A New Cause of ADHD

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Chemicals from plastics, pesticides, and food processing are linked to ADHD, according to a new paper in JAMA Open Network.

Jessica Shoaff and colleagues in Boston correlated ADHD symptoms with exposure to endocrine-disrupting chemicals (EDCs) in this cross sectional study of 205 adolescents. ADHD was tested with scales rated by parents, teachers, and the teen. Chemical exposure was measured by testing the adolescent’s urine for a handful of endocrine-disrupting chemicals including phthalates, parabens, phenols, and triclocarban. These chemicals are found in packaging equipment, cosmetics, fragrances, food processing, pharmaceuticals, and plastics.

They found positive associations between ADHD and chemical exposure, but associations can’t prove causation. They then adjusted for potential cofounders like fragrance use, diet, and substance use, and the associations remained. The biggest risk was with antiandrogenic phthalate concentrations: every 2 fold increase in this chemical was linked to a 34% increase in risk of ADHD symptoms. Next were the dichlorophenols; for these the risk of ADHD symptoms went up 15% with every 2-fold increase in concentration.

This is not the first study to identify this link, but it is the first in adolescents; previous studies – which were also associational – connected ADHD with prenatal or childhood exposure to endocrine disrupting chemicals. Endocrine disrupting chemicals are also linked to other health problems like early puberty, reproductive problems, cancer and respiratory illness.

So how do you avoid those chemicals? The ones that disrupt androgens are found in pesticides, insecticides, plastics, cosmetics, perfumes, and nail varnish. Dichlorophenols are also found in pesticides and insecticides, but also in chlorinated water – which includes swimming pools but also drinking water where the chlorine is used to kill of bacteria.

Potential solutions to this risk include purify tap water before drinking it, washing produce to get rid of pesticides, and treating insecticides like they are as likely to harm us as they are to harm the insects. And don’t microwave in plastic.


Shoaff JR, Coull B, Weuve J, et al. Association of Exposure to Endocrine-Disrupting Chemicals During Adolescence With Attention-Deficit/Hyperactivity Disorder-Related Behaviors. JAMA Netw Open. 2020;3(8):e2015041.

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