Risk assessment at contaminated sites in Sweden currently follows a methodology that includes the use of guideline values, which are not valid for a number of sites.

As an alternative to the use of guideline values, the use of a detailed, site-specific approach requires an understanding of the bioavailability in soil and sediment. Since it is still very much unclear how bioavailability will be incorporated into the risk assessment process in Sweden, the Swedish EPA commissioned an international team of experts consisting of SWECO VIAK and Geosyntec Consultants to develop a guidance manual that provides general recommendations on how bioavailability should be implemented in the nation’s risk assessment process.

Geosyntec and SWECO VIAK also were tasked to provide a focused recommendation on how to establish bioavailability factors for different chemicals in the Swedish model for guideline values. The project’s anticipated outcome is an increased use of the bioavailability concept in risk assessment in Sweden, which should lead to more cost effective site remediation.

The manual introduces stakeholders, authorities, consultants, and contractors to the scientific concepts of bioavailability, and presents a systematic protocol for inclusion of bioavailability in the human health risk assessment process for a given site in Sweden.

Specifically, Geosyntec provided a general overview of the scientific principles of bioavailability as it relates to soil and human exposure pathways. The firm also provided the technical basis for how bioavailability is included in risk assessment in North America, largely based on the National Research Council and U.S. Environmental Protection Agency guidance on these topics.

Different methods that can be used to obtain the necessary data for establishing bioavailability factors for different chemicals are summarized in the manual. It also presents numerous case studies where bioavailability was used in risk assessment in North America, and summarizes advances in risk communication in North America as they relate to bioavailability in risk assessment.

This first-of-its-kind guidance manual co-authored by Geosyntec is an important step in Sweden’s ability to cost-effectively manage and remediate its industrial sites impacted by contaminated soils and sediments.