A baseline risk assessment describes the source of contamination, how the contamination reaches people and the environment, the amount of contamination to which people or the ecological environment may be exposed, and the health or ecological effects that could result from exposure.

Superfund human health estimate of the likelihood and magnitude of health problems occurring if no cleanup action is taken at a site. Risk assessment may include both qualitative and quantitative evaluations of the likelihood that there will be harm to human health and the environment by the actual or potential presence of environmental contamination. Bayesian Analysis Also called subjective probability. These methods start with a description of the probability of an event as the degree of belief or confidence in that event occurring, given some state of knowledge. Bayesian methods combine subjective probabilities with data to arrive at posterior probabilities. Bayesian analysis provides a way of integrating professional judgement with data in a rigorous mathematical framework.