Association of phthalate concentration with lung function and FeNO level
Analysis of the association of the quartiles of phthalate metabolites with Rrs5 (Table 2, Figure 1) indicated the quartiles of urinary Σ4HMWP metabolites were associated with greater Rrs5 (Crude β: 0.028; 95% CI: 0.011 to 0.046; P = .001), but these associations were not significant after adjusting for height, gender, BMI z- score, aeroallergen sensitization, secondary smoking, and vitamin D level. However, after adjusting for these same confounders, Σ4HMWP was significantly associated with Rrs1 (Q1/Q4, adjusted β: 0.047, 95% CI: 0.009 to 0.084, P = .015), Rrs2 (Q1/Q4, adjusted β: 0.046, 95% CI: 0.007 to 0.084, P = .021), and Rrs3 (Q1/Q4, adjusted β: 0.057, 95% CI: 0.015 to 0.099, P = 0.008) (Figure 1A).
Children with higher quartiles of Σ3LMWP metabolites (Table 2, Fig. 1) also had significantly greater Rrs5 (Crude β: 0.028, 95% CI: 0.011 to 0.045; P = .001) and this relationship remained significant after adjustment for confounding (adjusted β: 0.020, 95% CI: 0.005 to 0.034; P = .010). In addition, after adjusting for confounding, quartiles of Σ3LMWP was also significantly associated with Rrs1 (Q1/Q4, adjusted β: 0.046, 95% CI: 0.008 to 0.083,P = .018), Rrs2 (Q1/Q4, adjusted β: 0.051, 95% CI: 0.012 to 0.089, P = .010), Rrs3 (Q1/Q4, adjusted β: 0.057, 95% CI: 0.015 to 0.099, P = .008), Rrs10 (Q1/Q4, adjusted β: 0.055, 95% CI: 0.010 to 0.099, P = .016), and Rrs15 (Q1/Q4, adjusted β: 0.055, 95% CI: 0.001 to 0.109, P = .044).
After adjustment for confounding, there was a significant association in the quartiles of urinary Σ4HMWP metabolites with FeNO (adjusted β: 0.053, 95% CI: 0.007 to 0.099; P = 0.024), but no significant association in the quartiles of urinary Σ3LMWP metabolites with FeNO (Table 2).