2 reports on this study: Science Direct and Associated Press
From Science Direct: Source: University Of North Carolina School Of Medicine
Posted: November 29, 2001
CHAPEL HILL - Children who grow up breathing polluted air may be at increased risk of lung disease, according to a study of school-age children in Mexico.
Researchers reached that conclusion after evaluating standard chest x-rays of 241 southwest metropolitan Mexico City children and another 19 from a small coastal town. The city children were exposed daily to high levels of a variety of pollutants, compared to the absence of such pollution in the coastal town comparison group.
The new research is being presented Thursday November 29th in Chicago at the 87th Scientific Assembly and National Meeting of the Radiological Society of North America.
The study investigators were led by Dr. Lillian Calderon-Garciduenas from the department of environmental sciences and engineering at UNC-CH and the National Institute of Pediatrics in Mexico City and Dr. Lynn A. Fordham, associate professor and section chief of pediatric imaging at the University of North Carolina at Chapel Hill School of Medicine.
"These were a large number of very healthy, middle-class children who received excellent health care. Dr. Calderon screened out any of the candidate children with asthma," Fordham said. "While I think these are preliminary findings, they appear to have important implications for the effects of air pollution on the lungs of otherwise healthy children."
Fordham points out that the chest x-rays from Mexico were interpreted by radiologists at UNC who had no knowledge of where the children lived. "We looked at the kids in a blinded fashion and with no knowledge of Dr. Calderon's project," she said. "We were able to separate out those who were exposed to air pollution and those who were not."
Excessive inflation (hyperinflation) of both lungs was found in 63 percent of the city group. About 52 percent of the city children showed an abnormal amount of interstitial markings in their lungs, changes that may be predictive of future lung abnormalities.
The study also found abnormalities in CT scans obtained in 25 of the children whose chest x-rays were the most abnormal. Mild wall thickening of bronchial air passages was seen in 10 CT's, four showed unusually prominent central airways, eight children had air trapped in their lungs, and one child had a lung nodule.
Further statistical analysis pointed to a significant link between hyperinflation, interstitial markings and exposure to the polluted atmosphere of southwest metropolitan Mexico City. All children in the Mexico City study group lived within a 10-mile radius of a pollution monitoring station and ozone levels were recorded for the year the children were recruited into the study. On average, during the 20-month study period, ozone levels exceeded air quality standards more than four hours per day. Some small particles of solids, or particulate matter (PM), were above U.S. standards.
"The children studied were very active, and many of them spent hours playing soccer in the later afternoon - when pollutant levels are at their peak," Fordham said. "I think the study may contain findings that are concerning to parents. They indicate that air pollution may cause lung disease in children. Children might be safer staying indoors in the after-school hours on days when ozone levels are high."
Thursday, November 29, 2001
By Tammy Webber, Associated Press
CHICAGO - Some children who appear in perfect health have measurable lung damage from exposure to air pollution, researchers found, suggesting such damage could lead to lung disease.
Past research has found that children living in polluted areas have higher rates of lung diseases such as asthma. But a new study is the first to use X-ray imaging to measure changes in children with no symptoms of lung problems, the researchers said.
Chest X-rays of 241 children in Mexico City were compared with those of 19 children living in a small coastal town. Throughout the 20-month study, smog levels in Mexico City exceeded U.S. air quality standards for more than four hours a day on average. Particulate matter, tiny pieces of soot and other materials in the air, also was above U.S. standards.
Researchers found 63 percent of the Mexico City children had excessive inflation of both lungs, said Dr. Lynn Ansley Fordham, an associate professor of radiology and chief of pediatric imaging at the University of North Carolina School of Medicine. In addition, 52 percent of the urban children had abnormal numbers of interstitial markings, fine lines that could indicate inflammation along the airways, Fordham said. CT scans of 25 children with the most abnormal X-rays found 10 with mild thickening of the walls of the bronchial airways, 8 with air trapped in their lungs, and 4 with unusually prominent central airways. One child had a lung nodule.
In the coastal town, one child had mild over-inflation of the lungs. The rest had no damage.
Lung damage could be a precursor to problems such as pulmonary disease, but the findings also might point to a reliable way to test children early, before lung disease develops, Fordham said. "X-rays are a relatively inexpensive, easy-to-obtain screening for children," said Fordham. "You can find (problems) and do something for those kids."
Fordham said some of the children might be helped by vitamins, better diet, and staying inside when air pollution is at its peak.She and Dr. Lilian Calderon-Garcidueana of the University of North Carolina and the National Institute of Pediatrics in Mexico City presented the study Wednesday at the Radiological Society of North America's annual meeting.
Joel Schwartz, an environmental epidemiologist at Harvard's School of Public Health, said other research has indirectly linked air pollution with respiratory ailments. But to find radiographic evidence of lung abnormalities in seemingly healthy children "is pretty unusual," he said. The results "are showing what we suspect: that there are chronic effects that can be seen in the lung that would show up this early ... on X-ray," said Schwartz, who was not involved in the study.
Some of the changes, such as airway thickening, might disappear if the children moved to a less polluted area, "but it would certainly take a long time to reverse," Schwartz said.
Although Mexico City is more polluted than U.S. cities, the results can be generalized to other polluted areas, Fordham said. She said a study on euthanized dogs in Mexico found that those from moderately polluted areas - similar to some areas of the United States - had thickening of the lungs' lining, inflammation, and particulate matter lodged in the lungs. The findings might be more severe in dogs because of their poor diets, but "we presume the same things could be found in people," said Fordham, adding that another study of children in a moderately polluted city is planned.
Fordham said it would be difficult to duplicate the study in the United States because of the high rates of asthma and higher levels of indoor air pollution from such things as carpet and glues, which could skew the results. It also was easier to find Mexican children who had lived in the same neighborhood all their lives.