Developmental bisphenol A exposure impairs sperm function and reproduction in zebrafish.

The developmental and reproductive toxicity of bisphenol A (BPA) has been demonstrated in a variety of model systems. Zebrafish (Danio rerio) were waterborne-exposed to BPA during three different developmental stages: embryonic period:6 h post fertilization (hpf) to 5 months post fertilization (mpf); larval period: 6 days post fertilization (dpf) to 5 mpf; and sexually mature period: 3 mpf to 5 mpf. Evaluations included F0 adult growth, reproduction parameters, and F1 offspring development. BPA exposure did not affect zebrafish growth in any of exposure groups. Testis weight was decreased only following the 6 hpf to 5 mpf 0.001 µM BPA exposure. The lowest effect level indicated by a reduction in sperm volume, density, motility, and velocity across a range of exposure durations was 0.001 µM, with all but sperm density significant for the longest exposure duration, which was also the only significant endpoint for the lowest exposure concentration in the 3-5 mpf exposure group. Nonmonotonic concentration-response curves were noted for all F0 reproductive endpoints for at least one of the two longest exposure durations. For the F1 offspring of fish exposed from 6 hpf to 5 mpf, malformations and mortality were increased following 0.001 µM BPA exposure, while egg production and fertilization were reduced in higher concentration treatment groups. Overall, BPA exposure during three different developmental periods impaired zebrafish reproductive development, with most significance changes found in the lowest concentration treatment groups. Genetic impacts on gamete development may underlie the secondary effects of reduced fertilization rate, embryonic mortality, and malformations.

TBBPA chronic exposure produces sex-specific neurobehavioral and social interaction changes in adult zebrafish.

The toxicity of tetrabromobisphenol A (TBBPA) has been extensively studied because of its high production volume. TBBPA is toxic to aquatic fish based on acute high concentration exposure tests, and few studies have assessed the behavioral effects of low concentration chronic TBBPA exposures in aquatic organisms. The present study defined the developmental and neurobehavioral effects associated with exposure of zebrafish to 0, 5 and 50nM TBBPA during 1-120days post-fertilization (dpf) following by detoxification for four months before the behaviors assessment. These low concentration TBBPA exposures were not associated with malformations and did not alter sex ratio, but resulted in reduced zebrafish body weight and length. Adult behavioral assays indicated that TBBPA exposed males had significantly higher average swim speeds and spent significantly more time in high speed darting mode and less time in medium cruising mode compared to control males. In an adult photomotor response assay, TBBPA exposure was associated with hyperactivity in male fish. Female zebrafish responses in these assays followed a similar trend, but the magnitude of TBBPA effects was generally smaller than in males. Social interaction evaluated using a mirror attack test showed that 50nM TBBPA exposed males had heightened aggression. Females exposed to 50nM TBBPA spent more time in the vicinity of the mirror, but did not show increased aggression toward the mirror compared to unexposed control fish. Overall, the hyperactivity and social behavior deficits ascribed here to chronic TBBPA exposure was most profound in males. Our findings indicate that TBBPA can cause developmental and neurobehavioral deficits, and may pose significant health risk to humans.