Phthalates and their metabolites in breast milk--results from the Bavarian Monitoring of Breast Milk (BAMBI)

Phthalates have long been used as plasticizers to soften plastic products and, thus, are ubiquitous in modern life. As part of the Bavarian Monitoring of Breast Milk (BAMBI), we aimed to characterize the exposure of infants to phthalates in Germany. Overall, 15 phthalates, including di-2-ethylhexyl phthalate (DEHP), di-n-butyl phthalate (DnBP), di-isobutyl phthalate (DiBP), di-isononyl phthalate (DiNP), three primary metabolites of DEHP [mono-(2-ethylhexyl) phthalate (MEHP), mono-isobutyl phthalate (MiBP), and mono-n-butyl phthalate (MnBP)], and two secondary metabolites of DEHP were analyzed in 78 breast milk samples. We found median concentrations of 3.9 ng/g for DEHP, 0.8 ng/g for DnBP, and 1.2 ng/g for DiBP, while other parent phthalates were found in only some or none of the samples at levels above the limit of quantitation. In infant formula (n=4) we observed mean values of 19.7 ng/g (DEHP), 3.8 ng/g (DnBP), and 3.6 ng/g (DiBP). For MEHP, MiBP, and MnBP, the median values in breast milk were 2.3 μg/l, 11.8 μg/l, and 2.1 μg/l, respectively. The secondary metabolites were not detected in any samples. Using median and 95th percentile values, we estimated an "average" and "high" daily intake for an exclusively breast-fed infant of 0.6 μg/kg body weight (b.w.) and 2.1 μg/kg b.w., respectively, for DEHP, 0.1 μg/kg b.w. and 0.5 μg/kg b.w. for DnBP, and 0.2 μg/kg b.w. and 0.7 μg/kg b.w. for DiBP. For DiNP, intake values were 3.2 μg/kg b.w. and 6.4 μg/kg b.w., respectively, if all values in milk were set half of the detection limit or the detection limit. The above-mentioned "average" and "high" intake values corresponded to only about 2% to 7%, respectively, of the recommended tolerable daily intake. Thus, it is not likely that an infant's exposure to phthalates from breast milk poses any significant health risk. Nevertheless, other sources of phthalates in this vulnerable phase have to be considered. Moreover, it should be noted that for infants nourished with formula, phthalate intake is of the same magnitude or slightly higher (DEHP) than for exclusively breast-fed infants.