垃圾焚烧厂的环境空气、飞灰和土壤二噁英水平研究及风险评价

为评价珠三角某垃圾焚烧厂内工人和周边村民的二噁英健康风险，采集并分析了该垃圾焚烧厂的厂内环境(空气和飞灰)邻近敏感点(邻近村落)环境(空气和土壤)的二噁英(PCDD/Fs)质量水平，运用美国环保署(USEPA)风险评价体系和蒙特卡洛模拟(Monte Carlo simulation)对厂内工人、邻近敏感点村民(成人、青少年和儿童)在呼吸吸入、皮肤接触和经口摄入等暴露途径的健康风险进行评估.结果表明:(1)该垃圾焚烧厂固化飞灰中的PCDD/Fs毒性当量(以I-TEQ计)范围为8.99~240.00 ng TEQ/kg，环境空气中的为0.03~0.20 pg TEQ/m3，邻近敏感点土壤中的为0.81~2.04 ng TEQ/kg. (2)飞灰、厂内环境空气和邻近敏感点环境空气的PCDD/Fs单体分布特征更加接近，土壤中PCDD/Fs单体分布稍有差别. (3)厂内工人和村民(成人、青少年和儿童)的致癌风险(CR)合计第95%值范围为4.55×10-7~6.04×10-6，为可接受风险范围(＜10-5)；非致癌风险(HI)合计第95%值范围为4.61×10-3~4.28×10-2，远低于1，非致癌风险极低；(4)厂内工人和成人村民的CR较高, 第95%值分别占风险安全值的60%和39%.厂内工人的CR从环境空气吸入(包括在厂内和敏感点)和飞灰意外经口摄入方式占比最高，分别达55.12%和38.43%；成人村民的CR中从环境空气吸入占主导(占97.79%).建议加强对环境空气二噁英监控和飞灰经口摄入的风险管控.

PCDD/Fs Concentration in Air,Fly Ash and Soil around a Municipal Solid Waste Incinerator and its Risk Assessment

The concentrations of polychlorinated dibenzo-p-dioxins and polychlorinated dibenzofurans (PCDD/Fs) in the air and fly ash in a municipal solid waste incinerator (MSWI) in the Pearl River Delta and in the air and soil at the nearest environment-sensitive spot (an adjacent village) were investigated to evaluate PCDD/Fs health risk to on-site workers and adjacent villagers. Human health risk evaluation manual from US Environmental Protection Agency (USEPA) and Monte Carlo simulation were used to evaluate the PCDD/Fs health risk to on-site workers and adjacent villagers (adults, teens and children) under inhalation, dermal and ingestion exposure. The results are as follows. First, the toxic equivalent concentration (I-TEQ) values of PCDD/Fs were 8.99~240.00 ng TEQ/kg in the fly ash after solidification, 0.03~0.20 pg TEQ/m3 in the air, 0.81~2.04 ng TEQ/kg in the soil of the environment-sensitive spot. Second, PCDD/Fs congener profiles in the fly ash, the air in MSWI and the air at the environment-sensitive spot were similar, while PCDD/Fs congener profiles in the soil samples showed a little difference. Third, the 95th percentile carcinogenic risk (CR) values for on-site workers and villagers (adults, teens and children) were 4.55×10-7~6.04×10-6, suggesting that the CR values were on an acceptable level (< 1×10-5); the 95th percentile non-carcinogenic risk values for the four groups of people were 4.61×10-3~4.28×10-2, much lower than the threshold values of 1, suggesting a quite low non-carcinogenic risk. Fourth, the 95th percentile CR for on-site workers and adult villagers were relatively high, accounting for 60% and 39% of the risk safety value respectively; inhalation of air (in the MSWI and at the environment-sensitive spot) and accidental ingestion of fly ash contributed most to CR to on-site workers, accounting for 55.12% and 38.43%, respectively; and inhalation of air was the largest contributor of CR to adult villagers, accounting for 97.79%. It is suggested to monitor PCDD/Fs concentrations in the air and controll risk of accidental ingestion of fly ash.