Three Studies Focus On Air Pollution's Effects On Children

Childhood Cancers Linked to Air Pollution in Early Life

Childhood cancers are strongly linked to pollution from engine exhausts, according to research in the September issue of the Journal of Epidemiology and Community Health.

The postal addresses of 22,500 children who had died of cancer in Britain between 1955 and 1980 were linked to emissions hotspots for specific chemicals, the researchers stated. These were identified from published maps of atmospheric pollution levels.

The chemicals included carbon monoxide (CO), particulate matter (PM), nitrogen oxides (NOx), 1,3-butadiene, benzene, dioxins, benzo(a)pyrene (BaP) and volatile organic compounds (VOCs).

Emission sources, including hospitals, bus/train stations, heavy transport hubs, and oil installations, were located using maps and information downloaded from the internet.

The expected deaths from childhood cancer were plotted against the actual deaths, and the postcodes where they had been born, lived and died were used to calculate distances from the particular hotspots and emissions sources.

The calculations revealed an excess risk of cancer for children living within 0.3 kilometers (km) of a chemical emissions hotspot and within 1 km of an emissions source, such as a transport hub, the researchers said.

1,3-butadiene and CO, both of which are produced by vehicle exhausts, and particularly diesel engines, were among the primary culprits, the findings suggested.

When combined with close proximity to an emissions source, such as a bus or coach station, a child was at 12 times the risk of dying from cancer.

The study suggests that the exposure of a child in the womb and soon after birth to atmospheric pollutants is likely to be the critical period. And he goes on to say that accepted atmospheric safety levels for 1.3-butadiene in the workplace are probably unlikely to protect unborn children from developing cancer. More controls should be placed on the sources of emission, the study concluded.

Low Levels Of Airborne Particulate Matter Increases Children's Likelihood Of Hospitalization For Respiratory Infections

According to a study published in the August issue of Pediatrics (http://www.pediatrics.org), the peer-reviewed, scientific journal of the American Academy of Pediatrics (AAP), more than 6,700 children under age 14 were hospitalized for respiratory infections between 1998 and 2001. Children generally breathe more rapidly than adults, exposing them to higher levels of air pollutants.

A new study, Coarse Particulate Matter and Hospitalization for Respiratory Infection in Children Younger than 15 Years in Toronto: A Case-Crossover Analysis, sought to determine the role of airborne particulate matter on the number of hospital admissions for respiratory infection. Data from the National Air Pollution Surveillance system was used to monitor daily air pollution levels and then compare hospitalization rates for respiratory infections. Boys seem to be affected more often than girls, but overall, even low levels of airborne particulate matter increased the likelihood of hospitalization for respiratory infections.

'Stop And Go' Traffic Increases Infant Wheezing

University of Cincinnati (UC) environmental health researchers have found that 17 percent of infants living near "stop and go" traffic suffer from wheezing.

The researchers said the study is the first of its kind to analyze the effects of "stop and go" bus and truck diesel traffic versus highway traffic on infant respiratory health.

Published in the August issue of the Journal of Allergy and Clinical Immunology (http://journals.elsevierhealth.com/periodicals/ymai), results of the four-year study suggest that the type of traffic and distance from it-- not just traffic volume--are associated with infant wheezing. Previous air pollution studies had not addressed these factors in infants.

"During the first year of life, an infant's lungs and immune system are still developing," said Patrick Ryan, lead author for the study in UC's Department of Environmental Health (http://www.eh.uc.edu). "Overexposure to harmful particulates at such a young age may play a role in the development of allergic conditions."

The researchers tracked the respiratory health of 622 infants living near three traffic conditions: highway traffic, "stop and go" traffic, and areas unexposed to major roads or bus routes. A "stop and go" traffic area was defined as being within 100 meters (about 100 yards) of a bus or state route with a posted speed limit of 50 mph or less.

Research showed that infants living within 100 meters of "stop and go" traffic wheezed twice as often as those living within 400 meters (about 400 yards) of interstates, and more than three times as often as unexposed children.

African American infants living near "stop and go" traffic experienced the highest wheezing rate -- 25 percent.

"Our study illustrates that living within a football field's distance of 'stop and go' traffic puts infants at a higher risk for wheezing," said Ryan. "Traditional wisdom told us that highway traffic was to blame. We now know that's not necessarily the case."

Earlier research has shown that diesel exhaust particles (DEP), breathable particles able to absorb and transport proteins, aggravate rhinitis (hayfever) and asthma symptoms. According to the Ohio Environmental Council, 23 percent of Cincinnati residents live in areas of elevated DEP exposure, deemed "hot spots."

"Our findings reinforce the need to control diesel exhaust emissions," said epidemiologist Grace LeMasters, PhD, professor of environmental health and principal investigator of the study.

This article originally appeared in the 08/01/2005 issue of Environmental Protection.

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