Update: Glyphosate and Cancer

In January, a judge ordered that the state of California can require Monsanto to label its Roundup product as a possible cancer threat. The court ruled on the basis of a 2015 monograph from the International Agency for Research on Cancer (IARC) classifying glyphosate, the main ingredient in Roundup, as probably carcinogenic to humans.

This occurs as just the latest in a long string of confusing events surrounding the status of glyphosate, leaving consumers to wonder whether the chemical is safe to use in in fields and backyards and whether they should fear the foods they eat.

Glyphosate has long been considered relatively safe and minimally toxic to use for both home and agricultural uses. The IARC called that into question, but several subsequent reports from leading U.S. and international agencies directly contradict the IARC findings.

In November, 2015, the European Food Safety Agency (EFSA) reported glyphosate “is unlikely to pose a carcinogenic hazard to humans.”

In May, 2016, a joint United Nations and World Health Organization (WHO) report found glyphosate is unlikely to pose a cancer risk at realistic exposure levels.

In September, 2016, The U.S. Environmental Protection Agency’s (EPA) issued a decision that the chemical is “not likely to be carcinogenic” to humans.

So, is glyphosate carcinogenic or not?

Possibly the most confusing contradiction is between the WHO and the IARC which is an arm of the WHO. The joint UN/WHO report contradicts the IARC findings that glyphosate causes cancer, but one thing to keep in mind is that the IARC examined whether any hazard exists, even at unlikely exposure levels while the joint UN/WHO report evaluated realistic risk in daily life.

The IARC monograph looked at whether any possible hazard exists under any circumstances, regardless how unlikely those circumstances are. In contrast, the join UN/WHO report analyzed possible risk as it can be realistically expected in daily life, such as at the table. Think about it this way. Sun exposure can be hazardous in terms of causing skin cancer. However, your degree of exposure determines the actual risk. Smart choices about sun exposure levels neutralize risk. Repetitive sunburns and daily, day-long exposure without protective measures maximizes risk. Similarly, bathing in glyphosate may cause cancer, but realistic exposure is unlikely to do so, according to the UN/WHO and the EFSA.

This is why the EFSA has established minimum toxicity levels they define as the acute reference dose, operator exposure levels, and acceptable daily intake (for consumers), beneath each of which they establish that glyphosate is unlikely to be carcinogenic.

In response to studies indicating genotoxicity (damaging to DNA), the EFSA reports that analysis was based on formulations that contain glyphsate as well as other ingredients. Studies evaluating only glyphosate did not find evidence of such toxicity, suggesting that co-formulations should be examined, but that glyphosate itself is not likely to produce genotoxic effects.

What does this mean?

As with any potential hazard in our lives, make smart choices. Agricultural workers and homeowners should follow safety guidelines and keep exposure within established minimum toxicity levels. Enforcement of residue levels keeps us safe at the table.