A new groundbreaking study
A new groundbreaking German study proves that pesticides spread much further from the field than previously believed. A team of scientists led by Professor Dr. Carsten Brühl tested topsoil, vegetation, streams and puddles from 78 locations over a 180 km stretch, from remote areas in the UNESCO forests on the mountain ranges to the farmland in the Upper Rhine area. The research team detected a total of 63 pesticides. Almost all measurement sites were contaminated. Residues were found in 97% of the soil and vegetation samples, often in complex mixtures of several active ingredients. This cocktail of pesticides is especially problematic because interactions can occur and effects can be amplified. The worrying results are consistent with previous smaller-scale studies in the South Tirol area in Italy. Large scale and prolonged pesticide use is a major factor in the sharp decline in populations of insects and other organisms essential for farming, as highlighted in our biodiversity campaign. The researchers see pesticide reduction as the only way to reduce the damage to biodiversity.
The study, published in Communications Earth & Environment, sheds a new light on the environmental impacts of conventional agriculture. It covers the Upper Rhine Valley in Germany that extends for about 300 kilometers between Bingen and Basel. It is a traditional agricultural landscape where cereals, vegetables, wine and fruit are grown due to favorable climatic conditions. Synthetic pesticides have been used extensively for over 50 years in conventional agriculture to control pests, weeds and fungal diseases. This usually involves a combination of different active ingredients and multiple applications per year. As a consequence, the so-called ‘non-target areas’ that are not directly sprayed, such as adjacent hedges, field margins, meadows or dry grasslands but also areas much further away are increasingly suffering from chronic pesticide contamination.
Environmental sampling over a 180-kilometer stretch
The research team carried out extensive sampling during the spraying season in June and July 2022. The systematic recording and presentation of pesticides on such a large scale is a new approach developed at the Institute for Environmental Sciences in Landau. With the help of state-of-the-art analytical techniques that can detect low concentrations, the study included 93 common pesticides.
Contamination from the lowlands to the highlands
On average, the vegetation was contaminated with six pesticides, and in some cases with as many as 21 substances. On average, five pesticides were measured in topsoil, with individual samples showing up to 26 different active ingredients. The active ingredients were also detected several hundred meters from agricultural land. According to the researchers, it is particularly worrying that even remote areas are not free of pesticides.
“Our results are clear: pesticides spread far beyond fields. This is more than just an agricultural problem – it is a reality that affects us all. We can encounter pesticides while taking a walk, in playgrounds or in our own gardens,” explains Ken Mauser, lead author of the study. Farmers and their families and neighbours are especially at risk and also sensitive groups such as children, pregnant women and the elderly. Only recently, Germany recognisied “Parkinsons caused by pesticides”as an occupational disease in viticulture in Germany.
One of the most frequently found pesticides was the fungicide fluopyram, which was detected in over 90% of all samples. Fluopyram is classified as a PFAS, a so-called “forever chemical”, and the breakdown product TFA can contaminate groundwater. According to the environmental scientists, the widespread distribution of the fungicide in the landscape seems extremely worrying due to its potential contamination of drinking water resources. In February 2025 PAN Europe and a coalition of organisations from civil society urged the EU to ban Fluopyram immediately.
The most frequently detected current use pesticides in topsoil in the study were the fungicides fluopyram (94% of all samples), boscalid (42%), spiroxamine (37%), and pyraclostrobin (22%). In vegetation, the fungicides fluopyram (92%), spiroxamine (55%), cyflufenamid (PFAS, 41%), and boscalid (38%) were the most found. In surface water, the predominant detections included the fungicide fluopyram (77%), the insecticide pirimicarb (67%), the herbicide metazachlor (63%), and the insecticide tebufenozide (63%). Each of these frequently detected pesticides is categorized as ‘High alert’ or ‘Moderate alert’ by the Pesticides Properties Database. in at least one of the three categories Environmental fate, Ecotoxicity and Human health. Of all 63 detected pesticides currently used in agriculture, 35% are categorized as High alert in Environmental fate, 43% as High alert in Ecotoxicity and 40% as High alert in Human health. Fluopyram and boscalid are also highly persistent substances with a typical half-life in soil of 309 days and 484 days, respectively, resulting in a igh risk to accumulate.
A smaller scale study in the Netherlands showed cocktails of different pesticides from other types of crops. They identified the volatile prosulfocarb, pendimethalin (toxic 12) and folpet (related to Parkinsons) as especially problematic. Of the 65 pesticides found in that study, 26% are neurotoxic or possibly neurotoxic, 77% have possible effects on development and/or reproduction, 31% have possible endocrine-disrupting properties and 42% are possibly carcinogenic. All agents found have potentially toxic properties for humans. No information is available on the effects of pesticide cocktails on biodiversity or the health of residents and users. See ‘A haze of pesticides over the land’ below.
“Cocktail effect” danger to health and biodiversity
The new German study also found mixtures of multiple pesticides. A total of 140 different combinations of at least two active ingredients were detected. “Pesticide cocktails are particularly problematic because interactions can occur and effects can be amplified. In the current authorization procedure, each pesticide is assessed individually. This is not enough to grasp the complex risks of the realistic exposure to mixtures,” emphasizes ecotoxicologist Carsten Brühl.
”Colleagues from Heidelberg were able to show that pesticide mixtures in similar concentrations to those detected in this study reduce the egg laying of insects by over 50 percent in the laboratory. It can therefore be assumed that these mixtures definitely have an impact on the environment, especially if they are also present chronically, i.e. throughout the year, as we were able to show in another study."
Pesticide reduction urgently needed
The study shows that pesticides do not only remain on agricultural land. They contaminate the entire landscape. The “cocktail effect” and the contamination of protected areas are worrying, according to the researchers. The scientists call for a strict pesticide reduction to protect people and the environment, plus monitoring of pesticide contamination in landscapes. This is in line with the goals of the COP 15 United Nations Biodiversity Conference, where countries agreed to halve global pesticide use by 2030. “Our approach of using landscape modeling to assess pesticide pollution can serve as a basis for future evaluations of the reduction efforts,” notes Carsten Brühl.
In addition, the researchers ask for large-scale pilot projects to create pesticide-free cultural landscapes on a scale of 10 x 10 kilometers. They see this as the only way to measure the positive effects of sustainable farming systems on biodiversity. Currently, pesticide-free agriculture, even when established in small areas, has no chance of realizing its potential in a landscape contaminated by pesticides. “Now it is up to politicians to develop and promote large-scale and effective pesticide-free approaches and to resolutely push ahead with the transformation to sustainable agriculture”.
The study: Current-use pesticides in vegetation, topsoil and water reveal contaminated landscapes of the Upper Rhine Valley, Germany (March 2025), Ken M. Mauser, Jakob Wolfram, Jürg Spaak, Carolina Honert & Carsten A. Brühl
Further study on the effects of pesticides on insects: Exposure of insects to current use pesticide residues in soil and vegetation along spatial and temporal distribution in agricultural sites, Carolina Honert, Ken Mauser, Ursel Jäger, Carsten A. Brühl. 2025
Read more:
- A cocktail of pesticides eradicates biodiversity - Interview with Prof. Dr. Carsten Brühl
- A haze of pesticides over the land, June 2024, about the Dutch Meten=Weten findings
- Pesticides do not remain in the valley, they go up the mountains, March 2024, new South Tirol study
- We need effective buffer zones - against a cloud of pesticides, PAN Europe, February 2023
