Testicular germ cell tumours and parental occupational exposure to pesticides: a register-based case-control study in the Nordic countries (NORD-TEST study).

Objectives: A potential impact of exposure to endocrine disruptors, including pesticides, during intrauterine life, has been hypothesised in testicular germ cell tumour (TGCT) aetiology, but exposure assessment is challenging. This large-scale registry-based case-control study aimed to investigate the association between parental occupational exposure to pesticides and TGCT risk in their sons.

Methods: Cases born in 1960 or onwards, aged between 14 and 49 years, and diagnosed between 1978 and 2013 in Denmark, Finland, Norway or Sweden, were identified from the respective nationwide cancer registries. Four controls per case were randomly selected from the general national populations, matched on year of birth. Information on parental occupation was collected through censuses or Pension Fund information and converted into a pesticide exposure index based on the Finnish National Job-Exposure Matrix.

Results: A total of 9569 cases and 32,028 controls were included. No overall associations were found for either maternal or paternal exposures and TGCT risk in their sons, with ORs of 0.83 (95% CI 0.56 to 1.23) and of 1.03 (0.92 to 1.14), respectively. Country-specific estimates and stratification by birth cohorts revealed some heterogeneity. Cryptorchidism, hypospadias and family history of testicular cancer were risk factors but adjustment did not change the main results.

Conclusions: This is the largest study on prenatal exposure to pesticides and TGCT risk, overall providing no evidence of an association. Limitations to assess individual exposure in registry-based studies might have contributed to the null result.