Trends in concentrations of selected dioxins and furans across various stages of kidney function for US adults.

Exposure to dioxins and furans has the potential to affect kidney function and could be associated with chronic kidney disease. Data for US adults aged ≥ 20 years from the National Health and Nutrition Examination Survey for 1999-2004 (N = 4433) were analyzed to study trends in adjusted concentrations (AGM) of 1,2,3,7,8-pentachlorodibenzo-p-dioxin, 1,2,3,6,7,8-hexachlorodibenzo-p-dioxin, 1,2,3,4,6,7,8-heptachlororodibenzo-p-dioxin, 1,2,3,4,6,7,8,9-octachlorodibenzo-p-dioxin, 2,3,4,7,8-pentachlorodibenzofuran, 1,2,3,4,7,8-hexachlorodibenzofuran, 1,2,3,6,7,8-hexachlorodibenzofuran, and 1,2,3,4,6,7,8-heptachlorodibenzofuran across the stages of kidney function (KF). Stages of KF were defined based on estimated glomerular filtration rate or eGFR expressed in mL/min/1.73 m2. For KF-1, eGFR was > 90, between 60 and 90 for KF-2, between 45 and 60 for KF-3A, and between 15 and 45 for KF-3B/4. AGMs for 1,2,3,7,8-pentachlorodibenzo-p-dioxin and 1,2,3,6,7,8-hexachlorodibenzo-p-dioxin increased consistently across the full spectrum of kidney function. For example, AGMs for the total population for 1,2,3,7,8-pentachlorodibenzo-p-dioxin were 2.5, 4.5, 9.3, and 14.9 fg/g lipid for KF-1, KF-2, KF-3A, and KF-3B/4, respectively. For other six dioxins/furans, AGMs increased over KF-1 through KF-3A but then decreased for KF-3B/4, for example, 1,2,3,4,6,7,8-heptachlorodibenzofuran for males, and AGMs for KF-1, KF-2, KF-3A, and KF-3B/4 were 7.9, 8.4, 10.7, and 7.5 fg/g lipid, respectively. For 1,2,3,4,6,7,8-heptachlorodibenzo-p-dioxin and 1,2,3,6,7,8-hexachlorodibenzofuran, smokers were found to have lower AGMs than nonsmokers. For example, for 1,2,3,4,6,7,8-heptaachlorodibenzo-p-dioxin, smoker-nonsmoker AGMs were 22.2 vs. 39.4 fg/g lipid at KF-1, 29.5 vs. 51.4 fg/g lipid at KF-2, 61.6 vs. 72.8 fg/g lipid at KF-3A, and 34.9 vs. 66.4 fg/g lipid at KF-3B/4. The reverse more often than not, was, however, observed for other six dioxins/furans. Smoker-nonsmoker AGMs for 1,2,3,7,8-pentachlorodibenzo-p-dioxin were 2.4 vs. 2.6 fg/g lipid at KF-1, 5.1 vs. 4.0 fg/g lipid at KF-2, 12.7 vs. 6.7 fg/g lipid at KF-3A, and 18.6 vs. 11.9 fg/g lipid at KF-3B/4. In conclusion, lipid-adjusted serum concentrations of dioxins and furans continue increasing as kidney function keeps deteriorating until KF-3A. However, these increases in serum concentrations until KF-3A may be followed by substantial decreases for selected dioxins/furans during KF-3B/4.