UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

	 		WASHINGTON, D.C. 20460

Office Of

Prevention, Pesticides

And Toxic Substances

MEMORANDUM

May 9, 2006

	

Subject: 	Carbaryl: Risk Analysis For Open Cab Airblast Applicators
Based On MRID 464482-01 	Using 2 Different Types Of Head Protection; DP
Barcode: D328176; PC Code: 056801

From:	Jeffrey L. Dawson, Chemist/Risk Assessor

		Reregistration Branch 1

		Health Effects Division (7509C)

		

Through: 	Whang Phang, PhD, Branch Senior Scientist 

		Reregistration Branch 1

		Health Effects Division (7509C)

										

To:	Christina Scheltema, Chemical Review Manager

		Special Review & Reregistration Division (7508C)

	Updated risk estimates for open cab airblast applicators using carbaryl
were completed based on the results of MRID 464482-01.  This study was
conducted by the Agricultural Handlers Exposure Task Force (AHETF) using
carbaryl and it evaluated open cab applicator exposures who wore typical
work clothing (i.e., long pants, shoes, socks, long-sleeved shirt),
chemical resistant gloves, no respirators, and either a "SouWester" hat
or hooded tyvek jacket.  Bayer Crop Protection, the primary registrant
for carbaryl, is a member of the AHETF so there are no data compensation
issues related to the use of MRID 464482-01 in this assessment.  A data
evaluation record exists for this study and can be referred to if
additional information regarding this study is desired (i.e., D316628;
Dated May 10, 2006).  Arithmetic mean unit exposure values were used in
these calculations from the study as recommended in the data evaluation
record.

	The purpose of this study was to develop data that could be used to
predict exposures based on clothing/personal protective equipment
scenarios that are not currently available in the Pesticide Handlers
Exposure Database (PHED) and not routinely considered in Agency risk
assessments for this job function.  In PHED, the airblast application
scenarios commonly employed (similar to those monitored in MRID
464482-01) involve (1) the use of double layer clothing, chemical
resistant gloves, respirators, and no head protection or (2) the use of
an enclosed cab tractor.  The carbaryl risk assessment (D287532; Dated
March 14, 2003) provided risk estimates based on these scenarios and it
was found that the Agency in its risk management decision desired the
use of enclosed cabs as a result.  However, as indicated in the record
of public comments (see www.Regulations.gov) related to the carbaryl RED
decision, a number of stakeholders voiced concerns (e.g., US Apple) over
the requirement for enclosed cabs based on two key issues including (1)
cost of closed cab tractors is prohibitive and (2) smaller, overgrown
tree canopies in many orchards/groves preclude the use of closed cab
equipment because these machines will not easily fit through rows for
application.  As a result of these concerns, the Agency has developed
risk estimates based on MRID 464482-01.

	

	The risk calculations which have been completed for the purposes of
this assessment are included in Appendix A in their entirety.  The basic
inputs for hazard, acres treated, and application rates remain unchanged
from the previous carbaryl risk assessment (D287532; Dated March 14,
2003).  In Appendix A, both PHED and MRID 464482-01 unit exposure values
were used for the calculations for comparative purposes.  The results
based on PHED are identical to those presented in the 2003 risk
assessment.  Both noncancer and cancer risk estimates were calculated. 
Noncancer risks (i.e., MOEs or Margins of Exposure) are summarized in
Table 1 below while cancer risks are summarized in Table 2.

Table 1:  Summary Of Noncancer Risks For Carbaryl Airblast Applicators
Based On PHED & MRID 464482-01

Application Target/Crops	Application Parameters	PHED - Based MOEs

[Included in D287532]	MRID 464482-01 Based MOEs

For Open Cab Airblast Application

	Rate

(lb ai/acre	Acres Treated	Open Cab Airblast

(double layer, gloves, PF 10 respirator, no hat)	Enclosed Cab With
Normal Work Clothing

(Eng. Control)	Open Cab Airblast

(double layer, gloves, no respirator,  "SouWester" hat)	Open Cab
Airblast

(double layer, gloves, no respirator, hooded tyvek jacket)

Citrus (CA 24C)	16	40	15.7	105	16.6	28.1

Citrus	7.5	40	33.6	224	35.4	60.0

Nut Trees	5	40	50.4	337	53.1	90.0

Pome & Stone Fruit (Max.)	3	40	83.9	561	88.5	150

Grapes	2	40	126	841	133	225

Pome & Stone Fruit (Avg.)	1.1	40	229	1529	241	409

Note:  Target MOE (i.e., MOE where risks are not of concern) is 100. 
These values are summarized from Table 8 in Appendix A.



Table 2:  Summary Of Cancer Risks For Carbaryl Airblast Applicators
Based On PHED & MRID 464482-01

Application Target/Crops	Application Parameters	PHED - Based MOEs

[Included in D287532]	MRID 464482-01 Based MOEs

For Open Cab Airblast Application

	Rate

(lb ai/acre	Acres Treated	Open Cab Airblast

(double layer, gloves, PF 10 respirator, no hat)	Enclosed Cab With
Normal Work Clothing	Open Cab Airblast

(double layer, gloves, no respirator,  "SouWester" hat)	Open Cab
Airblast

(double layer, gloves, no respirator, hooded tyvek jacket)

Citrus (CA 24C)	16	40	5.6 x 10-6	8.2 x 10-7	3.9 x 10-6	2.6 x 10-6

Citrus	7.5	40	2.6 x 10-6	3.9 x 10-7	1.9 x 10-6	1.2 x 10-6

Nut Trees	5	40	1.7 x 10-6	2.6 x 10-7	1.2 x 10-6	8.2 x 10-7

Pome & Stone Fruit (Max.)	3	40	1.0 x 10-6	1.5 x 10-7	7.4 x 10-7	4.9 x
10-7

Grapes	2	40	7.0 x 10-7	1.0 x 10-7	4.9 x 10-7	3.3 x 10-7

Pome & Stone Fruit (Avg.)	1.1	40	3.8 x 10-7	5.7 x 10-8	2.7 x 10-7	1.8 x
10-7

Note:  Target cancer risk is 1x10-6.  These values are summarized from
Table 10 in Appendix A and represent the risks for professional
applicators (i.e., 30 days/year = frequency of use).  Risks for private
growers (i.e., 10 days/year = frequency of use) are available in
Appendix A/Table 9 for comparison.  The trends identified in the results
for professional and private users are similar.



	The noncancer risk estimates based on MRID 464482-01 still remain of
concern for all but the lowest application rates considered (i.e., ~3 lb
ai/acre or less depending upon hat type used).  For all use scenarios,
risks are of slightly less concern than for the corresponding PHED-based
values based on high levels of personal protective equipment yet are
still significantly lower than those associated with the use of enclosed
cab tractors.  The trend for cancer risks is similar although it should
be noted that cancer risks are of much less concern because all cancer
risks based on MRID 464482-01 are similar to or less than 1x10-6.

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