<p>In 2002, ten different polymeric antioxidant by-products (ABP) were discovered in Danish drinking water. ABPs, also known as Arvin substances, are breakdown products from antioxidants when exposed to for example heat and pressure. At the time of discovery, ABPs were poorly studied and thus lacked toxicological and exposure data. This review aims to assess publicly available toxicological and exposure data to highlight potential human health concerns and data gaps of these ten different ABPs. Searches were conducted using PubMed, Scopus and European Chemicals Agency (ECHA) databases up to August 1, 2025 focusing on publications related to toxicity, ecotoxicity, or exposure data. Besides drinking water, ABPs have been detected in food, plastic kitchenware and in humans at various concentrations. Toxicological data were identified for ABP 1 (4-ethylphenol), ABP 2 (4-tert-butylphenol), ABP 4 (2,4-di-tert-butylphenol) and ABP 9 (methyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate). Oral exposure of rats to ABPs resulted in systemic effects, specifically in liver and stomach, while in zebrafish mainly developmental and systemic effects were observed. Limited to no toxicological and/or ecotoxicological data were available for ABP 3 (2,6-di-tert-butyl-p-benzoquinone), ABP 5 (3,5-di-tert-butyl-4-hydroxystyrene), ABP 6 (3,5-di-tert-butyl-4-hydroxybenzaldehyde), ABP 7 (3,5-di-tert-butyl-4-hydroxyacetophenone), ABP 8 (7,9-di-tert-butyl-1-oxaspiro(4,5)deca-6,9-diene-2,8-dione), and ABP 10 (3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid) and limited exposure or no data were available for ABP 5, 7, 8 and 9. The review highlights significant data gaps, precluding a comprehensive risk assessment, although human health concerns appear warranted given the available toxicological findings and ongoing exposure.</p>