In vitro oxidative stress, mitochondrial impairment and G1 phase cell cycle arrest induced by alkyl-phosphorus-containing flame retardants.

Phosphorus-containing flame retardants (PFRs) have been frequently detected in various environmental samples at relatively high concentrations and are considered emerging environmental pollutants. However, their biological effects and the underlying mechanism remain unclear, especially alkyl-PFRs. In this study, a battery of in vitro bioassays was conducted to analyze the cytotoxicity, oxidative stress, mitochondrial impairment, DNA damage and the involved molecular mechanisms of several selected alkyl-PFRs. Results showed that alkyl-PFRs induced structural related toxicity, where alkyl-PFRs with higher logKow values induced higher cytotoxicity. Long-chain alkyl-PFRs caused mitochondrial and DNA damage, resulting from intracellular reactive oxygen species (ROS) and mitochondrial superoxide overproduction; while short-chain alkyl-PFRs displayed adverse outcomes by significantly impairing mitochondria without obvious ROS generation. In addition, alkyl-PFRs caused DNA damage-induced cell cycle arrest, as determined by flow cytometry, and transcriptionally upregulated key transcription factors in p53/p21-mediated cell cycle pathways. Moreover, compared to the control condition, triisobutyl phosphate and trimethyl phosphate exposure increased the sub-G1 apoptotic peak and upregulated the p53/bax apoptosis pathway, indicating potential cell apoptosis at the cellular and molecular levels. These results provide insight into PFR toxicity and the involved mode of action and indicate the mitochondria is an important target for some alkyl-PFRs.

Screening for over 1000 organic micropollutants in surface water and sediments in the Liaohe River watershed.

High throughout screening method has gained attractive prospects because it offers a fast and effective approach to obtain a holistic picture of organic micropollutant (OM) pollution in a site specific environment. However, reliability and usefulness of the generated data sets for OM pollution profiles and occurrence levels have not been fully evaluated. In this paper, we screened 1030 OMs in surface water and sediments from the selected rivers of the Liaohe River watershed to (1) examine the usefulness of using qualitative data to gain insights into source identification and (2) further evaluate the reliability of the semi-quantification results in a filed study. The results showed that 81 and 89 OMs at concentrations up to 5670 ng/L and 6714 ng/g were identified in surface water and sediments, respectively. Qualitative data could be used to identify the similarity (or dissimilarity) of pollution sources at different locations for surface water, which could provide insights for source back tracking of water contamination. Accuracy tests showed that our semi-quantification results agree well with those from previously reported values and our target analysis. Though our results for the majority of newly quantified OMs need to be further confirmed, we have demonstrated that this method is suitable for understanding the pollution characteristics and occurrence levels of OMs in the environment for environmental scientists and managers.