Citing a newly released Canadian government study that shows smoke detectors to be 85 percent effective in giving the first warning of a home fire, the Consumer Product Safety Commission yesterday gave its complete endorsement of the devices for use in American homes.

CPSC commissioner David Pittle said more than 20 million smoke detectors will be installed in homes across the country by the end of this year, adding that he believed strongly that all detectors endorsed by reputable laboratories - regardless of type - are effective safeguards against deaths and injuries caused by home fires.

"We can't underscore enough how much we think consumers ought to have smoke detectors in their homes," Pittle said.

While Pittle said he could not recommend specific brand names of smoke detectors, he said consumers should look for the trademark of a recognized testing laboratory on the box or the product itself. He named Underwriters Labs (UL) and Factory Mutual (FM) as two such labs.

The CPSC said it was also making available to the general public a booklet entitled "What you should know about Smoke Detectors," which explains how and why detectors should be used.

The commission discounts recent controversy over which of two types of smoke detectors are better.

One type of detector is the Ionization model which uses a small and carefully shielded bit of radioactive material that "ionizes" the air in the detector's smoke chamber. As a result, a weak electrical current flows through that chamber. But when tiny particles of smoke drift into the chamber, they reduce the electrical current flow, causing the detector circuit to turn on the alarm horn or buzzer.

Although several groups have protested the presence of radioactive materials in the detector, the CPSC booklet quotes the Nuclear Regulatory Commission as saying that there is no significant radioactivity danger. "If you held an ionization smoke detector close to you for eight hours a day through a whole year," the report states, "you would receive only a tenth as much radiation as you'd get on one round trip airline flight across the USA."

The second type of detector uses a photoelectric cell that detects smoke by catching light rays deflected by smoke particles onto a photocell. When there are enough particles reflecting enough light, the photocell produces an electrical current which sets off the alarm.

The study by the Canadian Ministry of Housing evaluated some 64 fires in homes in which smoke detectors had been installed. "Analysis shows that the smoke detectors gave the initial warning in 54 instances," the report states. In at least 21 cases, the study found, the detectors may have saved lives.

Pittle said 18 states have mandatory smoke detector legislation already, while another 15 have partial inducements or legislation.

Pittle also called upon consumrs to develop family escape routes in case of fire, and to have members of the family practice using the escape routes at night.

For copies of the CPSC detector booklet, consumers can write to: Smoke Detector Booklet, Consumer Product Safety Commission, Washington, D.C. 20307, or call the toll-free CPSC Hotline at 800/638-2666 (in Maryland: 800/492-2937.)