4-Methylbenzylidene Camphor (4-MBC) is an extremely potent endocrine disruptor and coral toxin, which is why it has been banned in many countries. It causes rapid coral bleaching at very low concentrations by disrupting coral metabolism and triggering the expulsion of zooxanthellae. 4-MBC severely damages coral reproductive systems, causing feminization of male corals and reproductive failure. In fish and other marine animals, it interferes with thyroid and sex hormone function, leading to developmental abnormalities, altered behavior, and population declines. Studies show 4-MBC persists in marine environments, accumulating in sediments and continuing to release toxins that prevent coral recovery.