Regular exposure to pesticides can cause Parkinson’s disease. This is what several studies suggest. Parkinson’s disease has now also been recognized as an occupational disease in agriculture in Germany. What this means for those affected – and how the chemicals rage in the body.

Parkinson’s disease caused by contact with pesticides is now recognized as an occupational disease. This was decided by the Medical Expert Advisory Board at the Federal Ministry of Social Affairs. This has primarily financial consequences for those affected: Anyone who develops Parkinson’s disease as a result of working with pesticides, such as farmers and field workers, is entitled to support from the employers’ liability insurance association. Accident insurance benefits are now added to the normal health insurance benefits.

In Italy, Parkinson’s has been a recognized occupational disease in agriculture for more than ten years, as has been the case in France. In Germany, there has been a fight for recognition until now. “We have known for a long time that there is a connection between pesticide exposure at work and Parkinson’s disease,” says occupational physician Thomas Kraus in an interview with “NDR”. He is the chairman of the Medical Advisory Board.

In Germany, however, there are different guidelines for recognizing an occupational disease than in Italy and France. “It was extremely difficult to evaluate and process the scientific literature from around the world and then derive criteria for an occupational disease for German social law.”

So what does science say about the connection between Parkinson’s and pesticide use? One of the most recent publications is a study from the USA published at the end of February 2024. It shows that people in regions of the United States with higher exposure to pesticides and herbicides are more likely to develop Parkinson’s disease.

To do this, the team from the Barrow Neurological Institute in Phoenix analyzed data from around 21.5 million US citizens and the use of 65 different herbicides and pesticides. They found the strongest connection between a Parkinson’s diagnosis and contact with one of the substances for the herbicides simazine and atrazine and the pesticide lindane.

The results were independent of other factors such as air pollution in the respective location. However, pesticide and herbicide exposure figures are based on county-by-county estimates and not on exact data for each individual.

The three substances mentioned are no longer permitted in Germany. The use of atrazine has been banned since 1991, simazine since 2000 and since 2006 the production and use of lindane has been banned throughout the EU.

Other potentially dangerous substances that are still used in German agriculture carry corresponding warnings, and there are certain rules for mixing and spraying in order to adequately protect users. Anyone who is trained in the correct use of the products and wears appropriate protective clothing should not have to worry about health consequences. However, occupational physician Thomas Kraus complains in an interview with “NDR”: “There is often a lack of awareness of the danger and the instructions are inadequate. Recognition as an occupational disease could help. A new occupational disease often raises awareness and provides a boost for prevention. I now hope the same for Parkinson’s and the use of pesticides.”

How exactly pesticides in the body contribute to the development of Parkinson’s disease has not yet been conclusively clarified. It is possible that the toxins enter the brain in a roundabout way, for example via the intestines. Tests on mice that were injected with the pesticide Rotenone via a stomach tube show that Rotenone causes the protein alpha-synuclein to clump together in the intestinal cells. This abnormal form of the protein could spread from one cell in the intestinal nervous system to the next and then travel through the spinal cord to the brain.

Another study was published at the end of April 2024. It comes from researchers at the University of California. They examined the genetic information of almost 800 Parkinson’s patients from California. Many of them had worked with pesticides in cotton production for at least ten years.

The researchers assume that cotton pesticides change the autophagy process in the body. This refers to the ability of cells to break down damaged proteins and organelles. Disturbed autophagy could lead to the formation of toxic compounds and thus Parkinson’s disease.

Studies showed that patients had increased accumulation of the protein alpha-synuclein, which is already abundant in the brain and neurons. If the protein is no longer broken down sufficiently, it forms clumps known as “Lewy bodies” – a hallmark of Parkinson’s.

In order for Parkinson’s disease to be recognized as an occupational disease in those affected, two conditions apply:

The Federal Ministry of Labor and Social Affairs describes this as “diagnosed primary Parkinson’s syndrome without secondary genesis” (point 1) and speaks of “fulfillment of the dose level of at least 100 trend-corrected days of use with substances from one of the three functional groups of pesticides (herbicides or fungicides or Insecticides) through your own application” (point 2).