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Brock, JW, SP Caudill, MJ Silva, LL Needham, and ED Hilborn. 2002. Phthalate Monoester Levels in the Urine of Young Children. Bulletin of Environmental Contamination and Toxicology 68:309–314. |
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Brock et al. measured the level of several phthalate metabolites in the urine of 19 children living in the Imperial Valley, California. They found phthalates in all children examined, with levels higher on average than had been reported by Blount et al. (2000) using the same analytical tools to measure phthalate metabolites in a larger sample of American adults. What did they do? Brock et al. recruited 20 children (ages 12-18 months) for participation in this survey by approaching the parents as the children were brought to a clinic for their measles-mumps-rubella vaccine. Nothing was assumed or known about their potential exposure to phthalates upon recruitment. 18 of the 20 subjects were Latino; 2 were Caucasian. Urine was collected during this clinic visit and a second time during a home visit, about 4 weeks later. The primary caregiver was interviewed using a questionnaire to assess home pesticide use, occupational exposure and proximity to agricultural pesticide use. A second interview was conducted during the home visit, updating the pesticide information and also asking about the use of perfumes, cosmetics and soft plastic toys. The phthalate measurements were conducted using procedures developed for Blount et al. (2000). Because phthalate exposure is so widespread that laboratory contamination is unavoidable, Brock's lab at the CDC has pioneered a technique that measures the breakdown products of different phthalates in urine, their metabolites, instead of the original (parent) phthalates themselves. According to Blount et al: "This analytical approach allows us to directly measure the individual phthalate metabolites responsible for the reproductive and developmental toxicity of phthalates in animals while avoiding contamination from the ubiquitous parent compound." This approach thus allows Brock's team to confirm that the exposures were real and not due to laboratory contamination, as the laboratory contamination is by the phthalates, not by their metabolites. They report on the concentrations of the following metabolites:
Several other metabolites were measured but were not detected. What did they find? All children had phthalate metabolites in their urine, indicating exposure to the parent phthalates. For three of the four metabolites, concentrations averaged higher in children than those measured by Blount et al. in adults:
None of the measurements of phthalate metabolites showed any correlation with responses to the questionnaires. What does it mean? According to Brock et al.:
The types of phthalates detected suggest that exposure is via consumer products such as fragrance-containing soaps, shampoos and perfumes, as well as nail polish and beauty products. The presence of MEHP indicates that another route of exposure was via DEHP-containing toys. Whether these levels create health risks remains to be established. The higher levels indicate exposures within the range at which effects begin to appear in laboratory experiments with animals. The concluding comments from Blount et al. (2000) are equally germane to these new data:
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