In 1973, Suzanne Prosnier and her family moved into a neat suburban home in Scottsdale, Ariz., across the highway from some cotton, lettuce and sugarbeet fields.

Almost immediately her 10-month-old baby began to waken at night, writhing in pain. Her 10-year-old son complained of severe chest pains. A daughter stopped menstruating. Another son developed an ulcerated throat. Their dog began to vomit and its forelegs became paralzyed.

In the years since, the family's medical problems have continued: rectal bleeding, pneumonia, severe heaches, gastrointestinal disorders hives, bronchial asthma. Prosnier's sixth child was born with a hydro-cele (enlarged head) - the first abnormal birth in the family.

Prosnier and another Scottsdale housewife, Susan Watkins, told a House Commerce subcommittee yesterday that more than 300 people in a 6-mile-long area have suffered similar problems, which they attribute to aerial drift from pesticide spraying on nearby farmland.

Their testimony, which lawnmakers termed "troubling" "shocking" and "incredible," is the latest against involuntary exposure to chemical spraying.

Citing public concern over pesticide spraying for control of brush in western forests, gypsy moths in Virginia and West Virginia, and spruce budworm in Maine, the Environmental Protection Agency's assistant administration, Steven Jellinsek, said, "Citizens are asking for assurances of safety . . . and are seeking privacy from chemical instrusion in their lives."

Jellinek promised the subcommittee that "EPA will in the future be requiring more and early public notice of broad-scale spray programs." In an interview later, he said the agency is "very concerned" about the Scottsdale reports and will begin a monitoring study to see if buffer zones should be established between fields and houses.

Prosnier, who helped form a People's Environmental Organization for Pesticide Legislation and Engorcement, said citizens have been unable to reform spraying practices because EPA has delegated pesticide enforcement to state agricultural agencies dominated by farm and industry interests.

"When I called the Arizona State Pesticide Board to explain what was happening to us . . . the man with whom I spoke told me what was being sprayed was no more harmful "than table salt or aspirin," Prosnier testified.

However, she said, the combined effect of chemicals that have wafted from nearby farms into her home - including Toxaphene, Paraquat, Galecron, Azodrin, Bolstar, Orthene, Parathion and others - "may result in a poison far more toxic than the orginal compound."

Dr. John E. Davies, a University of Miami professor and expert on presticide health effects, testified, "There are a wide variety of health-related effects which stem from current pesticide usage practices, the nature and magnitude of which is ill-understood and incompletely investigated.

Environmentalists have charged over the years that week pesticide-control laws and poor enforcement can be blamed on the fact that House and Senate Agriculture committees, rather than committees with public health responsibilities, have jurisdiction.

To explain why EPA has not removed more potentially dangerous pesticides from the market, Jellinek said, "Congress has added more and more procedural requirements to the cancellation process that call for additional layers of agricultural and scientific review and economic impact analyses."

He added, "Congress had made clear that the benefits of pesticide use are to be given as much weight and consideration as their potential risks." Last year, he said, Congress passed amendments allowing applicators to use pesticides at higher concentrations, regardless of label directions - which could increase spray drift.

Susan Watkins, who moved to Scottsdale last year, told the subcommittee her two-week-old son fell ill shortly after the move with projectile vomiting, diarrhea, hoarse coughing and severe nervous seizures.

Her 10-year old daughter began to suffer recurring chest pains. "At times, the pain was so bad she couldn't stand up and at night I could hear her crying and moaning." She, her husband and another daughter have also had acute medical problems - all of which disappeared miraculously during a month they spent in Dallas. She attributes the problems to pesticide spraying. CAPTION: Picture, Suzanne Prosnier and Susan Watkins of Scottsdale, Ariz., at House hearing on involuntary exposure to chemicals. By James K. W. Atherton - The Washington Post