The collection of small endogenous molecules (metabolites) which occur in all living organisms is known as the metabolome. The measurement of single metabolites or metabolite panels has been used for centuries for disease diagnosis and more recently for asssessing the effects of environmental contaminants. Today, state-of-the art analytical tools allow us to characterize the metabolome with unprecedented speed and coverage. This project focuses on the development of metabolomic tools and their application to probing sub-lethal effects of emerging contaminants.