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Pesticides and IQ – Three Views

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Spraying pesticide in California

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The dangers of pesticides has been a hot debate for decades ever since Rachel Carson wrote “Silent Spring” in 1962 which documented the effects of pesticides on the environment.  The debate became viral on the internet this past week with the headline that read “Pesticides Affect IQs in Children” based on three major studies.  When the dust settled, three major views emerged, one view from the study researchers, one from American Council on Science and Health (ACSH), and another from the Organic Consumers Association (OCA).  It would be irresponsible to report on just one of the views without considering the counterarguments from all sides of the this important topic.

VIEW 1 – The Studies

The studies were conducted in urban New York (2 studies) and from Salinas, California (1 study), an agricultural area.  Moreover, the studies were conducted at Mount Sinai School of Medicine and Columbia University and at the University of California- Berkeley.  The National Institute of Environmental Health Sciences and the Environmental Protection Agency (EPA) financed all.

About 10 years ago, data was compiled from blood and urine samples from pregnant women to detect pesticide exposure.  The health of the babies born was monitored and regular urine samples were collected to determine pesticide exposure for until the age of seven.

The results were surprising – for example, the children with the highest levels of prenatal pesticide exposure scored 7 points lower on the IQ tests compared to the children with the lowest levels of exposure.   Dr. Philip Landrigan, a professor of pediatrics and director of the Children’s Environmental Health Center at Mt. Sinai said: “Babies exposed to the highest levels had the most severe effects.  It means these children are going to have problems as they go through life”.

VIEW 2   American Council on Science and Health

“ACSH’s mission is to ensure that peer-reviewed mainstream science reaches the public, the media, and the decision-makers who determine public policy.  Our objective is to restore science and common sense to personal and public health decisions, in order to foster a scientifically sound and sensible public health policy for the American people. ACSH is committed to improving communication and dialogue between the scientific/medical community and the public and the media, in an effort to ensure that the coverage of health issues is based on scientific facts – not hyperbole, emotion and ideology.”

The ACSH views are quite different in that they say the studies had many flaws.  First of all, the studies were published in a journal Environmental Health Perspectives that is notorious for reporting on junk science research.  The studies were published and extolled in the media in time for Earth Day providing fuel for environmental activists who oppose strongly the use of pesticides.

Third, they noted that the study did not control for some basic variables such as smoking, alcohol or drug use during pregnancy or any paternal traits.  Dr. Gilbert Ross from ACSH says: “The study is flawed methodologically, and assumptions are made based on simple assertions with no scientific support.  The authors acknowledge that the metabolites they measured did not necessarily come from the OP chemicals – they could have also come from ingestion of trace amounts of the metabolites themselves that had already formed elsewhere.  In addition, missing data is imputed – some arbitrary value is just stuck in where none existed.  It’s a sham”.

Dr. Ross points out how beneficial pesticides are in terms of fighting global starvation and says: “An overwhelming body of scientific evidence has clearly shown that OP residues have no adverse health effects, a finding in agreement with the EPA.”

VIEW 3 – The Organic Consumers Association (OCA) 

The OCA has compiled a fact sheet (July, 2005) that provides some basic data about the exposure to pesticides experienced by Americans and the potential health risks it can cause.  A summary:

  • The EPA states that standard chemicals are up to 10 times more toxic to children than to adults, depending on body weight.  Children receive 50% of their lifetime cancer risks in the first two years of life.
  • The FDA states that half of produce currently tested in supermarkets contains measurable residues of pesticides. Lab tests of eight industry-leader baby foods reveal the presence of sixteen pesticides, including three carcinogens.
  • In blood samples of children, aged two to four, concentrations of pesticide residue are six times higher in children eating conventionally farmed produce compared to those eating organic food.
  • The U.S. Department of Health and Human Services states that organophosphate pesticides are now found in the blood of 95% of Americans tested and are twice as high in samples from children than adults.
  • OP exposure is linked to hyperactivity, behavior disorders, learning disabilities, developmental delays, and motor dysfunction.
  • OPs account for half of the insecticides used in the U.S.

Bottom Line:

In my view, each opinion has its good points.   Correlation does not imply causation, so the ACHS viewpoint appears valid and other variables were not taken into consideration.  In reality, the use of pesticides is necessary to feed the world population, and reduce insect destruction.  However, the studies agreed on results and children and pregnant women are the most vulnerable.  The authors pointed out that the reduction of lead in the environment raised the IQ of children by four or five points. The view of OCA is documented and referenced with studies from government sources such as the EPA and FDA, not from small frivolous studies with biased viewpoints.


  • Control pests by sealing cracks in baseboards rather than using pesticides to prevent cockroach invasions.
  • You can buy organic foods, of course, but in times of rising food prices, this may not economically feasible for some people.  You can wash and peel conventionally grown produce carefully to lessen pesticide residues.
  • The Environmental Working Group has compiled a shopping guide showing which foods have the highest and lowest rates of pesticide exposure.  A quick guide: Strawberries, peaches, celery, apples and spinach usually have the highest levels of residues.  Onions, avocado, frozen corn and pineapple had the lowest levels of pesticide residue.
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0 thoughts on “Pesticides and IQ – Three Views

  1. Loved the Article. Good Work.


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