Quantitative Risk Assessment (QRA)
Health and Ecosystem Protection
The presence of contaminants at a site does not necessarily imply an immediate obligation for remediation. The decision to intervene should be based on the actual risk that the contamination poses. Through Quantitative Risk Assessment (QRA), ETP scientifically determines whether pollution levels constitute a danger to human health or ecosystems, avoiding unnecessary interventions and optimizing investments.
How Do We Build Risk Assessment?
Our studies are developed according to the methodologies recommended by the Portuguese Environment Agency (APA) and by reference international entities (such as the EPA). The process includes the following steps:
1. Conceptual Risk Model Development
The foundation of any AQR. We identify and map the interconnection between three essential factors:
The Source: What is the contaminant and what is its concentration?
An Exhibition Route How does the contaminant move? (e.g., inhalation of vapors, ingestion of water, dermal contact with soil).
The Receiver Who or what is at risk? (e.g., installation workers, neighboring residents, groundwater, local fauna).
2. Exposure and Toxicology Analysis
We calculate the exact dose to which receptors may be exposed over time, crossing this data with toxicological information on the compounds (carcinogenic and non-carcinogenic potential).
3. Risk Quantification and Setting Safety Target Levels (SSTLs)
If the calculations show that the risk is unacceptable, the ETP calculates the Site-Specific Target Levels (SSTLs) – meaning, the maximum acceptable concentration levels for that specific location. These values become the objectives for future remediation.
Advantages of the Risk-Based Approach
Instead of trying to return the soil to its “pristine state” (which is often technically and financially unfeasible), AQR allows for the definition of realistic cleanup goals, proportional to the current or future use of the land, ensuring complete safety without superfluous costs.