London School of Hygiene & Tropical Medicine

Glyphosate (Roundup) is one of the most commonly used herbicides in the world, and in most countries is available to the general public – you can buy it in the UK at your local garden centre. More court cases are pending in the USA, and similar cases in other countries are likely to follow.

The recent decision of a Californian court to award compensation of $289 million to a man who claimed that herbicides containing glyphosate had caused his cancer (a non-Hodgkin’s lymphoma) has potentially profound implications. Glyphosate (Roundup) is one of the most commonly used herbicides in the world, and in most countries is available to the general public – you can buy it in the UK at your local garden centre. More court cases are pending in the USA, and similar cases in other countries are likely to follow.

A key piece of evidence in the trial was that the International Agency for Research on Cancer (IARC), an agency of the World Health Organisation (WHO), has classified glyphosate as ‘probably carcinogenic’. This classification has been followed by major controversies, particularly in light of the recent relicensing of glyphosate by the European Commission, hundreds of litigation cases in the USA brought by cancer patients against Monsanto (the producer of glyphosate), and the decision of the California Environmental Protection Agency to label glyphosate as a carcinogen.

Disappointingly, but perhaps not surprisingly, this controversy has led to attacks not only on the IARC decision, but also on some of those involved in the IARC Monograph meeting which made the decision, and on IARC itself. These events are not happening in a vacuum. There have been attacks on previous IARC decisions on potential causes of cancer such as formaldehyde, diesel fumes and radiofrequency electromagnetic fields. More ominously, there are moves by some governments to threaten to cut the funding of IARC, in response to these recent ‘inconvenient’ decisions.

So how do the IARC Monographs work? IARC, by far the most authoritative agency in this field, is supported by funding from 26 countries, including the UK. There are independent Governing Councils and Scientific Councils, and also Advisory Groups that recommend which chemicals and other exposures should be considered for evaluation of their carcinogenicity. Monograph Work Groups are then assembled, each of which evaluates the human, animal and mechanistic evidence for carcinogenicity.

On this basis, the agents being reviewed are classified as carcinogenic (group 1), probably carcinogenic (group 2A, which includes glyphosate), possibly carcinogenic (group 2B), not classifiable (group 3), and probably not carcinogenic (group 4). The voting members of the Working Groups are not employed by IARC, and receive no financial compensation; observers from industry and other interested parties can attend the Working Group meetings but not vote. There are clear and strict rules about what evidence can be included in IARC Monographs, with clear rules for searching all of the published literature, and also clear rules that literature that is not publicly available cannot be considered.

I recently reviewed the IARC processes, and some of the criticisms that have been made of them from industry, in a scientific paper with more than 120 co-authors, a group which includes most of the leading researchers in occupational and environmental cancer epidemiology. Some of us disagreed with individual Monograph decisions, which is normal and healthy in science. However, we concluded that, although there is always room for evolution and improvement, that the IARC processes are sound, and that recent industry-funded criticisms have been unfair and unconstructive.

We all look up to IARC and see it as a beacon of independence and objectivity in a world which is becoming increasingly partisan and polarised, and in which scientific evidence is increasingly disparaged and ignored. Facts matter, science matters, and in this field, there is no other agency which even comes close to IARC in terms of independence, objectivity, and transparency.

A few of the myths about IARC that are currently being propagated include “IARC finds that everything causes cancer, “IARC does no research, it only has opinions” and “IARC has been found to be corrupted” – I could go on. The facts are that IARC is under attack because it is objective, effective, and sometimes produces inconvenient findings.

We need, and rely on, a court system which is independent, fair, and not subject to political, corporate, or community pressure. We also need independent scientific bodies such as IARC which can review the scientific evidence objectively, and without conflicts of interest, even if this leads to conclusions that some may find inconvenient.