External considerations Reduction of exposure or accessibility A Properties related to environmental distribution/dispersion 1. Volatility/density/melting point 2. Water solubility 3. Persistence/biodegradation a oxidation, b hydrolysis, C. microbial degradation 4. Conversion to biologically active substances 5. Conversion to biologically inactive substances 四大学化学学院 2002年7月26日四川大学化学学院 2002年7月26日 6 External considerations------ Reduction of exposure or accessibility ◼ A. Properties related to environmental distribution/dispersion ◼ 1. Volatility/density/melting point ◼ 2. Water solubility ◼ 3. Persistence/biodegradation ◼ a. oxidation, b. hydrolysis, ◼ c. microbial degradation ◼ 4. Conversion to biologically active substances ◼ 5. Conversion to biologically inactive substances