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Risk Assessment: So Much More Than a Regulatory Compliance Tool

While risk assessment is often associated with regulatory requirements, there is value in using the tools of risk assessment for project strategy and development. Getting insight into the potential for adverse risk at the beginning of a project can be done on a site-specific exposure basis with no data. If completed prior to data collection, the risk can be expressed as an action level rather than a risk and can provide valuable strategy information (i.e., identify analytes where detection limits may be challenging to achieve or what analytes might be risk drivers which may guide the strategy for sampling). Additionally, implementing risk assessment in the preliminary stages of a project can ultimately be a cost savings, focusing investigation and remedial efforts on the specific issues that may cause risk.

Risk Assessment – A Requirement or a Strategy

Risk assessment is a required element in federal and state environmental programs that are assessing potential environmental and/or community impact from industrial operations. The risk assessment itself is a probability analysis that typically follows environmental data collection (soil, water, sediment, air, etc.) and evaluates the potential for presence or absence of health risk using mathematical and statistical tools. The risk assessment provides vital information; in many instances it yields the necessary documentation and justification for either further evaluation and potentially even further data collection, implementation of a remedy, or no further action if the estimated risks are not elevated beyond acceptable criteria. However, risk assessment is more than just a regulatory compliance element; it is a valuable tool that can be used to form site strategies and have early site discussions with regulatory agencies or community stakeholders. It can also be used to streamline the necessary data collection prior to site investigation, a process that oftentimes entails a large investment of time and resources. Investment in customizing inputs to account for site-specific exposures can make huge differences in not only the understanding of the actual potential for adverse risk following exposure to impacted media, but more importantly, can affect future expense in site closure.

Key Considerations for Using Risk Assessment for Project Development and Execution

Some critical considerations, detailed below, make the use of risk assessment a game changer for environmental site assessment and remediation.

Site Data Analytics and Trends

First, consideration of the statistical method of data analysis is important at the beginning of a project, not when the risk assessment starts. Utilizing the 95% Upper Confidence Limit of the arithmetic mean (95UCL) as a conservative concentration includes many site-specific considerations that should be discussed prior to collection of data, including:

  • locations of samples (spatial variability),
  • depths of samples (vertical variability),
  • when should samples be collected (temporal variability),
  • type of sampling done (i.e.,composite, discrete or incremental), and
  • number of samples collected (data adequacy).

Understanding the site data concentrations and data trends are critical for a risk assessment to be an effective tool in managing sites. It can also identify metals or other analytes where an understanding of background conditions will require a targeted data collection approach. Additionally, as data is collected within an investigation, risk assessment can be utilized to statistically evaluate the site data in real time, indicating where more data may be needed for example to understand migration or where specific hot spots might exist that will require more investigation.

Exposure, Toxicity and Risk Evaluation

The second component of risk assessment considers how exposure might or does occur; exposure to a chemical can occur in a variety of ways, such as breathing it in through air or ingesting it via contaminated water. In order to add credibility to a risk assessment result, an understanding of the land use by the potentially affected population is needed. Considerations for exposure involve evaluation of current and likely future land use and specific details (e.g., number of days per year a person will reasonably be in contact with soil, groundwater, etc,). For example, an industrial worker may spend a portion of their time working outdoors at a facility, but if the ground is covered with snow, then exposure is not occurring at this time of the year. Weather records can be consulted for an area to understand specific conditions which may affect exposures. Another example of important exposure input to consider in risk assessment is the Conceptual Site Model, or CSM, which is site-specific for each risk assessment and focuses evaluation of site exposures to only current or possible future land uses. The CSM can point out differences in exposures which can be significant. For instance, if the water in a lake is impacted, there are different populations potentially exposed to the water and at different frequencies; the wildlife that live in the lake may be more vulnerable to the effects of contamination than the family that swims in the lake once a year, simply by exposure frequency.

Importantly, the toxicity of the chemical must also be considered along with the exposure input and the statistical estimate of concentration to understand the potential for risk. When combined, these components provide ample information to determine the absence or presence of risk at a contaminated site. If adverse risk is predicted, risk evaluation is helpful in the remedy evaluation stage of a project. Estimating residual risk can lend valuable information on the effectiveness of a remedy, which in turn balances the potential disruption of established habitats or current land uses.

Stakeholder Communications

Introducing risk assessment early in a project cycle can also assist when there is a community group or public exposure issue; through preliminary risk assessment, risk communication can be utilized for consistent messaging and to hear the concerns of nearby communities or stakeholders, allowing them to be a part of the process from an early stage. Risk communication is frequently used to express the likelihood of health effects following exposure in both short- and long-term situations. Although risk communication is typically thought of as facilitating a conversation with the public, it is critical to talk with the regulatory agency early and often at the start of a risk assessment project. By detailing the planned approach and addressing questions and comments prior to work completion, regulators and the industry can develop a trusting relationship, which is crucial in the world of risk assessment.

Next Steps: TRC Can Help

A common misconception surrounding risk assessment is that it is often thought of as a simple comparison of site analytical data to established screening values. And, while it can be only that in certain situations, a more strategic use of risk assessment includes incorporation of site-specific assumptions including land use, seasonality, existing engineering or institutional controls, zoning and intended future site use, which can all greatly impact the outcome of a risk assessment. Unnecessary remedial action can occur if site-specific exposure is not a priority in risk assessment. As discussed above, consideration of many of these components early in a project can set the tone for the project strategy.

At TRC, we have a team that focuses specifically on human health and ecological risk assessment, working closely with clients and other stakeholders to ensure transparent and technically sound risk assessments are submitted and approved at industrial sites. To learn more about our solutions and how we can support your specific risk assessment needs, explore our related pages or contact our expert below.

Learn More From Our Subject Matter Expert

Jenny Phillips

Jenny Phillips is the Director of the Technical Development Unit at TRC, and Strategic Technical Advisor for the Risk Assessment and Toxicology practice. As the Director of the Technical Development Unit, Ms. Phillips leads the Environmental Practice efforts to stay at the forefront of emerging and challenging issues for our clients, through innovation of new technologies, participation in advocacy groups and leads nearly 40 Center of Research and Expertise (CORE) teams. As a Diplomat of the American Board of Toxicology (DABT), Ms. Phillips is a subject matter expert in Risk Assessment participating on technical panels and on projects for clients with challenging project or legal issues.

As an important component of risk assessment, risk communication has been a focus of Ms. Phillips work for many years working closely with regulatory agencies, stakeholders and the public. Ms. Phillips works on emerging contaminant research and guidance development. Emerging Contaminants add additional challenges as the knowledge of toxicity often rapidly changes. For the past several years (10) Ms. Phillips has participated in several Interstate Technology Regulatory Council (ITRC) teams specifically as a co-leader for Per and polyfluoroalkyl substances (PFAS) related issues in risk assessment, including the derivation of risk-based guidance and regulatory values, and for Microplastics, as a co-lead for the health effects section. She has spoken on the toxicity and risk assessment of PFAS and Microplastics at a dozen or more conferences, workshops and seminars with an emphasis on risk communication. Contact Jenny at or connect with her on LinkedIn.

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