Global Pesticide Toxicity Is Rising Across Farming Regions

Modern farming depends extensively on pesticides to safeguard crops and sustain high food yields. Yet scientists have increasingly found that many of these substances do not simply eliminate pests: they may also damage insects, fish, soil-dwelling organisms and plants that underpin functioning ecosystems.

In response to those concerns, nations gathered at the 2022 United Nations Biodiversity Conference in Montreal pledged to halve pesticide-related risks by 2030. The commitment sought to curb biodiversity decline without jeopardising worldwide food supplies.

However, a new worldwide assessment indicates that the damage caused by pesticides is increasing in numerous agricultural areas.

Researchers at RPTU University Kaiserslautern-Landau investigated patterns of pesticide use in almost every farming region worldwide, producing one of the broadest assessments so far of the effects of chemical use on ecosystems.

Measuring pesticide harm

Previous research has often assessed pesticide risk by calculating the number of tonnes sprayed on crops. However, this approach overlooks a crucial issue.

Certain pesticides can inflict substantial damage at very low quantities, whereas others present less danger even when used at greater doses. To address this, the researchers applied a measure known as total applied toxicity, or TAT.

This approach brings together two elements: the amount of every pesticide applied by farmers and the toxicity of each chemical to living organisms.

Tracking ecosystem damage from pesticides

The team assessed 625 pesticides and evaluated their effects on eight groups of organisms commonly used in pesticide safety tests. These covered fish, insects, pollinators, soil organisms, plants and vertebrates.

Toxicity figures were obtained from regulatory bodies in Australia, Canada, China, the European Union, Japan, New Zealand and the United States.

“This gives us a whole new perspective on the potential risks to the environment and biodiversity posed by pesticide use,” said study co-author Dr. Ralf Schulz, science director at RPTU University Kaiserslautern-Landau.

Pesticide-use data

Making comparisons of pesticide risks between countries is difficult. Countries frequently gather information differently, while some do not publish detailed data at all.

To deal with this limitation, the researchers used commercial data on pesticide applications from 2013 to 2019. This timeframe corresponds with the baseline established under the United Nations biodiversity agreement.

“To ensure continuous and comprehensive monitoring, it is essential that all countries regularly report updated annual data on agricultural pesticide use, broken down by active ingredient,” said study lead author Jakob Wolfram, a researcher at RPTU University Kaiserslautern-Landau.

According to the authors, this reporting would make it possible to follow progress towards the goals agreed at the UN Biodiversity Conference in real time. In the absence of consistent reporting, assessing global progress is still challenging and incomplete.

Toxicity rising across ecosystems

The findings present a concerning outlook. Total applied toxicity rose for the majority of organism groups from 2013 to 2019. Terrestrial insects saw the quickest increase in harm, with soil organisms and fish next.

Risks also grew across many regions for pollinators and aquatic invertebrates. Overall, slight reductions were recorded only for aquatic plants and terrestrial vertebrates.

Two factors are behind the increase. The expansion of agricultural land leads to greater pesticide use, while older products are being replaced with more potent and toxic chemicals, particularly insecticides.

A limited number of pesticide classes account for most total toxicity. Pyrethroids and organophosphates produce considerable harm to fish and insects. Neonicotinoids have strong effects on pollinators. Some herbicides are responsible for plant toxicity, whereas fungicides have a major impact on soil life.

“This rise is driven in part by higher pesticide amounts being applied and in part by the growing toxicity of the active ingredients themselves, particularly insecticides,” said Dr. Schulz.

One notable finding is that around 20 active ingredients are responsible for more than 90 percent of pesticide toxicity in many countries. Substituting these chemicals could greatly lower environmental damage.

Ecological harm hotspots

Worldwide trends show marked regional variation. Brazil, China, the United States and India together account for over half of global pesticide toxicity.

Nigeria currently records lower levels, although swift growth in agriculture could alter future risk levels.

The crops grown are also highly important. Fruit, vegetables, maize, soya beans, rice and other cereals account for approximately 80 percent of pesticide toxicity worldwide. Extensive crop-growing areas combined with the selection of toxic pesticides produce ecological harm hotspots.

“The interaction between cultivated land area and the types of crops grown is a key driver of applied toxicity and is thus another factor that can be adjusted in agricultural planning to achieve the goal of protecting biodiversity,” said Wolfram.

Urgent action on pesticide harm

Without decisive measures, Chile alone is expected to achieve the United Nations target by 2030. China, Japan and Venezuela are making progress, but require more rapid change.

Numerous other countries would have to reduce pesticide toxicity to levels last recorded more than 15 years ago.

“This can likely only be achieved by shifting to less toxic active ingredients and expanding the transition from conventional to organic agriculture, which would also deliver broader benefits for global biodiversity,” said Wolfram.

The research delivers an unequivocal message: cutting pesticide harm is still achievable. It requires replacing the most toxic chemicals, strengthening data reporting and redesigning farming systems to safeguard food production and life on Earth.