Pyriproxyfen prenatal exposure to pregnant women and increased potential for hormone disruption and morphological abnormalities in the fetus

Background: Pyriproxyfen is an insecticide used to kill ticks, fleas, mosquitoes, and cockroaches. Reports support pyriproxyfen used in drinking water in Brazil as a juvenile toxic growth regulator/hormone analog preventing maturation of mosquito larvae. Fetal exposure to pyriproxyfen has been associated with increased incidence of microcephaly in Brazil. Objective: The aim of this study is to assess if pyriproxyfen exposure to pregnant women has the potential to alter normal fetal development, sexual and physical maturation. Methods: A systematic review of databases (PubMed, Scopus and Google Scholar) resulted in 2080 publications related to pyriproxyfen. Cross referencing pyriproxyfen and pregnancy resulted in 116 publications since 2010. Search narrowed using keywords pyriproxyfen, pregnancy, drinking water, and birth defects (44 references). Adverse effects from pyriproxyfen exposure in fish, reptiles were also retrieved. Results: Reports confirmed adverse developmental defects such as microcephaly, skin and eye toxicity in infants with pyriproxyfen exposure. Animal studies confirm malformations including bilateral gynandromorphism, eye and skin toxicity, endocrine and immunological disruption. Pyriproxyfen effectively interferes with reproductivity in mosquitoes and aquatic organisms through morphological changes in an endocrine system, sex organs, and secondary sexual behavior. Conclusion: Prenatal exposure to pyriproxyfen is associated with morphological abnormalities affecting fetal development. Studies support the plausible connection between congenital malformations in infants (as seen in ecological studies) and pyriproxyfen exposure in drinking water. Reproductive malformations (ambiguous genitalia, gynandromorphism, intersex) are voluntary reporting unless associated with CAH, and, therefore, may be unrecognized and underreported. Recommendations include the elimination of pyriproxyfen in drinking water sources.