PT07 Chemical and Biological Analysis of Endocrine Disrupting Compounds
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(PT122) A development test (extended early life-stage test) using fathead minnows: validation using 4-tert-pentyphenol.

Panter, G1, Hutchinson, T1, Hurd, K1, Stanley, R1, Duffell, S2, Tyler, C3, 1 AstraZeneca Global Safety, Health & Environment, Brixham, Devon, UK2 Syngenta, CTL, Macclesfield, UK3 Exeter University, Exeter, UK

ABSTRACT- Although screening assays have been successfully developed for the detection of (anti-)oestrogenic, (anti-)androgenic and aromatase inhibiting substances in the fathead minnow (Pimephales promelas), there is a need to validate fish chronic tests for measuring the effects of endocrine active chemicals (EACs) on life stages that are potentially the most sensitive. This work describes the initial validation of a protocol to detect the effects of EACs on the critical period of sexual differentiation in fish, according to the concept of the OECD fish development test. Fathead minnow embryo-larvae were exposed to 4-tert-pentylphenol in flow-through systems for up to 120 days post-hatch (dph), at 25±10C. The exposure protocol was adapted from OECD test guideline 210, but extended to allow the evaluation of gonadal development, secondary sexual characteristics, gonadosomatic index (GSI) and plasma vitellogenin. Nominal test chemical concentrations of 4-tert-pentylphenol were 56, 180 and 560 micrograms l-1, with fish sampled under continuous exposure after 30, 60 or 107 dph. In addition, fish were also exposed to 180 micrograms 4-tert-pentylphenol l-1 for periods of 0-30 or 0-60 dph, before being transferred to dilution water for the remainder of the study (107 dph). At 30, 60 and 107 dph, fish were sampled and evaluated for somatic (standard length, wet weight and condition factor) and reproductive endpoints, described above. At 30 and 60 dph delays in sexual differentiation and development were observed in exposed fish. At 107 dph, effects were seen on somatic endpoints, sexual differentiation, secondary sexual characteristics (tubercle number and prominence) and GSI. This work is a step towards the establishment of a test method for evaluating the effects of chemicals on fish development for ecological risk assessment purposes.

Key words: 4-tert-pentylphenol, Pimephales promelas, development test

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