Don’t leap to conclusions on backyard weedkiller worries

Regulators have an eye on herbicide Roundup but not all is as it seems, explains Jan Davis

A PIVOTAL debate now under way in the European parliament could revoke the licence for the most widely used herbicide in human history, with fateful consequences for global agriculture and its regulation.

Glyphosate is one of the world’s most widely used weedkillers. Used for more than 40 years, it is in hundreds of plant-protection products. You’d find it in most garden sheds across Australia under the brand name Roundup.

Commercial agriculture accounts for the bulk of global demand and the broad spectrum weedkiller makes up a quarter of global herbicide sales. The chemical is mainly used to combat weeds but also helps crops dry and ripen.

The use of glyphosate has long been challenged by environmental and health activists. Much of the opposition has been based on a large dossier claiming to find evidence that glyphosate is “probably carcinogenic”. This was published in 2015 by the International Agency for Research on Cancer (IARC), part of the World Health Organisation. What could be more scientifically respectable, you may ask.

Well, when it was subject to more detailed analysis, experts found the IARC report relies on a tiny number of studies, and even these don’t support its conclusion. The evidence it causes cancer in humans is especially tenuous, based on three epidemiological studies with confounding factors and small sample sizes linking it to Non-Hodgkin lymphoma (NHL).

The report was also shown to ignore studies that don’t support its claims. Foremost is the US Agricultural Health Study, which has been tracking 89,000 farmers and their spouses for 23 years. That study found “no association between glyphosate exposure and all cancer incidence or most of the specific cancer subtypes we evaluated, including NHL.”

Last year, the European Food Safety Authority completed a reassessment of

glyphosate as part of the EU’s pesticide renewal process, which included a consideration of the IARC assessment. Using a riskbased, weight-of-evidence assessment approach, European Food Safety Authority considered an extensive body of scientific evidence, including studies not assessed by the IARC, and determined there was no credible evidence that glyphosate causes cancer in humans.

Australia’s agvet chemical regulator, the Australian Pesticides and Veterinary Medicines Authority (APVMA) controls the use of all chemicals in Australia, including glyphosate. It is required under legislation to ensure that any pesticides registered for use in Australia have been through a robust chemical risk assessment process and are safe to use, provided they are used as per the label instructions.

In 2016, the APVMA also conducted an evaluation that included a commissioned review of the IARC monograph by the federal Department of Health, and risk assessments by expert international bodies and regulatory agencies.

The review commissioned by the Department of Health was in two phases. The first identified which studies relied on by IARC should be reviewed in more detail, while the second involved a detailed assessment of those studies.

APVMA concluded glyphosate does not pose a carcinogenic risk to humans and there are no grounds to place it under formal reconsideration.

Although the assessment of glyphosate by EFSA similarly concluded that glyphosate is not likely to be carcinogenic in humans, a number of members of the European Parliament were concerned that the assessment by IARC differed to that conducted by international regulators, including the European Food Safety Authority.

Last year, the European Commission temporarily extended the licence for glyphosate use for 18 months, pending more scientific analysis and following a split by member nations over a proposed nine-year extension. That followed a six-month extension that prevented the licence from expiring as originally scheduled in December 2015. The current licence expires next month.

Even if the licence is allowed to expire, member states may be able to request some exemptions from a ban, and the commission could propose a shorter renewal period with usage restrictions.

Any EU decision to further regulate or ban glyphosate will have consequences for Australian agriculture, so the process is being closely watched here.

Sadly, we live in an age where rational science-based evidence struggles to stand against ill-informed opinion.

Modern media builds walls around communities of shared views that confirm people’s thinking; and attack, ban or systematically repudiate people with differing ideas. Surrounded in our echochambers, self-appointed experts disconnect us from evidence-based dialogue, raise emotional arguments to the point where anecdote serves as evidence and build trust by elevating fears and vulnerabilities.

Let’s hope that this time common sense wins out.