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

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.