Parental Occupational Exposure to Heavy Metals and Welding Fumes and Risk of Testicular Germ Cell Tumors in Offspring: A Registry-Based Case-Control Study.

Background: Data are scarce on the association between prenatal/preconception environmental exposure and testicular germ cell tumor (TGCT) in offspring. We examined parental occupational exposures to heavy metals and welding fumes in relation to TGCT in offspring in a registry-based case-control study (NORD-TEST Study). Methods: We identified TGCT cases diagnosed at ages 14-49 years in Finland (1988-2012), Norway (1978-2010), and Sweden (1979-2011) through nationwide cancer registries. These cases were individually matched by country and year of birth to controls selected from population registries. Information on parental occupations was retrieved from censuses. From this, we estimated prenatal/preconception exposures of chromium, iron, nickel, lead, and welding fumes (all three countries), and cadmium (Finland only) for each parent using job-exposure matrices specifying prevalence (P) and mean exposure level (L). Exposure indices were calculated as product of P and L (P×L), and exposure categories were based on P×L or different combinations of P and L. Results: The study comprised 8,112 cases and 26,264 controls. We observed a statistically non-significant elevated risk of TGCT where P×L>0 except for paternal exposure to cadmium. We found no statistically significant dose-response relationship, but a statistically significant elevated TGCT risk associated with paternal exposure category where both P and L of chromium were high (vs. no chromium; odds ratio=1.37, 95% confidence interval; 1.05-1.79). Conclusions: Our study provides little evidence of associations between parental exposures to heavy metals/welding fumes and TGCT in offspring with the potential exception of high paternal chromium exposure. Impact: Further research on paternal chromium exposure is warranted.