Multigenerational testing reveals delayed chronic toxicity of bisphenol A to Daphnia magna: A common characteristic of endocrine-disrupting chemicals?

Bisphenol A (BPA) poses longstanding environmental concerns due to its widespread presence and recognized toxicity; however, its multigenerational ecotoxicity, in aquatic models such as water fleas, remains incompletely understood. This study examined the impact of sublethal BPA exposure on Daphnia magna across six generations, tracking changes in both life-history and population traits. Over the first five generations, BPA exposure produced minor and inconsistent effects on age at first oogenesis, age at first offspring production, growth rate, and fertility. The sixth generation exhibited prolonged oogenesis, delayed first offspring production, reduced body size, and decreased fertility, indicating delayed adverse effects. These multigenerational effects did not significantly alter population size or dynamics. Furthermore, BPA exposure did not affect feeding behavior in D. magna over six days, suggesting that food consumption-mediated mechanisms were unlikely a contributing factor. Our findings reveal BPA's delayed adverse effects on D. magna fitness, underscoring potential vulnerabilities for D. magna and other species under additional environmental stressors. These results support literature indicating that endocrine-disrupting chemicals can cause delayed and cumulative adverse effects on zooplankton descendants. Broadening multigenerational research to include a wider range of species, alongside sub-organismal analyses, is crucial to advancing regulatory frameworks and understanding underlying mechanisms.