Scientists told a Senate subcommittee yesterday that it is difficult, if not impossible, to find uncontaminated milk for newborn infants.

Human breast milk increasingly contains pesticide residues and other chemical contaminants that can cause cancer and other diseases, they said, while harmful lead deposits often are found in infant formulas.

And cow's milk, itself a major source of the contaminants found in human breast milk, is also a major contributor to childhood allergies, they told the Senate subcommittee on Health and Scientific Research.

The problem is that in this "period of industrial chemistry, we are beginning to reap the penalty of acute and chronic poisoning," said Dr. William B. Weil Jr., professor and chairman of the Department of Human Development at Michigan State University.

"As we have contaminated our environment, we have contaminated our bodies and in doing that we have contaminated human breast milk," he said.

Well said though "human breast milk has been, and still is, an excellent nutritional basis for infant feeding . . . we now find that liquid may contain pathogenic bacteria and viruses, opiates, salicylates, barbiturates, antibiotics, lead, mercury, arsenic, and a host of fat soluble chemical poisons."

Weil was one of nine witnesses to testify yesterday before the subcomittee, which is holding two hearings this week on the "implications of contamination of mothers' milk with pesticides and industrial chemicals." The second hearing is scheduled Friday.

Sen. Edward M. Kennedy (D-Mass.), chairman of and subcommitee, said the purpose of the hearings is not to discourage breast-feeding. Instead, "We feel that individual families should have all the information they need to make personal decision about the merits of breast-feeding their infants. We hope this session will aid in that educational process," he said.

Yesterday's testimony seemed to indicate that there is no method of milk-feeding an infant that does not have its risks.

For example, the Environmental Defense Fund - a Washington-based, private research group-presented a report that said pesticido residues, ingested through the consumption of vegetables and meals, are usually present in human milk more frequently and in higher levels than in cow's milk."

Many of those chemical residues - chlorinated hydrocarbons like DDT, dieldrin, and chlordane - cause cancer in test animals and therefore present a risk of cancer in human beings," the fund's reports said.

In addition to posing a careinogenic risk, ingestion of these pesticides can produce other chronic effects including liver damage (and) nervous system disorders . . .," the EDF report said.

"While under normal circumstances EDF would support a parental decision to breast feed a child, these are not normal times so this recommendation will have to be tempered," said the EDF report, entitled "Birthright Dented: The Risks and Benefits of Breast-Feeding."

A report by the Environmental Protection Agency noted that black women in the rural South were found to have levels of DDT contamination in their milk that were six times higher than those found in middle-class urban whites. Both black and white rural Southern infants in the study were ingesting [WORD ILLEGIBLE] of DDT through their mothers milk at rates higher than maximum daily intake levels recommended by United Nations agencies, EPA said.

But both the EPA and EDF studies said there was not enough evidence to say how, or if, the ingestion of the pesticides was affecting infants.

Indeed, the EDF noted that "allergic reaction to [cows] milk can be life-threatening for an infant" and that although a substitute infant formula may not be contaminated with chlorinated hydrocarbons as frequently as human milk, formulas contain their own set of contaminants which may pose serious health problems."

"Of immediate concern to all of us is what do we say to women who ask:

"Should I breast feed my baby under these circumstances'" Weil testified. "I have no easy answer," he said. "I really don't even have a good complicated answer."