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Phthalates are a family of multifunctional chemicals widely used in personal care and other consumer products. The ubiquitous use of phthalates results in human exposure through multiple sources and routes, including dietary ingestion, dermal absorption, inhalation, and parenteral exposure from medical devices containing phthalates. We explored the temporal variability over 3 months in urinary phthalatc metabolite levels among 11 men who collected up to nine urine samples each during this time period. Eight phthalate metabolites were measured by solid-phase extraction-high-performance liquid chromatography-tandem mass spectrometry. Statistical analyses were performed to determine the between- and within-subject variance apportionment, and the sensitivity and specificity of a single urine sample to classify a subject's 3-month average exposure. Five of the eight phthalates were frequently detected. Monoethyl phthalate (MEP) was detected in 100% of samples; monobutyl phthalate, monobenzyl phthalate, mono-2-ethylhexyl phthalate (MEHP), and monomethyl phthalate were detected in > 90% of samples. Although we found both substantial day-to-day and month-to-month variability in each individual's urinary phthalate metabolite levels, a single urine sample was moderately predictive of each subject's exposure over 3 months. The sensitivities ranged from 0.56 to 0.74. Both the degree of between- and within-subject variance and the predictive ability of a single urine sample differed among phthalate metabolites. In particular, a single urine sample was most predictive for MEP and least predictive for MEHP. These results suggest that the most efficient exposure assessment strategy for a particular study may depend on the phthalates of interest. Key words: biomarkers, human, phthalates, reliability, urine. Environ Health Perspect 112:1734-1740 (2004). doi:10.1289/ehp.7212 available via http://dx.doi.org/ [Online 16 August 2004]
Phthalates, Jtesters of phthalic acid, are a family of multifunctional chemicals that are widely used in personal and consumer products. Phthalatcs are used to hold color and scent in consumer and personal care products (Koo ct al. 2002); as solvents in paints, glue, insect repellents, lubricants, and adhesives [Agency for Toxic Substances and Disease Registry (ATSDR 20011; and to soften a wide range of plastics (Bradbury 1996), including polyvinyl chloride (PVC) used in the manufacture of medical products such as blood, intravenous, and dialysate bags and tubing (Nassbergcr et al. 1987). Dicthyl phthalate (DEP), di-w-buryl phthalate (DBP), and butyl benzyl phthalate (BBxP) are principally used in personal care products, such as...