Coexposure of French workers to night and/or shift work and chemical substances

Workers in various sectors can be exposed to multiple occupational hazards, including chemical substances and night or shift work. However, the health effects of such coexposures remain largely unexplored, and we lack data on the individuals concerned. This study aimed to quantify the number of French workers coexposed to chemical substances and night or shift work and provide statistical indicators for each sector and occupation. The analysis was based on data from the 2010 and 2017 SUMER surveys, which assessed occupational exposure in a representative sample of French workers. These data were crossed with workforce estimates from the French National Statistics Institute (INSEE) to estimate the total number of workers exposed. Four groups were defined on the basis of work schedules: (i) shift work without night work, (ii) shift work with night work, (iii) permanent night work (without shift work), and (iv) day work. The prevalence of chemical exposure in these groups was compared based on descriptive statistics. Of a total of 26.8 million French workers, about 6.5 million are exposed to night and/or shift work, with a higher prevalence among men (4.2 million) than women (2.3 million). The proportion of workers who were also exposed to at least one chemical substance was significantly higher among night or shift workers (36% to 49%) than among day workers (26%). The sectors most affected were healthcare, transport, construction, and manufacturing. Common chemicals included disinfectants (alcohols, quaternary ammonium compounds, and bleach), diesel exhaust, and industrial lubricants. Our results highlight the extent of coexposure to chemical substances and night or shift work among French workers. Given the potential health risks, particularly in the healthcare and industrial sectors, preventive measures should be implemented. Future research should investigate the long-term health effects associated with these combined occupational risk factors.