Risk Assessment – Ecological and
Human Health

Risk assessment is a process by which potential effects of contaminants in the environment are calculated and determines if the contaminants may present a human health risk or pose a threat to the environment. At Keystone Environmental, our risk assessments and risk management approaches are performed by specialist professional teams including toxicologists, engineers, contaminant hydrogeologists and biologists.

These types of projects are frequently goal driven – to manage the contaminants in place – by balancing engineering and toxicology expertise, the goal is achieved. We have applied this approach to significantly contaminated industrial sites, where the cost to clean-up far exceeded the value of the land, as well as to sites where industrial use was to change. We have also provided risk assessment/risk management solutions to enable the industrial operations to continue without interruption.

Assessing ecological risk and the potential effects on human health are the key focus for our risk assessment professionals. While the human health and ecological risk assessment may identify unacceptable risks to human health and the environment, it also needs to identify the specific factors that are driving those unacceptable risks. Developing site-specific toxicity reference values, our clients have realized cost reductions of over 75%, representing millions of dollars, by demonstrating that while standards are exceeded, the contaminants are not presenting an unacceptable risk.

Similarly, the risk assessment team is able to provide data that enable our engineers to design site-specific risk management measures leading to regulatory approval. We have applied human health and ecological risk assessment and risk management to achieve closure of pulp mills, chemical refineries, shipyards, dry cleaners, service stations, mine sites, and marine sediment associated with industrial facilities.

Keystone Environmental provides an array of human health and/or ecological risk assessment services, as follows:

• Completion of exposure assessments involving local population surveys
• Coordination and completion of epidemiological studies
• Indoor air-quality study design, sampling and health assessment
• Occupational risk assessment
• Public Health risk communication
• Evaluation or remedial options with respect to ecological impact/risk
• Completion of terrestrial species/habitat surveys
• Completion of aquatic species/habitat surveys
• Benthic invertebrate/sediment sample collection
• Soil/vegetation and soil/invertebrate sampling to assess bio-uptake
• Aquatic and terrestrial toxicity testing study design and sample collection
• Development of food web models

Keystone Environmental also applies risk assessments to demonstrate that contaminants do not pose a significant risk to the environment. Even at sites with significant concentrations and distributions of contaminants and expressed concern by the regulators, we have demonstrated that they do not present a risk to human health or the environment. In such cases, further testing, monitoring or clean-up is not required and can result in very significant savings to the client – sometimes in the millions of dollars.

Risk Assessment is the process of evaluating the potential for adverse effects caused by chemical, physical and/or biological stressors. The mere presence of a stressor or contaminant at a site does not necessarily constitute a risk. For a risk to exist, the following three basic conditions must be met:

• A hazardous stressor must be present (contaminants)
• Human and/or ecological receptors must be present
• There must be exposure or receptors to stressors

The four major steps in a risk assessment include:

1. Planning and Problem Formulation – This step is the most important step in risk assessment. It begins with defining the risk assessment objectives, which includes describing the human populations and terrestrial and aquatic ecosystems potentially at risk. Receptors potentially at risk are determined through an understanding of contaminant sources and fate and transport characteristics of different potential stressors (e.g., contaminants). The first step concludes with descriptions of the project goals, proposed methods to measure exposure and effects, as well as conceptual models that graphically identify the relationships between stressors and receptors.
2. Exposure Assessment – The purpose of the exposure assessment is to describe (normally in quantititaive manner) the degree or extent to which receptors are exposed to the various stressors of concern. Different approaches are used for the different receptor groups such as people, terrestrial vegetation, aquatic life and wildlife.
3. Toxicity or Hazard Assessment – The purpose of the toxicity or hazard assessment is to describe the potential effects of stressors on the various receptors of concern as a function of the exposure assessment (Step 2).
4. Risk Characterization – The risk characterization provides an estimate of the risk posed by the stressors of preliminary concern. Risk characterization combines information from the exposure assessment and toxicity assessment to estimate the type and magnitude of risk posed to the receptors of concern.

Risk assessment is used by regulatory agencies throughout British Columbia, Canada, the United States and most other developed countries around the world, as a means of assessing potential for adverse effects from stressors.

Risk assessments and related analyses are an important component of an increasing number of environmental decisions. The results of these assessments help determine the need for and/or nature of remedial actions at contaminated sites by supporting the derivation of clean-up levels, assisting in permitting new facilities, and in the development of closure plans for old facilities.

Keystone Environmental provides an array of risk assessment services, as well as services specific to human health or ecological risk assessment, as follows:

• Risk assessment strategy development and review
• Communication and negotiations with regulators and stakeholders
• Screening-level risk assessments and preliminary quantititative risk assessments
• Quantitative risk assessments incorporating deterministic and/or probabilistic approaches
• Derivation of risk-based clean-up levels
• Toxicity assessments and data evaluation
• Statistical analysis
• Database design and data management
• Chemical fate and transport modelling
• Soil, sediment, surface water, groundwater, air and tissue sampling for chemical analaysis
• Research and development to address sources of uncertainty
• Development of graphical conceptual site models
• Bioavailability/bioaccumulation studies
• Provision of third-party risk assessment reviews and provision of recommendations
• Provision of technical review and expertise for the development of regulatory policies and guidelines
• Risk assessment workshops and presentations