Tipping the Balance of Autism Risk

Potential Mechanisms Linking Pesticides and Autism

Janie F. Shelton; Irva Hertz-Picciotto; Isaac N. Pessah


Environ Health Perspect. 2012;120(7):944-951. 

In This Article

Pesticide Exposure in the General Population

Pregnant women are exposed to pesticides through a wide variety of sources. Although many of the mechanisms of action outlined here have been observed in association with higher exposures than are likely to occur in the general population, it is difficult to estimate the direct dosage to a pregnant woman who may be applying pesticides in or around her home or to her pets, consuming food with residues of pesticides and pesticide metabolites, and inhaling air from agricultural or urban spraying near her home and workplace. Moreover, urine and blood levels indicate exposure to pregnant women is widespread. In the 2003–2004 National Health and Nutrition Examination Survey (NHANES), which recruits a representative sample of the U.S. adult population, 83% of pregnant women had detectable levels of urinary dimethylthiophosphate, an OP metabolite [geometric mean (GM), 2.43 μg/L urine]. DDE, the breakdown product of the persistent OC pesticide DDT, was detected in 100% of pregnant women with a GM of 140.4 ng/g lipid (Woodruff et al. 2011). Trends in pesticide use in the United States since 1964 have shown steep increases in the use of OPs, which make up the vast majority of pesticide sales, and rapid decreases in OC use following the 1972 ban on DDT (Figure 1). More recently, as OPs have been banned for residential uses, pyrethroid sales have increased rapidly (Williams et al. 2008).

Figure 1.

Agricultural pesticide trends in the United States by percent of sales, 1964–2000 (U.S. Department of Agriculture 2006).


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