November 7, 2011
Clean-Up Tool For Our Commonest Contaminants
Australia has taken a key step towards improving measures of human health risk with the release of new guidelines targeting one of our commonest sources of industrial contamination.
A new guidance document on the health screening levels (HSLs) for petroleum hydrocarbons in soil, soil vapor and groundwater has been released by the Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE). It is expected to provide the basis for guidance in the updated national framework for the assessment of site contamination.“Petroleum products are our commonest source of contaminants and are found in many of the nation´s 160,000 contaminated sites,” CRC CARE managing director Professor Ravi Naidu says.
“What Australia has needed for a long time is a reliable way of knowing whether they constitute a health risk or not in different situations, to inform the decision about what level of clean-up is necessary. These new HSLs provide a screening tool to determine if a health risk exists.”
The HSLs help explain the possible level of health risk posed to the community and workers that may be exposed to petroleum hydrocarbon contaminants from a contaminated site, says CRC CARE Demonstration Program Coordinator, Dr Prashant Srivastava.
“Every site is different in terms of its soils and groundwater conditions, and this has a big influence on whether the hydrocarbon contaminants pose a risk to human health or not — and how the risk changes with time,” he explains. “The new HSLs cover a wide range of possible hydrocarbons, soil types and groundwater scenarios.”
Where hydrocarbon levels exceed the HSL, this alerts to the need for a closer investigation of the site to assess more fully the potential risk.
“Every former petrol service station, motor workshop, rail yard, fuel dump, gasworks or factory over the past 100 years is potentially a hydrocarbon-contaminated site. Most of these are now in the heart of our big cities where people live, work and play. There are so many of them that we need to be able to make good decisions about which ones are in need of remediation,” Dr Srivastava adds.
“The HSLs help us to decide the level of risk posed by different types of contamination in different situations, so clean-up can be prioritized.”
CRC CARE scientists have worked with environmental regulators, industry and remediation consultants for over five years to develop the comprehensive HSLs.
A primary focus has been on understanding ℠vapor pathways´ — how noxious fumes from hydrocarbon contaminants can seep through soil and groundwater to reach people living or working on or near a former industrial site. The HSLs have been developed to enable a rapid assessment of the risk to such people.
The full suite of HSL advice consists of a summary, a main report, advice on how to apply HSLs, an explanation of how different variables affect hydrocarbon contamination and an extension model, which can be used to derive numbers for a particular situation.
“These HSLs represent the state-of-the-art in risk assessment and policy in Australia,” Prof Naidu says. “The documents have been fully reviewed by experts in the US, Canada and Australia, and CRC CARE intends to update them in line with global advances in science, technology and policy.”
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