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. These claims are not supported by scientific evidence, and appear to be a conflation with research suggesting endocrine disruptors can have a feminizing effect on the genital development of non-human animals.[1][2]
Research in the 2000s suggested that the herbicide
atrazine, an
endocrine disruptor, may have a
feminizing effect on male frogs causing them to become hermaphrodites.[3][4] Other research failed to reproduce these results in frogs,[5][6][7] though reports of reproductive impact has been reported for other animals, and a meta-analysis conducted in 2010[8] 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.[5]
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.[9][10] This claim, which is far beyond what was originally reported in the scientific literature, subsequently became an
internet meme.[11][12]
This idea of a link between atrazine and gender was later revived by American politician and
anti-vaccine activist
Robert F. Kennedy Jr., who claimed that
gender dysphoria in children might be associated to atrazine contamination of water.[1] Kennedy's theory was criticized in various popular media outlets,[2][13][14] 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".[15] 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.[15] Endocrine disruptor exposure during
fetal development has been shown to affect
sexual differentiation of the brain in animals,[16] however any effect on human sexual orientation or gender identity requires further research.[16][17]
^
abCocchetti, Carlotta; Rachoń, Dominik; Fisher, Alessandra D. (2020), Pivonello, Rosario; Diamanti-Kandarakis, Evanthia (eds.),
"Environmental Impact on Sexual Response"(PDF), Environmental Endocrinology and Endocrine Disruptors: Endocrine and Endocrine-targeted Actions and Related Human Diseases, Endocrinology, pp. 312–328,
doi:
10.1007/978-3-030-38366-4_11-1,
ISBN978-3-030-38366-4, retrieved August 18, 2023, In particular, the hypothalamus and other sexually dimorphic brain areas are highly sensitive to endogenous sex hormones, and this may determine their vulnerability to EDCs' exposure during critical periods. This evidence could lead to hypothesize a possible etiological link between prenatal exposure to EDCs and the development of sexual orientation and core gender identity. Indeed, Bejerot et al. (2011) suggested a hypothetical link between EDCs and gender dysphoria, speculating about a possible role of phthalates (Bejerot et al. 2011). Phthalates are contained in many plastics, and their environmental concentrations have significantly increased in the last few years. Fetal exposure may lead to an increased androgen exposure, increasing the risk of developing gender dysphoria. However, this specific association has never been evaluated before and most of our knowledge is based on data from rodent studies. For this reason, more systematic investigations are required to establish EDCs' interference with sexual differentiation of the brain in determining sexual orientation and gender identity.
^Savic, Ivanka; Garcia-Falgueras, Alicia;
Swaab, Dick F. (2010), Savic, Ivanka (ed.),
"Sexual differentiation of the human brain in relation to gender identity and sexual orientation"(PDF), Progress in Brain Research, Sex Differences in the Human Brain, their Underpinnings and Implications, 186, Elsevier: 41–62,
doi:
10.1016/B978-0-444-53630-3.00004-X,
ISBN9780444536303,
PMID21094885, retrieved August 13, 2023, Recent data show that environmental compounds during early development may interfere with sexual differentiation of the human brain. Plastic softeners, that is, phthalate esters, are pervasive environmental chemicals with anti androgenic effects. Exposure to these compounds is accompanied by reduced masculine play in boys (Swan et al. 2010). Higher prenatal polychlorinated biphenyls (PCB) levels were related with less masculine play in boys, while higher prenatal dioxin levels were associated with more feminized play in boys as well as in girls (Vreugdenhil et al. 2002). The effect of such environmental endocrine disruptors on sexual differentiation of brain systems should be further studied in future.