A new study published in The Journal of Toxicology and Environmental Health purports to link certain pesticide/herbicide classes, as well as certain specific chemicals to an increased risk of obesity among farm applicators. Entitled "Pesticide Exposures and Body Mass Index (BMI) of Pesticide Applicators From the Agricultural Health Study," the statistical and data-collection sleight-of-hand that went into generating this lengthy piece of fiction that certainly has no basis in science.
The authors were led by Nancy L. LaVerda, George Washington University's doctoral candidate from their Dept. of Environmental and Occupational Health. (The senior author is Dr. David F. Goldsmith, her doctoral studies supervisor, a faculty member at both Georgetown and GW Universities.)
According to Dr. Goldsmith's introductory note via email, "This paper continues the many valuable findings from the Agricultural Health Study (AHS) [supported by NCI, NIEHS, NIOSH and EPA], but breaks new ground via the exploration of pesticide exposure and weight gain or rise in body mass index (BMI). The primary findings suggest a correlation showing an increase in BMI with exposure to triazine herbicides, with particular linkage to exposure to atrazine."
The authors collected at baseline dietary and pesticide application exposures via self-administered questionnaire to 8,365 male applicators (those who qualified to be assessed out of the initial group of 50,639 AHS licensed applicators, i.e., those whose data were available at baseline and at follow-up some years later, with the study beginning in 1993, as well as having BMI and caloric-consumption parameters of plausible levels).
The authors concocted an exposure criterion, and an exposure-duration calculation, and then an intensity-weighted parameter, "a product of intensity and duration of exposure and frequency of pesticide application."
Note that these data are all obtained via questionnaire, self-administered. No measurements of anything were made, none in the field and none upon the people being analyzed. Just estimates from the applicators' answers being poured into the data-analysis machine and calculated.
Here are some of the various hypotheses and analyses that, in addition to all the above, the researchers put their data through:
"The relationship between total cumulative days of exposure to pesticide functional/chemical classes and to the four most frequently used individual pesticides was studied in relation to body mass index (BMI) at the time of 5-yr follow-up (beginning in 1998) with the length of the exposure period dating back to age 20 yr. Multiple regression, Spearman correlation, ordinal logistic regression, and logistic regression models all utilized a Bonferroni-adjusted p value, were adjusted for relevant covariates, and were stratified by state of residence (Iowa/North Carolina) and presence/absence of weight-related health conditions."
Well, now, that's hard to argue with. All based upon recollections of the pesticide applicators themselves. And what did these calculations show: "Adjusted multiple regression yielded statistically significant positive parameter estimates for the study sample and Iowa subgroups with consistent findings for triazine herbicides and atrazine: Change in BMI per 100 cumulative pesticide exposure days ranged from 0.07 to 0.11 for triazine herbicides and from 0.10 to 0.19 for atrazine."
What made these folks think that an herbicide such as atrazine might, possibly, be linked in any way to obesity? This: "Endocrine-disrupting chemicals, including pesticides, may be associated with weight gain."
In summary, based upon the thoroughly discredited "endocrine disruptor" concept, and then following that bad link down the rabbit hole of data-dredging till statistically significant, they give us that ridiculous conclusion. If there was such a thing as an "endocrine disruptor" -- aside from hormonal pharmaceuticals -- atrazine would be the last candidate, as it has no effect on mammalian cells, as in zero, nil, nada. This whole study is laughable.
For the science-based lowdown on agricultural chemicals, see ACSH's publication here.