President Reagan's mandated "cost-benefit analysis" of proposed new regulations was the main reason the Food and Drug Administration did not prevent marketing of a dangerously defective infant formula, FDA Commissioner Arthur Hull Hayes Jr. told a House subcommittee yesterday.

The manufacturer, Wyeth Laboratories, also disclosed yesterday that in addition to an earlier batch of defective formula that was put on the market, it has discovered that 567,000 more cans must be recalled. That recall procedure was initiated last night, the FDA said.

The cans in the new batches, whose trade name is SMA, are marked with the codes A29M, A30M, B10M and B11M, among other coding numbers on the lid.

The FDA and Wyeth negotiated at length over the recall, with Wyeth trying to get the recall put in Class 3, the lowest priority. FDA argues that the recall should be in the most urgent category, Class 1, but no decision had been made.

The original batch of defective formula, whose brand name is Nursoy, contains no vitamin B6, the lack of which in an infant's diet can cause hyper-irritability, convulsions, and permanent brain damage such as cerebral palsy. Without the vitamin the body can't produce chemicals that enable nerve cells in the brain to "fire," or function, normally.

The new disclosure said the SMA brand formula contains some vitamin B6 but not the minimum amount required by law.

"The proposed regulations would have, if followed by the firm, prevented this distribution problem," Hayes told a hearing of the House Commerce subcommittee on oversight and investigations.

The delayed regulations could legally have been put into effect anytime after May of 1981, when the official public comment period on them ended.

"What happened to them?" asked Rep. Albert Gore Jr. (D-Tenn.) "Did they disappear in a Reagonomics black hole?"

Hayes answered that the FDA had to read letters of public comment on the proposed regulations and do "the economic impact analysis as we are mandated to do." That took more than seven months, he said.

Sanford Miller, director of the FDA's Bureau of Foods, said the FDA tried unsuccessfully for two months to obtain from the industry necessary information to do an economic analysis. Then, Arthur D. Little, Inc., was hired to do the "cost-benefit" analysis, which was finished within the last month.

Even after the delay, Hayes said it will now be another six months, and possibly more, before the regulations finally go into effect. Infant formula manufacturers need at least six months' preparation to carry out the regular testing of formula for all life-sustaining ingredients required in the proposed regulations, he said.

The Wyeth accident was caused by a worker who mistakenly put a canister of vitamin B1 into a container labeled vitamin B6.