There seems to be a rather sad group of people — mostly on the political Left, apparently — who are convinced that anything popular is bad. And they go to some lengths to prove it. Hence we have the unrelenting attacks on things as diverse as McDonald’s and cellphones. No compromise by McDonald’s ever suffices to blunt the attacks and no amount of evidence showing low levels of electromagnetic radiation to be harmless will ever convince. So the attacks go on. And among academics, the attacks take the form of “research”.

And pesticides are one of the unexonerable villains for some people. The fact that an upsurge of pesticide use has coincided with an unprecedented expansion of lifespans doesn’t cause a moment’s doubt.

But this runs us slap bang into the Rosenthal effect: The fact that with the best will in the world, a researcher’s expectations will influence what he finds in his research. It is because of that fact that “double-blind” studies are often conducted — thus leaving as little room as possible for the reseacher to bias his results, wittingly or unwittingly.

So we come to the research report below. It is a very well-designed piece of research. It is far more “watertight” than most other studies in the field. But at least three of the authors are anti-pesticide activists and there appears to have been no effort to make the study “double-blind”. That also makes it worthless in my view.

Prenatal Exposure to Organophosphate Pesticides and IQ in 7-Year Old Children

By Maryse F. Bouchard et al.


Context: Organophosphate (OP) pesticides are neurotoxic at high doses. Few studies have examined whether chronic exposure at lower levels could adversely impact children’s cognitive development.

Objective: To examine associations between prenatal and postnatal exposure to OP pesticides and cognitive abilities in school-age children.

Methods: We conducted a birth-cohort study (CHAMACOS) among predominantly Latino farmworker families from an agricultural community in California. We assessed exposure to OP pesticides by measuring dialkyl phosphate (DAP) metabolites in urine collected during pregnancy and from children at age 6 months and 1, 2, 3½ and 5 years. We administered the Wechsler Intelligence Scale for Children-IV to 329 seven-year old children. Analyses were adjusted for maternal education and intelligence, HOME score, and language of cognitive assessment.

Results: Urinary DAP concentrations measured during the 1st and 2nd half of pregnancy had similar relations to cognitive scores, thus we used the average of concentrations measured during pregnancy in further analyses. Averaged maternal DAP concentrations were associated with poorer scores for Working Memory, Processing Speed, Verbal Comprehension, Perceptual Reasoning, and Full Scale IQ. Children in the highest quintile of maternal DAP concentrations had an average deficit of 7.0 IQ-points compared with those in the lowest quintile. However, children’s urinary DAP concentrations were not consistently associated with cognitive scores.

Conclusions: Prenatal but not postnatal urinary DAP concentrations were associated with poorer intellectual development in 7-year-old children. Maternal urinary DAP concentrations in the present study were higher, but nonetheless within the range of levels measured in the general U.S. population.


Posted by John J. Ray (M.A.; Ph.D.). For a daily critique of Leftist activities, see DISSECTING LEFTISM. To keep up with attacks on free speech see TONGUE-TIED. Also, don’t forget your daily roundup of pro-environment but anti-Greenie news and commentary at GREENIE WATCH . Email me here

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