Estimating baseline toxicity of PAHs from marine chronically polluted sediments and bioaccumulation in target organs of fish hypothetically exposed to them: a new tool in risk assessment

In soils and sediments contaminated by Hydrophobic Organic Compounds (HOCs), the total concentrations are less indicative of potential exposure and distribution than the associated freely dissolved concentrations (C-free) or chemical activity. Therefore, these two parameters are increasingly used to assess sediment contamination with regard to their (1) partitioning into the water column, (2) bioaccumulation and (3) baseline toxic potential. In this work, sediments from a chronically polluted coastal area, with similar total PAH concentrations, were studied using PDMS coated glass jars (obtaining C-free(SW) and chemical activity) to predict baseline toxicity and potential bioaccumulation from these sediments. The results indicate that, on the one hand, the chemical activity of the sediments differed by up to one order of magnitude and was below the level at which lethal baseline toxicity is expected, but is still a cause for concern due to the presence of other pollutants and different mechanisms of action. On the other hand, the combination of C-free measurements and Biota to Sediment Accumulation Factors (BSAFs) allowed concentrations in different target organs of benthic flatfish, hypothetically exposed to these chronically polluted sediments, to be estimated. This new approach allows us to predict the concentration in biological tissues under the study of C-free(SW) in sediments, as a useful tool in risk assessment.