Insecticides used in and around homes, including products voluntarily removed from the market years ago, were found on the floors of a high number of U.S. homes in a study announced this week.

The results, reported in the journal Environmental Science & Technology, were derived from samples taken from hard-surface floors in a nationally representative sample of 500 residential homes in 2005 and 2006. The study was conducted by scientists at the Environmental Protection Agency (EPA) and the Department of Housing and Urban Development (HUD).

The most commonly detected chemicals and the percentage of floors on which they were found: