The combined toxicity of silver nanoparticles and typical personal care products in diatom Navicula sp.

Toxicity of silver nanoparticles (AgNPs) at environmentally relevant concentrations has been received an increasing attention, and their influence on the bioavailability of personal care products has been seldom studied. Here, the toxicity of AgNPs in typical diatom Navicula sp. was explored, and their influence on the bioavailability of typical personal care products such as triclosan (TCS) and galaxolide (HHCB) was also investigated. The underlying toxicity mechanisms were explored using liquid chromatography-mass spectrometry (LC-MS)-based metabolomics. Low concentrations of AgNPs (10 and 50 µg L-1) induced no observable responses of Navicula sp., in terms of growth rate, chlorophyll contents, and malondialdehyde accumulation. Furthermore, low doses of AgNPs could attenuate TCS or HHCB toxicity to Navicula sp., which was mainly attributed to the reduced oxidative stress. Metabolomics revealed that the disruption of DNA or RNA synthesis and instability of cytokinin-like substances may be also the reasons for the toxicity of AgNPs and TCS to Navicula sp. The damaged algal photosynthesis exposed to HHCB may be recovered by AgNPs, and the presence of signal chemicals (dehydrophytosphingosine and cardamonin) also showed a recovered algal growth. These results emphasize the potential of metabolomics to reveal toxicity mechanism, providing a new perspective on the aquatic risk assessment of nanoparticles and emerging organic pollutants.

Individual and combined toxicity of silver nanoparticles and triclosan or galaxolide in the freshwater algae Euglena sp.

With the widespread production and usage, silver nanoparticles (AgNPs) can be extensively found in the aquatic environment and co-exist with other pollutants for a prolonged time, leading to a more complex ecological risk in natural waters. In this work, the model freshwater algae Euglena sp. was selected to study the toxicity of AgNPs and explore their influences on the toxicity of two frequently detected personal care products, triclosan (TCS) and galaxolide (HHCB). The LC-MS targeted metabolomics was used to analyze the possible toxicity mechanism at the molecular level. Results showed that AgNPs was toxic to Euglena sp. upon 24 h exposure, but the toxicity decreased gradually as exposure times increased. AgNPs (<100 µg L-1) attenuated TCS and HHCB toxicity to Euglena sp., which could be attributed primarily to the decreased oxidative stress. Metabolomic analysis revealed that AgNPs induced a stress on algal defense system upon TCS exposure, but promoted the algal defense system upon HHCB exposure. Furthermore, DNA or RNA biosynthesis was accelerated in algae exposed to TCS or HHCB after the addition of AgNPs, implying that AgNPs may mitigate the genetic toxicity of TCS or HHCB in Euglena sp. These results emphasize the potential of metabolomics to reveal toxicity mechanism and provide new perspectives on the aquatic risk assessment of personal care products in the presence of AgNPs.