Points to Consider: Unsubstantiated Claims that Glyphosate is Linked to Kidney Disease

A number of recent reports have attempted to link pesticides improved through biotechnology with negative health impacts. Unfortunately, most of these efforts have been proven to be ideological attacks on technology rather than considered, scientific reviews designed to enhance knowledge. We take a closer look at a recent paper claiming to show a correlation between the widely used herbicide glyphosate (the active ingredient in Roundup) and kidney disease.

ORIGINAL PAPER:Glyphosate, Hard Water and Nephrotoxic Metals: Are They the Culprits Behind the Epidemic of Chronic Kidney Disease of Unknown Etiology in Sri Lanka? By Channa Jayasumana, Sarath Gunatilake, and Priyantha Senanayake. Int. J. Environ. Res. Public Health 2014, 11(2), 2125-2147; doi:10.3390/ijerph110202125

PRIMARY CLAIMS:

• Some journalists  and opposition groups  have suggested the paper shows chronic kidney disease is caused by exposure to glyphosate.
•  The paper makes no such claims, but only advances a “hypothesis” unsupported by any data, for which there is no plausible causal mechanism, and which is inconsistent with published, peer-reviewed science on the safety of glyphosate, and the findings of regulatory authorities around the world.

SALIENT FACTS & CONTEXT:  

• The journal in which this paper was published is a low-impact, pay-to-play journal;
• Without the benefit of any supporting data, with no credible hypothesis and no plausible causal mechanism, the paper insinuates that glyphosate may be the cause of chronic kidney disease of unknown origin (CKDu) seen in widely separated populations of agricultural workers in the tropics;
• The speculation advanced in the paper is inconsistent with the history and distribution patterns of chronic kidney disease of unknown origin;
• The speculation advanced in the paper is inconsistent with patterns and frequency of glyphosate use/exposure;
• The speculation advanced in the paper is inconsistent with a vast body of experience demonstrating the safety of glyphosate;
• The speculation advanced in the paper is inconsistent with findings of safety of glyphosate by regulatory bodies and farmers around the world.

ANALYSIS/REBUTTAL:

• Chronic Kidney Disease of unknown etiology (CKDU) was reported long before the first synthesis of glyphosate: http://www.sciencemag.org/content/344/6180/143.full?sid=fc05b4c6-fb34-49ba-bc5c-18cca2002dcb
• The incidence of CKDu does not correlate with patterns of glyphosate usage. (see http://www.sciencemag.org/content/344/6180/143.full?sid=fc05b4c6-fb34-49ba-bc5c-18cca2002dcb).
• Without benefit of any data, nor any plausible hypothesis, the authors speculate that glyphosate somehow combines (chelates) with metals to form a compound that, in combination with some agent X, is toxic to kidneys.
• Without benefit of any supporting data, the authors suggest that glyphosate combines with kidney-toxic metals in the diet to form some type of glyphosate-metal complex which is transported into the body and ultimately ends up in the kidney, contributing to chronic kidney disease.
• There are many alternative hypotheses- previous studies have associated kidney failure with a host of factors including employment as a farmer, dehydration, cadmium exposure, pathogens, toxic weeds (aristolochic acid), and others (see http://www.glyphosate.eu/glyphosate-and-chronic-kidney-disease-sri-lanka and http://www.sciencemag.org/content/344/6180/146.full).
• The suggested mechanism, via metal chelation, is implausible. There is no evidence supporting the existence of large, stable metal complexes with glyphosate, and there are far more effective chelators known in plants, to which dietary exposure has not led to renal failure as observed.
• Levels of glyphosate (and AMPA) levels in the urine of CKDu cases  are well below levels that would suggest exposure capable of causing chronic toxic effects, and 96.5 % of CKDu  cases showed levels below the reference limit.
• Work in rice paddies was negatively correlated with CKDu, arguing against allegations that factors associated with rice agriculture may explain CKDu.
• Selenium deficiency and family history of renal failure are risk factors for CKDu, implicating nutritional and hereditary factors. This is also supported by recent research  reporting a genetic variant (single nucleotide polymorphism [SNP]) as a significant risk factor for CKDu.

SUPPORTING INFORMATION:

Coverage in Science documents that:

• The cause of chronic kidney disease of unknown origin remains unknown;
• Multiple factors are likely to be involved;
• Chronic exposure to heat and dehydration are likely factors; and
• Exposure to glyphosate is not a plausible explanation (Jon Cohen.  2014. Mesoamerica’s Mystery Killer.  Science 11 April 2014: Vol. 344 no. 6180 pp. 143-147 DOI: 10.1126/science.344.6180.143).

Coverage in the popular media has been more cursory, repeating unsubstantiated assertions implicating glyphosate without reporting the extensive data and experience indicating otherwise (http://www.npr.org/blogs/health/2014/04/30/306907097/mysterious-kidney-disease-slays-farmworkers-in-central-america  and http://grist.org/news/is-monsantos-roundup-linked-to-a-deadly-kidney-disease/?utm_source=twitter&utm_medium=tweet&utm_campaign=socialflow

Additional relevant information can be found here http://www.glyphosate.eu/glyphosate-and-chronic-kidney-disease-sri-lanka and http://www.geneticliteracyproject.org/2014/04/30/is-glyphosate-used-with-some-gm-crops-dangerously-toxic-to-humans/#.U2i5kvldWSr and  http://www.bfr.bund.de/en/the_bfr_has_finalised_its_draft_report_for_the_re_evaluation_of_glyphosate-188632.html.