Maternal and infant urinary phthalate metabolite concentrations: are they related?
BACKGROUND
Phthalates are synthetic chemicals that are ubiquitous in our society and may have adverse health effects in humans. Detectable concentrations of phthalate metabolites have been found in adults and children, but no studies have examined the relationship between maternal and infant phthalate metabolite concentrations.


OBJECTIVE
We investigated the relationship between maternal and infant urinary phthalate metabolite concentrations.


METHODS
We measured nine phthalate metabolites in urine samples from 210 mother/infant pairs collected on the same study visit day (1999-2005) and obtained demographic history from questionnaires. Using multivariate linear regression analyses, we examined the degree to which maternal urine phthalate metabolite concentration predicted infant phthalate metabolite concentration. All analyses were adjusted for infant age, creatinine concentration, and race.


RESULTS
Correlation coefficients between phthalate metabolite concentrations in the urine of mothers and their infants were generally low but increased with decreasing age of infant. In multivariate analyses, mother's phthalate metabolite concentrations were significantly associated with infants' concentrations for six phthalate metabolites: monobenzyl phthalate, monoethyl phthalate, monoisobutyl phthalate, and three metabolites of di(2-ethylhexyl) phthalate: mono(2-ethylhexyl) phthalate, mono(2-ethyl-5-hydroxy-hexyl) phthalate, and mono(2-ethyl-5-oxo-hexyl) phthalate (p-values for all coefficients <0.05).


CONCLUSIONS
Mother's urine phthalate metabolite concentration is significantly associated with infant urine phthalate metabolite concentration for six phthalate metabolites. It is plausible that shared exposures to phthalates in the immediate surrounding environment accounted for these relationships, but other unidentified sources may also contribute to infants' phthalate exposures. This study indicates the importance of further identifying infant phthalate exposures that may be distinct from maternal exposures in order to decrease overall infant phthalate exposures.
Sathyanarayana
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S
Department of Pediatrics, University of Washington, Seattle, WA 98104-2499, USA. sathyana@u.washington.edu
Calafat
A M
AM
Liu
F
F
Swan
S H
SH
D000328:Adult; D000367:Age Factors; D002675:Child, Preschool; D002851:Chromatography, High Pressure Liquid; D003404:Creatinine / Q000652:urine; D004785:Environmental Pollutants / Q000378:metabolism / Q000652:urine*; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D018811:Maternal Exposure / Q000706:statistics & numerical data*; D010795:Phthalic Acids / Q000378:metabolism / Q000652:urine*; D053719:Tandem Mass Spectrometry; D014481:United States
D004785:Environmental Pollutants; D010795:Phthalic Acids; D003404:Creatinine