© Maine Today Media
In recent years, the prevalence of developmental disorders such as autism
, attention-deficit/hyperactivity disorder (ADHD)
have soared. While greater awareness and more sophisticated diagnoses are partly responsible for the rise, researchers say the changing environment in which youngsters grow up may also be playing a role.
In 2006, scientists from the Harvard School of Public Health and the Icahn School of Medicine at Mount Sinai identified five industrial chemicals responsible for causing harm to the brain
- lead, methylmercury, polychlorinated biphenyls (found in electric transformers, motors and capacitors), arsenic (found in soil and water as well as in wood preservatives and pesticides) and toluene (used in processing gasoline
as well as in paint thinner, fingernail polish and leather tanning). Exposure to these neurotoxins was associated with changes in neuron development in the fetus as well as among infants, and with lower school performance, delinquent behavior, neurological abnormalities and reduced IQ
in school-age children.
Now the same researchers have reviewed the literature and found six additional industrial chemicals that can hamper normal brain development. These are manganese, fluoride, chlorpyrifos, dichlorodiphenyltrichloroethane, tetrachloroethylene and polybrominated diphenyl ethers
. Manganese, they say, is found in drinking water and can contribute to lower math scores and heightened hyperactivity, while exposure to high levels of fluoride from drinking water can contribute to a seven-point drop in IQ on average.
The remaining chemicals, which are found in solvents and pesticides, have been linked to deficits in social development and increased aggressive behaviors.