Environmental exposure to dioxin-like compounds and the mortality risk in the U.S. population

Abstract

Background: Little is known about the mortality risk associated with chronic dioxin exposure in the general U.S. populations.

Objective: To explore the association between dioxin-like chemicals and mortality risk in a large population-based cohort study.

Methods: The analysis included 2361 subjects aged 40 years or older from the 1999-2004 National Health and Nutrition Examination Survey (NHANES). Exposure to a mixture of dioxin-like chemicals, including dibenzo-p-dioxins, dibenzofurans, and polychlorinated biphenyls was estimated using toxic equivalency values (TEQs) calculated with 2005 World Health Organization toxic equivalency factors. All-cause and cause-specific mortalities were obtained from the NHANES-linked follow-up data through December 31, 2006. Cox proportional-hazards models were applied to assess the associations of interest.

Results: A total of 242 deaths occurred during the follow-up period, including 75 from cardiovascular disease and 72 from cancer. There was an increased mortality risk associated with logarithmically expressed dioxin TEQs for all-cause deaths (hazard ratio=1.19, 95% confidence interval=1.02-1.39, p=0.02). Similar graded dose-response trends were found for cardiovascular and cancer mortality which did not reach statistical significance.

Conclusions: In general, higher dioxin exposure is associated with an increased mortality risk among subjects aged 40 and above. The cause-specific analyses and responsible mechanisms will require further investigation.