Synthetic Phenolic Antioxidants: A Review of Environmental Occurrence, Fate, Human Exposure, and Toxicity

Abstract

Synthetic phenolic antioxidants (SPAs) are widely used in various industrial and commercial products to retard oxidative reactions and lengthen product shelf life. In recent years, numerous studies have been conducted on the environmental occurrence, human exposure, and toxicity of SPAs. Here, we summarize the current understanding of these issues and provide recommendations for future research directions. SPAs have been detected in various environmental matrices including indoor dust, outdoor air particulates, sea sediment, and river water. Recent studies have also observed the occurrence of SPAs, such as 2,6-ditert-butyl-4-methylphenol (BHT) and 2,4-di-tert-butyl-phenol (DBP), in humans (fat tissues, serum, urine, breast milk, and fingernails). In addition to these parent compounds, some transformation products have also been detected both in the environment and in humans. Human exposure pathways include food intake, dust ingestion, and use of personal care products. For breastfeeding infants, breast milk may be an important exposure pathway. Toxicity studies suggest some SPAs may cause hepatic toxicity, have endocrine disrupting effects, or even be carcinogenic. The toxicity effects of some transformation products are likely worse than those of the parent compound. For example, 2,6-di-tertbutyl-p-benzoquinone (BHT-Q) can cause DNA damage at low concentrations. Future studies should investigate the contamination and environmental behaviors of novel high molecular weight SPAs, toxicity effects of coexposure to several SPAs, and toxicity effects on infants. Future studies should also develop novel SPAs with low toxicity and low migration ability, decreasing the potential for environmental pollution.

Terpenoids and Polyphenols as Natural Antioxidant Agents in Food Preservation

“…In fruits and vegetables, 2-naphthol (2NL), 4-phenylphenol (OPP) and 2,4-dichlorophenoxyacetic acid (2,4-DA) are the most commonly used [ 22 ]. Although these synthetic antioxidants are widespread and strictly regulated, there are safety concerns due to their overuse and/or misuse (e.g., a mixture of certain antioxidants may increase their toxic effects) [ 23 , 24 ]. An increasing number of studies conclude that high doses of chemical synthetic antioxidants may cause DNA damage [ 25 , 26 , 27 ] or in vitro toxicity in certain tissues [ 28 , 29 ].…”

Healthy Drinks with Lovely Colors: Phenolic Compounds as Constituents of Functional Beverages

“…In recent years, there has been a growing preference for natural phenolic antioxidants over artificial ones, fundamentally due to the increasing demand by consumers for functional foods and beverages with the addition of natural additives, which maintain their nutritional properties and flavor [68]. Besides, this trend results, according to the same authors, from the preference currently given to natural phenolic antioxidants in food stabilization, and the restrictions applied by the responsible entities on the use of synthetic phenolic antioxidants [69,70].…”

“…Several synthetic phenolic antioxidants (SPAs) are widely used in industrial and commercial products, but only a few can legally be added to food products [89]. Thus, with a common molecular structure in which the phenolic rings are replaced by alkyls hindered in the ortho position [70], butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), propyl gallate (PG), and tertiary-butylhydroquinone (TBHQ) are commonly used as food antioxidants [90]. However, BHA and BHT are the antioxidants most used as additives in food products [91,92].…”

Synthesis and application of new macromolecular hindered phenol antioxidants of polyamide 6

“…6 Its mechanism of action is as follows: phenolic hydroxyl, a free radical trap on antioxidants, reacts with peroxy or alkoxy radicals generated by PA6 amide groups as a result of thermal oxidative aging, and reacts with them to form stable compounds, preventing the reaction that free radicals seize hydrogen to break molecular chains to further continue, thus protecting polymer chains from such free radicals and delaying the thermal oxidative aging of polyamide. [7][8][9][10] Because of its remarkable anti-thermal aging effect and significantly less pollution to environment, 11 the hindered phenolic antioxidant has been paid significant attention and has seen rapid development.…”