Is there any evidence that glyphosate causes cancer?
Comprehensive toxicology studies in animals have demonstrated that glyphosate does not produce cancer 5, 14, 17, 18. In the course of glyphosate’s 40-year history it has been subjected to safety assessments by regulatory experts and authoritative review panels, which have also looked at its potential for carcinogenicity. None of these reviews nor long-term studies with rats and mice, have suggested any carcinogenic effects linked to glyphosate.
A number of epidemiological studies have also focused on health issues associated with pesticide exposure. One of the largest epidemiological studies of pesticide exposure and health outcomes is the Agricultural Health Study (AHS), which included approximately 57,000 participating US farmers who apply herbicides 6, 16. Publications arising from this data vary in the specificity of their conclusions regarding pesticides in general, classes of pesticides and in some cases individual insecticides, herbicides or fungicides. While some of these publications specifically mention glyphosate, none draw tenable associations with any specific cancer outcome.
Other studies failed to identify a link between glyphosate and incidents of cancers of any type. Nevertheless, associations between parental pesticide exposure and childhood leukaemia have been reported in a Costa Rican study 11. However, it was not possible to interpret the results for glyphosate because exposure was estimated along with “other pesticides”. Another publication reported an association between non-Hodgkin’s lymphoma and glyphosate 7 but this finding was not reproduced in a later study by the same group of researchers 4. In the AHS 16 no association was noted for glyphosate with any cancer, including cancer of the lung, oral cavity, colon, rectum, pancreas, kidney, bladder, prostate, melanoma, all lymphohematopoietic cancers and non-Hodgkin’s lymphoma. A very recent review article of glyphosate related epidemiology studies with cancer endpoints provides a consolidated summary of the relevant epidemiology cancer studies, concluding no relationship between glyphosate and any cancer outcome can be drawn from the considerable volume of published epidemiology data 10.
With all epidemiological studies, it should also be noted that the general level of exposure for farmers applying glyphosate and their families is estimated to be very low. Glyphosate exposure data obtained from participants on the agricultural health study published in 2004 and 2005 was used to calculate a geometric mean systemic dose for farmers applying glyphosate. Even for farmers who applied glyphosate on areas up to 400 acres, the geometric mean dosage was only 0.0001 mg/kg/day, which is approximately 0.03% of the current acceptable operator exposure level (AOEL) for glyphosate in the EU 1, 9.
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Last update: 03 June 2013