Perfluoroalkyl substance exposure and urine CC16 levels among asthmatics: A case–control study of children

Studies have reported an association between serum perfluoroalkyl substances (PFASs) and asthma. However, few studies have examined the possible associations between PFASs and the 16-kDa club cell secretory protein (Clara) (CC16) level, a prominent biomarker of asthma, among adolescents. We recruited a total of 231 asthmatic children and 225 non-asthmatic controls in the Genetic and Biomarkers study for Childhood Asthma (GBCA) in northern Taiwan from 2009 to 2010. Structured questionnaires were administered by face-to-face interview. Urine CC16 was determined by an enzyme-link immunoassay kit. Multiple general linear models were employed to examine the associations between PFASs and urinary CC16 levels. Asthmatic participants had significantly higher serum PFAS concentrations overall than the healthy controls. After adjusting for confounding factors, urinary CC16 was significantly, negatively associated with PFASs, especially PFOS, PFOA, PFDA and PFNA, and especially among males, as follows: PFOS (β = −0.003, 95% confidence interval [CI]: −0.004, −0.002), PFOA (β = −0.045, 95% CI: −0.086, −0.004), and PFHxA (β = −0.310, 95% CI: −0.455, −0.165) among asthmatic boys, and PFDA (β = −0.126, 95%CI: −0.241, −0.012) and PFNA (β = −0.329, 95% CI: −0.526, −0.132) among non-asthmatic boys. Among girls, PFDA (β = −0.088, 95% CI: −0.172, −0.004), was the only PFAS significantly associated with CC16. Significant interaction effects (p < 0.15) on CC16 levels were found between asthma and PFOS, PFOA, PFBS and PFHxA in all participants. Our overall results showed that serum PFASs were significantly, inversely associated with CC16 levels. Associations were stronger among males.