The complex and variable composition of natural sediments makes it difficult to predict the bioavailability and bioaccumulation of sediment-bound contaminants. Several approaches, including an experimental model using artificial particles as analogues for natural sediments, have been proposed to overcome this problem. For this work, we applied this experimental device to investigate the uptake and bioaccumulation of As(III) by the freshwater oligochaete Lumbriculus variegatus. Five different particle systems were selected, and particle-water partition coefficients for As(III) were calculated. The influence of different concentrations of commercial humic acids was also investigated, but this material had no effect on bioaccumulation. In the presence of particulate matter, the bioaccumulation of As(III) by the oligochaetes did not depend solely on the levels of chemical dissolved but also on the amount sorbed onto the particles and the strength of that binding. This study confirms that the use of artificial particles may be a suitable experimental model for understanding the possible interactions that may occur between contaminants and particulate matter. In addition, it was found that the most hydrophobic resin induced an increase in arsenic bioavailability, leading to the highest bioaccumulation to L. variegatus compared with animals that were exposed to water only.