Distribution And Health Risk Assessment Of Dioxins In Soil Around A Chemical Company

This paper studied the content and distribution characteristics of PCDDs/PCDFs in soil around a chemical company and surrounding area were by gas chromatography(HRGC)/high resolution mass spectroscopy(HRMS).Furthermore,discussed the source of PCDDs/PCDFs and evaluated possible human health risk.The study showed that the average value of total concentrations of PCDDs/PCDFs congener in soil was 109 pg/g.The average value of toxic equivalent was 10.1 pg/g I-TEQ.The important monomers of PCDDs/PCDFs were dominated by O8CDD and O8CDF in soil,accounting for 18.5%and 11.4 respectively,the main congener of PCDDs/PCDFs in waste gas was also OCDD and OCDF,accounting for 16.2%and 10.1%.The larger contribution of dioxin homolog in 60%soil point was H6CDFs,in 30%soil point was OCDD,the main homolog of dioxin in waste gas was also H6CDFs and OCDD,accounting for 22.9%and 16.2%.The analysis of PCDDs/PCDFs content,distribution characteristics and source in soil of the study area showed that the major source of PCDDs/PCDFs in this area was from the flue gas emissions.According to the relevant requirements of "Technical Guidelines for Risk Assessment of Polluted Sites"(HJ 25.3-2014)[1],.evaluating dioxins human health risk in soil.The results showed that the range of dioxins determination concentration was 3.72～20.3 pg/g I-TEQ,the average was 10.0 pg/g I-TEQ in nine soil points laid out by this research institute,all of which were at a safe level.Under the three exposed ways of mouth intaking,skin contacting and inhaling soil particles,only the four number point had lower carcinogenic risk,all other points had non-carcinogenic risk.The site area of four number point represents was unacceptable risk pollution area.Its soil risk control value based on the carcinogenic effect was 1.90 x 10’5 mg.kg-1.The study found that only 4#and 5#soil dioxin in the survey area soil to the exposed population.had lower cancer risk,therefore,it is necessary to take measures to control dioxin pollution levels in the soil strictly,formulate the standard limit of dioxins in the soil as soon as possible.