Objectives: Some phthalates, among them di-n-butylphthalate (DnBP) and butylbenzylphthalate (BBzP), are known reproductive and developmental toxicants in animals and suspected endocrine disruptors in humans. Children are probably the most susceptible to these effects. To obtain an estimate of internal exposure to DnBP and BBzP we compared the excretion of their metabolites in the urine of nursery school children with that of their teachers and parents.
Methods: We measured the urinary mono-ester metabolites of DnBP, mono-n-butylphthalate (MnBP), and BBzP, monobenzylphthalate (MBzP), in first-morning voids of 36 children (median age 4.7 years) and 19 adults (37.4 years).
Results: In all samples both metabolites were detected. Urinary MnBP concentrations (in microgrammes per litre) of the children and adults were 139 and 91.8 (median), respectively. MBzP concentrations were 22.1 microg/l and 12.7 microg/l (median), respectively. Concentrations in microgrammes per gramme creatinine for MnBP were 161 for the children and 91.8 for the adults (median). The maximum concentration found for children (2249 microg/g) was approximately 15-times higher than that for adults (149 microg/g). This maximum value for children was attributed to medication that contained DnBP. If this child was excluded, the maximum concentration was 517 microg/g. MBzP concentrations for children and adults were 37.0 microg/g and 9.8 microg/g (median), respectively. The maximum concentration found for children (193 microg/g) was approximately seven-times higher than that for adults (26.7 microg/g). Creatinine-adjusted concentrations were significantly higher for children for both MBzP and MnBP (P<0.0001). MnBP and MBzP exposures were found to correlate statistically significantly within the children's cohort (r=0.723, P<0.001). Within the children's cohort we found elevated MnBP exposure to be caused by augmented use of skin-care products (P<0.05).
Conclusion: We have shown that the internal exposure to MnBP and MBzP in children is approximately two- to four-times higher than in adults. Correlation of internal MnBP with MBzP exposure points to common sources of exposure for both phthalates. DnBP exposure seems, at least in part, to be connected with the use of body/skin care products and certain medications.