COLUMBUS, Ohio — A resurgence of bedbugs across the United States has homeowners and apartment dwellers taking desperate measures to eradicate the tenacious bloodsuckers, with some relying on dangerous outdoor pesticides and fly-by-night exterminators.

The problem has gotten so bad that the Environmental Protection Agency warned this month against the indoor use of chemicals meant for the outside.

The agency also warned of an increase in pest control companies and others making “unrealistic promises of effectiveness or low cost.”

Bedbugs, infesting U.S. households on a scale unseen in more than a half-century, have become largely resistant to common pesticides. As a result, some homeowners and exterminators are turning to more hazardous chemicals that can harm the central nervous system, irritate the skin and eyes or even cause cancer.

Ohio authorities, struggling against widespread infestations in several cities, are pleading with EPA to approve the indoor use of the pesticide propoxur, which the agency considers a probable carcinogen and banned for in-home use in 2007. About 25 other states are supporting Ohio’s request for an emergency exemption.

Meanwhile, authorities around the country have blamed house fires on people misusing all sorts of highly flammable garden and lawn chemicals to fight bedbugs. Experts also warn that some hardware products – bug bombs, cedar oil and other natural oils – claim to be lethal but merely cause the bugs to scatter out of sight and hide in cracks in walls and floors.