Development of sediment quality criteria in Norway

A Norwegian system for classification of environmental quality of contaminated marine sediments has been in force since 1997 and was revised in 2007. The 1997 classification had five quality classes based on the statistical distribution of levels of the contaminants in sediments along the Norwegian coast.Class I represents background and classes II-V describe four intervals of concentrations mainly from a percentile division of the total distribution. The revised classification is based on toxicity of the contaminants. It covers 43 compounds against 28 in the 1997 version. It is based on European Union systems for defining environmental quality standards and performing risk assessment. Five classes are retained. Class I is kept as the background range. The upper limits for class II and class III are the Predicted No Effect Concentrations (PNEC) for chronic respectively acute (intermittent) exposure from the compound. The upper limit of class IV is 2-5 x PNEC intermittent depending on compound, and class V is everything above this. The border between class II and class III is most significant as it separates no-effects sediments from those for which sediment remediation may be needed. The classification has been changed from concentration based to effects based and is in harmony with the Norwegian guideline for risk assessment of sediments. The classification system should be intermittently revised to include new or improved environmental quality standards as they are approved by the European Commission.