(MONEY Magazine) – In the mid-1980s, homeowners trembled over the health risks posed by radon, the odorless cancer-causing gas that the Environmental Protection Agency estimates is found in unhealthful concentrations in one out of eight U.S. houses. This year's scare: lead dust from lead-based paint. For years, lead paint has been known to be harmful to young children, who may put the paint chips in their mouths and risk brain damage. But now the U.S. Department of Housing and Urban Development reports that 74% of homes built before 1980 contain potentially dangerous levels of the toxin -- that is, more than one milligram of lead per square centimeter of paint. But don't overreact. Dick Morris, senior technical adviser for the National Association of Home Builders, points out that few houses have lead dust that's pervasive enough to be a major worry. Typically, he says, the stuff is restricted to isolated spots around the house and can be dealt with for $500 or less by scraping and using a lead-dust vacuum or by covering the area with plastic. The U.S. Consumer Product Safety Commission publishes a useful brochure explaining such procedures called What You Should Know About Lead- Based Paint in Your Home. Send 50 cents, with your name and address, to Consumer Information Center, Dept. 467X, Pueblo, Colo. 81009. If your house was built before 1980 and you're concerned about lead risk, your city or state health department can suggest a local testing service. This company will charge $100 to $400 to use an X-ray fluorescent lead-analyzer for determining your home's lead-paint content as well as to pinpoint problem areas. Only if the tests reveal that the paint is found at high levels throughout your home will you need to consider bringing in a contractor. Look for one who has performed lead-paint abatement at least a dozen separate times -- and get ready for some high costs and hassles. Expect to shell out $5,500 to $12,000. You'll spend even more to live outside your home while the work is done. The job takes three to four weeks for a standard three-bedroom house, and it's best to move out until the work is finished, says Jim Keck, president of Leadtec Services, a Baltimore consulting and training firm.