Crops genetically engineered to survive being sprayed with a 2,4-D and glyphosate herbicide mix have been approved in the US and Canada

Corn farmers in Iowa who spray the widely used herbicide 2,4-D have biomarkers of oxidative stress, a process that is linked with chronic diseases, including cancer, when compared with non-farming controls.

Exposure to the herbicide atrazine was associated with a biomarker of oxidative stress when the analysis was restricted to individuals with levels of a metabolite of the chemical, atrazine mercapturate, that were above the limit of detection. However, otherwise there were no associations between atrazine and oxidative stress.

These are the findings of a new study published in the journal Environmental and Molecular Mutagenesis.

Crops genetically engineered to survive being sprayed with a 2,4-D and glyphosate herbicide mix have been approved in the US and Canada.

Glyphosate has been identified as a probable carcinogen, so farmers spraying mixtures of 2,4-D and glyphosate may be raising their cancer risk even more than those spraying 2,4-D alone.
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A longitudinal study of atrazine and 2,4-D exposure and oxidative stress markers among Iowa corn farmers

Catherine C. Lerro, Laura E. Beane Freeman, Lützen Portengen, Daehee Kang, Kyoungho Lee, Aaron Blair, Charles F. Lynch, Berit Bakke, Anneclaire J. De Roos, Roel C.H. Vermeulen
Environmental and Molecular Mutagenesis
Volume 58, Issue 1, Pages 30–38
January, 2017
DOI: 10.1002/em.22069
http://onlinelibrary.wiley.com/doi/10.1002/em.22069/full (open access)

Abstract

Reactive oxygen species, potentially formed through environmental exposures, can overwhelm an organism's antioxidant capabilities resulting in oxidative stress. Long-term oxidative stress is linked with chronic diseases. Pesticide exposures have been shown to cause oxidative stress in vivo. We utilized a longitudinal study of corn farmers and non-farming controls in Iowa to examine the impact of exposure to the widely used herbicides atrazine and 2,4-dichlorophenoxyacetic acid (2,4-D) on markers of oxidative stress. 225 urine samples were collected during five agricultural time periods (pre-planting, planting, growing, harvest, off-season) for 30 farmers who applied pesticides occupationally and 10 controls who did not; all were non-smoking men ages 40–60. Atrazine mercapturate (atrazine metabolite), 2,4-D, and oxidative stress markers (malondialdehyde [MDA], 8-hydroxy-2′-deoxyguanosine [8-OHdG], and 8-isoprostaglandin-F2α [8-isoPGF]) were measured in urine. We calculated β estimates and 95% confidence intervals (95%CI) for each pesticide-oxidative stress marker combination using multivariate linear mixed-effect models for repeated measures. Farmers had higher urinary atrazine mercapturate and 2,4-D levels compared with controls. In regression models, after natural log transformation, 2,4-D was associated with elevated levels of 8-OHdG (β = 0.066, 95%CI = 0.008–0.124) and 8-isoPGF (β = 0.088, 95%CI = 0.004–0.172). 2,4-D may be associated with oxidative stress because of modest increases in 8-OHdG, a marker of oxidative DNA damage, and 8-isoPGF, a product of lipoprotein peroxidation, with recent 2,4-D exposure. Future studies should investigate the role of 2,4-D-induced oxidative stress in the pathogenesis of human diseases. Environ. Mol. Mutagen. 58:30–38, 2017. © 2016 Wiley Periodicals, Inc.