High exposure to perfluoroalkyl substances in drinking water is associated with increased risk of osteoporotic fractures - A cohort study from Ronneby, Sweden.

BACKGROUND

Perfluoroalkyl substances (PFAS) have been reported to be related to decreased bone mineral density, but the relationship with osteoporosis and fractures is less studied. This study aimed to investigate the risks of osteoporotic fractures in a Swedish population with long-term exposure to PFAS through drinking water.

METHODS

The Ronneby Register Cohort, including 61,504 individuals who had ever lived in Ronneby during 1985-2013, was used. Exposure to PFAS was assessed according to the yearly residential address with or without highly contaminated water supply and was categorized as 'never-high' and 'ever-high' exposure. The 'ever-high' exposure was further divided into 'early-high' and 'late-high' depending on if the exposure was before or after 2005. Inpatient and outpatient hospital diagnoses of fractures were retrieved from the National Patient Register. Major osteoporotic fractures (MOF, i.e., hip, vertebrae, proximal humerus and distal forearm fractures), and hip fractures were considered as the primary outcomes. Cox proportional hazard models with time-varying exposure were used to estimate the hazard ratios (HRs). Stratified analyses were performed in each sex and age group (<50 yrs and ≥ 50 yrs).

RESULTS

Elevated risks of MOF (HR 1.11, 95% CI 1.03-1.19) and hip fractures (1.12, 1.00-1.24) were observed when comparing 'ever-high' to 'never-high' exposure. The HRs were even higher for 'late-high' exposure (MOF: 1.29, 1.16-1.44; hip fractures: 1.22, 1.01-1.47). Further adjustment for highest achieved education slightly attenuated the estimates. Individuals above 50 years old showed even higher HR estimates. Similar patterns were found for all fractures.

CONCLUSION

Our results provide further evidence supporting the adverse effects of PFAS on osteoporosis. A better understanding of dose-response relationships as a basis for risk assessment is warranted.