Transgenerational impacts of TBBPA on the freshwater snail Lymnaea stagnalis

Tetrabromobisphenol A (TBBPA), a widely used brominated flame retardant, raises concern due to its endocrine-disrupting properties similar to BPA. Yet its long-term and transgenerational effects remain poorly understood, especially in freshwater organisms like the snail Lymnaea stagnalis, which plays a role in nutrient cycling and ecosystem stability. Although there is growing evidence that chemically induced effects can be transgenerational, ecotoxicological studies beyond one generation remain limited. This study investigated whether parental TBBPA exposure influences the vitality of exposed snails and the development of unexposed F1 and F2 offspring, addressing potential carryover and transgenerational effects.

Adults were exposed for up to 28 days at TBBPA nominal concentrations of 75 and 2000 µg/L. Egg masses from exposed parents (F1 embryos) were transferred to clean medium to isolate carry-over effects from direct exposure. Some F1s were raised to reproductive age in clean water, with resulting F2s raised similarly. For comparison, embryos from unexposed parents were directly exposed to 50–1,000 µg/L TBBPA and monitored for 14 days.

Parental exposure resulted in impaired reproduction (cumulative EC₅₀ 798 µg/L) from day 3. F1 reproduction was more sensitive (EC₅₀ 392 µg/L), suggesting transgenerational effects in the absence of direct exposure. F1 embryos also showed various abnormalities, including small shells, delayed hatching, reduced pigmentation, and malformations (EC₅₀ ~404 µg/L). Directly exposed embryos from unexposed parents showed similar abnormalities but greater sensitivity (EC₅₀ 294 µg/L at 14 days), with 100% mortality at 1000 µg/L.

Neither F1 nor F2 recovered from these effects (e.g decrease in shell size) over the 5-month observation period. This suggests that TBBPA can affect the viability of the offspring even in the absence of exposure, which may have long-term consequences for population stability and biodiversity. The results emphasize the need for multigenerational assessment beyond early life stages.