Employee exposure to solvents does not appear to increase the risk of Parkinson’s disease

Finnish Institute of Occupational Health media release 14 November 2023

The research project by Finnish Institute of Occupational Health studied if employees’ long-term exposure to solvents increases the risk of Parkinson’s disease. 

Parkinson’s disease is a complex degenerative brain disorder with symptoms that include slower movement, tremors, dystonia and impaired balance. As the population ages, the number of patients with symptoms has grown sharply also in Finland. 

Exposure to known neurotoxic exposure agents such as solvents, welding gases and metallic compounds usually happens at small workplaces and people may be exposed to several chemicals simultaneously. 

“There are very few extensive studies that survey the work-related risk factors of degenerative brain disorders. Reasons for this include difficulties in identifying cases and a lack of information about the mechanisms of the disorders,” says Markku Sainio, Chief Medical Officer for HUS, who worked previously for the Finnish Institute of Occupational Health 

“Degenerative brain disorders develop slowly and will often manifest only after work life, which makes studying their work-related risk factors difficult,” he continues. 

Approximately 17,200 people with Parkinson’s disease participated in the study and approximately 35,700 controls, born between 1930 and 1950 and aged 45–84. Of the people with Parkinson’s disease, a total of 16 per cent may have been exposed to chlorinated hydrocarbons during their working career.

Cumulative exposure to chlorinated hydrocarbons was connected to slightly elevated (23.5%) risk of Parkinson’s disease, but the difference was not statistically significant. 

“Based on the results, we can deduce that a connection between Parkinson’s disease and occupational exposure to solvents in Finland is unlikely. However, based on the study, the risk cannot be excluded for very highly exposed employees,” says Markku Sainio. 

Research project: Work-related risk factors of degenerative brain disorders

• The national case-control study focused on the connection between occupational exposure to solvents and Parkinson’s disease by utilising the classified occupational information in Statistics Finland’s population data and the FINJEM occupational exposure agent matrix, developed by the Finnish Institute of Occupational Health, to assess exposure. 
• Information about people with Parkinson’s disease was based on the Social Insurance Institution of Finland’s register for special medical reimbursements for the years 1980–2014. 
• People who had been granted reimbursements were used to create a case-control dataset and two controls with matching birth year and gender were assigned for each case from the population data system maintained by the Digital and Population Data Services Agency. 
• Read the research article: Parkinson's disease and occupational exposure to organic solvents in Finland: a nationwide case-control study - PubMed (nih.gov)

Further information

• Christer Hublin, Arbetshälsoinstitutet, Christer.Hublin@ttl.fi
• Aki Koskinen, Arbetshälsoinstitutet, Aki.Koskinen@ttl.fi
• Markku Sainio, HUS, Markku.Sainio@hus.fi