Risk-based concepts are everywhere. Most decisions we make—knowingly or not—are based on assessing the probability of an outcome or risk. Sometimes the potential outcomes of a decision are clear; sometimes it takes considerable analysis to draw conclusions regarding potential outcomes (i.e., what could go wrong?) and the likelihood and severity of those outcomes (i.e., how bad could it be?).

When it comes to environmental, health, and safety (EHS), it takes significant scientific knowledge, deep understanding of exposure, and a systematic process (i.e., an environmental risk assessment) to identify and evaluate risks and then make decisions on how to mitigate, manage, or remove them. We recently sat down with KTL Senior Consultant and risk expert Margaret Roy to talk more about the concept of risk and risk assessments.

Q: What is a risk assessment?

A: Risk assessment is a general term that summarizes an approach to identify uncertainties (i.e., risk), rate or gage the magnitude of the risk(s), and then develop a strategy to manage or reduce those risks. Managing risk is about managing uncertainties.

For example, you may choose to wait a few days to drive through a mountain pass that is expected to receive snow. You may or may not get stuck or involved in a car accident—it is uncertain—but you reduce your risk of an incident by waiting until after the storm and the roads have been cleared. In this case, a simple risk assessment was completed to manage the uncertainties associated with driving through a snowy mountain pass. Other management strategies could have been to take an alternate route or to drive a vehicle better suited for snowy conditions.

Q: What is an environmental risk assessment?

A: An environmental risk assessment characterizes the nature and magnitude of health risks to humans and ecological receptors from stressors (i.e., physical, chemical, or biological) that may be present in environmental media such as soil, drinking water, or air.

We are exposed to a variety of chemicals (e.g., that new car smell) and biological agents (e.g., the common cold) every day, and health-based risk assessments help manage what and how much we are exposed to. Human health risk assessments address questions such as:

• What types of health problems may be caused by an agent (like a chemical or radiation)?
• What is the chance that people will experience health problems when exposed to different levels of these agents?
• What is a “safe” level?
• Who is being exposed (children, the elderly)?

Ecological risk assessments ask the same questions as human health risk assessments, but for an ecosystem. Ecological risk assessments address questions such as:

• Would metals in a stream near an old abandoned mine damage the population of fish in the stream? If the fish population is impacted, what about the birds, mammals, reptiles, and amphibians that may live near the stream?
• Can the application of an insecticide harm an endangered bird species?
• What are the long-term effects on the ecosystem in a bay following the accidental release of oil from a tanker?

Q: What do environmental risk assessments evaluate?

A: Whether focused on human health or ecological impacts, at its core, an environmental risk assessment is exposure analysis—who is exposed to what, where, and how much? Everything has the potential to be poison; what makes the difference is the exposure or dose. Think about water consumption as an example. Drinking water is a healthy habit; however, too much water (gallons of water in an hour) can lead to water intoxication, which can result in negative health impacts or even death. The dose is what makes the poison.

For there to be negative health impacts, there need to be three key elements present. Together, these elements create a complete exposure pathway:

1. Stressor. Environmental risk assessments generally consider chemicals such as benzene and acetone, as well as inorganics like mercury or arsenic.  
2. Exposure. A person or animal ingests or inhales the chemical, or it is absorbed through the skin.
3. Toxic Effect. The recipient experiences some sort of negative impact or toxic effect.

For example, we can ingest water without any ill effects, but past a certain amount, electrolytes in your body go out of balance. For lead, exposure to a child over time can lead to developmental and lifelong health issues.

Q: What is the process for conducting an environmental risk assessment?

A: The process for conducting an environmental risk assessment has been developed by the scientific community over the past 60 years. The Environmental Protection Agency (EPA) and many states publish guidance documents and analyses of chemical toxicity that are applied using the following process:

1. Define the Problem: What are the chemicals, where are the chemicals (e.g., drinking water, air), what are the concentrations of the chemicals?
2. Quantify the Exposure: Who is being exposed? For example, is it a residential community, a worker, or bird in a forest?
3. Calculate the risk: Risk is defined by comparing the exposure dose to a safe concentration.

