Associations between allergic symptoms and phosphate flame retardants in dust and their urinary metabolites among school children

Background: Phosphate flame retardants (PFRs) are ubiquitously detected in indoor environments. Despite increasing health concerns pertaining to PFR exposure, few epidemiological studies have examined PFR exposure and its effect on children's allergies. Objectives: To investigate the association between PFRs in house dust, their metabolites in urine, and symptoms of wheeze and allergies among school-aged children. Methods: A total of 128 elementary school-aged children were enrolled. House dust samples were collected from upper-surface objects. Urine samples were collected from the first morning void. Levels of 11 PFRs in dust and 14 PFR metabolites in urine were measured. Parent-reported symptoms of wheeze, rhinoconjunctivitis, and eczema were evaluated using the International Study of Asthma and Allergies in Childhood questionnaire. The odds ratios (ORs) of the Ln transformed PFR concentrations and categorical values were calculated using a logistic regression model adjusted for sex, grade, dampness index, annual house income, and creatinine level (for PFR metabolites only). Results: The prevalence rates of wheeze, rhinoconjunctivitis, and eczema were 22.7%, 36.7%, and 28.1%, respectively. A significant association between tris(1,3-dichloroisopropyl) phosphate (TDCIPP) in dust and eczema was observed: OR (95% confidence interval), 1.44 (1.13-1.82) (> limit of detection (LOD) vs < LOD). The ORs for rhinoconjunctivitis (OR = 5.01 [1.53-16.5]) and for at least one symptom of allergy (OR = 3.87 [1.22-12.3]) in the 4th quartile of Etris(2-chloro-isopropyl) phosphate (TCIPP) metabolites was significantly higher than those in the 1st quartile, with significant p-values for trend (P-trend) (0.013 and 0.024, respectively). A high OR of 2.86 (1.04-7.85) (> LOD vs < LOD) was found for hydroxy tris(2-butoxyethyl) phosphate (TBOEP)OH and eczema. OR of the 3rd tertile of bis (1,3-dichloro-2-propyl) phosphate (BDCIPP) was higher than the 1st tertile as a reference for at least one symptom (OR = 3.91 [1.25-12.3]), with a significant P-trend = 0.020. Conclusions: We found that TDCIPP in house dust, and metabolites of TDCIPP, TBOEP and TCIPP were associated with children's allergic symptoms. Despite some limitations of this study, these results indicate that children's exposure to PFR may impact their allergic symptoms.