The study described below is of unusually high quality, so its negligible findings are all the more impressive for that. The researchers had a good measure of child IQ and even measured maternal IQ: Most unusual. And their measure of maternal pesticide exposure was direct rather than inferential. And they even used standard deviations in subsectioning their data — a big advance on the rubbishy use of extreme quintiles that one so often encounters in the medical literature.
A simple Pearson product moment coefficient would have been more informative but such statistics tend to expose how little of the variance is explained by the variable of interest so one understands why all but the bold avoid supplying such information (Disclosure: I ALWAYS used Pearsonian correlations in reporting my own research findings).
At the end of the day, however, an IQ difference of 1.4 points is well within the margin of error at age 7 years. I would describe the findings in exactly the opposite way to how the authors describe them. I would say that the study is a strong indication that pesticides have negligible to nil effects on child IQ.
And a maybe amusing bit: The amount of pesticide in her had no effect on the mother’s IQ. I quote: “There were no significant interactions between CPF and any covariates”. Do you grow out of having pesticide in you?
(“Rauh” is German/Yiddish for rough)
7-Year Neurodevelopmental Scores and Prenatal Exposure to Chlorpyrifos, a Common Agricultural Pesticide
By Virginia Rauh et al.
BACKGROUND: In a longitudinal birth cohort study of inner-city mothers and children (Columbia Center for Childrenâ€™s Environmental Health), we have previously reported that prenatal exposure to chlorpyrifos (CPF) was associated with neurodevelopmental problems at child age 3 years.
OBJECTIVE: The goal of the study was to estimate the relationship between prenatal CPF exposure and neurodevelopment among cohort children at age 7 years.
METHODS: In a sample of 265 children, participants in a prospective study of air pollution, we measured prenatal CPF exposure using umbilical cord blood plasma (picograms/gram plasma), and 7-year neurodevelopment using the Wechsler Intelligence Scales for Children (WISC-IV). Linear regression models were used to estimate associations, with covariate selection based on two alternate approaches.
RESULTS: On average, for each standard deviation increase in exposure (4.61 pg/g), Full-Scale IQ declined by 1.4%, and Working Memory declined by 2.8%. Final covariates included maternal educational level, maternal IQ, and quality of the home environment. There were no significant interactions between CPF and any covariates, including the other chemical exposures measured during the prenatal period (environmental tobacco smoke and polycyclic aromatic hydrocarbons).
CONCLUSIONS: We report evidence of deficits in Working Memory Index and Full-Scale IQ as a function of prenatal CPF exposure at 7 years of age. These findings are important in light of continued widespread use of CPF in agricultural settings and possible longer-term educational implications of early cognitive deficits.
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