Steps and Components of the PHA Process

Overview of the Process

The PHA process helps ATSDR find out:

• Whether people living near a hazardous waste site are being exposed to toxic substances.
• Whether that exposure is harmful.
• What must be done to stop or reduce exposure.

Steps in the PHA Process

Description of Steps in the PHA Process diagram

During the PHA process, ATSDR:

• Evaluates site conditions and determines the nature and extent of environmental contamination.
• Engages communities at the beginning of site activities and involves them throughout the process to respond to their health concerns.
• Defines potential human exposure pathways related to site-specific environmental contaminants.
• Identifies who may be or may have been exposed to environmental contamination associated with a site (past, current, and future).
• Evaluates sampling data, screens detected contaminants to identify those that require further examination, and if appropriate, defines exposure units for completed and potential exposure pathways before or after the screening analysis.
• Estimates the exposure point concentrations and performs exposure calculations to evaluate non-cancer and cancer effects to assess potential human exposures to site-specific contaminants.
• Examines the public health implications of site-related exposures through the examination of environmental and health effects data.
• Clearly communicates the findings of its evaluations, while acknowledging the impact of uncertainties and limitations.
• Provides recommendations to site-related entities, partner agencies, and communities to prevent and minimize harmful exposures.

Basic Components of the PHA Process

The PHA process helps identify appropriate public health actions and respond to community health concerns related to hazardous waste sites. There are five basic components of the process: triggers, data and information, scientific evaluations, products, and outcomes. Once the first component—triggers—is initiated, ATSDR uses the Steps in the PHA Process to address and fulfill the needs of the next three PHA process components: data and information, scientific evaluations, and products. The recommendations that come out of ATSDR’s PHA process lead to the fifth component: outcomes.

PHA Process Basic Components

Description of PHA Process Basic Components

Triggers

The PHA process is triggered when an individual, a community group, or other parties submit a petition to ATSDR to investigate a specific site or facility; when a site is proposed or listed on the National Priorities List (NPL)external icon; or when other federal, state, or local agencies or tribal health departments ask ATSDR for technical assistance

Triggers that Initiate the PHA Process

Data and Information

Under CERCLAexternal icon, ATSDR must collect information about the hazardous waste site, site-related contaminants, communities potentially affected by the site (e.g., demographics), possible exposures to site-related contaminants, community health concerns, and health outcome data.

Scientific Evaluations

ATSDR performs different types of scientific evaluations during the PHA process (see table). After examining the available information and data, health assessors conduct an exposure pathways evaluation. For completed and potential exposure pathways, health assessors will perform a screening evaluation using the available sampling data. Based on the screening results, you may need to conduct an evaluation of exposure point concentrations (EPCs) and exposure calculations (exposure doses, hazard quotients, and cancer risks). Then, if necessary, you would perform an in-depth toxicological effects evaluation. The sequence of steps can differ based on site-specific factors. For instance, health assessors might define an exposure unit before or after the screening analysis.

Scientific Evaluations that Can Be Conducted During the PHA Process

Products

At the end of the PHA process, you will develop a document that includes various types of information collected during the PHA process, such as the site’s hazardous substances and responses to community concerns. The report will include findings about whether people could be harmed by coming into contact with the contaminants and provide recommendations to protect public health. ATSDR uses different types of products to communicate the PHA process findings (see table). These products serve as an aid for developing public health actions. The audience for such products often includes environmental and public health agencies, communities, and ATSDR itself.

You may develop various types of outreach, such as fact sheets or other materials, to communicate information related to the PHA process activities for your site. Whether and when to produce these materials and in what format is up to the health assessor, others involved in the PHA process at a site, and their management.

Products to Communicate PHA Process Findings

Outcomes

The PHA process produces several possible outcomes, such as the need to better define exposures or to prevent illnesses in a community. In response, ATSDR might recommend follow-up health actions, such as initiating an exposure investigation (to better define site exposures), conducting a health study (to identify elevated illness or disease rates in a site community), working with the community to implement a health education program for the community and health professionals, or providing technical assistance to other agencies (such as local health departments) in response to their requests. ATSDR’s health recommendations can also support site investigations conducted by other programs (within ATSDR and by external agencies), such as by helping fill data gaps.

The PHA process enables ATSDR to prioritize and identify additional steps needed to answer public health questions. Some recommended actions may be initiated before the completion of your site document, such as certain health education activities or efforts to obtain additional exposure data. Other actions may begin during the PHA process but end after the release of a document (e.g., PHA, HC). For instance, a health assessor may recommend continued maintenance and monitoring of engineering controls at a site, noting in the document that attention to ongoing institutional controls are vital to continued protection of public health into the future.

The type and number of outcomes will depend upon site-specific factors and actions deemed appropriate by the health assessor, others involved in the PHA process at a site, and their management. Some possible outcomes from the PHA process are in the table below.

Possible Outcomes from the PHA Process