Multi-trophic-level toxicity assessment of selected bromophenols

Bromophenols (BPs) are a class of aromatic compounds that have become pervasive environmental pollutants due to their widespread industrial use, particularly in the production of flame retardants. However, BPs can enter the environment not only through manufacturing, but also through leaching and metabolic breakdown, raising concerns about their ecological and human health impacts. Tetrabromobisphenol A (TBBPA) is one of the most extensively utilized brominated flame retardants and found in a variety of consumer products, but it can undergo environmental and metabolic breakdown, releasing lower brominated phenols like 2,6-dibromophenol (2,6-DBP) as key intermediates. While TBBPA’s toxicity (immunotoxicity, endocrine disruption) is well-documented but debated, its transformation product, 2,6-DBP, is understudied.

Given their environmental persistence, potential bioaccumulation, and co-occurrence in ecosystems, the assessment of the potential toxicological effects of individual BPs (2,6-DBP and TBBPA), as well as their mixture, using a multi-trophic level approach is crucial. In the present study, three test models/organisms were utilized. Specifically, the bioluminescent bacterium Aliivibrio fischeri (microbial indicator), the freshwater microlaga Chlorococcum sp. (primary producer), and human lymphocytes were exposed to various concentrations of the studied BPs and their mixture. According to the results, both 2,6-DBP and TBBPA can be characterized as “toxic” towards Aliivibrio fischeri and caused an around 30% reduction in the number of human lymphocytes. By evaluating responses at different biological levels, this research aims to provide a more comprehensive understanding of the ecological and health risks posed by these emerging contaminants.