In April 2008, the Union of Concerned Scientists said that more than half of the nearly 1,600 EPA staff scientists who responded online to a detailed questionnaire reported they had experienced incidents of political interference in their work. The survey included chemists, toxicologists, engineers, geologists and experts in other fields of science. About 40% of the scientists reported that the interference had been more prevalent in the last five years than in previous years. The highest number of complaints came from scientists who were involved in determining the risks of cancer by chemicals used in food and other aspects of everyday life.