Widespread Sexual Disruption in Wild Fish

TLDR

Endocrine‑disrupting chemicals can mimic or block steroid hormones, yet evidence for a global environmental health problem remains limited. The study demonstrates a high incidence of intersexuality in wild roach (Rutilus rutilus) populations across the United Kingdom. Widespread intersexuality in UK roach was linked to sewage‑derived estrogenic chemicals, marking the first documented case of sexual disruption in wild vertebrates and confirming that ambient chemical levels can cause reproductive and developmental effects.

Abstract

A number of chemicals present in the environment have been shown to mimic or antagonize the actions of steroid hormones, an issue often described as "endocrine disruption/modulation". There is very little evidence, however, to support the hypothesis that exposure to endocrine-disrupting chemicals is a global environmental health problem. In this paper, we demonstrate a high incidence of intersexuality in wild populations of riverine fish (roach; Rutilus rutilus) throughout the United Kingdom. These reproductive disturbances are consistent with exposure to hormonally active substances and are associated with discharges from sewage treatment works that are known to contain estrogenic chemicals. This is the first documented example of a widespread sexual disruption in wild populations of any vertebrate and indicates that reproductive and developmental effects do result from exposure to ambient levels of chemicals present in typical British rivers.