Urinary metals and leukocyte telomere length in American Indian communities: The Strong Heart and the Strong Heart Family Study

Introduction: While several mechanisms may explain metal-related health effects, the exact cellular processes are not fully understood. We evaluated the association between leukocyte telomere length (LTL) and urine arsenic (Sigma As), cadmium (Cd) and tungsten (W) exposure in the Strong Heart Study (SHS, N = 1702) and in the Strong Heart Family Study (SHFS, N = 1793). Methods: Urine metal concentrations were measured using ICP-MS. Arsenic exposure was assessed as the sum of inorganic arsenic, monomethylarsonate and dimethylarsinate levels (Sigma As). LTL was measured by quantitative polymerase chain reaction. Results: In the SHS, median levels were 1.09 for LTL, and 8.8,1.01 and 0.11 mu g/g creatinine for Sigma As, Cd, and W, respectively. In the SHFS, median levels were 1.01 for LTL, and 43, 0.44, and 0.10 mu g/g creatinine. Among SHS participants, increased urine Sigma As, Cd, and W was associated with shorter LTL. The adjusted geometric mean ratio (95% confidence interval) of LTL per an increase equal to the difference between the percentiles 90th and 10th in metal distributions was 0.85 (0.79, 0.92) for Sigma As, 0.91 (0.84, 1.00) for Cd and 0.93 (0.88, 0.98) for W. We observed no significant associations among SHFS participants. The findings also suggest that the association between arsenic and LTL might be differential depending on the exposure levels or age. Conclusions: Additional research is needed to confirm the association between metal exposures and telomere length. (C) 2018 Elsevier Ltd. All rights reserved.