Association between arsenic exposure from drinking water and proteinuria: results from the Health Effects of Arsenic Longitudinal Study

Background Proteinuria has been recognized as a marker for an increased risk of chronic renal disease. It is unclear whether arsenic (As) exposure from drinking water is associated with proteinuria. Methods We evaluated the association between As exposure from drinking water and proteinuria in 11 122 participants in the Health Effects of Arsenic Longitudinal Study (HEALS). Proteinuria was detected by urinary dipstick tests at baseline and at 2-year intervals. As exposure variables included baseline well As and changes in urinary As during follow-up modelled as time-dependent variables in the analyses. Results At baseline, well As was positively related to prevalence of proteinuria; prevalence odds ratios (PORs) for proteinuria in increasing quintiles of well As (7, 8-39, 40-91, 92-179 and 180-864 mu g/l) were 1.00 (ref), POR 0.99 [95% confidence interval (CI) 0.77-1.27], POR 1.23 (95% CI 0.97-1.57), POR 1.50 (95% CI 1.18-1.89) and POR 1.59 (95% CI 1.26-2.00) (P for trend < 0.01). Hazard ratios for incidence of proteinuria were POR 0.83 (95% CI 0.67-1.03) and POR 0.91 (95% CI 0.74-1.12) for participants with a decreasing level of > 70 and 17-70 mu g/l in urinary As over time, respectively, and were POR 1.17 (95% CI 0.97-1.42) and POR 1.42 (95% CI 1.16-1.73) for participants with an increasing level of 16-68 and > 68 mu g/l in urinary As over time, respectively, compared with the group with relatively little changes in urinary As as the reference group (urinary As -16 to 15 mu g/l). Conclusion The findings suggest that there are adverse effects of As exposure on the risk of proteinuria and the effects are modifiable by recent changes in As exposure.