It's a classic chicken-and-egg thing: Can you get a healthier chicken if you let it roam free? Or do you end up with disease in your flock?

This is a question that is still being debated, even though new federal requirements for what it takes to label food as organic took effect yesterday. After years of deliberation, the Department of Agriculture followed the advice of a national standards board and decreed that for eggs to earn the organic label, the chickens that lay them must have "access to the outdoors." That has provoked a hen fight among regulators, proponents of organic practices and the egg industry.

Egg producers fear that allowing chickens to roam free will result in outbreaks of salmonella enteritis and avian influenza, diseases that affect humans and birds. They contend that letting chickens roam outdoors exposes them to rodents and predators, substantially increasing their chances of becoming sick and laying bad eggs. Any hint of infection means that domestic markets are roiled and exports are cut off, they argue. Instead, the chickens should be allowed to run free in well-ventilated houses with open but screened sides, producers say.

The United Egg Producers, an organization that represents the majority of domestic egg companies and producers in the $4 billion-a-year industry, has enlisted the aid of members of Congress and avian pathologists to drum home to the USDA the risks they see in letting layers spend time outside. For even though organic eggs account for only about 5 percent of the 70 billion eggs sold annually in the United States, those sales are growing by about 30 percent a year.

The group had numerous meetings with top USDA officials, pleading for a variance so growers that want to raise birds inside still can have their eggs certified organic. "They are simply ignoring the potential risks to humans and birds. Outbreaks will hurt industries and will cost millions of dollars. It's a narrow-minded view of something that could turn out to be catastrophic," said Kenneth Klippen, the trade group's vice president of government relations.

One scientist, Robert J. Eckroade, an associate professor of avian medicine at the University of Pennsylvania School of Veterinary Medicine, said open access is at odds with other efforts the USDA is making to eradicate salmonella. "The arguments against it are so overwhelming that we couldn't believe they weren't going to change it," he said.

The egg producers think the solution is to certify the chickens based on what they are fed, not where they roam. The certification process, they said, should let producers raise birds inside if they are exposed to fresh air and sunlight.

At earlier stages in the rulemaking, officials from the department's Food Safety and Inspection Service and the Animal and Plant Health Inspection Service seemed sympathetic. But the final rule followed the advice of the National Organic Standards Board, which said open access means the birds must have the choice to be inside or outside.

Farmers who raise hens who live for several years and have to produce eggs regularly told the board that open access would actually create stress -- which decreases egg production -- rather than a natural environment as the rule intends.

"Freedom of movement and the ability to exhibit natural behavior is an important part of the organic system. . . . Many years of studying chicken behavior and health does not support the notion that outdoor access improves the hen's welfare, otherwise chicken farmers would not have abandoned the practice in the 1940's," Steven P. Mahrt, a certified organic egg producer in Petaluma, Calif., wrote to the board in May 2001.

Some other organic farmers disagree. They think the rule has too many exceptions and will allow large companies to skirt the rules and figure out ways to confine the birds while still labeling their flocks organic. "We see pasturing of poultry to be the only production standard that will stop factory-style production of organic poultry," Wholesome Harvest, a coalition of organic farmers, said in testimony to the board.

Backers of the stricter rule worry that some producers may take advantage of provisions that allow the birds to be confined temporarily for inclement weather, or if their health, safety or well-being are jeopardized, and if there is risk to soil or water quality.

USDA officials said the rule has enough flexibility to take the producers' concerns into account. "If there is an animal-health issue, the rule would have to accommodate it," said Barbara Robinson, USDA deputy administrator for transportation and marketing programs. "The organic industry pressed hard for it, and we have every intention of enforcing it."

David Carter, chairman of the National Organic Standards Board, said the group is likely to continue discussing the issue, even though it voted 12 to 1 in May 2001 for the strict open-access provision.

The board concluded that the potential benefits of having the birds outside outweighed the risks. "There are concerns with increased disease exposure for poultry, but many organic poultry producers feel this is not the case and, in fact, there are health benefits," it said in a draft recommendation late last year.

Although the chicken is already out of the barn -- as far as open access is concerned -- Katherine DiMatteo, executive director of the Organic Trade Association, believes the controversy is being blown out of proportion since the rule doesn't prescribe how long or how often a chicken must be outside.

"We are trying to honor and respect the normal behavior of the animal, balanced with environmental and health concerns," she said.