Human Health Risk Assessment

Why is this important? How do we do HHRAs? What assistance is available? Read more about it.

What is it?

A Human Health Risk Assessment (HHRA) is the process that evaluates the likelihood that adverse health effects are occurring or may occur as the result of exposure by humans to one or more stressors by one or more exposure pathways. In CERCLA or RCRA Corrective Action, HHRA is used specifically to mean a qualitative and/or quantitative evaluation of the actual or potential impacts of contaminants from hazardous waste sites on human receptors. There are several classes of human receptors, based on age, gender, and include special populations such as the immunocompromised. For risk to human health to exist, the contaminant must have the ability to cause an adverse effect and it must co-occur with or contact a person long enough and at a strong enough intensity to cause the adverse effect.

Why is this important?

We hold ourselves to a very high standard to protect human health, as well as the environment. An HHRA is an integral portion of the RI/FS process, designed to support risk management decision-making. The RI component of the process characterizes the nature and extent of contamination, and estimates risk to relevant humans posed by contaminants at the site. The FS component develops and evaluates remedial options. Even though the majority of DoD sites are not designated as Superfund sites, HHRAs are performed using the US EPA Risk Assessment Guidance for Superfund, also known as RAGS. Volume I Human Health Evaluation Manual, Interim Final, Dec 1989 at http://www.epa.gov/oswer/riskassessment/ragsa/index.htm is the first of six parts (A – F) detailing the lengthy processes.

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How do we do HHRAs?

Following the US EPA Superfund guidance for HHRAs, we utilize a multi-step process, with five basic steps:

Planning and Scoping
Hazard Identification
Dose-Response Assessment
Exposure Assessment
Risk Characterization

The EPA begins its risk assesment by first planning and conducting research; Hazard identification looks at whether a stressor has the potential to cause harm to humans; Dose-response assessment examines the numerical relationship between exposure and effects; Exposure assessment covers what is known about the frequency, timing, and levels of contact with a stressor; and Risk characterization details how well the data support conclusions about the nature and extent of the risk from exposure to stressor(s).

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What assistance is available?

The science of HHRA has really expanded, and EPA offers many guidance documents at the EPA website. For assistance with specific HHRA issues, individuals or installations may contact the Army Institute of Public Health/U.S. Army Public Health Command (AIPH/PHC), U.S. Army Edgewood Chemical & Biological Center (ECBC), the U.S. Army Corps of Engineers (USACE), U.S. Army Corps of Engineers Environmental and Munitions Center of Expertise (EM CX) Directorate, or the USAEC individuals who specialize in risk assessment protocols, ecology, toxicology and natural resources.

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Human Health Risk Assessment