Glyphosate foes driven by hatred of Monsanto

The New Zealand Environmental Protection Authority made the right call last week to leave glyphosate off a list of chemicals it will reassess to determine their risk to people and the environment. In doing so, it resisted political pressure to put use of glyphosate-based weedkillers like Roundup in the spotlight. Associate Environment Minister and Green MP Eugenie Sage had wanted the EPA to consider classifying glyphosate as a hazardous chemical.

There’s a movement, particularly in Europe, to have glyphosate banned. But those efforts are driven as much by hatred of Monsanto, the US company that produces Roundup as well as genetically modified seeds, as by suggestions glyphosate causes cancer in humans.

A decision in 2015 by the World Health Organisation’s International Agency for Research on Cancer (IARC) to classify it as ‘‘probably carcinogenic to humans’’ gave opponents ammunition.

The IARC finding was cited in the case of 46-year-old Dewayne Johnson, who in August won a landmark US$289 million court victory against Monsanto. Johnson claimed that, as a school groundskeeper in San Francisco, exposure to Roundup was responsible for the Non-Hodgkin lymphoma that is killing him.

Did IARC get the science wrong? No. It was widely criticised for excluding important information, but the trouble stems from a misunderstanding of IARC’s role.

The agency reviews scientific literature to determine ‘‘hazard’’. More relevant is ‘‘risk’’.

Red meat is ‘‘probably carcinogenic’’ as well, according to IARC, but in reality it depends on how much of it we consume, how it is cooked and numerous other factors.

IARC leaves regulators to determine risk and in 2016 the EPA found that ‘‘based on a weight of evidence’’, glyphosate was unlikely to cause cancer when used as recommended.

A reassessment would change nothing, but drag it firmly onto the battlefield to join 1080, water fluoridation and genetic modification in being demonised for non-scientific reasons.