Organophosphate esters, airway inflammation, and lung function among U.S. participants: A nationally representative cross-sectional study from NHANES, 2011-2012

Abstract

Background: Human beings are widespread exposed to organophosphate esters (OPEs), but little is known about their effects on respiratory health.

Objectives: To investigate the associations of exposure to OPEs with lung function and airway inflammation among U.S. participants from NHANES, 2011-2012.

Methods: A total of 1636 participants aged 6-79 years were included. Concentrations of OPE metabolites were measured in urine and lung function was assessed with spirometry. Fractional exhaled nitric oxide (FeNO) and blood eosinophils (B-Eos), two important inflammatory biomarkers, were also measured. Linear regression was performed to examine the relationships of OPEs with FeNO, B-Eos and lung function. Bayesian kernel machine regression (BKMR) was used to evaluate the joint associations between OPEs mixtures and lung function.

Results: Three of seven OPE metabolites had detection frequencies > 80 %, including diphenyl phosphate (DPHP), bis (1,3-dichloro-2-propyl) phosphate (BDCPP), bis-2-chloroethyl phosphate (BCEP). A 10-fold increase in DPHP concentrations were associated with 1.02 mL decreases in FEV₁ (β = -0.01, 95 % CIs = -0.02, -0.003) and FVC (β = -0.01, 95 % CIs = -0.02, -0.003), respectively, and the similar, modest decreases were seen for BDCPP. For each 10-fold increase in BCEP concentration, FVC was also reduced by 1.02 mL (β = -0.01, 95 % CIs = -0.02, -0.002). Moreover, the negative associations were only found in non-smokers aged >35 years. The aforementioned associations were confirmed by BKMR, but we cannot definitively identify a constituent driving this association. B-Eos was negatively associated with FEV₁ and FEV₁/FVC, but not with OPEs. No associations were found of FeNO with OPEs and lung function.

Conclusions: Exposure to OPEs was associated with modest decrements in lung function, although the observed decrease in FVC and FEV₁ is unlikely to be of real clinical relevance for the majority of subjects in this series. Moreover, those associations presented age and smoking status-dependent pattern. Unexpectedly, the adverse effect was not mediated by FeNO/B-Eos.

Keywords: Bayesian kernel machine regression; Lung function; NHANES; Organophosphate esters; Respiratory inflammation.