BE IT CHILDREN'S SLEEPWEAR, spray cans, saccharin or some other common household item, the various government warnings about potential carcinogenic (cancer-causing) chemicals keep coming out in hot and heavy profusion - and subject to change without notice. Is nothing safe anymore? Well, not quite. There are still a lot of things that you can handle, wear, eat, drink or breathe with reasonalbe safety. The problem is that, without having learned the answer to the basic question of what really causes cancer, we have been inventing new chemicals, and marketing new products containing them, faster than we can do adequate research on their possible carcinogenic affects. We know enough about these potential effects to raise a host of questions - but not enough to answer these questions in any final way. It is a question of too little learning, to bend the words of Alexander Pope, about a lot of dangerous things. As a result, we are still at the stage when the more we learn, the more we have to worry about.

The confusion and anxiety are compounded by the hodgepodge of federal agencies and laws presently dealing with carcinogens, or cancer-causing chemicals. But the real source of public disquiet is more fundamental; as pointed out by Daniel S. Greenberg and Judith E. Randal last month in an article in the Outlook section of this newspaper, there has been a overemphasis on finding cures for cancer rather than on reasearch into its origins and prevention. A lot of the confusion would be eliminated if the government were in a position to concentrate its energy and its policy on forewarming and protecting the public, rather than on allowing items to be marketed - only to recall them.

Only recently has the government even been given any reasonably authority to require federal pre-market testing of chemicals. But even that authority, under the Toxic Substances Control Act, has not been working well, according to yet another recent report in Outlook, by Rachel Scott: Environmental organizations say that the Environmental Protection Agency's office of toxic substances has been reluctant even to ask manufacturers to identify themselves in listing chemicals they produce.

If anything is clear, it is that there is no need to create a new federal agency to handle the carcinogens problem. On the contrary, what's sorely missing is a coordinated government approach for evaluating risks to human health. Barbara Hackman Franklin, a member of the U.S. Consumer Product Safety Commission, has formally urged President Carter to establish a federal policy on identifying and regulating potential carcinogens. She notes that "as a nation, we're short on screening tests and testing protocols that are reliable, fast and cheap . . . The challenge - and, I believe, the opportunity - is to develop nothing less than a strong, sustained and coordinated national commitment to find better ways to bring the hazards down to much smaller size without unnecessarily burdening or inhibiting industry."

Failure to meet that challenge, by directing more of the government's money, attention and research to cancer prevention under a coordinated federal policy, will only lead to further public confusion - at best. At worst, continued indifference to the need to practice more effective preventive medicine with respect to carcinogens will seriously aggravate an already grave national health problem.