Di-n-butylphthalate and butylbenzylphthalate — urinary metabolite levels and estimated daily intakes: pilot study for the German Environmental Survey on children

Abstract

We analysed urine samples from the 2001/2002 pilot study of the German Environmental Survey on Children (GerES IV) for the concentrations of the di-n-butylphthalate (DnBP) metabolite mono-n-butylphthalate (MnBP) and the butlybenzylphthalate (BBzP) metabolite mono-benzyl-phthalate (MBzP). The study population consisted of 239 children (106 boys, 133 girls) aged between 2 and 14 years (median 8.5 years). We applied two calculation models to estimate the daily intake for the two parent phthalates from metabolite excretion. One was based on the creatinine-related metabolite concentrations; the other was based on the volume-related metabolite concentrations. Median urinary metabolite concentrations were 174 g/l (136 g/g creatinine) for MnBP and 19.7 g/l (15.3 g/g creatinine) for MBzP. Such levels have been determined in German children before. Compared to the USA, German median MnBP levels were about 3–10 times higher, whereas MBzP levels were in the same range. Median daily intakes calculated with the creatinine-based model were 4.07 (range: 0.66–76.4; 95th percentile: 14.9) g/kg body weight (bw)/day for DnBP and 0.42 (range: 0.06–13.9; 95th percentile: 2.57) g/kg bw/day for BBzP. Daily intakes calculated with the volume-based model were approximately two times higher with a median of 7.61 (range: 0.91–110; 95th percentile: 30.5) g/kg bw/day for DnBP and a median of 0.77 (range: 0.05–31.3; 95th percentile: 4.48) g/kg bw/day for BBzP. Using the creatinine model, 28 (11.7%) of the 239 children exceeded the TDI for DnBP of 10 g/kg bw/day defined by the European Union. Employing the volume model, 89 (37.2%) children exceeded the TDI. For BBzP, no preventive limit values (TDI or RfD) were exceeded. For both phthalates and independent of the model, we found increasing daily intakes with decreasing age. Between 25% (creatinine model) and 50% (volume model) of the 2–4-year old children had daily intakes for DnBP above the TDI.