Does bisphenol A induce superfeminization in Marisa cornuarietis? Part II: Toxicity test results and requirements for statistical power analyses

Valery E. Forbes1*, John Aufderheide2, Ryan Warbritton2, Nelly van der Hoeven3, Norbert Caspers4

1 Department of Environmental, Social and Spatial Change, Roskilde University, Universitetsvej 1, PO Box 260, 4000 Roskilde, Denmark
2 ABC Laboratories, Inc., 7200 E. ABC Lane, Columbia, MO 65202, USA
3 ECOSTAT, Vondellaan 23, 2332 AA, Leiden, The Netherlands
4 Bayer Industry Services, D-51368 Leverkusen, Germany

Corresponding Author:

Valery Forbes
Department of Environmental, Social and Spatial Change,
Roskilde University
Universitetsvej 1,
PO Box 260,
4000 Roskilde,
Denmark
fax: (+)31-45 46 74 30 31;
email: vforbes@iruc.dk

Summary

This study presents results of the effects of bisphenol A (BPA) on adult egg production, egg hatchability, egg development rates and juvenile growth rates in the freshwater gastropod, Marisa cornuarietis. We observed no adult mortality, substantial inter-snail variability in reproductive output, and no effects of BPA on reproduction during 12 weeks of exposure to 0, 0.1, 1.0, 16, 160 or 640 mg/L BPA. We observed no effects of BPA on egg hatchability or timing of egg hatching. Juveniles showed good growth in the control and all treatments, and there were no significant effects of BPA on this endpoint. Our results do not support previous claims of enhanced reproduction in Marisa cornuarietis in response to exposure to BPA. Statistical power analysis indicated high levels of inter-snail variability in the measured endpoints and highlighted the need for sufficient replication when testing treatment effects on reproduction in M. cornuarietis with adequate power.

keywords: Endocrine disruption; Low-dose effects; Reproduction; Risk assessment; Statistical power; Variability

logo ECOSTAT Ecotoxicol. Environm. Safety, 66: 319-325, 2007