Multigenerational exposure to silica nanoparticles causes severe fertility loss in Caenorhabditis elegans

Silica (SiO₂) nanoparticles (NPs) are the most abundant NPs used in various applications, such as food, drug delivery, and construction. Due to their extensive usage, they are continuously released into the environment in large quantities. In this direction, investigating the impact of repeated exposure to NPs on environmental organisms is crucial. Therefore, to determine the impact of SiO₂ NPs and their multigenerational toxicity, an established model of nano-ecotoxicology, Caenorhabditis elegans was employed. First, the impact of SiO₂ (0.2–0.3 µm, bulk) and SiO₂ NPs (40 nm) exposure on the vital processes namely survival, growth, behavior, and reproduction were determined. Worms showed a concentration-dependent response to SiO₂ NPs exposure, while no impact on exposure to bulk SiO₂. The transcription factor (daf- 2) and vitellogenin (vit- 2 and vit- 6) expression were downregulated, while oxidative stress and germline apoptosis increased in worms exposed to SiO₂ NPs. At environmentally relevant concentrations of SiO₂ NPs caused a significant impact on the reproductive output of worms. To determine the multigenerational impact on reproduction, worms were exposed for 11 generations and found a decline in progeny count across all the generations screened. When the worms were removed from exposure after 6 generations, it took 5 generations to regain their original vitality. This study indicates that exposure to the SiO₂ NPs has a cumulative impact on the reproductive output across generations. Such a decline in the reproductive output in the long term could eventually disturb the ecological balance. Hence, appropriate measures are necessary to manage the presence of NPs in the environment.