Pyridaben Registrant Meeting

– 03

- 13

- 2013

- Nissan

- Canyon

- Gowan

- EPA Meeting Highlights Nissan, Canyon, Gowan, and US Environmental Protection Agency
March 13 , 2013

On March 13 , 2013 , at the request of Nissan, Canyon, and Gowan , the technical registrant s for pyridaben , representatives from the companies met for one hour with US Environmental Protection Agency (EPA) to discuss the data requirements required in the pyridaben data call

- in (DCI). During the presentation the registrants informed the EPA of the current status of the DCI and proposed several modifications to the testing required for ecological effects and fate data requirements. The registrants indicated protocols would be submitted for the review of the EPA.

# Pyridaben: EPA

- Nissan/Canyon Meeting
March 13, 2013

# Introduction

• Pyridaben

– Miticide /insecticide

– Used primarily on selected orchard crops

• Citrus

• Pears

• Pecans

• Apples


### • Primary Discussion Topics

– DCI requirements

• Nissan’s proposals and rationale for addressing DCI requirements

• Environmental fate requirements followed by ecotoxicology requirements

– Available data

# Pyridaben

• Key uses

– Citrus: 1 app/season, average 0.375 lbs a.i ./A ; timing depends on pests. Maximum allowable 0.5 lbs a.i ./A.

• Pests: citrus rust mite, citrus red mite

– Pears: 1 app/season, 0.375 lbs a.i ./A (mites); 1 app/season, 0.75 lbs a.i ./A (pear psylla ), timing depends on pests

• Pests: mites, pear psylla

– Pecans: 1 app/season, average 0.309 lbs a.i ./A , timing depends on pests, up to a maximum of 0.5 lbs a.i ./A

• Pests: Mites and aphids

– Apples: 1 app/season, average 0.309 lbs a.i ./A , timing depends on pests, up to a maximum of 0.5 lbs a.i ./A

• Pests: Mites

– Ornamentals: Maximum single application rate 6 oz/100 gal (equivalent to 0.281 lbs a.i ./A)

# Pyridaben

• Key physiochemical properties

– Water solubility: Very low; 10

- 20 ug a.i ./L

• Technical challenges for some studies, particularly studies conducted in seawater (lower solubility)



### – Soil adsorption: High binding to soil/sediment

– Susceptible to photodegradation : DT50<2d

– Susceptible to microbial degradation

– Low vapor pressure

– Application methods: Ground and Airblast

# EPA Ecotoxicology and Environmental Fate DCI Requirements

• Studies required include:

– Environmental Fate

• Aerobic soil metabolism (4 soils)

• Aerobic aquatic metabolism (2 sediments)



### – Key consideration:

• EPA believes that pyridaben is persistent in the environment based primarily on laboratory data

• Microcosm studies indicate otherwise

# Aerobic Soil Metabolism

• Several studies have been conducted on aerobic soil metabolism

• EPA has found deficiencies in all but one of these studies and has requested that testing be repeated

• Nissan initially proposes to conduct additional aerobic soil metabolism testing on a WA soil

– Major growth area for pome ;

– Correlates with soil dissipation data;

– High probability of obtaining ‘virgin’ soil



### • If results similar to previous results (route) Nissan proposes to reduce the number of soils used for additional aerobic soil metabolism testing

– Two soils total

– Testing with two labels

– Radiolabeled test material available

# Aerobic Soil Metabolism HLS Study Protocol and Questions

• Test substance: Two 14 C radiolabeled forms

• Test soil: To be obtained from a site in Washington, USA

• Application rate: 1.12 kg a.i ./ha (equiv. 1.12 ppm , 16 oz/A, max. rate )

• Conditions: At pF 2 to 2.5 at 20 o C in the dark

• Analysis: Duplicate samples per label will be taken at appropriate time intervals and identified and characterized if necessary.

• Sampling intervals: T 0 , 7, 14, 30, 60, 90 and 120 days

• If DT 50 is >120 days, additional sampling times such as at 180, 240, 300 and 365 days are required?

• If test interval > 120 days, concern about microbial viability

• Trapping media: Volatile metabolites including CO 2 will be trapped and quantified.

# Aerobic Aquatic Metabolism

• Aerobic aquatic metabolism previously conducted on two sediments

• EPA found deficiencies in previous studies and requested that the studies be repeated

• Nissan has concerns about microbial viability if use U.S. water and sediment and ship to HLS UK. Can EU water and sediment be used?

• Microcosm data available on the fate of pyridaben in aquatic systems

• Possible to use these data to address some of EPA’s questions concerning aquatic metabolism?

# Aerobic Aquatic Metabolism
HLS Study Protocol and Questions

• Test substance: Two 14 C radiolabeled forms

• Test sediment: To be obtained from two sites in USA? In the OPPTS GL two sediments to be used for this study are strictly defined.

• Application amount: 794 u g /vessel (equiv. 1.12 kg a.i ./ha, 16 oz/A) * The calculated concentration of pyridaben in water (110 u g /L) exceeds its solubility (22 u g /L). Is this acceptable?

• Conditions: Water/sediment volume ratio = 3/1 to 4/1 at 20 o C in the dark

• Analysis: Duplicate samples per label will be taken at appropriate time intervals and identified and characterized if necessary.

• Sampling intervals: T 0 , 1, 2, 7, 14, 30, 60 and 100 days * If DT 50 is >100 days, additional sampling times such as at 150, 240, 300 and 365 days are required?

