UNITED STATES ENVIRONMENTAL PROTECTION AGEN C Y WASHINGTON D .C

. , 20460

OFFICE OF CHEMICAL SAFETY AND POLL U T I O N PREVE N TIO N



### MEMORANDUM

SUBJECT:



### FROM:

THRU:

TO: June 24, 2015 PC de: 116001 , 116002 ,1160 04 DP Barcode: 426692

Larry Liu, PhD, Chemist

# ~ Bria n Montague, Fishery Biologist 

## d

_ -**~ :..;:~**  Env ir onmental Risk Branch 5

### ~**~"'f!** E n v ironmental Fate and Eff ec t s Di v i s i o n ( 7507P )

Mah Shamim

, Branc h Chief Env ironment al Risk Branch 5 E n v ironm enta l Fa t e and Effec t s Di vis ion (750 7P )

Brittany Pruitt

, Chem i cal Review Manager Av i vah Jacob

, Team Leader

, RMIB3 Pesticide R e

- evaluatio n Di vis i o n (7508P)

EFED Triclopyr team has reviewed comments r eceived from the Californ ia Stor m water Quality Association (CASQA), the Sa n Francisco Bay Re giona l Water Qu a lit y Co ntrol Board (a CASQA member), Dow AgroSciences LLC, and the Ph ys i c i ans Co mmitte e fo r Respon sib l e Medicine. The team r ecogn i zes th at though so m e of th e co mm ents made by CASQA are specific to Triclopyr uses and detections i n Califo rni a, many of the comments are not chemically specific

, but do indicate the importance of considering urban use scenarios in future risk assessments for
any c h e mical s und e r go in g r eg i strati on review. In that con t ext the Tr i c lop yr Eco l ogica l Ri sk
team wi ll mak e a tt e mpt s to better characterize these u se pattenw w h ere current mode lin g scenarios can be applied o r modified. In addition, urban incidents and monitoring data for all U.S. states , including California

, w ill be assessed as part of the registration rev i ew process. Both CASQA and the Sa n Francisco Bay R egional Water Qu a li ty Control Board have a l so cited

a dditional inform a tion re g ardin g the toxi c it y of the TCP d eg r adate t o th e freshwat e r inverteb rate, Daphnia ca rinat a w hich w ill be eval uat ed a l ong w ith the curre nt aquatic data set for this degrada t e. D ow AgroSciences has comme nt ed o n issues related to a soil ph oto l ysis re view (MRID 44329901) as well as requirements for H oneybee 1 0 day chro ni c and l arva l t esting

curre ntly requi red fo r outdoor u se c h em i cals. T h e Ph ys i c ian s Committee ha s c it ed existence of a European te s t fo r Oral Toxicity to Pa sser in e spec i es w i t h T ricl opyr b utoxy ethy l este r and recommended that this study be used to fulfi ll the 850.2100 FIFRA data requirement. EFED has responded below to the indi vidual comments by category and source for the comment.Comments Regarding Monitoring , Exposure Modeling and Environmental Fate

CASQA and SFB Comment regarding Urban Runoff: Submitters (CASQA and SFB) indicated that the risk hypothesis and conceptual model do not recognize triclopyr application to impervious surfaces and storm drainage system design. Also, CASQA requested clarification regarding how the E

- FAST and the Surf ace Water Concentration Calculator (SWCC) would be used and/or modified for modeling urban use and subsequent run

- off from pervious (turf/landscape) and impervious surfaces (around buildings and throughout rights

- of

- way) in the measures of exposure. CASQ A cited an article (M.P. Ensminger, et. al. 2013) 1 in which triclopyr and other 6 3 pesticides or associated degradates were examined between 2008 and 2011 in urban surface waters and sediments in three urban areas in California. As reported, these three areas (i.e., Sacramento, San Francisco Bay, and Orange County) were not affected by agricultural inputs. Results indicated that triclopyr was one of the three most frequently detected herbicides in surface water (the other two herbicides were 2,4

- D and di camba)

. Triclorpyr was found more frequently in southern California (Orange County with 82% detection frequency) than in northern California (Sacramento with 62% detection frequency and San Francisco Bay with 40% detection frequency). They also stated that more monitoring information could be obtained from California Department of Pesticide Regulation.

