Dissolved organic matter heightens the toxicity of tetrabromobisphenol A to aquatic organisms.

Tetrabromobisphenol A (TBBPA) is a new type of persistent organic pollutant, which causes environmental pollution and health problems, and has attracted the attention of the international research community. Once released into the environment, TBBPA can interact with dissolved organic matter (DOM), which affects its behavior. However, the effect of DOM on the biological toxicity of TBBPA remains unclear. The toxic effects of TBBPA on three model aquatic organisms (Chlorella pyrenoidosa, Daphnia magna, and Danio rerio), in the absence and presence of DOM were investigated. The order of acute toxicity of TBBPA to the three aquatic organisms was D. magna > D. rerio > C. pyrenoidosa. In the presence of DOM the median effect/lethal concentrations values of TBBPA to the three aquatic organisms decreased by at least 32 (C. pyrenoidosa), 52 (D. magna), and 6.6% (D. rerio), implying that DOM enhanced the acute toxicity of TBBPA to all the organisms. Moreover, the higher the concentration of DOM, the higher the acute toxicity of TBBPA. Furthermore, the presence of DOM increased total reactive oxygen species (ROS) induced by TBBPA in a concentration-dependent manner. A tracking analysis of total ROS in the three aquatic organisms also showed that the presence of DOM aggravated the accumulation of total ROS induced by TBBPA, indicating that oxidative stress is a characteristic mechanism of toxicity of TBBPA to aquatic organisms when DOM is present. In addition, the evaluated risk quotient indicated that the ecological risk of TBBPA to aquatic organisms can increase in environments rich in DOM.