Endocrine Disruptor

An endocrine disruptor is a chemical that interferes with hormonal systems, altering hormone synthesis, transport, receptor binding, or metabolism in exposed organisms. Marine examples include tributyltin, which causes imposex (imposition of male sex organs) in female gastropods at concentrations below 1 ng/L, plus PCBs, phthalates such as DEHP, alkylphenols, and synthetic estrogens. Effects appear at sublethal doses and often follow non-monotonic dose-response curves, complicating threshold setting. The EU defines endocrine disruptors under criteria in Regulation (EU) 2017/2100 and 2018/605 and lists them as substances of very high concern under REACH.