Association of urinary perchlorate, nitrate, and thiocyanate concentrations with pulmonary function in children aged 6-19 years

Abstract

Background: Humans are widely exposed to mixtures of environmental perchlorate, nitrate, and thiocyanate. However, the associations of perchlorate, nitrate, and thiocyanate with pulmonary function in children were unclear.

Methods: To investigate the associations of urinary perchlorate, nitrate, and thiocyanate concentrations with pulmonary function in children, a total of 2,271 children and adolescents aged 6-19 years with complete data on perchlorate, nitrate, and thiocyanate and pulmonary function were analyzed from the U.S. NHANES 2007-2012. Exposure to perchlorate, nitrate, and thiocyanate was estimated by measuring urinary concentration, and pulmonary function was assessed by spirometry. Linear regression and generalized linear models were performed to estimate the associations of perchlorate, nitrate, and thiocyanate concentrations with pulmonary function measures. Stratified subgroup analyses were performed to examine whether age (6-12 and 13-19 years) and sex differences modified these associations.

Results: In the overall population, concentrations of perchlorate and nitrate, except for thiocyanate, were associated with a modest decrease in pulmonary function. After stratification by age and sex, those negative associations were more pronounced among the children aged 6-12 years. In children aged 6-12 years, perchlorate concentration was negatively associated with FEV1 (p-trend = 0.04) among boys. In children aged 6-12 years, nitrate concentration was negatively associated with FEV1, FVC, and PEF, respectively (all p-trends < 0.05), in both boys and girls.

Conclusions: Our study suggested that exposures to perchlorate, nitrate, except for thiocyanate were associated with impaired pulmonary function in children and adolescents aged 6-19 years, and those associations were more pronounced among children aged 6-12 years. Further replications of the associations in a large prospective cohort study are warranted.

Keywords: Children; NHANES; Nitrate, thiocyanate; Perchlorate; Pulmonary function.

Fig. 1

Flow diagram of the study population

Fig. 2

Regression Coefficients (95% CI) for pulmonary function by urinary perchlorate, nitrate, and thiocyanate in children and adolescents aged 6–19 years in the NHANES 2007–2012 survey. Generalized linear models were performed to estimate the associations, with the lowest perchlorate, nitrate, and thiocyanate quartile used as a reference group; p-value test for trend. Models are adjusted for age, sex, height, race, NHANES cycles, BMI- for age, serum cotinine level, family income to poverty ratio, education, and have you had wheezing or whistling in your chest in the past 1 year? (yes/no)

Fig. 3

Regression Coefficients (95% CI) for pulmonary function by urinary perchlorate (A), nitrate (B), and thiocyanate (C) in children and adolescents stratified by age (6–12 and 13–19 years) and sex (boys and girls): NHANES 2007–2012 survey. Generalized linear models were performed to estimate the associations, with the lowest perchlorate, nitrate, and thiocyanate quartile used as a reference group; p-value test for trend. Models are adjusted for age, height, race, NHANES cycles, BMI- for age, serum cotinine level, family income to poverty ratio, education, and have you had wheezing or whistling in your chest in the past 1 year? (yes/no)