UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

MEMORANDUM 

Date: 08-AUG-2013 

OFFICE OF CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

SUBJECT: Prometryn: Response to Comments on the Human Health Assessment 

Scoping Document. 

PC Code: 080805 

Decision No.: 479824 

Petition No.: N/A 

Risk Assessment Type: N/A 

TXR No.: N/A 

MRID No.: N/A 

DP Barcode: 0412527 

Registration No.: N/A 

Regulatory Action: Registration Review 

Case No.: 467 

CAS No.: 7287-19-6 

40 CFR: § 180.222 

FROM: Kelly M. Lowe, Environmental Scie~ist :-

Sarah J. Levy, Chemist~ C) 

Risk Assessment Branch 1 (RAB 0 

Health Effects Division (HED, 7509P) 

THROUGH: 

George 

Dana Vogel, 

F. Kramer, 

Acting 

Ph

Branch 

.D., Senior 

Chief 

Chemist 

~5= ~ ~ RAB 1/HED (7509P) 

TO: Christina Scheltema, Chemical Review Manager 

Pesticide Re-Evaluation Division (PRO) (7508P) 

The HED Prometryn Risk Assessment team has received comments on the Prometryn 

Registration Review Scoping Document (EPA Docket ID: EPA-HQ-OPP-2013-0032-0011) and 

attached is HED's response to comments. Comments relevant to HED's scoping document were 

provided by Syngenta. The Agency has considered these comments and will utilize them, along 

with any newly available data, during the registration review of prometryn. 

Page I of4 

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Prometryn Response to Comments DP# 412527 

Comment #1: 

EPA Statement: (Page 3) "After preliminary review ofthe metabolism in rice study, it 

appears that the metabolism in rice presents a different metabolic profile than the celery 

and cotton profiles; therefore, HED is still requesting a root crop metabolism study." 

Syngenta Comment: A root crop (carrot) metabolism study is being conducted per 

EPA's request. However, we respectfully request clarification regarding the conclusion 

that prometryn's metabolic profile in rice is different than that in cotton and celery. In 

HED's response to the prometryn metabolism in rice study, HED concluded that 

prometryn's metabolic profile in rice was qualitatively different than that in celery and 

cotton and that in celery and cotton parent was the major residue, while in rice metabolite 

GS-17794 was the major residue. We believe that the rice metabolism study shows a 

qualitatively similar metabolic profile to that of cotton & celery. Furthermore, we 

believe that the quantitative differences HED noted can be attributed to normal variance 

that is commonly seen in metabolism profiles of different crops. Should the carrot 

metabolism study reveal a similar metabolic profile to that of rice, cotton and celery, 

prometryn will have four metabolism studies showing a similar metabolic profile in four 

dissimilar crops. We would like confirmation that if the above determination is made by 

HED, further crop metabolism studies with prometryn will not be required at that time. 

HED's Response: HED agrees with Syngenta that prometryn's metabolic profile appears 

similar in cotton, celery, and rice. However, HED misstated that the profile was 

qualitatively different. The statement should have read that the metabolic profile in rice 

was quantitatively different in rice than that in celery and cotton - not qualitatively 

different. HED agrees that if the root metabolism study shows that the metabolic profile 

is qualitatively similar to the other metabolism studies submitted, additional metabolism 

studies involving root crops will likely not be requested. 

Comment #2: 

EPA Statement: (Page 7) "HED is also requesting a ruminant feeding study at this time 

since the livestock dietary burden could change significantly pending the results of the 

root crop metabolism study." 

Syngenta Comment: Based on the qualitatively similar metabolic profiles demonstrated 

in cotton, celery and rice, there is no reason to believe that the carrot metabolism study 

will indicate the need for a ruminant feeding study. Should the carrot study reveal a 

metabolic profile with qualitatively significant differences, we would like to discuss the 

appropriateness of a ruminant feeding study with HED at that time. 

HED's Response: HED agrees with Syngenta that the need for a ruminant feeding study 

should be evaluated after the carrot (or other root crop) metabolism study is submitted 

and evaluated by HED. 

Comment #3: 

EPA Statement: (Page 19, Attachment 4) "Celeriac; Postemergence. Up to the 6- to 8-

leaf stage; Max App Rate: 4 lb ai/A." 

Syngenta Comment: Syngenta's prometryn product labels specify a maximum single 

application rate to celeriac of 2 lb ai/ A. We are not aware of any prometryn product 

labels that allow a single application rate of 4 lb ai/ A to celeriac. 

Page 2 of4 
Prometryn Response to Comments DP# 412527 

HED's Response: There is a registered product (Prometryn 4L; EPA Reg. #66222-15; 

label date 2-JUL-2012) that allows for one postemergence application to celeriac at a 

maximum rate of up to 8 pts ( 4 lb ai) per acre up to the 6 to 8 leaf stage. This is not a 

Syngenta product. 

