Organophosphate ester flame retardants and plasticizers in house dust and Child Behavior Checklist outcomes: A nested study in the Canadian CHILD Birth Cohort

Abstract

Organophosphate esters and plasticizers (OPEs) are used in consumer materials to meet flammability standards. Toxicological and epidemiological evidence suggests some OPEs are developmental neurotoxicants. We investigated associations between OPE exposures as measured in house dust and emotional and behavioral problems in young children. We used data from the CHILD Cohort Study (n = 601), a prospective birth cohort recruited in 5 cities across Canada (2008-2012). OPEs were measured in house dust at 3-4 months postpartum, and parents completed the Child Behavior Checklist (CBCL), which measures emotional and behavioral problems when their child was 5 years. We used logistic regression to examine associations between OPE Z-scores (individual and summed chlorinated [ΣOPECl] and non-chlorinated [ΣOPENCl]) and CBCL problem scale scores (borderline and clinical T-scores ≥60 and normal <60). Tris(2-chloroethyl) phosphate (TCEP) showed strong, positive associations with CBCL Total and Externalizing scores at or above the clinical cutoff, meaning children with higher levels of TCEP in house dust postpartum had higher odds of developing clinically relevant behavioral problems in early childhood compared to children with lower levels (Total ORadj: 1.37, 95% CI: 1.01, 1.87; Externalizing ORadj: 1.36, 95% CI: 1.00, 1.85). Similarly, 4-isopropylphenyl diphenyl phosphate, a Firemaster 550 component, had a strong, positive association with Internalizing scores (ORadj: 1.24, 95% CI: 1.02, 1.51). We observed a weak association between ΣOPECl and Total scores (Odds Ratio [OR] adjusted: 1.14, 95% Confidence Intervals [CI]: 0.97, 1.33) and null associations for ΣOPENCl. Associations were generally stronger among boys (ΣOPECl Total ORadj: 1.31, 95% CI: 1.02, 1.68).