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News article12 April 2023Directorate-General for Environment4 min read

Swedish risk assessment of contaminated sites points to the need for more objective measures

Issue 599: European countries have developed their own methods of risk assessing contaminated sites. A comparison of Swedish (qualitative) and German (quantitative) methods shows that they can produce vastly different results for the same sites.

Figures in white hazmat suits working onsite.
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Waste disposal, mining and industrial activities have caused widespread contamination of soil and water around the world, with pollutants including metals, mineral oil and polyaromatic hydrocarbons (PAHs). Plastic particles, perfluoroalkyl substances (PFAS) and pesticides are also increasingly detected in the environment. There are probably more than 250 000 contaminated sites in Europe requiring remedial action, while, potentially, polluting activities are occurring at nearly three million sites.

Untreated sites may pose a risk to human health and the environment, as well as decreasing the value of affected property. Appropriate risk assessment is necessary to identify and prioritise remedial action, or plan how sites may be managed and reused. Many European countries have developed their own method of classifying sites into risk classes. However, no study has systematically compared the advantages and disadvantages of methods used in different countries.

To address this knowledge gap, researchers compared two different methods: the Swedish Method for Inventories of Contaminated Sites (MIFO) and the German Individual Assessment of Contaminated Sites Method (EB), devised by the Hessian Agency for Nature Conservation, Environment and Geology.

The Swedish method is a qualitative, text-based decision-support system that draws on available information, which may include sample analysis from the contaminated sites but not necessarily. In the Swedish method, four criteria are assessed: hazard of contamination, level of contamination, potential of contaminant spread, and sensitivity of the environment at the site (e.g. soil, groundwater) – and risk class is determined with the help of a chart, based on the investigator’s reading of the information. Risk classes run from 1 (very high risk) to 4 (low risk).

By contrast, the German method is a model-based decision-support system, using a quantitative approach to assess air, soil, surface- and groundwater at contaminated sites. Points are assigned to indicate level of contamination, condition, and usage of groundwater, for example. Depending on the total number of points for each of the four environmental compartments – and with the most weight being given to the compartment with the highest score – sites are automatically classified into one of three risk classes.

The researchers selected 51 contaminated sites in Anderstorp, an industrial area in Småland, Sweden, which had already been risk assessed using the Swedish method. They note that the area, in the Nissan River valley, is a major groundwater resource. They re-classified the sites according to the German method (adding a fourth risk class to align with the Swedish method) and considered the differences in classification.

Under the Swedish method, just four of the 51 sites were assigned to risk class 1 and 20 to class 2 – these 24 sites (47%) would be high priority for remediation. Twenty-one sites were put in class 3 and six in class 4. Based on the same information, the German method put 10 sites in class 1 and 34 sites in class 2, meaning that 44 of the 51 sites (86%) would be considered a high priority for remediation. The comparison reveals that with the Swedish method, 39% fewer contaminated sites were assigned to the highest risk classes.

The researchers also found that nearly half of the original Swedish assessments contained incorrect or incomplete information, and less than a third had a fully completed risk chart. Meanwhile, they judged that only 35% of the assessments followed a traceable train of thought. They explain that the lack of completion of these template documents was perhaps due to their text intensive structure and complexity of the risk chart, making them time-consuming to fill out. The form is also open to interpretation and relies on the variable expertise of the assessor, who may be an environment professional or a non-specialist such as a property owner.

By comparison, the German method uses a quicker, numerical spreadsheet, with fewer fields requiring text. Only relevant information is required. Classification is points-based and less open to interpretation. This makes it more advantageous over the current Swedish system, say the researchers, who recommend including a quantitative approach with a point and/or ranking system, like that used in the German method, to increase objectivity in future risk class categorisation of contaminated sites.


Wanner, P., Freis, M., Peternell, M. and Kelm, V. (2023) Risk classification of contaminated sites - Comparison of the Swedish and the German method. Journal of Environmental Management, 327: 116825. Available from:

To cite this article/service:

Science for Environment Policy”: European Commission DG Environment News Alert Service, edited by the Science Communication Unit, The University of the West of England, Bristol.

Notes on content:

The contents and views included in Science for Environment Policy are based on independent, peer reviewed research and do not necessarily reflect the position of the European Commission. Please note that this article is a summary of only one study. Other studies may come to other conclusions.


Publication date
12 April 2023
Directorate-General for Environment

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