Study Suggests New Link Between Air Pollution and Infant Deaths

While risk is fairly small, researchers say finding is troubling

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By Randy Dotinga
HealthDay Reporter

WEDNESDAY, Aug. 9, 2006 (HealthDay News) -- New research into the fates of infants exposed to the smoggy air of Los Angeles provides yet another link between air pollution and respiratory illness and death in babies.

Only a tiny number of infants in the study actually became ill or died from lung-related problems, but the researchers found the infants were more likely to do so if they had recently been exposed to high levels of air pollution. The babies were also at somewhat higher risk of dying from sudden infant death syndrome, or SIDS.

Study co-author Michelle Wilhelm said the meaning of the research is clear. "It just adds to the body of evidence showing that exposure to high air pollution can lead to infant death," said Wilhelm, an adjunct assistant professor of epidemiology at the University of California, Los Angeles.

Wilhelm and her colleagues examined the records of 19,664 infants who died between 1989 and 2000 in California's South Coast Air Basin, which includes much of the area in and around Los Angeles, including parts of Orange, Riverside and San Bernardino counties. About three million babies were born during that time in the area.

For each infant who died, the researchers found 10 living infants to use as comparisons. Then, they examined the local levels of air pollution for all the babies at two weeks, one month, two months and six months before the deaths occurred.

Overall, only about two infants per 10,000 died of respiratory-related illnesses. But according to the researchers, the risk of respiratory death more than doubled in infants aged 7 months to 12 months who were exposed to "high average" levels of very small particles of pollution known as particulate matter.

The risk of dying of SIDS went up by 15 percent to 19 percent for every 1 part per hundred million increase in average nitrogen dioxide levels at two months before death.

The researchers also found that younger infants were more likely to suffer higher rates of death from respiratory illness if they were exposed to higher levels of carbon monoxide two weeks before death.

The study findings were published in the August issue of the journal Pediatrics.

Wilhelm acknowledged that the number of deaths from respiratory disease was still very small despite the heavy air pollution in Los Angeles, considered one of the smoggiest places in the country. Still, "the potential for disease prevention through further air pollution abatement may be substantial since millions of infants are exposed to similar or greater air pollution concentrations worldwide," she said.

Dr. Rachel Moon, a pediatrician and SIDS specialist who's familiar with the study, questioned whether other factors could affect the respiratory health of the infants, such as whether they spent time outdoors or were exposed to cigarette smoke. "That would have a huge impact on their pollution exposure, (but) none of this was measured," said Moon, of the Children's National Medical Center, in Washington, D.C.

As for the seemingly higher risk of SIDS, Moon said researchers already knew that tobacco exposure is a major risk factor, possibly due to tiny particles that get into the lungs.

What's next? Dr. Jonathan Grigg, professor of pediatric respiratory and environmental medicine at Queen Mary's School of Medicine and Dentistry in the United Kingdom, said the current methods of research into the effects of air pollution on infants are "still very crude."

Ideally, he said, researchers would actually put portable air-monitoring devices on infants to get more reliable numbers.

More information

To learn more about air pollution and its effects on your health, visit the American Lung Association.

SOURCES: Michelle Wilhelm, Ph.D., adjunct assistant professor of epidemiology, University of California, Los Angeles; Rachel Moon, M.D., associate professor of pediatrics, George Washington University School of Medicine and Health Sciences, Washington D.C.; Jonathan Grigg, M.D., professor, pediatric respiratory and environmental medicine, Academic Division of Paediatric, Institute of Cell and Molecular Science, Barts and The London, Queen Mary's School of Medicine and Dentistry, United Kingdom; August 2006, Pediatrics

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