LGBT chemicals conspiracy theory

Beginning in the 2010s, various media personalities promoted conspiracy theories claiming that exposure to endocrine disrupting chemical pollutants in the water supply are responsible for an alleged increase in the gay or transgender population. Claims of an increase in these populations and a link between chemical exposure and sexual development in humans have not supported by scientific evidence; such claims appear to be a conflation with research suggesting endocrine disruptors can have a feminizing effect on the genital development of non-human animals.

Animal testing in the 2000s suggested that the herbicide atrazine, an endocrine disruptor, may have a feminizing effect on male frogs causing them to become hermaphrodites. Other research failed to reproduce these results in frogs, though reports of reproductive impact has been reported for other animals, and a meta-analysis conducted in 2010 on selected amphibians and freshwater fish showed sublethal reproductive effects at ecologically relevant concentrations. Reviewing 19 studies in total, the United States Environmental Protection Agency concluded in 2013 that atrazine has no consistent effects on development in amphibians.

In 2015, American conspiracy theorist and radio personality Alex Jones claimed that atrazine had caused a majority of frogs in the US to become homosexual, and that the US government was waging a "chemical warfare operation" to increase rates of homosexuality and decrease birth rates. This claim, which is far beyond what was originally reported in the scientific literature, subsequently became an internet meme.

This idea of a link between atrazine and gender was later revived by American politician and environmental lawyer Robert F. Kennedy Jr., who suggested that gender dysphoria in children might be associated to atrazine contamination of water. Kennedy's theory was criticized in various popular media outlets, and evidence of the correlation between endocrine disorders and gender dysphoria remains unclear.

Scientific consensus, as summarized in a 2016 review in Psychological Science in the Public Interest, is that there is "no persuasive evidence that the rate of same-sex attraction has varied much across time or place". In contrast to claims about chemicals in the water, the effects of hormones on sexual orientation appear to occur at the prenatal stage, during organization of the brain. Endocrine disruptor exposure during fetal development has been shown to affect sexual differentiation of the brain in animals, however any effect on human sexual orientation or gender identity requires further research.