David Platt Rall, 73, a former cancer researcher who directed the National Institute of Environmental Health Sciences for two decades and helped create the scientific field of environmental health, died Sept. 28 in a Bordeaux, France, hospital.

He and his wife, Gloria, residents of Washington, were vacationing when they were injured in an auto accident 10 days earlier. She is recovering from her injuries, friends said.

Dr. Rall, who retired in 1990 as head of the Durham, N.C.-based institute, was a leading authority on toxicology and environmental health.

He was former associate scientific director of the National Cancer Institute in Bethesda and was founding director of the National Toxicology Program, the largest toxicity testing program in the world.

He held the rank of assistant surgeon general in the Public Health Service.

Dr. Rall's 170 published scientific papers were in areas including comparative pharmacology, cancer chemotherapy, pesticide toxicology and drug research and regulation. He chaired or served on a number of interagency and international committees on toxicology and environmental health.

Dr. Rall was a pioneer in the study of how the environment affects health and "established the credibility of our two federal environmental health organizations," said his successor, former Howard University cancer center director Kenneth Olden.

Dr. Rall also had directed the science and environmental health policy project at Physicians for Social Responsibility and was a board member of the Environmental Defense Fund.

Working on behalf of the physicians organization, Dr. Rall campaigned to strengthen laws protecting the nation's water supply against pesticide poisoning.

Under his direction, the institute, part of the National Institutes of Health, released studies showing that asbestos and other fibrous materials stimulate the release of a highly reactive form of oxygen that has been shown to damage lung tissue.

His researchers also developed a strategy for evaluating the carcinogenicity of environmental agents that reduced the need for laboratory animals.

Epidemiologists at the institute also linked asbestos exposure to increased incidence of lung tumors and established that smoking greatly increased the risk of cancer in workers exposed to asbestos.

During Dr. Rall's tenure, investigators found that exposure to very low levels of lead during early childhood could lead to significant delays in cognitive and behavioral development.

Dr. Rall was a graduate of North Central College in his native Naperville, Ill. He received a medical degree and doctorate in pharmacology from Northwestern University. He interned at Bellvue Hospital in New York.

He joined the National Cancer Institute in 1954. His research there resulted in methods for preventing the spread of leukemia to the brain. He became increasingly interested in how anti-cancer drugs tended to be highly toxic when used in effective dosages. That led him to study the impact of chemicals in the environment on people's health.

University of Maryland professor Ellen Silbergeld called Rall "truly the intellectual and ethical founder of modern environmental medicine."

Dr. Rall was foreign secretary for the Institute of Medicine of the National Academy of Sciences, a director of the Environmental Defense Fund, an officer in the international scientific organization Ramazzini, director of the Alliance to End Childhood Lead Poisoning, scientific adviser to the United Auto Workers and scientific counselor to the National Institute for Occupational Safety and Heath.

His first wife, Edith Rall, died in 1987.

In addition to his wife, survivors include two children from his first marriage, Jon Rall of Lake Forest, Calif., and Cate Ertel of Siegsdorf, Germany; a brother, Dr. Edward Rall of Washington; and two grandchildren.

The Associated Press contributed to this report.