The FDA announced the third urgent recall in one week of dangerously defective infant formula from Wyeth Laboratories, bringing the total formula recall to nearly 3 million cans in the United States, Puerto Rico and the Bahamas.

The formula is lacking sufficient vitamin B6, a nutrient essential to infant health, FDA said. "A vitamin B6 deficiency of more than a few weeks can cause an infant serious health effects, including convulsions," it said.

In the most serious cases, permanent brain damage can result, because vitamin B6 is a chemical necessary for the normal firing of brain and nerve cells.

Wyeth spokesmen testified at a congressional hearing yesterday that they have known about the defective batches of SMA for 10 days or more, but had not begun a recall because they didn't want to recall good batches unnecessarily.

The FDA and Wyeth announced a week ago that they were recalling 571,000 cans of Nursoy brand infant formula because they contained no vitamin B6. By yesterday, the company said it had retrieved 520,000 cans, but 50,000 were apparently with consumers.

On Thursday, FDA announced that an additional 567,000 cans of infant formula, this time SMA brand formula, was being recalled. A spokesman for American Home Products Corp., parent company of Wyeth, said the SMA contained some B6, but not enough to ensure infant health.

Yesterday, the FDA announced a third urgent recall, this time for about 1.8 million cans of SMA. This batch also contains some B6, but not the amount required by law.

All the batches of defective formula resulted from a single accident in January, when a worker mistakenly dumped vitamin B1 into a container marked for vitamin B6. The B1 was then added to the formula as if it were B6. So the batches made during a three-week period in January and February contained too much B1 and no additional B6.

The Nursoy on the market with no B6 has code numbers embossed on the can lids--A26M, B2M and B9M. The SMA that contains some, but not enough, B6, has code numbers embossed on can lids or bottle labels. The code numbers are A25M through A31M, and B1M through B15M.

The FDA said that parents of infants who have consumed any of the recalled formula as their only source of vitamins should call a doctor for advice.