EFED Response: EFED will consider relevant submitted routes of exposure, including applications on impervious surfaces, in the revised risk hypothesis and conceptual model. The article by M.P. Ensminger, et. al. (2013) will be included an d considered in making decisions on the registration review for this chemical.

At the present time, EFED considers the use of the impervious scenario (a PRZM modeling scenario) as the mo st suitable available modeling approach for impervious runoff. The PRZM impervious scenario may be used in the tier 2 coupled aquatic models SWCC along with a residential or other suitable scenario such as rights

- of

- way (ROW) to obtain EECs. The conceptu al model for the residential scenario integrates simultaneous modeling of the individual use scenario with an impervious scenario. This approach assumes that no watershed is completely covered by either the 1⁄4 acre lot (the basis for the residential scenar io) or undeveloped land (the basis for the ROW scenario) for residential and ROW use patterns; therefore, differential amounts of runoff will occur within the watershed. The impervious scenario was developed to represent the paved areas within a watershed not including roads, parking lots, sidewalks, and buildings outside the 1⁄4 acre lot (the 1⁄4 acre lot scenario accounts for impervious surfaces such as buildings within the represented area). By modeling a separate scenario for impervious surfaces, it is al so possible to estimate that amount of exposure that could occur when the pesticide is oversprayed onto this surface. Using two scenarios in tandem requires post

- processing of the modeled output in order to derive a weighted EEC that represents the contri bution of both the pervious ( i.e. , residential and ROW scenarios) and the impervious surfaces. Exposure from both scenarios can also be weighted and aggregated. The daily time series from each model run should be copied from the times series file (NAME_T S.out)

1 Ensminger MJ.P. R. Budd, K.C. Kelley, K.S. Goh . 201 3

. Pesticide occurrence and aquatic benchmark exceedances in urban surface waters and sediments in three urban areas of California, USA, 2008

– 2011 ( Urban and Agricultural Sources of Pyrethroid Insecticides to the Sacramento

- San Joaquin Delta of California )

. Environ Monit Assess (2013) 185:3697

– 3710

.generated from the PRZM graphical user interface (PE5.pl) into the spreadsheet provided. The time series data are then weighted based on percentage of impervious surface, the percentage of the pervious surface treated, and an adjusted time series i s created. Rolling averages for the relevant durations of exposure ( e.g. , 21 day and 60 day averages) are calculated, and the relevant

one

- in

- ten year return EEC is generated from these distributions. The Agency intends to use available non

- agricultural u se and usage data, such as the Kline database, the California Department of Pesticide Regulation’s (CDPR) Pesticide Use Reporting Data and Pest Control Operator’s usage survey (the most current database includes 2012 use information) , and the Residential J oint Venture Task Force homeowner survey data, to make certain reasonable assumptions regarding various applications and information related to urban/residential use. Due to the limited data available, exposure to the environment and uncertainties will be characterized. Detailed information on non

- agricultural use and usage of triclopyr products, specifically triclopyr BEE , would be useful in order to reduce those uncertainties for the final environmental risk assessment for triclopyr

. Dow AgriSciences C omment: Dow indicated that TCP (a minor degradate) cited in the PF was for dark control in the soil photolysis study (MRID 44329901) and less TCP was detected in the sunlight

- exposed samples. In dark control samples, TCP reached a maximum of 5.1% AR (19 DAT) and levels at study te rmination (31 DAT) were 4.6% AR. In sunlight

- exposed samples, TCP reached a maximum of 1.9% AR (3 DAT) and levels at study termination were 1.2% AR.

EFED Response: S ince the levels of TCP detected in the sunlight

- exposed samples were lower than those in the dark control in the soil photolysis study, it appears that natural sunlight has no direct effects on the formation of TCP. EFED will revisit the endpoints cited i n the Problem Formulation and make corrections as needed.

