Organophosphate esters, airway inflammation, and lung function among U.S. participants: A nationally representative...

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

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

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.

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.

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.