Photoinitiators in Breast Milk from United States Donors: Occurrence and Implications for Exposure in Infants

Although photopolymerization is generally considered a green technology for polymer production, it is not a panacea. Indeed, recent reports have identified environmental contamination by photoinitiators (PIs), key additives used in photopolymerization. In the present study, the occurrence of 25 PIs-8 benzophenones (BZPs), 9 amine co-initiators (ACIs), 4 thioxanthones (TXs), and 4 phosphine oxides (POs)-was investigated in human breast milk samples from United States donors. Fifteen PIs were detected in the breast milk samples, with Sigma PIs in a wide range of 0.46-81.7 ng/mL (geometric mean (GM): 10.9 ng/mL). BZPs (GM: 10.3 ng/mL) were the dominant group, contributing 94.4% to Sigma PIs, followed by ACIs (GM: 0.19 ng/mL), POs (GM: 0.15 ng/mL), and TXs (GM: 0.028 ng/mL). Among the 15 detected congeners, benzophenone (GM: 8.23 ng/mL) was the dominant congener, contributing 82.9% and 79.0% to Sigma BZPs and Sigma PIs, respectively. No significant relationship was found between the PI concentrations and donor characteristics (age and ethnicity). The estimated daily intakes (EDIs) of PIs (920-7.90 x 10(3) ng/kg bw/day) via breastfeeding were calculated for infants. The calculated EDIs correspond to low health risks. To our knowledge, this is the first investigation reporting the occurrence of 15 PIs in human breast milk and evaluating the implications for exposure in infants.