Leading the Effort to Identify and Prevent Chemical Toxicity in Children

Over the past 20 years, childhood lead poisoning and its effects on children's mental health have declined dramatically in the United States due to limits on lead in gasoline, paint, food cans and other consumer products.

Dedicated EIS officers such as Philip Landrigan first documented the effects of lead poisoning on American children, forever changing public perception and policy.

"When I first came into the EIS in 1970, CDC didn't have an environmental component. The Environmental Protection Agency had not yet been established. Environmental health was not a term that really had reached public or medical consciousness," Landrigan recalls. "Most people at the time had an inaccurate view of what constituted safe blood lead levels. People thought that either you had a terribly serious, often fatal illness or you were okay. There was no gray in between."

Landrigan, a Harvard Medical School-educated pediatrician, played an important role in debunking those preconceptions. In the winter of 1971, he headed to El Paso, Texas, at the urging of the county health department to investigate possible health effects of low level exposure to lead in children living near a large lead smelter. Landrigan knew something about lead poisoning. As a resident at Boston Children's Hospital, he had treated children with lead poisoning caused by paint ingestion. He was joined by EIS officer Steve G. Gehlbach (EIS 1970), a close friend and also a pediatrician from Boston.

The two doctors first reviewed the county's data on environmental contamination. They found high levels of lead in air, soil and dust. Then they visited nearby child care centers to take blood samples. Their initial studies revealed that 60% of the children 10 years or younger living within one mile of the smelter had lead poisoning, with blood lead levels greater than 40 micrograms. "The norm for this level of lead absorption for the entire U.S. population was about 5-10%, so this was a very abnormal situation," says Landrigan, who decided to remain with CDC to finish the research he had begun.

He extended his EIS service another year and returned to El Paso in the summer of 1972 to lead an investigative team of 10 EIS officers. Their research, which was published in The New England Journal of Medicine in 1975, concluded that lead emissions from the smelter were a key source of lead poisoning in children in the community. They found that the children had absorbed lead by inhaling it from the air and by ingesting it through hand-to-mouth contact from dust and soil, which explained why younger children tended to have much higher levels of absorption compared to older children. Further studies revealed that the children with the higher lead exposure had lower IQs and had problems with their behavior and reaction time compared to children from the same community with lower lead levels.

"This research and similar research elsewhere showed that there is a spectrum of lead toxicity. At the high end, coma and convulsions resulted, but at the lower levels, there is still damage to the brain, which shows up as loss of IQ, slowing of reaction time, hyperactivity, short attention span and inability to concentrate on a task," notes Landrigan. "This more subtle, but very real damage has come to be known as subclinical lead poisoning."

"The work we did in El Paso and the work that other people did around the country made us all realize that chemicals like lead could be toxic to children at levels previously thought to be safe. We came to realize that a large number of chemicals, including polychlorinated biphenyls (PCB's), methyl mercury and certain pesticides could all cause injury to children's developing brains."

Landrigan and his team went on to tour 20 different smelters around the United States, taking blood samples from children to document their toxicity exposure. In one lead smelter in Kellogg, Idaho, they found that a staggering 98% of children living within a mile of the smelter had lead poisoning.

"Our lead toxicity research definitely raised public consciousness about environmental hazards and resulted in a lot of favorable changes in public health policy," Landrigan notes. "One very important consequence of our work was the U.S. government's decision in 1976 to take lead out of gasoline. The lead was phased out over a period of many years. As a result of that decision, there has been a 90% reduction in blood lead levels in American children."

In the 1970's, Landrigan and a small group of EIS officers established the Environmental Hazards Activity, today known as CDC's National Center for Environmental Health. Its mission is to study outbreaks of disease caused by exposure to chemicals in the environment. The co-founders included Landrigan, Ed Baker, Malcolm Harrington and Dale Morse, all EIS alumni.

"A lot of energy went into the lead smelter work. We also got involved in studies of pesticide poisoning, toxic chemical spills and cases of contaminated ground water," says Landrigan.

Landrigan continued to work for CDC until 1985 when he left to lead the Department of Community and Preventive Medicine at Mount Sinai School of Medicine in New York, which boasts such prestigious alumni as current CDC Director Jeffrey P. Koplan, and CDC's chief epidemiologist Stephen Thacker. He currently is working with CDC, the EPA, NIH and the Surgeon General's Office to organize an ambitious, multi-year prospective epidemiological study of 100,000 American children. The study, similar in scope to the Framingham, Massachusetts study of adults after World War II that helped document the risk factors of heart disease, will trace the long-term impact of children's health and development from early exposure to chemical toxins.

Landrigan credits his early work at the El Paso smelter with his decision to devote his public health career to the study of chemical pollutants on children's health.

"I continue to believe that the EIS represents a wonderful gateway into a career in public health. A high proportion of people who go into the EIS stay in public health."

Thanks to the landmark investigative work of Landrigan and his EIS colleagues, Americans are more aware of the insidious threat lead and other toxins pose to the most vulnerable segment of the population – children.