### Comments Regarding Effects Studies:

CASQA Comment: Though CASQA generally supports the fate and toxicity assessments, some minor modifications were suggested

. CASQA has cited a study for TCP wit h Daphnia carinata (Caceres, T. 2007. Water Research, Nov;41(19):4497

- 503) that shows it to be more toxic than the tested paren t (which in this case was Chlorpyrifos).

EPA Response: This open literature study, which investigates the potential synergi stically additive toxicity of Chlorpyrifos and TCP together, will be requested for review. This study citation has also been provided to the Chlorpyrifos Registration Review team. T he Agency has evaluated laboratory data for Daphnia magna with the TCP de gradate (MRID 41829005) and this study already shows TCP to be more toxic than the TEA salt and Triclopyr Acid, but less toxic than the Butoxyethyl ester. However, no data has been reviewed to show the potential for synergistic increase in toxicity when both triclopyr and TCP are present together.
CASQA Comment: CASQA is requesting that a cumulative aquatic TCP risk assessment be done for chlorpyrifos to allow for a more accurate and separate aquatic benchmark for this degradate.

E PA Response: I n general , OPP has not done separate risk assessments for metabolites, even though they may be common to multiple parent actives. We do combine the toxicity and fate data for a single degradate from all data submitted by registrants for support of their actives, b ut use patterns, use sites and application rates may differ and therefore alter the exposure levels for the degradate under the criteria specific to these uses.
CASQA Comment: Exp and the data requirements for TCP to include chronic testing with Daphnia carinata in addition to Fish Early Lifestage testing.
EFED Response: The Agency has already received a TCP chronic toxicity study with Daphnia
magna (458861301) to support Triclopyr actives and this study is under review. I f acceptable this study should p rovide an adequate set of endpoints for assessment of freshwater invertebrate hazard potential for any active ingredient for which TCP is a degradate of concern

. Dow AgroSciences Comment regarding Honeybee Larval Chronic Toxicity Testing requirement with T riclopyr Acid technical.

Comment: As triclopyr is an herbicide, does not have an insecticidal mode of action, and is not an insect growth regulator, it is not expected to impact terrestrial invertebrates such as honeybees. This is further corroborated by the following:

1. Triclopyr acid is practically non

- toxic to honeybees based on acute oral and contact toxicity tests (see comment below). 2 . Once plant uptake occurs, triclopyr acid is quickly conjugated and forms polar acid labile conjugates. Research demonstrated that < 0.06% applied dose was detected in fruit (Yackovich and Lardie 1996) and 0.006% of triclopyr’s applied dose was detected in ryegrass seed (Yackovich et al. 1993). Based on this evidence, triclopyr acid does NOT preferentially translocat e to plant flowers, seeds, and/or fruit. Since triclopyr does not preferentially move tountreated plant areas as well as its rapid conjugation, the likelihood of adult honeybees
t ransporting triclopyr residues to the hive via contaminated nectar and polle n is negligible thus eliminating potential larval exposure. Furthermore, since triclopyr acid is practically non

- toxic to adult honeybees, it is feasible that triclopyr acid would have minimal, if any, impact on larval development or survival.

3. Finally, triclopyr is primarily used in rice, rang eland and pasture, rights

- of

- way , forestry, and turf for the control of broadleaf and woody plants. Herbicide applications rarely occur during flowering growth stages due to grazing and other mechanical inputs and, therefore, foraging worker bees would have minimal, if any, exposure to triclopyr residues from treated crops thus reducing the probability of transporting contaminated nectar and pollen back to the hive.

