PARENT SESSION
5C Ecological relevance of endocrine disruption
9:00 AM to 7:00 PM, Tuesday, 08 May 2001
Session Chair:

(T/MF207) Effects of Bisphenol A on larval growth, development and sexual differentiation of Xenopus laevis.

Pickford, Daniel¹, Caunter, John¹, Hetheridge, Malcolm¹, Hutchinson, Thomas¹, ¹

ABSTRACT- In a GLP-compliant study, commissioned by the Bisphenol A Global Industry Group, we investigated the effect of larval exposure to Bisphenol A (BPA) on growth, development and sexual differentiation in Xenopus laevis. Larvae were maintained in flow-through conditions at 22±1°C and exposed to BPA at nominal concentrations of 1.0, 2.3, 10, 23, 100, 500 g l^-1, from developmental stages 43/45 (beginning of independent feeding) through to 66 (completion of metamorphosis). Each test concentration, plus dilution water control (DWC) and positive control (PC, 17-estradiol, 2.7 g l^-1) employed 4 replicate test vessels with a starting density of 40 larvae/tank. Growth and development assessments were performed on all larvae in one replicate per test concentration on exposure days 32 and 62. Individual froglets were removed from test vessels upon reaching stage 66, and the study was terminated on exposure day 90. Froglets were dissected and sex was determined by inspection of gross gonadal morphology. Test concentrations of BPA had no effect on survival, growth, developmental stage distributions at exposure days 32 and 62, or mean time to completion of metamorphosis, when compared to DWC. Analysis of post-metamorphic sex ratio by G-test indicated no significant deviations from expected (50:50) sex ratio, in the DWC or any of the BPA test concentrations. In contrast, sex ratio in the PC (31% male, replicates pooled) deviated significantly from expected, and indicated that larvae had been feminised by exposure to the natural estrogen, 17-estradiol. Exposure to BPA in the concentration range 1.0 - 500 g l^-1 in flow-through conditions had no observable effect on larval growth, development or sexual differentiation (as determined by gross gonadal morphology) in this study.

Key words: Bisphenol A, sex differentiation, estrogen, amphibia