Dangerous substances are found in many workplaces. The 2000 European Working Conditions Survey (ESWC) found that 16% of workers in Europe reported handling hazardous products and 22% reported being exposed to toxic vapours. The theme for the 2003 European Week for Safety and Health at Work was the prevention of risks from dangerous substances. To mark this European Week, EU-OSHA produced a series of factsheets focusing on the communication of OSH-related information on dangerous substances including biological agents. This factsheet introduces key issues related to this topic.