Prenatal and Postnatal Exposure to Phthalate Esters and Asthma: A 9-Year Follow-Up Study of a Taiwanese Birth Cohort

<div><p>Previous studies have shown that phthalate exposure in childhood is associated with the development of respiratory problems. However, few studies have assessed the relative impact of prenatal and postnatal exposure to phthalates on the development of asthma later in childhood. Therefore, we assessed the impact of prenatal and postnatal phthalate exposure on the development of asthma and wheezing using a Taiwanese birth cohort. A total of 430 pregnant women were recruited, and 171 (39.8%) of them had their children followed when they were aged 2, 5, and 8 years. The International Study of Asthma and Allergies in Childhood questionnaire was used to assess asthma and wheezing symptoms and serum total immunoglobulin E levels were measured at 8 years of age. Urine samples were obtained from 136 women during their third trimester of pregnancy, 99 children at 2 years of age, and 110 children at 5 years. Four common phthalate monoester metabolites in maternal and children’s urine were measured using liquid chromatography-electrospray ionization-tandem mass spectrometry. Maternal urinary mono-benzyl phthalate [MBzP] concentrations were associated with an increased occurrence of wheezing in boys at 8 years of age (odds ratio [OR] = 4.95 (95% CI 1.08–22.63)), for upper quintile compared to the others) after controlling for parental allergies and family members' smoking status. Urinary mono-2-ethylhexyl phthalate [MEHP] levels over the quintile at 2-year-old were associated with increased asthma occurrence (adjusted OR = 6.14 (1.17–32.13)) in boys. Similarly, the sum of di-2-ethyl-hexyl phthalate [DEHP] metabolites at 5 years was associated with asthma in boys (adjusted OR = 4.36 (1.01–18.86)). Urinary MEHP in maternal and 5-year-old children urine were significantly associated with increased IgE in allergic children at 8 years. Prenatal and postnatal exposure to phthalate was associated with the occurrence of asthma in children, particularly for boys.</p></div

Characteristics of children at 8 years of age classified by asthma status (n = 171).

<p>Data are presented as number (%) or median ± standard error.</p><p>IgE, immunoglobulin E.</p><p>^a<i>p</i> values for differences between groups were estimated using Chi-square (Fisher’s exact) test.</p><p>^b<i>p</i> values for the difference between non-asthmatic children and asthmatic children using a Mann-Whitney U test.</p><p>Characteristics of children at 8 years of age classified by asthma status (n = 171).</p

Flow chart of the recruitment process of pregnant women and follow up of their children.

<p>Pregnant women were invited to participate in the study. During the follow-up period, phthalate metabolites present in maternal and children’s urine were measured. At 8 years of age, the presence of asthma and wheezing was assessed using the International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire.</p

Association between maternal and children’s log-transformed urinary phthalate metabolite concentrations (μg/g creatinine) and log-transformed total serum immunoglobulin E levels (IU/ml) in 8-year-old children.

<p>Data are presented as unstandardized regression coefficient (B) and <i>p</i>-value.</p><p>Associations were adjusted for gender and parental allergies.</p><p>MEHP: mono-2-ethylhexyl phthalate; ΣDEHP: sum of metabolites of di-2-ethylhexyl phthalate; MBzP: mono-benzyl phthalate; MEP: mono-ethyl phthalate; MBP: mono-butyl-phthalate.</p><p>^aAllergic children included children with asthma, dermatitis, rhinitis, and conjunctivitis.</p><p>*Indicates a significant (<i>p</i> <0.05) association, estimated using linear regression, between log-transformed phthalate metabolite concentrations and log-transformed serum immunoglobulin E concentrations.</p><p>Association between maternal and children’s log-transformed urinary phthalate metabolite concentrations (μg/g creatinine) and log-transformed total serum immunoglobulin E levels (IU/ml) in 8-year-old children.</p