A fish bioaccumulation study is commonly required for test chemicals that are relatively persistent in water (higher log Pow) and if it is intended for aquatic use. There are various kinds of fish bioaccumulation studies and the most common EPA guidelines which describe the details and design of these bioaccumulation studies are governed by OPPTS 850.1730 and OPPTS 860.1400. In addition, there is an OECD Guidelines 305 for testing of chemicals under flow-through conditions. More recently, the European Commission, Health and Consumer Protection Directorate General (SANCO/11187/2013) has published a working document on the pesticide residues in fish. The challenges encountered in designing different kinds of fish metabolism studies will be discussed.There are two US EPA Guidelines 850.1730 and 860.1400 which cover fish bioaccumulation studies. Although sufficient details are mentioned to design a conventional fish bioaccumulation study under 850.1730, the EPA Guidelines 860.1400 is very vague and ambiguous. Under 860.1400, fish metabolism studies in a predator or a bottom feeder are required whenever a pesticide is applied directly to water to control aquatic weeds or pests. However, the guidelines do not give specific details in regard to the duration of exposure, size of fish, number of fish, and sampling interval. It states that if no residues are found in metabolism studies, residue studies are not needed in predator or bottom feeder but residue studies are still required for shellfish.Again, designing of a metabolism study based on the EPA Guideline 860.1400 is challenging because the explicit details are missing The logic behind conducting an additional metabolism study is not well understood specifically for those active ingredients for which a conventional fish bioaccumulation study (under EPA 850.1730) has already been conducted and when the Bioaccumulation Factor (BCF) was extremely low <1000. The EPA Guideline 850.1730 further mandates that no metabolite identification is warranted when the BCF is <1000. Therefore, for such molecules, the need or requirement for an additional metabolism study under 860.1400 for new aquatic use is not warranted as this study will not provide any additional information.

Need for additional aquatic bioaccumulation studies pose designing challenges

248th National Meeting (2014)

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