Occurrence of Multiple Classes of Emerging Synthetic Antioxidants, Including p-Phenylenediamines, Diphenylamines, Naphthylamines, Macromolecular Hindered Phenols, and Organophosphites, in Human Milk: Implications for Infant Exposure

Abstract

Synthetic antioxidants (AOs) have received increasing attention in recent years due to their environmental ubiquity. However, lactational exposure to these emerging contaminants of current concern remains unknown. In this study, 21 amine antioxidants, 18 macromolecular hindered phenol antioxidants, 3 organophosphite antioxidants, and 2 p-phenylenediamine-derived quinones (PPD-Qs) were integrated into a dedicated screening in human milk from South China. Among all 42 target AOs, 19 were detected, but no PPD-Qs were detected in any of the samples. Eight AOs, including N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD), were frequently detected in more than half of the samples. The summed concentrations of all detectable AOs in human milk ranged from 133 to 7,560 pg/mL, with a median of 713 pg/mL. Significant correlations were observed among the concentrations of amine and phenol antioxidants. The preliminary risk assessment revealed that under the high exposure scenario, the overall daily intake of all identified AOs through breastfeeding might pose a non-negligible health risk to newborns. This study is the first to attempt to comprehensively identify a wide range of emerging AOs prevalent in human milk. The findings call for urgent concern for infant exposure to these widely used but less well evaluated chemicals and a possible increased accumulative risk in the future.

Identification and Prioritization of Organic Pollutants in Human Milk from the Yangtze River Delta, China

“…The most commonly used organophosphite antioxidant tris­(2,4-di- tert -butylphenyl) phosphite (AO168) had a DF of 47%. AO168 was first found in indoor dust from Canada, and it is a precursor of tris­(2,4-di- tert -butylphenyl) phosphate (AO168 = O). , AO168 has been detected in human milk from Guangzhou, China, at concentrations of <MQL-484 pg/mL . Meanwhile, high AO168 concentrations (ND to 6.79 × 10 3 ng/g) have recently been found in packaged foods, indicating that humans can be exposed to AO168 in food …”

In Vitro and In Vivo Biotransformation Profiling of 6PPD-Quinone toward Their Detection in Human Urine

“…Given the association of 6PPD and 6PPD-Q with human-related sources, such as roadside soil, runoff water, indoor dust, and air particles, there is a plausible risk of human exposure to these compounds through diet, inhalation, and skin contact. Nonetheless, studies on their detection in human samples are scarce. − To date, only one comprehensive biomonitoring study has been conducted, analyzing 150 urine samples from diverse populations (adults, children, and pregnant women) in South China. This study reported higher urinary concentrations of 6PPD-Q compared to 6PPD, with pregnant women showing higher median levels of both 6PPD and 6PPD-Q (0.068 and 2.91 ng/mL, respectively) than adults (0.018 and 0.40 ng/mL) and children (0.015 and 0.076 ng/mL) …”

Characterization of Chemical Additives in Daily Clothing Regarding Human Exposure and Environmental Emissions

“…As high-volume production chemicals, synthetic antioxidants (AOs), organophosphate esters (OPEs), and phthalate esters (PAEs) are extensively used across various industrial and consumer products, − including clothes. Consequently, the broad and massive use of these substances could inevitably result in their emission to the surrounding environment − and their internalization into human circulation. − Exposure to these contaminants can have severe toxic effects, including acute mortality, endocrine disruption, neurotoxicity, genotoxicity, and carcinogenicity. − Indeed, AOs have been detected in fabric materials used, for example, in children’s car seats, , but research on daily clothing items remains scarce. Moreover, textiles have large surface areas to absorb semivolatile organic compounds (SVOCs).…”