Toxic chemicals including pesticides linked to neuro-developmental disabilities such as autism, attention-deficit hyperactivity disorder and dyslexia.

pesticidesA collaborative new study by the Harvard School of Public Health, (HSPH), and the Icahn School of Medicine at Mount Sinau revealed that toxic chemicals may be the root of neurological disorders including autism, attention-deficit hyperactivity disorder and dyslexia.

The study findings were published in the Neurology journal with recommendations for a global prevention study and is based on a previous review 2006 review study that identified five industrial chemicals as “developmental neurotoxicants,” or chemicals that can cause brain deficits.

“The greatest concern is the large numbers of children who are affected by toxic damage to brain development in the absence of a formal diagnosis. They suffer reduced attention span, delayed development, and poor school performance. Industrial chemicals are now emerging as likely causes,” said Philippe Grandjean, adjunct professor of environmental health at HSPH.

The study highlights the concern expressed by the European Union, (EU), who has taken the unusual steps of restricting U.S. produce as not conforming to the EU’s pesticide standards.

The new study offers updated findings about those chemicals and adds information on six newly recognized ones, including manganese, fluoride, chlorpyrifos and DDT (pesticides), tetrachloroethylene (a solvent), and the polybrominated diphenyl ethers (flame retardants).

The study outlines possible links between these newly recognized neurotoxicants and negative health effects on children, including:

  • Manganese is associated with diminished intellectual function and impaired motor skills
  • Solvents are linked to hyperactivity and aggressive behavior
  • Certain types of pesticides may cause cognitive delays

Grandjean and co-author Philip Landrigan, Dean for Global Health at Mount Sinai, suggest that the results showcase a silent pandemic of chemicals that contribute to neuro-behavioral deficits that are eroding intelligence, disrupting behaviors, and damaging societies. They recognize that controlling the pandemic is difficult because of a scarcity of data to guide prevention and the huge amount of proof needed for government regulation.

“The problem is international in scope, and the solution must therefore also be international,” said Grandjean. “We have the methods in place to test industrial chemicals for harmful effects on children’s brain development — now is the time to make that testing mandatory.”

The latest US Environmental Protection Agency (EPA) information on US pesticide usage, from 2007, reports that over 1 billion tons of pesticides are used in the US every year. This is 22% of the estimated 5.2 billion pounds of pesticides used worldwide.  Agricultural use accounted for 80% of pesticide use in the US.  Of the pesticide classes, herbicides are the most widely used in all US sectors.  

The Environmental Working Group compiles a yearly list of fruits and vegetables with the highest levels of pesticide residues, based on USDA and FDA testing data.  The current top 12 are:  

  • Apples
  • Celery
  • Sweet Bell Peppers
  • Peaches
  • Strawberries
  • Nectarines (imported)
  • Grapes
  • Spinach
  • Lettuce
  • Cucumbers
  • Blueberries
  • Potatoes


  1. Philippe Grandjean, Philip Landrigan. Neurobehavioural effects of developmental toxicityLancet Neurology, February 2014 DOI: 10.1016/S1474-4422(13)70278-3
  2. US Environmental Protection Agency. (2012). Pesticides and food: Healthy, sensible practices. Retrieved September 20, 2012

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