ONCE UPON A TIME, usually when little children were going to bed, they would put on special bedclothes called pajamas. But one day the government said to the people who make pajamas that they'd better make pajamas that wouldn't burn too easily in accidental fires. So pajama people treated their outfits with something called Tris. But then there was some question about whether Tris might cause cancer. Then certain pajama people found something else called Fyrol-2. But guess what? It, too, may cause cancer. So today there are probably a lot of children who just wear thermal underwear to bed and hope there's no fire.

This little bedtime story is true, of course, and is an example of how so many things that we all wear, handle, eat, drink or breathe may be hazardous to our health. Moreover, our confusion and anxiety have been aggravated by the uncertainty and often conflicting opinions of various federal agencies dealing with toxic substances or carcinogens (cancer-causing chemicals). Nevertheless, as we have noted previously in this space, there is a new effort under way to coordinate the government's approach to health harzards, to make the regulatory processes and information more understandable.

Since August, when this plan was announced, four agencies - the Consumer Product Safety Commission, the Environmental Protection Agency, the Food and Drug Administration and the Occupational Safety and Health Administration - seem to have made some headway. They began by directing their branches around the country to share facilities, laboratories and information. The agencies also set out to develop "compatible" testing standards and guidelines - a most important part of this effort - and to define what constitutes a "risk" and how to announce test results.

Consumer Product Safety Commission Chairman S. John Byington cites as one example the interagency regulation of chlorofluorocarbons in aerosols. Agencies have exchanged information, pooled their research money and come up with various proposals for uniform regulations. Another member of the product safety commission, Barbara Hackman Franklin, while terming this effort "encouraging," says that still greater attention must be devoted to the ways in which agencies move from research results to regulation. The government still has few carcinogen-screening tests that are reliable, fast and inexpensive, she points out, urging a stronger "sustained and coordinated commitment" to identify and regulate cancer-causing chemicals.

Indeed, much of the public's confusion could be eliminated if the government would concentrate its energy and policies on forewarning and protecting people rather than on allowing items to be marketed - and later having to recall them. For this to happen in any sustained fashion, however, will require the strong support and leadership of the White House.