The discussion on Glyphosate & RoundUp (or other Glyphosate containing pesticide products) on Twitter continues. A quite interesting one, actually. I would like to take the opportunity to reply to a few comments made.

I’m aware that it is a bit unfair to use the space provided by a blog to answer comments and critique statements that were posted in 140 character bursts. But please feel free to comment below, or send me comments to my University email. I would re-post them here.

Whatever I write, it will have a mostly European perspective. Simply because that is the regulatory setting that I am most familiar with.

Data availability for Glyphosate

An extensive set of studies is available for glyphosate itself. Covering the regulatory requirements (obviously), plus a range of additional (often academic) studies, even including limited epidemiological evidence. That is, the data situation of glyphosate is better than for almost any other chemical out there.

Unfortunately, that doesn’t mean that the data are complete. Quickly browsing through the glyphosate evaluation that is published by the European Food Safety Authority EFSA  reveals for example that data are missing for several metabolites (N-acetyl-glyphosate (NAG) and N-acetyl-AMPA) (EFSA, 2015). And I guess that nobody would accuse EFSA of scientifically unfunded scare-mongering. Furthermore, to quote EFSA directly:

[…] a data gap has been identified for the full battery of Tier I screening assays on the hazard assessment of endocrine disruptors in accordance with the EDSP, or the Level 2 and 3 tests currently indicated in the OECD Conceptual Framework (OECD, 2012b), and analysed in the EFSA Scientific Opinion (EFSA SC, 2013). Although the experts agreed that there is no evidence for endocrine-mediated effects for glyphosate, a firm conclusion cannot be reached now and a data gap was proposed.

And that doesn’t even begin to touch on the issue of carcinogenicity, or Glyphosate’s ecotoxicological evaluation, including potential groundwater contamination.

Data availability for Glyphosate-containing pesticide products

In contrast to Glyphosate itself, toxicological data on the long-term effects of Glyphosate-containing products are basically missing. Not to mention data on tank-mixes, i.e. the concoctions that are sprayed after mixing several products together in a tank. Dr. Alison Bernstein (@mommyphd2 on Twitter. If I got it correctly, she is Assistant Professor of Translational Medicine and Molecular Medicine at Michigan State University in real life), argued that those data are almost impossible to generate. Simply because there is a myriad of Glyphosate containing products out there, all with a different chemical composition. An evaluation of the chronic toxicity of all possible products on the same level of scientific scrutiny as for the one single active ingredient would therefore be incredible expensive .

Dr. Bernstein commented as follows:

Who pays for such studies?

Real question bc dwindling public resources, instant discrediting of anything with a whiff of a financial COI, how to implement that IRL…

in practice, it seems it will turn in an effective ban on all new products and many existing safe products bc will be impossible to meet

George Nikolich (@ganikol on Twitter, no further information on his background found) added:

What about tank mixes, inc standalone adjuvants, conv & org? Virtually inf combos. Need reasonable approach based on sci & plausibility.

Both definitely have a point (actually, more than one). But just to answer the first question: industry. For me that is simple. Selling those products is their business model. So they need to invest the resources to prove their safety. And those studies need to be public, from the beginning to the end, i.e. from study design to the reporting of the raw data. I don’t buy the argument that such studies have to be confidential in order to protect business. If indeed study results have to be kept confidential in order to protect a given business under the current legal frameworks, then we have to change those legal frameworks. But not the way we do chemical safety assessment.

Of course, companies cannot (should not) be chased with never-ending requests for additional studies. So we need to make sure that we have an agreed set of data requirements from the very beginning. Which is what regulatory frameworks are for. Those are constantly evolving.  Just taking a look at e.g. Regulation 1107/2009 (EU Parliament 2009) which sets the frame for the European evaluation of pesticides… Well, I’ve seen far, far worse.

Nevertheless, it is definitely a substantial shortcoming if „reasonable approaches“ for the evaluation of the long-term safety of pesticide products are missing – while people are exposed on an everyday basis. If we cannot ensure the long-term safety of these products – how can we justify using them? The current situation simply means that nobody can guarantee the long-term safety of operators, i.e. the people that handle pesticide products day-in, day-out. Even bystanders might be exposed the spraydrift, although most likely not as often.

It may be worth to emphasize that this problem is not confined to RoundUp and colleagues. The same goes for all other pesticide products and even chemical products in general. Small surprise that occupational cancer is a massive problem (responsible for 32% of deaths in occupational settings, see here). And no, I am not saying that those caused by Glyphosate. There are dozens or even hundreds of carcinogens out there that people are exposed to.

In fact, that might be one of the reasons on the diverging opinions of EFSA and the IARC. To simply quote EFSA again:

There are several reasons explaining the diverging views (of Glyphosate’s carcinogenicity, my comment) between the different groups of experts. On one hand, the IARC did not only assess glyphosate but also glyphosate-based formulations, while the EU peer review is focused on the pure active substance; the peer review recognised that the issue of toxicity of the formulations should be considered further as some published genotoxicity studies (not according to GLP or to OECD guidelines) on formulations presented positive results in vitro and in vivo. In particular, it was considered that the genotoxic potential of formulations should be addressed;

In summary

Let’s face a harsh truth: we will never be able to guarantee the safety of pesticides (or any other chemical, for that matter) to a 100%. There will always be data gaps and doubts. So we need to have a more honest discussion about the health end environmental risks that we are willing to accept in order to harvest benefits (pun intended) from the use of chemicals. We need to look at this from a public health, an occupational and an environmental perspective. Pesticide use is perhaps putting things under a microscope. With very tangible benefits, but also very tangible risks.

And let’s also face it: glyphosate is by no means a special case. There are no scientific reasons why the hazard or risk profile of exactly this compound is so controversial. If I’d have to pick a compound that is more problematic for human health: let’s talk Chlorpyrifos. Which is easy for me to say, as the compound is currently simply not allowed on the European market.

At the end…

On a more humorous side-note: I thoroughly enjoy it when people start wondering „where I fit in“:

References

EFSA (2015) ‘Conclusion on the peer review of the pesticide risk assessment of the active substance glyphosate’, EFSA Journal, 13(11), p. 4302. doi: 10.2903/j.efsa.2015.4302.

EU Parliament (2009) ‘Regulation (EC) No 1107/2009 of the European Parliament and of the Council of 21 October 2009 concerning the placing of plant protection products on the market and repealing Council Directives 79/117/EEC’, Official Journal of the European Union, (309), pp. 1–50.