Trends and variability in the levels of urinary thiocyanate, perchlorate, and nitrate by age, gender, race/ethnicity, smoking status, and exposure to environmental tobacco smoke over 2005-2012

Data from National Health and Nutrition Examination Survey for 2005-2012 were used to study the trends and variability in the levels of urinary thiocyanate (u-SCN), perchlorate (u-P8), and nitrate (u-NO3) by gender, race/ethnicity, active smoking, and exposure to environmental tobacco smoke (ETS) at home for those aged 12-19 and >= 20 years old. For those aged >= 20 years, adjusted levels of u-SCN, u-P8, and u-NO3 (i) were lower for males than females (p < 0.01), and (ii) were higher for non-Hispanic white (NHW) than non-Hispanic black (NHB) (p < 0.01). Also, for those aged >= 20 years NHB had higher adjusted levels than Mexican American (MA) for u-SCN (p < 0.01) but NHB had lower adjusted levels than MA for u-P8 (p < 0.01) and u-NO3 (p < 0.01). For those aged 12-19 years, adjusted levels of u-SCN, u-P8, and u-NO3 did not vary by gender (p > 0.05), and adjusted levels of u-P8 and u-NO3 for NHB were lower than for NHW(p < 0.01) as well as higher for NHB than MA for u-SCN (p < 0.01) and lower for NHB than MA (p < 0.01) for u-P8 and u-NO3. Among those aged >= 20 years, active smoking was associated with higher adjusted levels of u-SCN (p < 0.01) in a dose-response manner and active smoking was associated with lower adjusted levels of u-P8 (p < 0.01) in a dose-response manner. Exposure to ETS was associated with higher adjusted levels of u-SCN (p = 0.02) and lower adjusted levels of u-P8 (p < 0.01) among >= 20 years old. Adjusted levels of u-P8 decreased over 2005-2012 among both 12-19 (p < 0.01) and >= 20 years old (p = 0.04). There was borderline increase in the adjusted levels of u-NO3 for those aged >= 20 years (p = 0.05) over 2005-2012. (C) 2016 Elsevier B.V. All rights reserved.