Study on the composition and risk of chlorinated organic compounds in landfills and surrounding groundwater

Chlorinated organic compounds are difficult to degrade and highly toxic, and landfills are important gathering places for chlorinated organic compounds. To evaluate the uncertain risk of landfill leachate contaminating groundwater with chlorinated organic compounds, a groundwater sample was collected from an informal landfill site. Combined with the collected data on the composition and concentration of chlorinated organic compounds in groundwater near 13 landfills in 6 countries including China, Germany, the United States, Spain, Poland, and Norway, a risk assessment model was used to assess their health risks. A total of 41 different types of chlorinated organic compounds, categorized into 10 classes, were identified in the groundwater near the landfills studied. The chlorinated cycloalkanes pose the highest carcinogenic risk, with all measurements surpassing 10⁻⁴, far exceeding the tolerable limits for human exposure, and presenting significant health hazards. The F-53B of chloropolyfluoroalkyl ether sulfonate has the lowest carcinogenic risk, between 10⁻⁶ and 10⁻⁴, and has a possible carcinogenic risk. The non-carcinogenic risk of chlorinated alkanes is the highest, among which the non-carcinogenic risk value of α-hexachlorocyclohexane (HCH) exceeds 1, more than the acceptable level for human beings. However, chlorinated organic pesticides such as propiconazole and permethrin have the lowest non-carcinogenic risk, and their non-carcinogenic risk value does not exceed the acceptable level for human body. Greater emphasis should be placed on risk management strategies for specific chlorinated organic compounds, namely γ-HCH, chlorobenzene, and 1,2-dichlorobenzene. Various methods, including oxidative dechlorination, reductive dechlorination, and co-metabolism dechlorination, can be employed to expedite the dechlorination and degradation processes, ultimately eliminating associated risks.