Abstract: The latest regulation on land application in America is EPA 40CFR Part503. Risk assessment method used in the constitution of the 503 Regulations was reviewed, four stages including hazard identification, namely dose-response evaluation, exposure evaluation, characterization of risks were introduced. The nature of evaluation is determined by hazard identification, which is the first factor to risk assessment and the deterministic impact to human or eco-system caused by the pollutions. The main content of dose-response evaluation is to evaluate the dose of chemicals when the response forms the pollution. Exposure evaluation is to evaluate all kinds of characteristic data form the exposed people after the concentration of environmental pollutions is measured and detected. The identification of characterization of risks is necessary to risk management.