Organochlorine Pesticide Residue β-HCH Associated with an Increased Risk of Autism

November 07, 2023

Toxicity Signal Identified in Both a Human Analysis and a Zebrafish Experiment

A new Norwegian study has discovered a significant association between the organochlorine pesticide residue β-Hexachlorocyclohexane (β-HCH) and autism spectrum disorder (ASD). The current study’s design involved recruiting 1,199 mothers to enroll in the prospective birth cohort (HUMIS, 2002–2009) study, which examined human breast milk. Breast milk levels of 27 chemicals were measured for this study, including polychlorinated biphenyls (PCBs), organochlorine pesticides (β-HCH), polybrominated diphenyl ethers (PBDEs), and perfluoroalkyl (PFAS) substances as a proxy for perinatal exposure. The authors then employed a multivariable logistic regression to determine association, utilized elastic net logistic regression as a variable selection method, and conducted an in vivo study with zebrafish larvae to confirm the neurodevelopmental effect. They found that infants exposed to the highest quartile of β-HCH had double the odds of autism compared to those exposed to the lowest quartile. The neurotoxicity of β-HCH was also confirmed through zebrafish experiments involving both acute and chronic exposures. Interestingly, the study did not find a significant association between ASD and perinatal exposure to PCBs, PBDEs, and PFASs. The study’s findings suggest that the critical exposure window might be the prenatal period, and alterations in the function of the dopaminergic system have been implicated with autism. β-HCH is a pesticide banned decades ago, and unfortunately, its residue is still detected in breast milk.

Original Study

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