Key aspects of any Pollutant Release and Transfer Register (PRTR) programme are the estimation techniques used to generate data on releases. Companies (facilities) that report data to a national PRTR generally estimate the data using, for example, emission factors or mass balance calculations, rather than using measured data, such as specific continuous monitoring data. As different industrial processes and activities involve different throughputs, equipment and operating conditions, different methods for estimating pollutant releases and transfers are required. The scope of this document is to describe methods and considerations for determining quantities of a pollutant that has been released into the environment or otherwise managed as waste. This document provides an overview of example transfers that contain chemicals of concern, the sources of those transfers, the chemicals included and management methods for these transfers.