Association of cobalt exposure with all-cause and cardiovascular mortality in U.S. adults.

Background: Cobalt exposure is recognized as a potential risk factor for cardiovascular disease (CVD). However, the impact of cobalt exposure on mortality, particularly concerning CVD-related deaths, in the U.S. remains uncertain.

Methods: Data from the National Health and Nutrition Examination Surveys (NHANES) spanning 1999-2018 were utilized to assess urinary cobalt levels in participants aged 20 years and older (n = 15,873). For the analysis of blood cobalt, data from NHANES covering the years 2015-2018 were considered, limited to participants aged 40 years and older (n = 6,692). The follow-up period extended until December 31, 2019.

Results: The median values of ln-transformed urinary cobalt (creatinine corrected) and blood cobalt were - 1.10 ln(µg/g) and - 1.90 ln(µg/L), respectively. For urinary cobalt, during a median follow-up period of 130.0 months (interquartile range: 70.25-189.0), 2,304 participants died, with 613 deaths attributed to CVD. After adjusting for potential covariates, an increase in urinary cobalt level was significantly associated with a higher risk of all-cause mortality and CVD mortality (per 1 ln-unit increment, HR: 1.19, 95% CI: 1.07, 1.32; HR: 1.30, 95% CI: 1.06, 1.60, respectively). For blood cobalt, the adjusted HRs were 1.57 (95% CI: 1.15, 2.14) for all-cause mortality and 2.02 (95% CI: 1.10, 3.72) for CVD mortality.

Conclusions: In the U.S., low-level environmental cobalt exposure is a significant risk factor for both all-cause mortality and CVD mortality.

Synopsis: Cobalt, a metallic element commonly encountered by the general population through food, water, or air inhalation, emerges as a novel risk factor for cardiovascular disease mortality.