PARENT SESSION

(05-05) Risk assessment of an endocrine disruptor: Bisphenol A.

Caley, J.^*,1, Dungey, S.¹, ¹ Environment Agency, Wallingford, United Kingdom

ABSTRACT- Bisphenol A (2,2-bis(4-hydroxyphenyl)propane) was prioritised for risk assessment in 1997 under the EU Existing Substances Regulation. About 650,000 tonnes/year are manufactured in Europe and it is mainly used to make polycarbonate and epoxy resins. It is a solid, with a water solubility of ~300 mg/l and a log K_OW of 3.4, and is readily biodegradable with a low to moderate bioaccumulation potential in aquatic species. Predicted environmental concentrations (PECs) have been calculated using the methods in the EU Technical Guidance Document and the EUSES model. Algae appear to be the most sensitive species in acute tests (96-hour EC₅₀ = 1 mg/l, although values for fish and invertebrates are similar). A multigeneration test with fathead minnow Pimephales promelas gives the most robust measure of endocrine effects currently available in aquatic species. The lowest NOEC is for egg hatchability (at 16 g/l - also the NOEC for vitellogenin production in males and oviduct formation in male carp), giving a predicted no effect concentration (PNEC) for water of 1.6 g/l. There is evidence of some inhibition of sperm development at the lowest concentration tested (1 g/l). This finding has been challenged due to criticisms about the methodology used, but this endpoint will be investigated further. This PNEC may not protect all organisms - effects have been observed in aquatic snails, including the stimulation of egg production outside the breeding season (an EC₁₀ of 13.9 ng/l has been derived for the Apple snail, Marisa cornuarietis). However, experimental difficulties in the tests mean the results have to be viewed with caution. This has important implications for the risk assessment. The current PNEC leads to a risk for the aquatic environment for a number of minor uses of bisphenol A. Any PNEC set around the level of effects in snails will give a risk for all uses. Consequently there is an urgent need to establish a clear NOEC for snails, and results should be available during 2003.

Key words: bisphenol A, endocrine disruption, risk assessment, aquatic snails