus should be protective of FL
citrus	0.38	5 lb, 3 times, Aerial	Jan 4, 18, Feb 1

FL strawberry regional PCA.csv	Florida Strawberry with the regional PCA
should be protective of entire USA	0.38	5 2-lb applications	Jan 3, 10,
17, 24, Feb 1

CA strawberry regional PCA.csv	California strawberry with regional PCA
should be representative of California (used CA lettuce scenario as
surrogate)	0.56	5 2-lb applications	March 3, 10, 17, 24, 31

CA citrus regular regional PCA.csv	California Citrus should be
protective of California	0.56	5 lb, 3 times, Aerial	Jan 4, 18, Feb 1

CA citrus 12 lb regional PCA.csv	CA citrus alternative 12 lb
application, should be protective of California	0.56	1 12 lb	Jan 4

CA grape regional PCA.csv	California Grapes should be protective of
California	0.56	2 lb 5 times	June1, 8, 17, 24, July1

PA apple regional PCA.csv	Apple Pennsylvania along with reional PCA is
protective of Mid Atlantic apples	0.46	3 lb 5 times, 14 days interval
June 1, 15, 29, July12, 26

OR apple springtime regional PCA.csv	Apple Oregon along with regional
PCA is protective of Western apples	0.63	3 lb 5 times, 14 days interval
April 15, 29, May 11, 25, june 4

PA apple thinning regional PCA.csv	Pennsylvania one thinning application
with regional PCA, protective of Mid Atlantic apples	0.46	Single 3-lb
application 	April 15

OR apple thinning regional PCA.csv	Oregon one thinning application with
regional PCA protective of Western apples	0.63	Single 3-lb application 
June 15

PA apple thinning regional PCA 2lb less than label.csv	Pennsylvania one
thinning application at 2lb (BEAD value for ~90% use) with regional PCA,
protective of Mid Atlantic apples	0.46	Single 2-lb application 	April 15

OR apple thinning regional PCA 2 lb less than label.csv	Oregon one
thinning application at 2lb (BEAD value for ~90% use) with regional PCA
protective of Western apples	0.63	Single 2-lb application 	June 15



Table 2. Carbaryl Parmeter Inputs to PRZM/EXAMS	

Parameter	Value	Source	Comments

Molecular Wt	201.22 g/mol



Solubility	32 mg/L



Vapor Pressure	1.36 x 10-6 torr at 25 C	D26726, Ferrira and Seiber
(1981) as appears in D267276

	Henry’s law Constant	1.28 x 10 -8 atm/ m3/mol	Suntio, et al. (1988)
as appears in D288455 and  D267276

	Hydrolysis Half life 	12 days at pH = 7	MRID 00163847

44759301; D288455

	Koc	198 mL/g	D288455

	Aerobic Aquatic half life	Insignificant with respect to hydrolysis	MRID
46580701, 46580702	New submission. On the order of 100 days. Much
unextracted material, hydrolysis likely source of degradation

Aqueous photolysis	21 days	D288455

	Foliar degradation	3.71 days (0.187 perday)	D288455

	Aerobic Soil Metabolism	12 days	D288455	Single study. 3X the single
value

Ferreira, G.A. and J.N. Seiber, 1981. J. Agric. Food Chem., 29:93-99

Suntio, L.R., et al., 1988. Rev. Environ. Contam. Toxicol., 103:1-59.  

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