Human carcinogenic risk analysis and utilization of shale gas water-based drilling cuttings in road materials

Abstract

Water-based drilling cuttings (WDC) generated during shale gas development will endanger human health and ecological security. The modern analytical techniques are used to analyze the organic pollutants in WDC, and the human health and ecological security risks of harmful pollutants in WDC under specific scenarios are evaluated. The results showed that the content of organic pollutants in WDC was evaluated by human health and safety risk assessment. The comprehensive carcinogenic risks of all exposure pathways of single pollutant benzo(a)anthracene, benzo(a)pyrene, benzo(k)fluoranthene, and indeno(1,2,3-cd)pyrene were acceptable. However, the cumulative carcinogenic risk of exposure to dibenzo(a,h)anthracene particles via skin exposure was not acceptable. It was considered that only dibenzo(a,h)anthracene had carcinogenic effect, and the risk control limit of dibenzo(a,h)anthracene in WDC was 1.8700 mg/kg by calculation. As well as, the “WDC-cement” gel composite structure was deeply analyzed, and the physical and chemical properties and mechanism of organic pollutants in cement solidified WDC were analyzed, which provided theoretical support for the study of WDC pavement cushion formula. Based on the above conclusions and combined with the actual site, by studying and adjusting the formula of WDC pavement cushion, the WDC pavement cushion was finally designed by 6% cement + 50% WDC + 44% crushed stone. The 7d unconfined compressive strength met the requirements of the Chinese standard “ Technical Guidelines for Construction of Highway Roadbases ” (JTG/T F20-2015). Also, the process route of WDC as road cushion product was sampled and analyzed. In addition, the leaching concentration of main pollutants all met the relevant standards of China. Therefore, this study can provide a favorable way for the efficient, safe, and environmentally friendly utilization of WDC, and ensure the ecological environment safety and human health safety of WDC in resource utilization.

Prioritizing Organic Pollutants for Shale Gas Exploitation: Life Cycle Environmental Risk Assessments in China and the US

“…To address the scarcity of concentration data, previous work established a physicochemical model to estimate concentrations of organic compounds in shale gas FPW, thereby bolstering the monitoring and management of high-risk chemicals . Furthermore, current research in China has predominantly focused on the target analysis of known compounds in shale gas wastewater, with limited exploration of unknown compounds. , Given the complex nature of chemical mixtures in shale gas wastewater, integrating big data, effect-directed analysis, and nontarget analysis can be beneficial in identifying key contributors to toxicity in this intricate system. − This comprehensive approach would deepen our understanding of the toxic effects associated with shale gas wastewater and enable the development of more effective mitigation strategies. Moreover, the absence of toxicity data for some identified compounds also hampers the proper risk assessment of the wastewater.…”

“…It could be traced back to ingredients such as quaternary ammonium surfactants used as drag reducers during drilling and fracturing. ,, This traceable relationship between environmental pollutants and their sources contributes to the development of pollutant prevention and control strategies. Furthermore, current research in China predominantly focused on target analysis of known compounds present in shale gas FPW, with limited exploration of unknown compounds. , Given the complexity of chemical mixtures in shale gas FPW, the combination of effect-directed analysis and nontarget analysis can be beneficial in identifying the specific drivers of toxicity within this intricate system, and can thus gain a deeper understanding of the toxic effects associated with shale gas FPW and effectively target their mitigation efforts. , …”

“…56 In the US, PAHs, especially dibenz-(a,h)anthracene, contributed great human health impacts due to its high concentration and carcinogenic potential. 57 Although the reported environmental concentrations of halogenated alkanes were relatively low (80% of which had concentrations below 10 μg/L), they still presented significant environmental risk owing to their elevated human and ecological toxicity. 58 Compounds with the highest IS were also ranked as priority products by different risk assessment methodologies (Figure S9).…”

“…62 Furthermore, current research in China has predominantly focused on the target analysis of known compounds in shale gas wastewater, with limited exploration of unknown compounds. 57,63 Given the complex nature of chemical mixtures in shale gas wastewater, integrating big data, effect-directed analysis, and nontarget analysis can be beneficial in identifying key contributors to toxicity in this intricate system. 63−65 This comprehensive approach would deepen our understanding of the toxic effects associated with shale gas wastewater and enable the development of more effective mitigation strategies.…”

“…Furthermore, current research in China predominantly focused on target analysis of known compounds present in shale gas FPW, with limited exploration of unknown compounds. 57,63 Given the complexity of chemical mixtures in shale gas FPW, the combination of effect-directed analysis and nontarget analysis can be beneficial in identifying the specific drivers of toxicity within this intricate system, and can thus gain a deeper understanding of the toxic effects associated with shale gas FPW and effectively target their mitigation efforts. 63,64 It is also crucial to acknowledge the potential role of toxic pollutants beyond organic compounds, including heavy metals and radioactive elements.…”