Campus Review Vol 29. Issue 7 July 2019 | Page 21

industry & research campusreview.com.au Agriculturalists also take issue with WHO’s decision, arguing that glyphosate has helped produce significantly higher yields since the 1980s and improved soil by doing away with till farming. According to the chairman of Grain Producers Australia, Andrew Weidemann: “A ban on glyphosate would be a disaster agronomically.” Ivan Kennedy, professor emeritus in agricultural and environmental chemistry at the University of Sydney, spoke with Campus Review about WHO’s classification of glyphosate, the recent US verdicts and what Australian agriculture would be like without glyphosate. CR: Professor, you believe WHO’s labelling of glyphosate as a probable carcinogen to humans was a bad decision. Why? IK: I’ve been reassuring farmers for some years now that they have nothing to fear from glyphosate. I do that on the basis of lots of evidence, essentially [evidence] that has been used for the last 40 years. I also do it based on glyphosate’s actual structure and its mode of action. It consists of three parts: one that you could think of as carbon dioxide; another is ammonia; and the third is phosphate. These are all essential elements in our nutrition and metabolise in our body. The likelihood that such a compound would be carcinogenic is inherently unlikely. Glyphosate has none of the features of common carcinogens. It’s not aromatic, it doesn’t have halogens, it doesn’t contain heavy metal. Just on that basis, I find any suggestion that it is carcinogenic most unlikely. Nevertheless, around the world, the various agencies – the European Food Safety Agency, the Food and Agriculture Organization, the United Nations, the Pest Management Regulatory Agency of Health Canada, the US Environmental Protection Agency, as well as the Australian Pesticides and Veterinary Medicines Authority – attest to the lack of carcinogenicity in many trials that have been conducted. You have to remember that Roundup itself has adjuvants, other chemicals, which vary from time to time, depending upon the projected use. Possibly some of those, generally speaking, are more toxic, and perhaps some of those might have some influence. I’m not an expert on carcinogenicity myself. Many agriculturists believe that glyphosate is a wonder chemical, because it can precisely target weeds. Why are we unlikely to create a similar chemical? Well, in a sense, it was found by accident. I’m sure the researchers that found it were seeking something as good, but its mode of action is to interfere with an enzyme occurring only in plants. It’s a shikimate synthase, which makes shikimic acid, which is an essential precursor for making lignin and wood. Of course, plants are the only species – perhaps as well as a small number of bacteria – that can actually carry out these reactions. You can’t really design for something like that unless you’ve got that kind of intimate knowledge that glyphosate mimics phosphene or pyruvate, which is a key element in our metabolism. So it looks like phosphene or pyruvate, but only to this particular enzyme that occurs in plants. None of the enzymes in animals that use phosphene or pyruvate are affected. The Grains Research and Development Corporation, as well as Bayer in Europe, have had a program in recent years – a well-funded program – to engage expert chemists on planning to develop replacement chemicals. I’m not fully up-to-date on that program, but I haven’t heard if it’s come up with anything that has the particular characteristics of glyphosate. Glyphosate acts directly on plants, through the leaves. As soon as it hits the soil, it becomes inactivated, so it has very little residual effect, unlike most other herbicides, some of which can hang around for months affecting other plants and also exerting any possible toxicity that they have. I’m going to turn to the legal matters here, and I know this is not necessarily your area, but I’m sure you would have an opinion on it. Do you think the fact that a jury and not a judge decided on the Monsanto verdicts influenced the outcomes of the US lawsuits? I certainly do. Obviously in cases involving cancer, there’s an emotional element. A jury, of course, is not equipped to handle the scientific evidence. It’s not decision- making that they’re accustomed to using. Very few of them are likely to be experts in the area, so I think the court cases in the US have been civil cases where the standard of evidence is much lower than other parts of the justice system. Personally, I would prefer to see such court cases conducted by judges who would consult with experts arguing on both sides, and really weigh up the evidence on that basis. That’s certainly my opinion. I don’t really think juries are equipped to make these sorts of decisions on a scientific basis. Critics of glyphosate, and Bayer more generally, say that denying that glyphosate is a carcinogen is akin to what happened with Big Tobacco. They argue that vested interest groups paid for certain kinds of research outcomes and so on. Is this a fair call, or is the science still undecided? I don’t think it’s a fair call. In the case of tobacco, and the mechanism of cancer, that was pretty obvious. The compounds that are in tobacco smoke can be demonstrated to be carcinogenic. Just in the way that the carbon products that you get from your barbecue steak can be carcinogenic, but only at a very low rate. In the case of tobacco, it’s clear that the scientific evidence was that it was cancer causing. In the case of glyphosate, there’s The likelihood that such a compound would be carcinogenic is inherently unlikely. no such evidence for that carcinogenicity. Certainly in humans. There is some work that’s been done with animal species that are very prone to developing cancer. There’s a suggestion, and I think that’s what the International Agency for Research on Cancer was thinking of when they made their decision. In my opinion, they should have restricted the judgment to possible cancer, and I think their object is really to encourage research. They make a qualitative judgment, just based on the public literature. They don’t do anything quantitative; they don’t do a proper risk assessment. Really, they’re just ringing a bell: “Here’s something to look at.” But that should never have become evidence in a legal situation. ■ 19