Development of Toxicity Reference Values (TRVs) for Birds Exposed to PFOS, PFOA and Associated Mixtures of Fluorinated Compounds

Dr. Matt Simcik | University of Minnesota

ER-2624

Objective

ER-2624_project_graphic

This project addresses the need to develop an improved understanding of the ecotoxicity associated with the release of aqueous film-forming foam (AFFF), which has been used by the Department of Defense for over 40 years for fire-training and emergency response activities. As a result of these activities, ground water, surface water, and biota in the vicinity of relevant military installations have become contaminated with perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and other poly--- and perfluoroalkyl substances (PFASs). The overall objective of this project is to develop avian ecotoxicity information for compounds associated with AFFF in birds. Specifically, this project aims to determine the acute toxicity of PFOS and PFOA separately and in combination in an avian species recognized as a surrogate for wild avian species, the Japanese quail (Coturnix japonica). This project also aims to determine the acute toxicity of other perfluoroalkyl substances relative to PFOS in Japanese quail using two historic formulations of AFFF, notably 3M and Ansul formulations, which represent electrochemical fluorination and fluorotelomer technologies. Finally, this project will develop toxicity reference values (TRVs) for PFOS and PFOA in Japanese quail based on chronic feeding studies.

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Technical Approach

The acute toxicity of PFOS, PFOA, PFOS plus PFOA and 3M and Ansul AFFF formulations will be determined by feeding 10-day-old Japanese quail PFOS at dietary concentrations of [0, 8.7, 18, 35, 70, 141, 281, 562, or 1125 μg/g] feed, PFOA at dietary concentrations of [0, 44, 88, 175, 350, 700, 1400, 2810, or 5625 μg/g] feed, or PFOS plus PFOA at the same concentrations used for the individual compounds. Concentrations of 3M AFFF in feed will be [0, 1.1, 2.2, 4.4, 8.8, 18, 35, 70, or 140 μl/g] feed that is anticipated to result in PFOS concentrations of [8.8, 18, 35, 70, 140, 280, 560 or 1120 μg/g] feed and PFOA concentrations of [0.11, 0.22, 0.44, 0.88, 1.8, 3.5, 7.0, or 14 μg/g] feed based on the assumption that the 3M AFFF contains 8,000 mg PFOS/l and 100 mg PFOA/l. Concentrations of Ansul AFFF in feed will be [0, 1.5, 2.9, 5.8, 12, 23, 46, 92, or 184 μl/g] feed that is anticipated to result in 6:2 fluorotelomer thioamido sulfonate (FtTAoS) concentrations of [9.2, 18, 35, 70, 140, 281, 561 or 1122 μg/g] feed and 4:2 FtTAoS concentrations of [1.7, 3.2, 6.4, 13, 25, 51, 101, or 202 μg/g] feed based on the assumption that the Ansul AFFF contains 6,100 mg 6:2 FtTAoS/l and 1,100 mg 4:2 FtTAoS /l (Backe et al. 2013). All diets will be fed for five days. Following exposure, birds will be fed clean feed for an additional 17 days. Half of the birds will be euthanized on day 8 of the trial and sampled for blood and liver. The remaining birds will be euthanized at the end of the 22-day trial and sampled for blood and liver. Pooled serum samples will be analyzed for PFOS and/or PFOA. Additional endpoints to be assessed include body weight, gain, feed consumption, liver weight, LC50 (dietary concentration that results in 50% mortality of a population for a given exposure time), LD50, and LT50 (the exposure time that results in 50% mortality of a population for a given dose). Comparison of LC50, LD50 and LT50 values will then be used to determine the relative potency of PFOA, the PFOS plus PFOA mixture, and the two AFFFs with respect to PFOS.

Chronic toxicity of PFOS and PFOA will be determined by feeding male/female pairs of Japanese quail [0, 2.5, 5, 10, 15 or 20 μg PFOS/g] feed, or [0, 12.5, 25, 50, 75 or 100 μg/g] feed PFOA beginning at four weeks of age. The lowest feed concentrations are within the range of concentrations found in the field. Photoperiod will be modified at 12 weeks of age (eight weeks on treatment) to initiate egg laying. Previous studies indicated male bobwhites and mallards achieved a steady state of PFOS (based on serum concentrations) after 10 weeks on experimental diets. Egg laying is anticipated to commence around the time that steady state should be achieved. Birds will be fed treatment diets for an additional 10 weeks with eggs collected daily and set weekly. Hatchlings will be maintained on clean feed through 14 days of age. Reproductive endpoints to be evaluated during the study include egg production, embryo viability, hatchability, hatchling growth and chick survivability to 14 days of age. These parameters can be used for establishment of no adverse effect levels, lowest observed adverse effect levels and/or benchmark doses (BMD) and concentrations (BMC) and the lower 95% confidence limit of the BMD (BMDL) and BMC (BMCL) at the 10% effect level for PFOS and PFOA expressed in terms of average daily intake of PFOS or PFOA, dietary concentrations of PFOS or PFOA and serum PFOS or PFOA concentrations.

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Benefits

The ultimate benefit of this project will be generation of data that will assist in the development of site-specific risk assessments and decisions related to mitigation of exposure and/or future environmental cleanup of areas affected by use and release of AFFF. (Anticipated Project Completion - 02/2020)

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Points of Contact

Principal Investigator

Dr. Matt Simcik

University of Minnesota

Phone: 612-626-6269

Program Manager

Environmental Restoration

SERDP and ESTCP

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