Comprehensive Characterization of Organic Light-Emitting Materials in Breast Milk by Target and Suspect Screening

Organic light-emitting materials (OLEMs) are emerging
contaminants
in the environment and have been detected in various environment samples.
However, limited information is available regarding their contamination
within the human body. Here, we developed a novel QuEChERS (quick,
easy, cheap, effective, rugged, and safe) method coupled with triple
quadrupole/high-resolution mass spectrometry to determine OLEMs in
breast milk samples, employing both target and suspect screening strategies.
Our analysis uncovered the presence of seven out of the 39 targeted
OLEMs in breast milk samples, comprising five liquid crystal monomers
and two OLEMs commonly used in organic light-emitting diode displays.
The cumulative concentrations of the seven OLEMs in each breast milk
sample ranged from ND to 1.67 × 103 ng/g lipid weight,
with a mean and median concentration of 78.76 and 0.71 ng/g lipid
weight, respectively, which were higher compared to that of typical
organic pollutants such as polychlorinated biphenyls and polybrominated
diphenyl ethers. We calculated the estimated daily intake (EDI) rates
of OLEMs for infants aged 0–12 months, and the mean EDI rates
during lactation were estimated to range from 30.37 to 54.89 ng/kg
bw/day. Employing a suspect screening approach, we additionally identified
66 potential OLEMs, and two of them, cholesteryl hydrogen phthalate
and cholesteryl benzoate, were further confirmed using pure reference
standards. These two substances belong to cholesteric liquid crystal
materials and raise concerns about potential endocrine-disrupting
effects, as indicated by in silico predictive models.
Overall, our present study established a robust method for the identification
of OLEMs in breast milk samples, shedding light on their presence
in the human body. These findings indicate human exposure to OLEMs
that should be further investigated, including their health risks.