Toxic Effects of Bisphenol A and Bisphenol S on Chlorella Pyrenoidosa under Single and Combined Action

Bisphenol A (BPA) is an important industrial chemical; bisphenol S (BPS) is a substitute for BPA. Both are frequently detected in rivers, sewage, and surface water, and have a great impact on the water environment. The effects of BPA and BPS on cell growth, chlorophyll a content, and oxidative stress of Chlorella pyrenoidosa (C. pyrenoidosa) were studied. When BPA and BPS acted alone or in combination, compared with the blank control group, the growth of C. pyrenoidosa in the experimental group showed a pattern of "low promotion and high inhibition", and the inhibition rate reached the maximum on the 6th day. Under the combined action, the reactive oxygen species (ROS) level of C. pyrenoidosa first increased, and then decreased. In addition, the activity of superoxide dismutase (SOD) and peroxidase (POD) increased with the increase in combined concentration. In the 0.5 P treatment group, SOD and POD activity reached peak values of 29.59 U/mg∙prot and 1.35 U/mg∙prot, respectively. The combined toxicity of BPA and BPS to C. pyrenoidosa was evaluated as a synergistic effect by using toxicity unit and additive index methods. This study evaluated the effects of BPA and BPS on algae in the aquatic environment, providing some data support for their potential ecological risks.