This chapter discusses the interactions between parasites and pollutants in the environment and their implications for animal health. A mathematical framework is presented to examine these dynamics, focusing on parasitic helminths, their hosts and pollutants. The model is designed to provide general insights into these interactions, without specific calibration for any particular system. The potential of parasites to reduce the burden of pollutants in hosts is highlighted, qualifying it as an ecosystem service. The model incorporates the dynamics of hosts, parasites and pollutants, considering factors such as host survival, parasite distribution, pollutant absorption and excretion rates. The results suggest that parasites can significantly reduce pollutant concentrations in hosts, particularly in larger-bodied hosts. However, the presence of parasites also leads to lower host abundance. The study emphasises the importance of further research to understand these complex interactions and their implications for ecosystems. It also raises questions about the role of parasites in mitigating the impact of pollutants and the potential consequences of parasite loss.