Tetrabromobisphenol A (TBBPA), a widely used brominated flame retardant, is prevalent in various environmental matrices due to its extensive use and release from plastic products. TBBPA exposure is linked to endocrine disruption, reproductive toxicity, and potential carcinogenicity. Microplastics (MPs), defined as plastic particles smaller than 5 mm, have become common persistent pollutants in marine, inland, and freshwater environments, including remote regions like the polar areas. Ionic strength and dissolved organic matter (DOM) can influence the sorption behavior of MPs, which due to their small size and large areas can significantly facilitate the transfer and accumulation of hydrophobic organic contaminants (HOCs) and heavy metals (HMs). Humic acid (HA), a mainly negatively charged natural organic matter, can interact with MPs, creating new sorption sites and potentially altering contaminant dynamics.

This study investigates the toxicity of TBBPA on the seawater microalgae Tisochrysis lutea. Additionally, the study evaluates the toxicity of TBBPA after adsorption onto LDPE MPs, both in the presence and absence of humic acid (HA) in four water matrices (seawater, lake water, wastewater and ultra-pure water), on Tisochrysis lutea.

The results showed significant inhibition of microalgae growth due to TBBPA exposure. The toxicity decreased in the presence of LDPE microplastics due to the potential adsorption of TBBPA onto the LDPE. In contrast, the presence of humic acid increased the toxicity of TBBPA, possibly by altering its sorption behavior on LDPE, making it more bioavailable. The findings aim to elucidate the complex interactions between MPs, TBBPA, and environmental factors, contributing to a better understanding of the ecological impact of these co-existing contaminants.