Occupational exposure to Cr(VI) in Finland in 1980–2016 and related lung cancer risk assessment

Occupational exposure to hexavalent chromium [Cr(VI)], a known lung carcinogen, remains a relevant concern. When performing exposure assessment for risk assessment, biomonitoring is an important tool, reflecting actual internal exposure of workers. Here, we present total urinary chromium (U–Cr) biomonitoring data from several occupational sectors, spanning 1980–2016 (n > 42,000). Based on these data, we estimated lifelong (40-year) occupational lung cancer risks in the Cr-plating and welding sectors. We used published regression formulas to relate internal (U–Cr) and external Cr(VI) inhalation exposures, allowing risk assessment based on a published lung cancer dose-response. Generally, measured U–Cr levels decreased considerably over the study period. The overall highest U–Cr P95 levels (representing realistic worst-case) were measured in the interval 1980–1989 in casters, maintenance workers and welders (40–45 μg/L). By the interval 2010–2016, the U–Cr P95 had decreased to ≤9.5 μg/L in all studied sectors. Lifelong external Cr(VI) exposure estimation for 1980–2019 was 0.16–0.32 mg/m³ x year for platers and 1.03 mg/m³ x year for welders. Worst-case lifelong lung cancer relative risk (RR) estimates were 1.28–1.56 for platers and 2.80 for welders; attributable risks (AR) were 22–36% for platers and 64% for welders. Uncertainties that may have impacted the risk assessment are discussed.