DAS disagrees that an acute and chronic larval t oxicity tests are necessary based on the available information.
EFED Response: Dow has cited what appear to be residue tolerance studies in fruit and seeds as well as previously evaluated honeybee acute studies

, as a basis to dismiss the requirement as be ing unnecessary. The Pollinator Protection Policy currently be ing implemented for pesticides is not promulgated entirely for systemically acting chemicals, though this could be one criteria of

concern. The policy states

, “ In general, outdoor spray app lications are assumed to have a reasonable potential to result in exposure of adult bees and their brood (eggs, larvae, pupae) to pesticides if they are applied to pollinator attractive crops or drift to pollinator attractive plants during periods when bee s are likely to be foraging.” Exposure to residues in flowering plants ( invasive or native) is a criteria and direct spraying of Triclopyr products in rights of way, pastureland, forests, and rangeland could certainly present the potential for food source contamination for wild or commercially provided pollinators. To our knowledge there are no current label restrictions on applying Triclopyr products wh en target or non

- target plants are blooming. It is assumed that nectar or pollen could also be exposed to residues of triclopyr under these circumstances. In addition, acute contact and oral toxicity testing with adult bees do not necessarily reflect pot ential toxicity to developing larvae. In order to conduct Tier I assessment of pollinator risk

, chronic ef fects to adults and larval bees are considered . The registrant may wish to consult the Office of Pesticide Programs Guidance for Assessing Pesticide Risks to Bees implemented June 23, 2014 regarding determination for testing needs and assessment of exposure potential currently used by the Agency

.

Dow AgroSciences comment r egarding Honeybee Adult 10 Day Oral Chronic Toxicity Testing requirement with T riclopyr Acid technical.

Dow Comment: An adult honey bee acute oral and contact toxicity studies were conducted according to OECD guidelines 213 and 214 [Hahne 2001; Dingledine and Jaber 1985]. Overall, results from these tests indicate that triclopyr ac id is practically non

- toxic to bees based on the acute oral and contact 48

- hour LD 50 values of > 100 μg a.i./bee and > 100 μg a.i./bee, respectively. Furthermore, since acute effects were not observed, chronic effects would not be expected due to the absen ce of acute toxicity. These endpoints provide evidence that triclopyr is practically non

- toxic to adult honey bees thus chroniceffects are not anticipated. Therefore, DAS disagrees that the chronic adult oral tests are necessary based on the information p rovided. Studies can be provided to the EPA upon request.
EFED Response: The current 48 hour acute contact and oral toxicity testing using Triclopyr acid with adult bees may not reflect potential chronic toxicity to adult bees from longer term exposure to residues via ingestion of pollen or nectar. In order to conduct Tier I assessment of pollinator risk, chronic effects to adults and larval bees are considered. The registrant may wish to consult the Office of Pesticide Programs Guidance for Assessing Pes ticide Risks to Bees implemented June 23, 2014 regarding determination for testing needs and assessment of exposure potential currently used by the Agency.

Physicians Committee for Responsible Medicine comment r egarding Oral Toxicity Requirement for Passerine species 850.2100

. Comment: We have found existing data for the avian oral toxicity endpoint in passerines (850.2100). This study used 12 birds in each of the 5 concentrations, in addition to the control.

Citation: Holmes, SB, et al. “Effects of lethal and sublethal concentrations of the herbicide, triclopyr butoxyethyl ester, in the diet of zebra finches.” J Wildl Dis. 1994 Jul; 30(3):319

- 27.

“The 8

- day median lethal dietary concentration, LC50 (95% confidence interval), of TBEE to zebra f inches was 1,923 (1,627 to 2,277) mg/kg.”

If this data is not accepted by the Agency then we recommend that OECD Test Guideline 223, Avian Acute Oral Toxicity Test, be used as the protocol instead of EPA Guideline 850.2100 in the interest of reducing th e numbe rs of animals used by up to 61% . We also refer the registrant to the “Guidance for Classifying Studies Conducted Using the OECD Test Guideline 223 (TG223) (Acute Avian Oral Sequential Dose Study)” available on the Agency’s website.
EFED Response: T he study cited as an oral study appears to be a dietary study. The Agency does accept dietary studies as a substitute for guideline 850.2100 when oral studies are found to be impractical due to regurgitation issues or other problems encountered during the study

. Though there is guidance available regarding classification of OECD 223 studies, EFED generally recommends against reliance on TG 223 for passerine species since this guideline was not tested or validated for passerines.