Predicting Toxicity Of 1,2,4,5-tetramethylbenzene And Applied In Healty Risk Assessment

The treatment of soil pollution is one of the hot issues in the field of environmental engineering nowadays.Human health risk assessment as pre-step is very important for the pollution prevention and control.However,due to the complexity of pollutants in the contaminated sites,many pollutants lack relevant toxicity parameters,so it is difficult to carry out effective assessment.In this paper,1,2,4,5-tetramethylbenzene was used to predict the non-carcinogenic toxicity parameters.Taking the soil characteristics of Shanghai as an example,the risk control value was calculated by health risk assessment.The main contents are as follows:1)To carry out the oral toxicity test of 1,2,4,5-tetramethylbenzene in rats and calculate the extrapolation start value of 1,2,4,5-tetramethylbenzene using BMDs and PROAST software with baseline dose method.?2?The LD₅₀ of 1,2,4,5-tetramethylbenzene is predicted by TEST software.Meanwhile It is verified the accuracy of toxicity prediction of TEST.Based on the non-carcinogenic toxicity parameters of each benzene series and the LD₅₀ value to obtain the oral non-carcinogenic toxicity parameters of 1,2,4,5-tetramethylbenzene;?3?According to the experimental method and non-experimental method,The two soil risk control values of 1,2,4,5-tetramethylbenzene are deduced based on the human health risk assessment in the case of Shanghai residential land.The main findings are as follows:?1?It is preliminary predicted that the NOAEL is 500 mg/kg/day according to the rat oral toxicity test.The extrapolated start value of 1,2,4,5-tetramethylbenzene is406mg/kg/day using the baseline dose method.There is no difference between the values which obtained by BMDs and PROAST software.The result is significant lower than NOAEL value and baseline dose method has advantage over NOAEL method.During the study,the uncertainty coefficient is set to 1000 and it is derived that the non-carcinogenic oral toxicity parameter RfDo is 0.406 mg/kg/day.?2?TEST software is used to predict the LD₅₀ of 10 conventional benzene compounds and these values are contrast fitted with experience values.The results showed that values obtained by chromatogram method in TEST software are the most accurate and the coefficient R is 0.9379,meanwhile the chi-square goodness-of-fit test result is significant correlation.The chromatogram method predicts that 1,2,4,5-tetramethylbenzene rat oral LD50 is 5590mg/kg which is close to experience value.It shows the forecast is relatively accurate.The RfDo of 1,2,4,5-tetramethylbenzene is found to be 0.21mg/kg/d via the logarithmic relationship between LD50 and RfDo which is concluded by fitting.?3?Taking Shanghai sticky soil as an example,it is calculated that the soil risk control value of 1,2,4,5-tetramethylbenzene is 4910mg/kg?experiment combined reference dose method?and 2540mg/kg?non-experimental method?via from 2 toxicity parameters assuming residential land.The results show that the value of the toxicity parameters has a great impact on human health risk assessment.It is concluded that using the reference dose method to deduce the toxicity parameters is more scientific and reasonable and the toxic parameters obtained by non-experimental methods is more conservative.This method could be selected in the absence of experimental condition but also need considering the actual situation analysis.