Iris, at 17 months, wears diapers, waves a pacifier -- and already is menstruating. Rosie Maria, 15 months old, has developed large breasts. So has Manuel, a 9-year-old boy from Aguadilla whose estrogen level exceeds that of an ovulating woman. Shirley, an 8-year-old with the breasts of a grown woman, also has large cysts on each of her adult-sized ovaries.

These children are part of a public-health disaster that has been called Puerto Rico's Love Canal. The affliction is abnormal sexual development. It is estimated that 3,000 youngsters are affected.

In the United States and other countries, this condition is rare. The outbreak here, health authorities agree, far exceeds any known incidence. The long-term effects are uncertain, but doctors say that, at minimum, the victims' height, fertility and psychological health will be affected.

The cause is unknown, but the Puerto Rican doctors treating more than half the cases suspect an environmental contaminant, most likely estrogen in the food chain.

One possible source of the estrogen is growth stimulants for chickens and cattle. Their use is restricted here as well as in the United States, but critics say their misuse is common. The Food and Drug Administration, which made special visits to feed stores, disagrees.

But premature thelarche -- breast development -- and precocious puberty not only have become a growing health concern and embarrassment to this island of 3.2 million, but are causing major repercussions to an economy where meat producers are the third-largest employers.

A political and scientific battle over the problem has erupted. Parents and others charge that the island and U.S. governments have done too little too late; government health authorities and the Puerto Rican food industry reply that conclusions are being drawn too soon.

"The scientific world does not move at the pace everyone would want," notes Jaime Dueno Rivera, Puerto Rican commissioner of health. "Honestly, we have not been able to conclude anything."

But the two pediatric endocrinologists who alerted the island to the problem say their patients have improved when local poultry, milk and eggs are withdrawn from their diets. "I'll be happy if it's something else, but until the government does sufficient tests, we have to continue with what works," said Dr. Carmen Saenz, director of pediatrics at Hospital De Diego in San Juan.

Saenz encountered the condition in the mid-1970s and has seen 778 affected children, most in the past two years. She has seen a menstruating 9-month-old. "As a woman, a mother and a human being, I cannot just sit back and watch," she said.

She wrote letters and medical journal articles to prod other doctors and regulatory agencies to act. She contacted local medical associations, the Puerto Rican Health Department, the FDA, the U.S. Department of Agriculture, the World Health Organization and the U.S. surgeon general, among others. Most of her letters, she says, went unanswered.

She was joined by the only other pediatric endocrinologist in private practice on the island, Dr. Adolfo Perez-Comas. In his office in the western city of Mayaguez, he has a file drawer filled with color photographs of his 751 patients, documenting the startling changes that have occurred in their bodies.

Some children have undergone plastic surgery because of their emotional trauma. A 14-year-old girl Comas saw 11 years ago already has had an ovary surgically removed because of cysts. "We will have problems with final stature, and who knows about their reproductive health," Comas said.

Because both doctors found high levels of estrogen in the blood of as many as 80 percent of their patients, they searched for sources of the female hormone.

They discovered that the condition often receded when they asked parents to remove locally produced poultry, milk, eggs and sometimes beef from the diet. As a result, they suspected that the children were reacting to animal-growth stimulants that contain various forms of estrogen.

Such hormones are supposed to be sold only by prescription. But an investigator working for Saenz claims to have bought pellets of the carcinogen diethylstilbestrol (DES) and synthetic estrogen implants without the required prescriptions at two local feed stores last year.

In 1961, the U.S. government banned DES in poultry after dogs that ate food made from discarded chicken parts and men who ate chicken necks developed feminine traits. The implants were banned in cattle in 1979, but illegal sales and use continued for months and years after.

"The unauthorized over-the-counter trade in veterinary prescription drugs has been, in our experience, rampant and uncontrolled," said Matt Kessler, a veterinarian in suburban Santurce. "The situation is by no means unique to Puerto Rico, and is dictated by the low profit margin farmers receive for their product."

Saenz also put 60 samples of chicken in her hospital's freezer and had a friend take them for testing by Dr. Alfred Bongiovanni, a University of Pennsylvania endocrinologist. He found significant levels of estrogen in much of the chicken.

