We conducted an ecological study to investigate associations between occupational sectors and the incidence of Parkinson’s disease, using three existing data sources. First, we calculated the number of new cases of Parkinson’s disease between 2010 and 2014 in each of the 3,689 cantons of metropolitan France (N=112,625). The number of new cases per canton ranged from 0 (in 12 cantons) to 2,828 cases, with an average of 19 cases. Cases of Parkinson’s disease were identified using anonymized data on reimbursements for antiparkinsonian medications from the National Health Data System (SNDS) via a validated method described in a previous publication⁽¹⁾.

The aim was to identify occupational settings potentially at risk for Parkinson’s disease. To this end, we examined the association between the proportion of workers in 38 economic sectors covering all existing activities (sectors identified using data from the 2006 INSEE census) and the incidence of Parkinson’s disease. We used a specific statistical approach (hierarchical regression) that allowed us to account for the multiplicity of statistical tests and information on exposure to pesticides, solvents, and metals by economic sector obtained from the 2010 Medical Surveillance of Occupational Risk Exposures (Sumer) survey conducted by Dares and the Directorate General for Labor.

We find a higher incidence of Parkinson's disease in cantons characterized by a significant proportion of workers in three sectors: “Agriculture, forestry, and fishing” (+4.2%), “Textile manufacturing, clothing, leather, and footwear industries” (+2.4%), and “Metalworking and manufacture of metal products” (+2.4%).

The association with the agricultural sector, characterized by significant exposure to pesticides, was indeed expected; numerous studies have shown that occupational exposure to pesticides, working as a farmer, or living in rural areas are risk factors for Parkinson’s disease.

In contrast, associations with the textile industry on the one hand and the metallurgy sector on the other had not yet been identified in the French context. Possible explanations for the observed associations could include exposure to solvents or endotoxins in the textile industry, and to metals in the metallurgy sector. However, caution is warranted in interpreting these results, as our ecological approach does not allow us to demonstrate causal links.

This national study helps identify occupational sectors or work situations that may pose a risk for Parkinson’s disease. Only specific studies based on individual data—such as cohort or case-control studies—will be able to confirm our findings and provide a better understanding of the exposures that may be involved.

Santé publique France is conducting research on neurodegenerative diseases in close collaboration with Inserm. As part of this effort, our next steps will focus on better understanding the role of exposure to metals and solvents in Parkinson’s disease. To this end, we will utilize additional data sources, such as those on air pollutant emissions.

In addition, we will conduct a similar study based on occupational sectors for another neurodegenerative disease, amyotrophic lateral sclerosis. Indeed, studies suggest a link between certain occupational exposures, particularly to lead, and this disease.