Massive Emissions of a Broad Range of Emerging Hindered Phenol Antioxidants and Sulfur Antioxidants from E-Waste Recycling in Urban Mining: New Insights into an Environmental Source

To recognize new pollution caused by synthetic antioxidants in the environment, a wide range of 18 emerging hindered phenol antioxidants (HPAs) and 6 emerging sulfur antioxidants (SAs) were investigated, for the first time, through a dedicated target screening in representative e-waste recycling indoor work environments. All 18 emerging HPAs and 6 emerging SAs were detected in 45 e-waste dust samples collected from different categories of recycling workshops. Of the 24 detected target antioxidants, 22 were first reported in e-waste dust and 9 were newly identified in the environment. Pentaerythritol tetrakis(Irganox 1076), and triethylene glycol bis(3-tert-butyl-4-hydroxy-5-methylphenyl) propionate (Irganox 245) were the most abundant antioxidants, with median levels of 1560-4700 ng/g, comparable to or higher than those of other e-waste pollutants. Significantly positive or negative correlations were observed among these "novel" antioxidants, indicating that they have similar or competitive uses in electronic products. Waste wires and cables and waste electronic plastics were identified as the two main sources of emission of HPAs to the indoor environments during e-waste recycling. Our findings raise the need for further investigations of the environmental behavior, fate, and risks of these widely used but rarely evaluated "novel" antioxidants.