Discussion on methodology of delimiting protection zones for drinking water source in river.

Recycled plastic bags which are made from plastic waste contain many toxic and hazardous substances.However,because of its cheapness,the recycled plastic bags occupy large market share.Two kinds of simulated tests were designed,and amount of harmful substances moved from different colors of recycled plastic bags to food stimulants under certain conditions were designed.To make use of health risk assessment framework of EPA,health risks of human body was done for recycled plastic bags to package food.Based on assessment results,total carcinogenic risk and non-carcinogenic risk values of blue,yellow and white bags are less than 1,showing that the hazardous substances will not produce a significant hazard on human health.But the risk assessment of black and red plastic bags,risk values of Pb both exceed the critical value 1,showing that hazardous substances of black and red recycled plastic bags arouse a non-carcinogenic health risk to human body.