Some packaged sandwiches sold on Amtrak trains could present a possible danger of botulism poisoning if not handled properly according to officials of the Food and Drug Administration.

The sandwiches, which are treated with nitrogen to remove most of the oxygen from the package in order to preserve the contents longer, can become a fertile growth area for botulism toxin if they are not refrigerated and otherwise handled properly, according to internal FDA documents obtained by The Washington Post.

But FDA administrators and Amtrak officials stress that no reported cases of botulism have resulted from the sandwiches, which have been used on a limited basis by Amtrak for eight months.

Last month, however, Amtrak began using the sandwiches nationwide. Amtrak officials said they expect to purchase about 4 million of the sandwiches a year eventually.

he sandwiches are produced by American Micro-Fare, a Dallas-based company owned by Clint Murchison Jr., who also owns the Dallas Cowboys American Micro-Fare is also known as Cowboy Kitchens.

The sandwiches involved include ham salad, pastrami, turkey, cheese, roast beef, and others that are kept in Amtrak freezers before being thawed and transferred to refrigeration units on trains.

The major advantage of the new nitrogen packing system is that it extends shelf life. However, FDA officials say that a side effect to removing oxygen from the packaging is creation of an atmosphere in which botulism can spread.

Amtrak and American Micro-Fare officials say that if the sandwiches are handled properly, there are no problems.

But FDA investigators worry about Amtrak's ability to handle the sandwiches safely.

"It is our opinion that these products could, under certain conditions, represent a potential danger to public health," FDA official Caesar Roy wrote in a memorandum to the FDA Dallas district office last year, asking that office to review test data submitted by American Micro-Fare.

"Although some of the product samples analyzed revealed oxygen levels as high as 22 percent, many were at a low enough level to allow the growth of C. Botulinum (botulism)," Roy said.

But Roy said that, without specific information concerning the ability of botulism to grow in the sandwich atmosphere, and until further testing is done, "We are not prepared to take regulatory action at this time."

In a letter that Roy proposed be sent to American Micro-Fare, he said: "We recognize that it is very unlikely for food poisoning to occur if your product is handled as you recommend. However, it is our experience that abuse does occur at retail stores and in the home." The letter was not sent.

FDA inspectors began purchasing some of the sandwiches in various cities to test their pH level, which is the measure of acidity or alkalinity. If food is too acid, organisms like botulism can grow, according to the FDA.

According to another internal FDA memorandum from one of the field offices to the Washington headquarters, the pH levels of various sandwiches tested there ranged from 5.4 to 6.5.

"The pH range conducive for the potential growth of botulism organisms is that which is over 4.6," the report said.

One internal FDA memorandum written early presents a chronology of action by FDA inspectors who were trying to get Amtrak to hold off using the sandwiches until they were proven safe.

According to that memo, Amtrak official Gary McKenzie told FDA investigators that Amtrak had improved refrigeration units on its trains, and the sandwiches "pose no health hazard." Even after he reportedly was told by FDA inspectors that "botulism toxin was produced in ham salad sandwiches held at 72 degrees for 21 days," McKenzie insisted the sandwiches were safe, according to the memo.

"Mr. McKenzie stated that the sandwiches would never be on the trains for that length of time and at that temperature," the report said.

On April 19, McKenzie also told the FDA that he would sell the sandwiches "until FDA can show Amtrak just reasons why not to use the sandwiches," the memo says.

Frank Creager, president of American Micro-Fare, said in a telephone inteview that there was no danger of bacteria growth under "any reasonable conditions."

Tests conducted for the company at the FDA's request revealed no problems, he added.

Although the FDA investigators admitted that there was no solid proof that the botulism exists, they are asking their superiors to consider holding the sandwiches off the market until the manufacturer conclusively proves them to be safe rather than allowing their sale until the FDA proves them to be dangerous.

The internal memos reveal that the FDA has discounted all of the tests performed for the company.

And, according to Dr. R. B. Read, director of the FDA's Division of Microbiology, the FDA is conducting a second round of tests on the sandwiches, on its own in search of more conclusive evidence.

But a memo concerning a March 14 telephone discussion among three FDA investigators reveals that "the imminent health hazard associated with these sandwiches was unanimously acknowledged . . . the need to act quick (sic) and decisively in dealing with Amtrak was acknowledged."

And The National Automatic Merchandising Association, a trade group for the vending and food service industry, has recommended that its member companies not employ nitrogen packagaing because it "could be dangerous" if used with perishable foods.

Amtrak spokesman Joe Vranich confirmed that the railroad has been using the sandwiches since September.

"Amtrak has not received any adverse information from the FDA regarding them," he added, "although we have asked."