“Novel” Synthetic Antioxidants in House Dust from Multiple Locations in the Asia-Pacific Region and the United States

Abstract

Synthetic antioxidants represent a complex group of additive chemicals broadly used in consumer products. While traditional antioxidants such as 2,6-di-tert-butyl-4-methylphenol (BHT) have been well studied, a variety of “novel” antioxidants have emerged with extensive applications but received much less attention. Our study aimed to explore a suite of 34 emerging antioxidants in house dust from four different regions, including Guangzhou (China), Adelaide (Australia), Carbondale (Illinois), and Hanoi (Vietnam). The results revealed broad occurrence of several rarely investigated chemicals in house dust across regions, including triethylene glycol bis­(3-tert-butyl-4-hydroxy-5-methylphenyl)­propionate (AO245), 2,6-di-tert-butyl-4-(dimethylamino)­methylphenol (AO4703), 2,2′-thiene-2,5-diylbis­(5-tert-butyl-1,3-benzoxazole) (BBOT), 1,3-diphenylguanidine (DPG), 2,4-bis­(1,1-dimethylethyl)­phenol (2,4DtBP), and 2,6-bis­(1,1-dimethylethyl)­phenol (2,6DtBP). In particular, DPG exhibited a median concentration of 5030–11 400 ng/g in house dust from the studied regions except for Hanoi (305 ng/g), generally 1 order of magnitude greater than that of BHT (890–1060 ng/g) and dominating the compositional profiles of antioxidants. Estimated intake of target antioxidants by toddlers via dust ingestion, even under the high exposure scenario, was determined to be 2–4 orders of magnitude lower than the reference doses of selected antioxidants. However, potential risks from long-term exposure to a cocktail of antioxidants under environmentally relevant concentrations merit further investigations due to insufficient knowledge on the sources, fate, and toxicokinetics of these chemicals to date.

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

“…The total concentration of all HPAs (∑ 18 HPAs) in e-waste dust ranged from 3.71 × 10 3 to 1.15 × 10 5 ng/g, with a median of 1.22 × 10 4 ng/g. The concentrations and DFs of HPAs in e-waste dust were comparable to or slightly lower than previously reported e-waste dust concentrations of polybrominated diphenyl ethers (PBDEs), − tetrabromobisphenol A, decabromodiphenyl ethane, and liquid crystal monomers but higher than reported e-waste dust concentrations of polychlorinated biphenyls (PCBs), , organophosphate triesters, dechlorane plus, hexabromocyclododecanes, , alternative flame retardants, , and other emerging e-waste pollutants. , The median concentrations of most individual HPAs in e-waste dust were >1 order of magnitude higher than those detected in general indoor dust. ,, These e-waste dust detection results highlight the abundant, ubiquitous presence of a broad range of HPAs in e-waste recycling areas and indicate that e-waste recycling contributes to massive emissions of HPAs in work environments.…”

“…52,53 The median concentrations of most individual HPAs in e-waste dust were >1 order of magnitude higher than those detected in general indoor dust. 13,26,30 These e-waste dust detection results highlight the abundant, ubiquitous presence of a broad range of HPAs in e-waste recycling areas and indicate that e-waste recycling contributes to massive emissions of HPAs in work environments.…”

“…To the best of our knowledge, available field studies have been limited to recognition of Irganox 2246 and Irganox 1076 in e-waste dust 29 and air particles. 13,26,30,31 Data for other emerging HPAs as well as other environmental compartments are lacking. As HPAs contain a large number of congeners, a systematic, comprehensive identification of a broader range of HPAs and their potential sources in the environment is urgently needed considering that their ecotoxicological parameters were not tested before they were placed on the market.…”

“…In fact, to improve the antioxidative performance and slow the migration of SPAs from polymeric products, in recent years, a large number of BHT-derived high-molecular weight (HMW) SPAs, also termed hindered phenol antioxidants (HPAs), represented by 2,2′-methylenebis­(4-methyl-6- tert -butylphenol) (Irganox 2246) and octadecyl-3-(3,5-di- tert -butyl-4-hydroxyphenyl) propionate (Irganox 1076), have been prioritized for development and massive uses in the manufacture of polymers. − However, information about the release and environmental presence of these emerging HPAs remains scarce. To the best of our knowledge, available field studies have been limited to recognition of Irganox 2246 and Irganox 1076 in e-waste dust and a few in house dust and air particles. ,,, Data for other emerging HPAs as well as other environmental compartments are lacking. As HPAs contain a large number of congeners, a systematic, comprehensive identification of a broader range of HPAs and their potential sources in the environment is urgently needed considering that their ecotoxicological parameters were not tested before they were placed on the market.…”

E-Waste Recycling Emits Large Quantities of Emerging Aromatic Amines and Organophosphites: A Poorly Recognized Source for Another Two Classes of Synthetic Antioxidants

“…Synthetic antioxidants are high-production-volume (HPV) industrial chemicals that have been widely used as additives in plastics, rubbers, wires, cables, and other polymer materials to prevent oxidative degradation of the products. − Because of the ever-evolving need for polymeric products, especially tire rubber, the global usage of synthetic antioxidants reached as high as 523,800 tons in 2018 and is expected to grow in the future . On the basis of their chemical structures, commercial synthetic antioxidants are generally divided into four major classes: hindered phenolic antioxidants (HPAs), sulfur-containing antioxidants (SAs), aromatic amine antioxidants (AAs), and organophosphite antioxidants (OPAs) .…”