Is the breast still best?

When Lori Peltier began nursing the first of her two children 11 years ago, she was convinced that "the breast is best." Now the Pennsylvania pharmacist wonders if she unknowingly jeopardized her kids' health.

Shortly after weaning her firstborn, Peltier learned that breast-feeding exposes infants to a smorgasbord of harmful contaminants, including pesticides, dioxins, polychlorinated biphenyls (PCBs) and DDT, at levels up to 40 times greater than the daily exposure for most adults.

"I didn't even know these toxins were in breast milk until afterward," Peltier said. "You really get shaken up by things like that." Today, Peltier's daughter and son are healthy, as are countless other breast-fed children. But a growing number of researchers suspect that their heavy chemical burden may one day rob them of their health and opportunity to bear children.

Many of the chemicals that concentrate in breast milk -- including DDT, some PCBs and dioxins -- are among a growing list of pesticides and industrial chemicals that mimic the hormone estrogen. These synthetic hormones can disrupt development of the immune, nervous, endocrine, reproductive and digestive systems. The reproductive system is particularly vulnerable. Animal populations have dropped precipitously after synthetic hormones left the males "chemically castrated."

Each year, billions of pounds of these chemicals are dumped over America's croplands and waterways. Animals feeding in tainted fields, rivers and lakes store the contaminants in their fat. Unlike some chemicals, synthetic hormones do not readily flush out of the body. The higher an animal is on the food chain, the greater his burden of these fat-soluble contaminants.

Two of the most ubiquitous contaminants. DDT and PCBs, were banned in the United States more than 20 years ago. But the pesticide DDT is still widely used in developing countries and scattered worldwide by the wind. The clear, oily, insulating compounds known as PCBs are often found in waterways after being carelessly discarded in the wake of the 1974 ban. DDT and PCBs are so pervasive that every person on Earth is believed to have at least a trace in his body.

In the 1940s, just after the dawn of the chemical revolution, the rate of human reproductive ills soared. Reports of undescended testicles, prostate cancer and testicular cancer rose sharply in males. In the last three decades alone, the rate of testicular cancer tripled. Since World War II, the sperm count of men in industrialized countries has dropped 50 percent.

Women, meanwhile, are suffering record rates of endometriosis, a painful disease that sometimes leads to infertility. Between 1970 and 1987, tubal pregnancies in the United States increased 400 percent. The rate of breast cancer has climbed one percent annually over the last 50 years.

Studies suggest that the link between these problems and the chemical revolution is more than mere coincidence. Researcher Mary Wolff of Mount Sinai School of Medicine found that the tissue of women with breast cancer had unusually high levels of DDE, a breakdown produce of DDT. A German study reported elevated levels of PCBs in women suffering from endometriosis.

Other researchers studying fertility problems in men found that those with the weakest sperm often had the highest concentrations of PCBs in their semen. But not as high as that of a breast-fed baby. Because these chemicals are fat-soluble, they concentrate in fatty breast milk. Infants take in more synthetic hormones while nursing than at any other time in their lives.

"The dose they get postnatally [from breast milk] is much greater than the prenatal dose," said Joseph Jacobson, a psychology professor at Wayne State University in Detroit. Jacobson studied the development of children whose mothers ate PCB-tainted fish from Lake Michigan. Infant formula, on the other hand, is made with vegetable fat and contains few synthetic chemicals. Cow's milk also has relatively low contaminant levels, because cows eat low on the food chain.

But in spite of its beefed-up chemical load, breast milk may indeed be harmless. The problem is, no one knows. Studies in Michigan and North Carolina showed no immediate effects in children nursed by mothers with high levels of PCBs and DDE in their milk. Problems in the infants were linked to exposure in the womb.

Jacobson. working with Dr. Walter Rogan of North Carolina, found that mothers with high levels of PCBs and DDE gave birth to children who developed slowly, physically and mentally. "The fetus is much more vulnerable [than a breast-fed baby]," Jacobson said.

Yet he and Rogan admit they don't know the synthetic hormones' full effects. Their subjects were young children. Many of the problems associated with synthetic hormones -- sterility, cancer and miscarriage -- do not strike until adulthood.

Rogan did find that at age 14, children who had been nursed still had higher levels of contaminants in their blood than those who had been bottle-fed. "I suspect your levels remain high throughout life," he said. So should moms forego the breast for the bottle?

Surprisingly, researchers give a resounding no. They're still unsure of breast-feeding risks, but have no doubt about its many benefits. "I nursed my three children and if I still had young children today, I'd nurse them," said Linda Birnbaum, executive director of toxicology at the Environmental Protection Agency's health effects lab. "I think the benefits outweigh the potential risks."

Breast milk not only meets all of an infant's nutritional needs, it also gives her mom's disease-fighting antibodies. Breast-fed babies suffer fewer bouts of diarrhea and ear infection than bottle-fed babies. Studies also show that they perform better on intelligence tests and talk earlier than average.

"I stand firmly, 100 percent behind breast-feeding," said Betty Crase, director of the Center for Breast-Feeding Information at La Leche League International. "Babies who've been breast-fed are still healthier and still have a higher I.Q."

If breast is indeed best, infants of mothers heavily exposed to hormonal contaminants may be getting too little milk. Rogan and his colleagues found that high levels of estrogen-mimicking DDT shut off women's milk supplies early. "We see a difference in the duration of lactation of almost 40 percent between mothers with low levels and those with high levels," Rogan said.

In the United States, cutting nursing short may cause little harm. But in third-world nations, where clean water may be scarce and formula unaffordable, it could be disastrous. "Human milk is the one thing that keeps these [impoverished] babies alive," Crase said. "Babies could end up sicker without breast milk. More would die." Crase worries that publicity about the dangers of hormonal contaminants will scare women away from breast-feeding. Her organization encourages women to minimize their contaminant risk by avoiding pesticides and cutting down on animal fat during pregnancy and lactation.

Jacobson's research suggests that women should follow that advice even before becoming pregnant. "Our data suggests it's not so much what you eat during pregnancy," he said, "but over your whole lifetime."

Theo Colborn, senior researcher at the World Wildlife Fund in Washington, contends that Peltier and other mothers shouldn't have to weigh the benefits and risks of something as natural and wholesome as breast-feeding. She is calling on the government to delve into the long-term effects of exposure. "These are long-term studies that have not been done," she said.

By the time her second child was born, Lori Peltier knew all about synthetic estrogens in breast milk. Yet, she still chose to nurse. "I was convinced I was doing the right thing," she said. "I still believe the benefits outweigh the risks."

Contacts: La Leche League International. 1400 N. Meacham Road, Schaumburg, IL 60173/[phone]; American Academy of Pediatrics, 141 Northwest Point Road, Elk Grove Village.. IL 60007/ [phone].