IN TOO MANY FAMILIES and for far too long a time, there has been much understandable parental consternation about children's sleepwear - is or isn't it treated with a flame-retardant called Tris, and if so, is or isn't it safe to use after a certain number of washings? Even now, the answers to these questions aren't coming at all easily. What the government is saying is that Tris was causing kidney cancer in rats and therefore might cause cancer in humans. Perhaps that doesn't sound like a terribly complicated proposition. And yet the manner in which the federal government has been almost a model of how not to handle a serious matter of public safety.

The trouble began in 1972, when the government banned the sale of children's nightwear that wasn't treated with flame retardants. That made sense, but the possible harmful effects of Tris weren't called to public attention at the time. A good 14 months ago, however, the Environmental Defense Fund asked for action on Tris. On March 27, 1976, the Consumer Product Safety Commission was reported to be investigating "as a priority item" the possibility that Tris might cause cancer. But months would pass before that would turn into action. At the time, the Environmental Defense Fund was petitioning the commission to require that sleepwear treated with the chemical be labeled with the warning "Contains the flame retardant Tris. Should be washed at least three times prior to wearing."

Commission officials said then that they were requesting data from the Environmental Protection Agency and other groups. Meanwhile, laboratory experiments by several groups were showing that under certain conditions Tris causes mutations in cells. This suggested that the chemical should be tested as a possible carcinogen, some scientists said.

But rather than err on the side of safety - or at least see to it that Tris would be labeled - the commission waited until April of this year to order a ban. Retailers and the garment industry were left to repurchase the affected garments returned by consumers. Eventually, thanks to a court order, the manufacturer of the chemical itself was required to share some part of the recall costs.

But without those labels that were suggested for Tris in the first place, consumers were left to figure out whether the fabric they'd bought had been treated with tris. We could go on, but it suffices to say that the plot thickened and took a final, curious twist with a commission statement to the effect that more than 95 per cent of surface Tris could be removed by three washings; the statement failed, however, to address the question of whether that would remove any potential danger. So at this point the safest course for consumers, apparently, is to scrap any questionable sleepwear and buy new garments.

That's a costly, dangerous and unnecessary way for us all to find out that the Consumer Product Safety Commission didn't have its act together. As staff writer Bill Curry reported in a profile of the commission last month in this newspaper, the agency's failures stem in part from its small size and vast task; it is also only fair to note that the commission operates under the constraints of numerous laws and courts challenges.

The situation, as we understand it, is not quite as hopeless as the Tris case makes it sound. The commission, it is said, has begun to reassess certain of its policies. Frankly, we don't know how far this reassessment will go. What does seem clear, from the sorry story of Tris, is that there is a need for radical improvement of procedures for dealing with products that may seriously threaten public health and safety. After all, the purpose of this sort of thing, or so it seems to us, is supposed to be a forewarn and protect, rather than to permit and then - in a cloud of confusion - to recall.