Human Health Risk Assessment

In a multi-part blog series this installment examines the human health risk assessment process.  However, keep in mind that this process should be accompanied by an ecological risk assessment and followed by appropriate risk management measures.


The cleanup of hazardous conditions is risky business.  In the real world it can be very difficult to remove absolutely all of a given chemical from the environment after a release.  Because of this regulators such as the EPA and Virginia Department of Environmental Quality (VADEQ) have used some sophisticated models to determine acceptable concentrations as cleanup goals or standards.  These acceptable levels are generally referred to as risk-based concentrations and differ for each chemical.  The risk is generally identified by the type of exposure (i.e. dermal contact, ingestion, inhalation, etc.) and can also be evaluated based on an acute or chronic exposure regime.  


It should be noted that generally the values provided by regulators are single points applied to all situations.  A Monte Carlo simulation can be run to identify the "what if" of different situations, however the computer models involved and analysis required of this type of evaluation is prohibitive to most consultants.


The cleanup of contaminated sites requires extensive experience and a team of scientists and engineers to accomplish the goal, but it is almost impossible to eliminate all of a chemical from the environment once released.  Risk-based cleanup standards provide a reasonable cleanup goal for the polluter/consultant and a safe place for humans. 


Photo via: B. Sandman