Ghosh Pooja, Thakur Indu Shekhar
School of Environmental Sciences, Jawaharlal Nehru University, New Delhi 110067, India.
Ecotoxicol Environ Saf. 2017 Sep;143:120-128. doi: 10.1016/j.ecoenv.2017.05.019. Epub 2017 May 16.
In the present study, landfill soil of three municipal solid waste landfill sites of Delhi, India were toxico-chemically analyzed for human risk assessment as inadequate information is available on the possible health effects of the contaminants present in landfill soil. The landfill soil samples were prepared for analyzing heavy metal concentration, organic contaminants and toxicity analysis separately. Composite soil sample collected from three landfill sites were analyzed for heavy metal by ICP-AES. Metal concentration so obtained was below the permissible limit of soil but higher than the set limits for effluent. Some of the persistent organic contaminants like phthalates, benzene derivatives, halogenated aliphatic compounds and PAHs derivatives were detected by scan mode GC-MS. Further, concentration of 17 polycyclic aromatic hydrocarbons (PAHs) in landfill soil of Delhi was evaluated by selective ion monitoring GC-MS in order to ascertain their contamination levels and potential health risk. The concentration of total PAHs in the samples ranged from 192 to 348µg/kg. The maximum concentrations of PAHs were found in Ghazipur landfill site followed by Okhla and Bhalswa landfills. Cancer risk (CR) values of sampling sites were within the acceptable range for adults, adolescents and children (both male and female) suggesting that PAHs present in landfill soil are unlikely to pose any cancer risk for population based on dermal contact, ingestion and inhalation exposure pathways. However, landfill soil organic extract showed significant cytotoxic and genotoxic effects on HepG2 cell line as revealed by MTT and Comet assays respectively. The observed MTT EC values ranged from 7.58 to 12.9g SedEq/Lalong with statistically significant DNA damage. Thus, although the soil organic extract contained low concentrations of PAHs with negligible carcinogenic potential, but the mixture of organic pollutants present in soil were found to be toxic enough to affect human health due to their synergistic or additive actions.
在本研究中，对印度德里三个城市固体废弃物填埋场的填埋土壤进行了毒理化学分析，以评估其对人类的风险，因为关于填埋土壤中污染物可能产生的健康影响的信息不足。分别制备了填埋土壤样品，用于分析重金属浓度、有机污染物和毒性分析。采用电感耦合等离子体发射光谱法（ICP-AES）对从三个填埋场采集的复合土壤样品进行重金属分析。所获得的金属浓度低于土壤允许限值，但高于废水设定限值。通过扫描模式气相色谱-质谱联用仪（GC-MS）检测到了一些持久性有机污染物，如邻苯二甲酸盐、苯衍生物、卤代脂肪族化合物和多环芳烃衍生物。此外，采用选择离子监测气相色谱-质谱联用仪对德里填埋土壤中17种多环芳烃（PAHs）的浓度进行了评估，以确定其污染水平和潜在健康风险。样品中总PAHs浓度范围为192至348μg/kg。在加济布尔填埋场发现的PAHs浓度最高，其次是奥克拉和巴尔什瓦填埋场。采样点的癌症风险（CR）值在成人、青少年和儿童（男性和女性）的可接受范围内，这表明基于皮肤接触、摄入和吸入暴露途径，填埋土壤中存在的PAHs不太可能对人群造成任何癌症风险。然而，分别通过MTT和彗星试验表明，填埋土壤有机提取物对肝癌细胞系（HepG2）具有显著的细胞毒性和遗传毒性作用。观察到的MTT半数有效浓度（EC）值范围为7.58至12.9g SedEq/L，同时伴有具有统计学意义的DNA损伤。因此，尽管土壤有机提取物中PAHs浓度较低，致癌潜力可忽略不计，但由于土壤中存在的有机污染物混合物具有协同或加和作用，发现其毒性足以影响人类健康。
