Time trends and the influence of age and gender on serum concentrations of perfluorinated compounds in archived human samples.

Fifty-seven pooled archived human serum samples were analyzed to assess the time trends as well as influence of age and gender on selected perfluorinated compounds (PFCs) in Norwegian residents. The study comprised determinations of 19 PFCs in serum samples pooled according to year of collection from 28 years in the period 1976 to 2007. A 9-fold increase in the serum concentrations of perfluorooctyl sulfonate, perfluorooctanoic acid, and perfluoroheptyl sulfonate was measured for men (40-50 years) from 1977 to the mid 1990s where the concentrations reached a plateau before starting to decrease around year 2000. A similar trend was also seen for perfluorohexyl sulfonate, perfluorononanoic acid, perfluorodecanoic acid, and perfluoroundecanoic acid, but no clear decline was observed for these PFCs in the recent years. No statistically significant difference was observed between the PFC levels in the male and female serum pools, though the statistical power is low due to few data points. For most PFCs, the concentrations in the human serum samples were found to increase with age in the pools from 2007, while the results for 1976, 1987, and 1998 were more varying. Several PFCs were significantly intercorrelated.