Benzothiazole and 2-mercaptobenzothiazole impair reproduction by disrupting sperm function in Caenorhabditis elegans

Benzothiazoles (BTs), derived primarily from tire wear particles, are ubiquitous contaminants that pose significant environmental hazards and health risks. This study evaluated the effects of benzothiazole (BTH) and 2-mercaptobenzothiazole (MBT) on reproductive toxicity by using the model organism Caenorhabditis elegans. Synchronized L1 larvae were exposed to BTH or MBT at 0, 0.1, 1, 10, and 50 μg/L for 60 h. Germline apoptosis, oogenesis, sperm activation, and sperm migration were tested in parental worms, and some reproductive endpoints were further examined in non-exposed F1 offspring. Our findings demonstrate that BTs at environmentally relevant concentrations induced germline apoptosis and inhibited oogenesis. Furthermore, in male worms, sperm activation and migration were significantly disrupted in parental worms, where increased failure rates of sperm activation were also observed in non-exposed F1 generation. Transcriptomic analysis showed substantial alterations in the expression of spermatogenesis-related genes, with enrichment of pathways involved in spermatid differentiation. Our findings show that BTs disrupt germ cell development and sperm function in C. elegans, with parental exposure linked to measurable reproductive defects in offspring, underscoring potential long-term environmental health risks of tire wear particles.