Cancer Incidence among Glyphosate-Exposed Pesticide Applicators in the Agricultural Health Study

Abstract

Glyphosate is a broad-spectrum herbicide that is one of the most frequently applied pesticides in the world. Although there has been little consistent evidence of genotoxicity or carcinogenicity from in vitro and animal studies, a few epidemiologic reports have indicated potential health effects of glyphosate. We evaluated associations between glyphosate exposure and cancer incidence in the Agricultural Health Study (AHS), a prospective cohort study of 57,311 licensed pesticide applicators in Iowa and North Carolina. Detailed information on pesticide use and other factors was obtained from a self-administered questionnaire completed at time of enrollment (1993–1997). Among private and commercial applicators, 75.5% reported having ever used glyphosate, of which > 97% were men. In this analysis, glyphosate exposure was defined as a) ever personally mixed or applied products containing glyphosate; b) cumulative lifetime days of use, or “cumulative exposure days” (years of use × days/year); and c) intensity-weighted cumulative exposure days (years of use × days/year × estimated intensity level). Poisson regression was used to estimate exposure–response relations between glyphosate and incidence of all cancers combined and 12 relatively common cancer subtypes. Glyphosate exposure was not associated with cancer incidence overall or with most of the cancer subtypes we studied. There was a suggested association with multiple myeloma incidence that should be followed up as more cases occur in the AHS. Given the widespread use of glyphosate, future analyses of the AHS will allow further examination of long-term health effects, including less common cancers.

Pesticide exposure as risk factor for non‐Hodgkin lymphoma including histopathological subgroup analysis

“…Since then, however, some experimental studies indicate genotoxic, hormonal and enzymatic effect in mammals, as reviewed. 32 Of particular interest is that glyphosate treatment of human lymphocytes in vitro resulted in increased sister chromatid exchanges, 33 chromosomal aberrations and oxidative stress. 34,35 Odds ratios (OR) and 95% confidence intervals (CI).…”

“…36 Recent findings from other groups also associate glyphosate with different B-cell malignancies such as lymphomas and myeloma. 32,37,38 Glyphosate has succeeded MCPA as one of the most used herbicides in agriculture, and many individuals that used MCPA earlier are now also exposed to glyphosate. This probably explains why the multivariate analysis does not show any significant ORs for these compounds.…”

The non-Hodgkin lymphomas: A review of the epidemiologic literature

“…Recent reports from the Agricultural Health Study, evaluating glyphosate (n 5 57,311 applicators), pendimethalin (n 5 24,374 applicators), metolachlor (n 5 50,193 applicators), diazinon (n 5 23,106 applicators), alachlor (n 5 26,510 applicators), chlorpyrifos (n 5 54,383 applicators), atrazine (n 5 36,513 applicators), and carbofuran (n 5 49,877 applicators) exposure, found no significant exposure-response gradients in NHL risk based on lifetime or intensity-weighted days of exposure. [41][42][43][44][45][46] Furthermore, there were no significant associations with any of these chemicals, based on comparing the incidence of NHL in the highest category of cumulative lifetime exposure to the lowest (atrazine RR 5 1.61, 95% CI: 0.62-4.16, p for trend 5 0.35; 48 alachlor RR 5 1.14, 41 ).…”

Occurrence and fate of the herbicide glyphosate and its degradate aminomethylphosphonic acid in the atmosphere

“…From a human health perspective, glyphosate is classified as carcinogenic category E because of evidence of noncarcinogenicity for humans [21]. Some studies have suggested a link between glyphosate exposure and the risk of non-Hodgkin's lymphoma or human placental cell damage [22,23].…”