Biomonitoring involves taking samples of blood, tissue, urine or hair to detect the presence of certain substances in the human body. The process is today used by environmental campaigners, lobbyists and the EU Commission as a tool to assess human exposure to pollution as part of health and environmental policy-making. However, the lack of scientific knowledge on the paths taken by the pollutants and their actual risk for human health is making biomonitoring a controversial issue.