The science says used correctly, Roundup is safe

I have to admit, I'm not much of a gardener. While I don't exactly have overflowing flowerbeds, I do like to keep things tidy. So, like many Aussies, I often turn to the old Roundup to keep stray weeds and lawn edges under control. You just spray and walk away, and a couple of days later, poof, the weeds are dead.

So, how does this magic happen? The active ingredient in Roundup is a chemical called glyphosate. Glyphosate works by interrupting something called the shikimic acid pathway. This is a biochemical pathway that plants use to make amino acids - the building blocks of proteins. Glyphosate interrupts this process, and when it does, the plant dies. Humans and animals don't have the same pathway for making amino acids, and so glyphosate doesn't kill us.

Or does it? Roundup, and its manufacturer Monsanto, have been hitting the headlines in the last couple of years, with claims that the product is carcinogenic.

Last year, a former school groundskeeper in the US successfully sued for damages, claiming that Roundup contributed to the development of his non-Hodgkin lymphoma. Two other complainants in the US have also successfully sued the manufacturers this year, again in relation to cancer diagnoses. And a couple of weeks ago, the first legal case has been launched here in Australia, with a Melbourne gardener blaming his non-Hodgkin lymphoma on years of exposure to Roundup.

Roundup is one of the most widely used herbicides in Australia. So, how worried should we be?

Despite these landmark court decisions, long-term scientific studies of glyphosate have found that it is safe for people and animals, and that there is no - or an exceptionally small - risk of cancer associated with its use.

The Australian Pesticides and Veterinary Medicines Authority, alongside the US Environmental Protection Agency and other regulators, take the position that glyphosate is non-carcinogenic and that there's no need for further regulation.

The European Food Safety authority has also investigated the use of glyphosate, and again found no link between its use and cancer.

In reading about these court cases and verdicts, remember that the decision of a jury is not a scientific study - it is opinion, not fact. At the end of the day, if you are using your Roundup according to the instructions on the packaging, the real science says you will be just fine.

Dr Mary McMillan is a lecturer at the School of Science and Technology, University of New England