The situation came to light only after the 18-month-old daughter of a newspaper reporter developed the condition in 1981. The daughter was sent to Saenz, who confided to the reporter that she had seen dozens of similar cases.

"She asked me not to write anything until she could get the local doctors and agencies to respond," said Robert Friedman, who writes for the San Juan Star, the island's English-speaking daily. He is a native New Yorker; his wife is from Philadelphia. "After six more months, she hadn't gotten anywhere and she let me go ahead."

Friedman's March 1982 reports on the phenomenon caused panic in the poultry industry. The anxiety heightened when the FDA took a small random sample of meats locally and initially found high estrogen levels in two poultry samples. Further chemical tests disproved the initial findings, according to an FDA memorandum. But the uncertainty caused shoppers to forgo fresh poultry.

"The market went all to hell in a basket," said Dennis Toppel, director of the meat department for Pueblo International, the island's largest-volume supermarkets, with 36 stores.

In a commonwealth where unemployment is 22 percent and poultry is the island's third-largest native industry, the doctors' doubts about chicken were vigorously attacked. The Puerto Rican Farmers Association accuses the island's meat importers of a conspiracy to ruin local production.

Kentucky Fried Chicken, among others, ran full-page ads proclaiming its product's wholesomeness. Rivera, the health commissioner, called a news conference to reassure citizens that nothing was wrong and the problem was minor.

Later, Rivera changed his mind after the doctors presented their photographs and case records before a legislative committee.

After the publicity, the local USDA office began testing local foods. In May, it sent five samples of beef and one each of pork and poultry to the agency's lab in Beltsville. The federal agency did not find high estrogen, said Dr. Earl Montgomery, director of emergency programs for USDA's Food Safety and Inspection Service.

But because of the FDA's initial findings of "suspicious estrogen activity" in poultry, the agency took 63 poultry and 20 beef samples from local processing plants and 48 beef samples from other islands in September 1982, also with negative results. A sample of eggs was examined later and cleared.

"We feel we have looked at the meat and poultry supply," said Montgomery. "Based on our monitoring sampling plan, we would not step up our sampling." He noted that his department was gathering information on how to improve the analysis of estrogen in meats, including the more sophisticated techniques of Bongiovanni, the Philadelphia doctor who did find estrogen in the Puerto Rican chicken.

Bongiovanni's test, Montgomery said, "is considered very sophisticated. But for me, what we're doing is sufficient to find estrogen."

Meanwhile, the FDA sent many of its 22 investigators to island feed stores. They identified themselves as investigators and asked if hormone implants were sold.

"We found almost no evidence that there was a problem," said Dr. Lynn Campbell, the FDA's local director. "There was one incident where some veterinary medicine was provided to a farmer to implant in cows."

The federal agencies gave their sampling results to the federal Centers for Disease Control (CDC) in Atlanta. That agency is studying the situation with a commission of five doctors that the Puerto Rican health commissioner established.

The five doctors are doing statistical analyses on 130 cases of females affected with thelarche and sent graduate students to sample eight of the families' food and drink. But the commission's two years have yielded no conclusions, according to its chairman, Dr. Lillian Haddock, an adult endocrinologist and dean of academic affairs of the island's Medical Sciences Campus.

"We think the results will show the same compound in the control and study groups," said Dr. Vernon Houk, director of the CDC's Center for Environmental Control. He criticized Saenz and Comas for "tend ing to report their findings in the press."

"Unfortunately," Houk said, "if you're going to handle this scientifically, you work behind closed doors . . . . Two chickens don't mean all the poultry in Puerto Rico is suspect."

For the bewildered parents of the affected children, the immediate need is to shield their offspring.

"I cannot let her walk the streets alone because of the men," said Juanna Lopez, whose overdeveloped 8-year-old daughter has had two operations to remove ovarian cysts, the first when she was 3. The girl's father, a truck driver, often accompanies her to school.

One San Juan mother whose 9-year-old son is seeing a psychologist because of his distress agonized, "This problem is digging at him." Her son's bones have matured faster than normal, which means his growth will be stunted: "The doctors have told us he'll never be taller than 5 feet 3."

Luiz Gonzalez, from Las Marias, said she was tormented by her 3-year-old daughter's problem with enlarged breast tissue and ovarian cysts. "As a mother I want to help my daughter, but I can't. It's so difficult to wait for a final answer."