a nested case-control study among 215 boys from Denmark and Finland
Geographical differences in occurrence of diseases in male reproductive organs including malformation in reproductive tract have been reported between Denmark and Finland. The reason for these differences is unknown, but differences in exposure to chemicals with endocrine disrupting abilities have been suggested. Among these chemicals are perfluoro¬alkylated substances (PFASs) a group of water and grease repellent chemicals used in outdoor clothes, cookware, food packaging and textiles. We therefore investigated differences in PFASs exposure levels between Denmark and Finland and associated PFASs levels in cord blood with congenital cryptorchidism. Boys from a joint ongoing prospective birth cohort study were included. We analyzed PFASs levels in cord blood serum samples from 29 Danish boys with congenital cryptorchidism; 30 healthy Danish matched controls recruited from 1997-2001, 30 Finnish cases and 78 Finnish healthy matched controls recruited from 1997-1999. Additionally, 48 Finnish cases recruited from 2000-2002 were included. PFOA and PFOS were detected in all 215 Danish and Finnish cord blood samples with significantly higher levels in Danish (medians; PFOA 2.6 ng/mL, PFOS 9.1 ng/mL) compared to Finnish (medians; PFOA: 2.1 ng/mL, PFOS 5.2 ng/mL) samples. We found no associations between cord blood PFOA and PFOS levels and congenital cryptorchidism after adjustment for confounders. Our data indicate that women in Denmark and Finland are generally exposed to PFOA and PFOS but with country differences in exposure levels. We found no statistical significant association between PFOA and PFOS levels in cord blood and congenital cryptorchidism, however, our study was small and larger studies are warranted.