Early Life Exposure to Tris(2-butoxyethyl) Phosphate (TBOEP) Is Related to the Development of Childhood Asthma

We investigated the association between exposure to 29 organophosphate esters (OPEs) and the onset of childhood asthma and recurrent wheeze. Using a case-cohort design nested in the Canadian CHILD Cohort Study, we included a random sample of children (n = 429), all children with asthma at 5 years (n = 128), and all children with recurrent wheeze between 2 and 5 years (n = 331). The association between 14 highly detected OPEs measured in house dust vacuumed when children were 3–4 months of age, including the child’s sleeping environment, and asthma at 5 years and recurrent wheeze between 2 and 5 years was assessed using logistic regression. The most abundant OPEs were TBOEP (median: 45730 ng/g) ≫ TCiPP (6065 ng/g) > TCEP (5260 ng/g) > TPhP (4440 ng/g) > EHDPP (1750 ng/g). Concentrations were higher than those in most other studies worldwide, potentially due to the inclusion of dust from the child’s sleeping area. A 2–4-fold increased odds of asthma was observed across all quartiles of exposure to TBOEP compared to the lowest quartile, including a positive dose–response relationship. Inverse relationships (p < 0.05) were observed with the odds of asthma and recurrent wheeze for 24DiPPDPP, B4tBPPP, tri-m-cresyl phosphate (TmCP), and EHDPP, and between 4tBPDPP and odds of asthma.