Of the 667 subjects, sufficient urine amounts to measure phthalates were available for 658 (98.7%).
All measured phthalate metabolites were detected in greater than 99% of urine samples with the exception of MEHP, which was detected in 79% of urine samples.
Medians, percentiles, and ranges (minimum maximum) of all measured phthalate concentrations were computed.
The measured phthalate concentrations were among the highest of any of the target compounds, including pesticides, polycyclic aromatic hydrocarbons, and polychlorinated biphenyls.
Details of laboratory methods for measuring phthalate metabolites are reported elsewhere [ 21].
Higher maternal education predicted lower concentrations of all measured phthalates, with children of mothers who were college graduates having 10%, 33%, and 36% lower concentrations of ∑DEHP metabolites, MBzP, and MEP, respectively, compared to children of mothers who did not graduate from high school.
ASD risk was not associated with any of the measured phthalates in house dust.
Exposure distributions for the measured phthalate metabolites in the conception cycle are shown in Table 1.
Most monitoring studies measured phthalate concentrations in similar foods which were then combined to report one summary measurement per food group/category (i.e. concentrations of white bread and wheat bread combined for one summary "bread" measurement).
Because phthalate diesters are rapidly metabolized and the metabolites are excreted mainly in the urine, with elimination half-lives of usually < 24 hr (Koch et al. 2005), measured phthalate levels reflect very recent exposure to the parent compounds (phthalate diesters).
