The risks of herbicide exposure

Plaintiff DeWayne Johnson looks on at the start of the Monsanto trial in San Francisco,...
Plaintiff DeWayne Johnson looks on at the start of the Monsanto trial in San Francisco, California. Photo: Reuters
A civil jury in San Francisco created history when it awarded $NZ440million to a groundsman who said his lymphoma resulted from years of applying Monsanto's trademarked Roundup herbicide.

The product, the man claims, did not include adequate warning of its links to cancer.

The state Superior Court jury agreed Roundup contributed to the man's cancer and Monsanto should have provided a label warning of the potential health hazard.

It is the first case filed by a cancer patient against the agribusiness giant to reach trial. It was expedited because court documents indicate the man is dying. His victory is likely to provide a precedent for many others.

Monsanto is appealing, meaning the case will continue for a while longer, leaving the groundsman wondering if he will ever get the money awarded to him.

The company says scientific studies and two government agencies concluded Roundup does not cause cancer.

The case is meaningful in a New Zealand context because Roundup is easily sourced and is widely used as a weedkiller in this country. Farmers, for instance, use the weedkiller to kill pasture before cultivating for new crops.

Home gardeners use smaller quantities but are more likely to take fewer safety precautions than those using the product on a large scale. Suggestions are for home gardeners to actually pull out their weeds, rather than spray.

Associate Environment Minister Eugenie Sage will be asking the Environmental Protection Agency to consider adding
Roundup to a list of hazardous substances for reassessment.

Ultimately, it is the agency's decision whether the weedkiller is added to the list.

The impact of the US finding is being debated widely, partly due to the involvement of large corporations and also because the Insecticide Resistance Action Committee assesses a chemical's carcinogenic potential but does not generally conduct a full risk assessment.

The case in the US cites adjuvants - additives in the Roundup beyond the active glyphosate compound - may have had a synergetic effect to cause the cancer. Synergetic effects occur when two chemicals, which are relatively benign separately, act together to make a small effect much worse.

Scientists say the terms of the case are interesting as the plaintiff did not need to demonstrate conclusively glyphosate caused the cancer, only that it was a plausible contributing factor. Also, Monsanto is unable to prove glyphosate definitely did not cause the cancer.

There is still no proof either way, but the success of the prosecution will encourage others to seek remuneration using the IARC classification as evidence.

Even if it is carcinogenic, as claimed by IARC, this would appear to be in a category less risky than eating preserved meats. Yet there is no outcry asking for these to be banned.

Roundup is not and never has been a safe panacea for all weed control. Scientists continue to learn more about the chemical and its effects. However, the alternative options are not very appealing and many are much worse for people and the environment. Improvement is needed but for farmers, Roundup is one of the safe options around.

A sudden reaction to one case in one US law court, which has not yet gone to the appeal court, is not an appropriate method of developing health policy in New Zealand. But it is appropriate New Zealand keeps watch on the overseas evidence about the risk of cancer from glyphosate exposure.

Glyphosate is one of the major weed-control tools. Calls for it to be banned will hopefully take into consideration the low risk of problems and the crucial importance of the herbicide for sustainable weed control worldwide.



EWG's tests found glyphosate, the active ingredient in Roundup, in all but two of 45 samples of products made with conventionally grown oats. These products were breakfast cereals off a supermarket shelf tested at an independent lab.

In my experience it is a common practice on NZ dairy farms to graze cattle on grass that has been sprayed with Round Up. Some farmers believe it will increase milk production.