Total material requirement (TMR), a measure of all of the material input required by a national economy, is sometimes criticized for failing to link material flows within an economy and their global environmental impacts. This article presents a three‐step method for bridging this gap. The method shows how to (1) analyze TMR accounts to identify potentially environmentally relevant flows (PERF), that is, material flows with potential environmental impacts abroad; (2) assess the socioenvironmental impacts of the identified PERF; and (3) determine the main economic activities underlying these PERF. Using this method we are able to add an environmental dimension to TMR accounts and to make the connection between economic activities and their socioenvironmental impacts worldwide. This methodology has been applied to the Basque Country (BC) region (Spain). An in‐depth analysis of the trends in the TMR of the BC shows that tin imports associated with tin capsule production account for around 7% of the TMR. These high figures are due to the substantial hidden flows (HF) of tin imports, which is an indicator of potential environmental impacts abroad. We find that tin extraction and concentration involve several social and environmental impacts such as waste generation, soil, water, and air pollution affecting biodiversity and human health, and child labor. These impacts are located in Indonesia, China, Peru, Bolivia, Brazil, Malaysia, and Thailand.