1. Explore relationships between daily loads of AAs and their metabolites across a longitudinal study in two contrasting urban areas in Southwest England. 2. Understand spatiotemporal changes to AA/metabolite ratios to inform usage patterns of AAs (e.g. oral vs topical) as well as identify any direct disposal events. 3. Estimate AA intake in the studied catchments using WBE and compare with prescription data to understand prescription compliance and spatiotemporal prescription-AA consumption trends.