Risk assessment is much more than just a number. As part of the risk assessment, risk characterization must consider multiple variables, and then apply a big dose of common sense: Who is exposed, is it a vulnerable group like children? How do the chemicals move in the environment or change in our bodies? Are some of the assumptions used in developing the risk assessment overly conservative given the site conditions (e.g., does a bird really live on the site its whole life and consume only earthworms?)? Risk characterization is a very thoughtful process that considers the big picture of the risk assessment.

Q: How certain are the results of an environmental risk assessment?

It is important to note that all risk assessments carry some level of uncertainty, as risk assessors must often estimate exposure, use their own experience and judgment, and rely on scientific research to calculate risks. This is why it is important that the risk assessor have substantial knowledge and understanding of exposure in a variety of technical areas, including:

• Ecology
• Toxicology/ecotoxicology
• Analytical chemistry
• Soil/sediment
• Geology/hydrogeology
• Surface water/groundwater modeling
• Demographics/population biology
• Statistics
• Communication
• COMMON SENSE 

Good risk assessments discuss data gaps and other limitations in models and assumptions used to estimate exposures. Note that because of the inherent uncertainties, risk assessment is often an iterative process that involves screening initial information, identifying gaps, refining the scope of the assessment, and then collecting and assessing additional data.

Q: How are risk assessment results used?

A: Put simply, risk assessment informs risk management decisions. Risk management integrates the results of the risk assessment with other considerations (e.g., economic implications, legal concerns) to determine what risk reduction/management activities should be implemented. Importantly, risk assessment/management pays particular attention to connections. What is all connected? Where is the contaminant traveling? How does one decision to manage risk impact the rest of the supply chain or ecosystem?

There are many different ways risk assessment is used, including the following:

• Evaluating the likelihood that observed effects are caused by past or ongoing exposure to specific stressors and then predicting the likelihood of future effects.
• Supporting many types of actions, including:
  • Regulating hazardous waste sites, industrial chemicals, and pesticides.
  • Reusing property and material (e.g., soil, gray water, brownfield sites).
  • Protecting ecosystems from chemical, physical, or biological stressors.
  • Setting environmental limits for chemicals.
  • Conducting Superfund site remediation.
• Providing information to risk managers that can be used to:
  • Communicate with interested parties.
  • Limit exposure to the ecological stressor.
  • Negotiate remediation options with stakeholders (e.g., brownfields sites).
  • Develop monitoring plans to confirm risk reduction and ecosystem recovery.

Q: How do I know if I need an environmental risk assessment and how do I proceed?

Environmental risk assessments are often driven by regulatory programs. For example, if you own a gas station and you have a leaking unground storage tank (LUST), then your company may enter a state’s LUST program. The risk assessor would help figure out where to sample to understand how far the contamination has traveled, who may be exposed, and how much soil should be remediated or removed to mitigate the risks. There is a risk that gasoline could leach down to the groundwater. If the groundwater is a drinking water source, then many people could be exposed. Removing the soil may be the best way to mitigate the risk to groundwater.

Risk assessment, in general, is also a tool that can—and should—be used to evaluate the risks associated with business decisions. For example, a local farm has access to an irrigation well, but the groundwater is known to have low levels of solvent. Risk assessment could be applied to assess whether the irrigation water is safe for the workers to be directly exposed to, but also if the water is safe to use on the agricultural crops. The assumptions used in the exposure analysis could be tailored specifically to the conditions at the local farm so the best decisions on use of the irrigation water can be made.

Risk assessment is a strategy that can be applied to all sorts of different businesses and industries, but conducting a health-based risk assessment requires specialized expertise. Bringing in a risk expert is prudent to help ensure that the entire exposure pathway is evaluated and the most effective risk management solutions can be identified and implemented.