• Trapping media: Volatile metabolites including CO 2 will be trapped and quantified.

# Microcosm Data

• Nissan has conducted three different microcosm studies

– Two focus on effects on biota

– One focuses on fate in an aquatic system

– Nissan believes these data provide useful, informative information concerning the fate and effects of pyridaben in aquatic systems

– Results are consistent among studies

– Nissan urges EPA to use these data in its evaluation of pyridaben

# Pyridaben

• Ecotoxicology data requirements

– Seedling emergence

– Vegetative vigor

– Estuarine

- marine fish acute toxicity ( sheepshead )

– Estuarine

- marine invertebrate chronic toxicity ( mysid )

– Estuarine

- marine fish chronic toxicity ( sheepshead )

– Acute sediment toxicity

– Bioconcentration in oysters

– Field testing for pollinators

# Seedling Emergence and Vegetative Vigor

• Tier I seedling emergence and vegetative vigor testing conducted at 0.5 lb a.i ./A

– NOEC not obtained for three species in seedling emergence testing corn, lettuce, and tomato

– NOEC not obtained for four species in vegetative vigor testing

– Nissan propose to conduct Tier II seedling emergence testing with corn, lettuce, and tomato

– Nissan propose to conduct Tier II vegetative vigor testing with soybean, tomato, oat, ryegrass

# Estuarine

- marine acute toxicity

• Testing has previously been conducted on sheepshead minnows

– Less sensitive than freshwater species

– LC50 approximately equal to water solubility limit for technical pyridaben

– EFED suggested conducting testing with TEP to address the water solubility limitation

– Nissan willing to conduct testing with TEP

– Question: TEP is a wettable powder, how does this resolve solubility issue?

– Question: How will EFED conduct the risk assessment if results with TEP indicate LC50>water solubility limit?

• Validity of RQs calculated with toxicity data > water solubility?

# Mysid Lifecycle Testing

• Does the non

- persistence of pyridaben under use conditions enter into decision concerning these data requirements

• Conditional data requirements according to 40CFR

• Existing mysid acute study NOEC=0.14ug a.i ./L, LOAEC=0.18 ug a.i ./L



### • Existing mysid lifecycle study: NOEC = 0.13 ug a.i ./L

– EFED requested a repeat study b/c NOEC = high test concentration

– Based on available data, next highest test concentration in dose scheme would be an effect concentration

– How much would be gained in repeating this test?

# Sheepshead ELS Testing

• Current acute toxicity data indicates LC50>limit of water solubility

• Acute to chronic ratio based on freshwater species

– Is this a viable approach coupled with a sheepshead acute study



### • Rapid loss of pyridaben from the water column

– DT50 < 2 days



### • Sheepshead less sensitive than freshwater species

• Re acute to chronic ratio

• Conservative value based freshwater species?

# Acute Sediment Toxicity

• Nissan proposes to conduct acute sediment toxicity testing

• Question concerning species selection

– Guidelines indicate chironomids or amphipods as test species

– Plan to conduct using chironomids

# Bioconcentration in Oysters

• Request based on results of fish bioaccumulation testing and perception of persistence

– Standard bioaccumulation testing indicated a BCF = 342

- 439; BCF from fish lifecycle testing = 1168

– 3780

– Microcosm data indicates that pyridaben not persistent in aquatic systems



### • EPA has expressed concern about bioaccumulation in sediment

- dwelling organisms

• Oysters are filter feeders rather than deposit feeders

– EPA’s oyster bioaccumulation guideline is similar in design to the standard fish bioaccumulation guideline

# Bioaccumulation in Oysters

• Based on EPA concerns about sediment dwellers and partitioning of pyridaben to sediment, Nissan proposes an alternative test:

• OECD 315, Bioaccumulation in sediment

- dwelling benthic oligochaetes

– More realistic experimental design than the oyster bioaccumulation test (3 compartments)

– Directly addresses bioaccumulation from the ingestion of sediment containing a pesticide

– Directly addresses bioaccumulation in sediment

dwelling organisms from pore water

# Field Testing with Pollinators

• While Nissan recognizes this data requirement is based on the acute contact toxicity results, it is not clear whether EPA’s concern is for adults or larval stages

• Nissan has submitted a bee brood feeding study (hive study) to EPA to address this data requirement

• Nissan believes that this study will address EPA’s questions concerning effects on bees

• Nissan proposes to wait until EPA reviews the submitted study before conducting additional work

# Conclusion

• Nissan is moving ahead with studies to address the pyridaben DCI

• Nissan has previously submitted microcosm data that provides useful information to relevant to EPA’s review of pyridaben

• Nissan has proposed some modifications to the testing required in the DCI and appreciates EPA’s feedback concerning those modificationsStudy initiation Study completion Final report OCSPP850.4100 Terrestrial plant (seeding emergence) 08/15/2013 09/15/2013 January 201 4

OCSPP850.4150 Terrestrial plant (vegetative vigor) 08/22/2013 09/22/2013 January 201 4

OCSPP850.1075 Estaurine/marine fish acute 0 7/1/2013 0 7/15/2013 December 2013

OECD.315 Bioaccumulation August, 2013 October 2013 March 201 4
OCSPP850.1735 Acute sediment organism November 2013 November 2103 March 201 4 Expected study schedule