Fipronil Focus Meeting Notes - Docket 

May 14, 2013 1:00-2:00 pm

Non-EPA attendees

BASF: Jack Arthur, Amy Dugger-Ronyak, Charles Hastings, Jeff Holmsen, Scott Jackson, Scott Lane, Spencer 

Mortensen

Bayer: Ann Blacker, Jan Brill, Karen Sheerer

Gharda Chemicals, LTD: Ram Seethapathi

Hisun: James Messina (Exponent)

Horizon Vally and Prodigy: Leanne Pruett (Pyxis RC)

Irvita: Anne Turnbough (CSI)

Norbrook: Lee Whaley

Raymat Materials: Iain Weatherston (J&T Associates)

Virbac: Michelle Foster

EPA attendees

RD: Richard Gebken

PRD: Susan Bartow, Cathryn Britton, Kevin Costello

HED: Wade Britton, William Irwin, Mike Metzger, Ideliz Negron, Shanna Recore, Ana Rivera-Lupianez

EFED: Ed Odenkirchen, Robin Sternberg, Stephen Wente

BEAD: Sepehr Haddad

Participating by phone

BASF: Charlotte Sanson, Ralph Warren

Gharda: Frank Sobotka

Merial: Jim Gerhart, Jay Harriman, Karen Mardis

1. Introductions

2. Discussion of EPA’s “Focus” Questions

The purpose of a focus meeting is to clarify use and label uncertainties early in the registration review 

process. Several questions were provided to the registrants before the meeting (see below) regarding 

fipronil use, application rates, and a required study. These questions were discussed. The registrants 

will also provide written answers to the questions where possible.

• Question 1 – Many of the labels give application rates in mass/placement for outdoor bait station 

applications. OPP would assume that the fipronil is removed by the insects and spread out over a 

surface area of land (i.e., in the insect carcasses). Therefore, we would need to know the number of 

placements per acre, 100 ft2

, or 1000 ft2 and how frequently the bait is replaced to calculate an 

annual application rate. Does the registrant have any information on this? Would they be willing to 

put it on their labels?

- Bayer is the only registrant with the outdoor bait station use. Bayer representatives indicated 

that they did not have data to directly answer the questions, but offered biological opinions in 

writing.
• Question 2 – The Frontline spray treatment product application rate for cats and dogs is given as 2 

pump/1 lb body wt. Is this similar to a spot treatment (applied to a small area of the animals back)? 

This may be a use that would not trigger an ecological assessment, but it would be good to discuss 

at the meeting. If we were to assess, the application rate would need to be converted to mass of 

A.I./1 lb body wt. In that case, do the registrants have any recommendations for better estimating 

the application rate?

- The registrant, Merial, provided a written response to this question.

• Question 3 – Several uses (christmas tree plantations, forest trees (softwoods, conifers), ornamental 

and/or shade trees, ornamental herbaceous plants, ornamental non-flowering plants, ornamental 

woody shrubs and vines, and potting soil/topsoil) have application rates in lbs/ft3 (mass/volume). 

Do the registrants have any recommendations for estimating maximum mass/area? Are all of these 

uses associated with potted plants? OPP would probably assume a 6 inch depth of soil to convert to 

mass/area. Is this appropriate in the registrants’ view?

- Bayer representatives responded that they did not have an objection to the 6 inch depth and 

that they would provide information regarding a maximum mass/unit area.

• Question 4 – Several uses (commercial/institutional/industrial premises/equipment (outdoor), 

household/domestic dwellings outdoor premises, industrial/construction areas (outdoor), 

ornamental and/or shade trees, and wood protection treatment to buildings/products outdoor) 

have application rates in lbs/gal (mass/volume). Do the registrants have any recommendations for 

estimating maximum mass/area?

- OPP agreed to provide product numbers for the specific uses in question.

• Question 5 – USEPA calculated application rates for the drainage system use are over 1,000 lbs/acre. 

Rates have also been calculated as mass/drain. Do the registrants have any recommendations for 

better estimating maximum mass/area? Potentially, it may be that OPP simply needs more 

information or a better description of this use.

- OPP agreed to provide product numbers for the specific products with the use in question.

• Question 6 – Many of the labels give application rates in volume/mound for fire ant applications. 

OPP would assume that the fipronil is removed by the insects and spread out over a surface area of 

land (i.e., in the insect carcasses). Therefore, we would need to know the number of mounds per 

acre, 100 ft2

, or 1000 ft2 to calculate an annual application rate. Do the registrants have any 

information on this? Would they be willing to put it on their labels? Also, regarding ant mound 

treatments, information on the number of mounds treated per surface area would be beneficial for 

our assessments.

- The registrants indicated that non-bait fipronil products are not used for fire ant mound 

treatment. Labels should be verified to see if this use is still listed.
• Question 7 – According to the recent AHETF Seed Treatment Survey, corn seed is treated for over 

240 days per year. Is fipronil being used to treat corn seed all year round?

- The registrants indicated that 240 days per year was an extremely high estimate. Fipronil is only 

used to treat corn seed for export. BASF representatives indicated that they would check with 

the end users to get an accurate number of days that fipronil is used to treat corn seed.

• Question 8 – OPP would like to discuss the 90-day dermal study (870.3250) with respect to HASPOC

recommendations for the study. In January, 2012, the HASPOC provided recommendations for the 

study (TXR # 0056207). Specifically, the text from the document recommended,

“IV. HASPOC RECOMMENDATIONS:

The HASPOC agreed with the team that a 90-day dermal study is required for fipronil for the 

following reasons: (1) repeated intermediate-term (1 -6 month) exposure to fipronil is likely based 

on the use pattern and updated Residential SOPs; (2) there is increasing toxicity with exposure 

duration, and thus the 21-day study is not adequate to assess exposures up to 6 month; and (3) 

extrapolating from a subchronic oral rat study is not appropriate because the rabbits appear to be 

significantly more sensitive than the rat and a dermal study of appropriate duration (i.e., 90 days) is 

not available in this species.

Based on these considerations the HASPOC recommended a 90-day dermal toxicity study in rabbits 

(870.3250) and the study should measure appropriate parameters (hormones, enzymes, weights 

and histopathology) related to the toxicity of the target organs (thyroid and liver). In addition, the 

HASPOC recommends the team should review the existing 21-day dermal study as well as the 

toxicity endpoints selected for risk assessments.”

- The group discussed the request to conduct the study with rabbits rather than rats. The 

registrants proposed to submit an in vitro data comparison to support species selection 

for this study. OPP agreed to review and consider the registrant’s proposal.

3. Wrap up and Next Steps

• OPP discussed the Agency’s policy change to assess short, intermediate, and long-term durations of 

exposure for spot on treatment products and pet collar products.

• The registrants indicated that it was unclear if all of the end use registrants are aware of registration

review.

• OPP agreed to clarify whether the 90-day dermal study required in the registration review DCI 

should be conducted with TGAI or TEP.

• The registrants indicated that they were planning to finalize the Fipronil Task Force membership in 

early June.