Comment #4: 

EPA Statement: (Page 19, Attachment 4) "Cotton; Groundboom; Preplant; Max App 

Rate: 1 lb ai/A." 

Syngenta Comment: The Section 3 Caparol4L label allows for groundboom or aerial 

preplant incorporated application to cotton at up to a maximum single application rate of 

2.4 lb ai/A in AZ, CA, and NM only. 

HED's Response: HED agrees that the maximum rate identified in the scoping document 

for preplant ground applications to cotton is not in fact the highest rate allowed by 

prometryn FIFRA Section 3 labels. The 1-lb ai/ A rate was the highest rate identified for 

SLN uses. HED will use the higher Section 3 registered rates in the registration review 

assessment. 

Comment #5: 

EPA Statement: (Page 19, Attachment 4) "Cotton; Ground boom; Postemergence; Max 

App Rate 1.6 lb ai/A." 

Syngenta Comment: The Section 3 Caparol4L label allows for groundboom or aerial 

post-emergence application to cotton at up to a maximum single application rate of2.4lb 

ail A in CA only for winter weed control. 

HED' s Response: The postemergence rate identified in Attachment 4 is meant to 

represent the maximum label rate allowed for applications made after the crop has 

emerged. The Caparol4L label appears to allow a rate of2.4 lb ai/A after weeds have 

emerged, but before the crop has emerged. HED will confirm the prometryn use pattern 

during registration review to ensure the correct application rate is used in the human 

health risk assessment. 

Comment #6: 

EPA Statement: (Page 20, Attachment 4) "Leafy petioles crops (cardoon, celery, Chinese 

celery, celtuce, Florence fennel, rhubarb, Swiss chard)." 

Syngenta Comment: The crops cardoon, celtuce and Swiss chard were removed from all 

Syngenta prometryn product labels. Rhubarb is also not labeled as part of this crop 

group, as different directions for use are given in a specific rhubarb section. 

HED's Response: It is noted that the Syngenta Caparol4L label (EPA Reg. #100-620; 

dated 27-SEP-201 1) does not include use on cardoon, celtuce, and Swiss chard. 

However, at the time of completion of the scoping document (28-FEB-2013), another 

product label for Prometryn 4L (EPA Reg.# 66222-15; dated 2-JUL-2012) did include 

this crop group in the use directions. Label amendments for this product were approved 

by EPA in March 2013. The most recent prometryn labels will be reviewed for 

registration review and the human health assessment will reflect the current prometryn 

Page 3 of4 
Prometryn Response to Comments DP# 412527 

labels. 

Comment #7: 

EPA Statement: (Page 20, Attachment 4) "Leafy petioles crops (cardoon, celery, Chinese 

celery, celtuce, Florence fennel, rhubarb, Swiss chard); Post-transplant Max App Rate: 

3.2lb ai/A." 

Syngenta Comment: Syngenta's prometryn product labels specify a maximum single 

application rate to celery, Chinese celery and Swiss chard of 1.6 lb ai/A. While some 

non-Syngenta prometryn labels allow application to celery at an application rate of up to 

3.2 lb ai/ A, we are not aware of any prometryn product labels that allow a single 

application rate of3.2 Jb ai/A to the leafy petioles crop subgroup. 

HED's Response: According to the label for Prometryn 4L (EPA Reg. #66222-15), 

applications to transplanted leafy petiole crops can be made at up to 6.4 pt/A in HI (3.2 lb 

ai/A). 

Comment #8: 

EPA Statement: (Page 20, Attachment 4) "Leafy petioles crops (cardoon, celery, Chinese 

celery, celtuce, Florence fennel, rhubarb, Swiss chard); Postemergence Max App Rate: 1 

lb ai/A." 

Svngenta Comment: In the post-emergence directions for use section for celery, Chinese 

celery and Florence fennel on the Caparol 4L label, the maximum single application rate 

is 1.6 lb ai/ A, instead of 1.0 lb ai/ A. 

HED's Response: Based on the Caparol4L label (EPA Reg. #100-620; dated 27-SEP20 11 ), the highest application rate for postemergent broadcast applications is 2 pt/ A or 1 

lb ai/ A. According to the product label, these applications are allowed after the crop has 

2-5 true leaves and can be made over the top of the crop. This same product label 

appears to allow a higher rate of 3.2 pt/ A or 1.6 lb ai/ A for pre-emergence applications. 

Comment #9: 

EPA Statement: (Page 20, Attachment 4) "Pigeon peas; Application Equipment: 

Ground boom." 

Syngenta Comment: The Caparol 4L label also allows aerial application to Pigeon Peas 

in Puerto Rico only. 

HED's Response: HED agrees that aerial application should be considered in the 

assessment as an additional application method for pigeon peas. This will be reflected in 

the registration review assessment. 

Comment# 10: 

Svngenta Comment: We have evaluated the MRLs established in the US, Canada, EU, 

and Australia and have compiled this information in Appendix 1. 

HED's Response: HED will work to harmonize tolerances and minimize trade irritants 

during registration review. 

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