Risk assessment is the process of determining chemical tolerance limits in the environment and can be defined as Z Hazards x L Exposures. Hazard can be factored into two responses to a chemical: cellular damage by the chemical and repair/protection by the host. The Mixed Function Oxidase system is very responsive to xenobiotics and may reflect hazard. A recent electrophilic SE2 mechanism suggested that this was the result of a relationship between the oxidation potential of the induced MFO active site and the C-H bond strength of xenobiotic. This study tested and supported this model of enthalpic biochemical control, demonstrating that an induced active site has the potential to metabolize any C-H bond that is weaker than the C-H bond strength of its inducer. Chlorinated chemicals exhibited a stronger oxidation potential than predicted, presenting a risk of uncontrolled oxidations that may initiate chemical disease.