We sat down (virtually) with editors Robin Mesnage and Johann Zaller to discuss their book Herbicides: Chemistry, Efficacy, Toxicology, and Environmental Impacts (2021), including misinformation, glyphosate, and the future of herbicide research.

• In a nutshell, what is this book about?

Herbicides make up around 40% of the global pesticide use and have become a pillar of modern agricultural production systems. They are applied also in private gardens, in urban environments mainly for cosmetic purposes, along roadsides and railway tracks, in landscape turf management, and even in nature conservation areas to kill invasive plants.

With their beneficial influence on yields and production costs, there is a downside: water and soil contamination, loss of biodiversity, and public health impacts such as acute poisoning and chronic diseases associated with herbicide exposure.

While scientific evidence of adverse effects on human health and ecosystems is mounting, there is no book that summarises it. We gathered a team of internationally recognised experts to shed light onto this complex topic and present the state of the science, including chemistry, efficacy, analysis, toxicology, environmental impact, and legal aspects.

A quantitative glance at some key topics of this book is provided in the concluding chapter:

• Why did you feel this book needed to be written?

Use of herbicides increased dramatically in recent decades and formed a billion-dollar market. As a consequence, information which can be easily accessed on the internet is a double-edged sword. Safety evaluations have often been compromised by scientific misconduct or influenced by campaigns of advocate groups. It is increasingly difficult to differentiate between evidence-based knowledge and deliberate misinformation. We felt an urgent need for a comprehensive overview by internationally recognized experts.

• What level of readership is the book geared to and why?

We wrote it to engage both specialists in the research community and informed persons responsible for legislative, funding, and public health matters. Depending on the existing knowledge, some chapters are also appropriate for a dedicated readership in the NGO sector.

Appeal to a broad readership was necessary because the use of herbicides and their non-target effects is not only an issue of human and environmental health but also has important political, legal, and economic implications.

• What makes your book stand out from the rest?

The book is unique in summarising this knowledge using a concise and multidisciplinary approach.

Providing 9 billion people with healthy food through sustainable farming is a great challenge humanity has to face. It implies a global revolution of food systems. Socioeconomic factors such as food availability, wealth disparity, waste management, and dietary choice are equally important for ensuring global food security. It is up to scientifically informed policymakers to decide whether food production without synthetic herbicides should be fostered. The book is meant to provide insights from multiple scientific disciplines to reach that decision.

The book also addresses contemporary debates, for example on the toxicology of glyphosate. Glyphosate gained a high level of public interest when Roundup users were diagnosed with non-Hodgkin’s lymphoma and started suing pesticide manufacturers.

• What is the message you most want to convey through your book?

Each chapter contains a multitude of messages, according to the contributor’s personal area of expertise. Our objective was to provide an overview according to the precautionary principle, that is, the responsibility to protect the public and environment from unnecessary exposure when there is a plausible risk.

Another key message is that every herbicide carries risk. Contrary to a widespread assumption, herbicides not only kill weeds but have direct and indirect impacts on a wide variety of non-target organisms and the function of ecosystems. Safe use requires definition of an acceptable level. Weighing the risk-benefit ratio involves toxicological, economic, social, and environmental considerations.

Of course, each chapter also highlights existing knowledge gaps in target and non-target effects, product composition, analytical approaches to detection in the environment and our bodies, and legal aspects to monitor and control.

• What was a unique experience you had during your career?

RM: When I started my PhD in 2010 at the University of Caen in Normandy, I was thrown into the deep end of the pesticide safety controversies. The research group was in the middle of the first study of the long-term toxicity of Roundup and a Roundup-tolerant GM maize. The network of activists involved in the publication of this study orchestrated a communication operation that caused an explosion of media coverage by spreading graphic images of rats with large tumors. This had a strong influence on public opinion about GM foods and even led to serious political consequences. This first-hand view of the profound intertwinement among science, political ideologies and economic interests during my doctorate clearly influenced the decision to write this book.

JZ: As an ecologist working on climate change aspects, I long ignored the issue of herbicides (and pesticides in general). I simply thought that there is not much to research because those substances are rigorously tested before they are released into our environment. Then, after diving into the huge body of literature I realized that many studies lack a holistic perspective, including interactions between species, between different substances applied in the fields, ethical and socioeconomic aspects. Since then I have tried to ask what is behind bold statements about the necessity and harmlessness of pesticides: Is there a possible conflict of interest? Have some aspects been forgotten or ignored? Are alternatives considered at all?

• In your view, what’s next for the future of herbicide research?

The concluding message of the book is that there is no one-size-fits-all approach for weed control. Herbicide research will have to become more localized depending on existing pressure of particular weed species, by integrating effects of crop rotations and the inclusion of regional farmers’ knowledge. Each country and climatic region will account for the particularities of its environment. This will also help in tackling issues caused by climate change, as the development of local solutions will be facilitated. So there are many important topics for future research, preferably multidisciplinary.

Ready to read this book?

Herbicides is now available on ScienceDirect. Or buy your own copy on the Elsevier store  and save 30% + free shipping with promo code STC30.