NEW YORK (Reuters Health) - Children raised in homes heated by coal may suffer stunted growth from prolonged exposure to indoor air pollution, according to a study of families in the Czech Republic.
By age 3, children who lived in households where coal was used for heat were about a half-inch shorter (1.3 cm), on average, than those raised in homes that relied on other forms of heating fuel. The effect on growth was even greater for children exposed to both coal and cigarette smoke at home, according to the researchers, who report their findings in the Archives of Pediatrics & Adolescent Medicine.
Whether these children will catch up to their peers on the growth chart, or if the effect is permanent, is unclear, the scientists said. However, studies of children exposed to cigarette smoke, which stunts growth, show that shorter stature continues into adolescence and possibly into adulthood, said Irva Hertz-Picciotto of the University of California, Davis, who is an author of the new study.
Roughly half the world's population burns coal, dung, wood or crop wastes for heating or cooking, according to the World Health Organization. Indoor air pollution causes up to 1.6 million deaths a year, the group has estimated.
Coal smoke is known to cause lung damage, but the new study "is significant because it indicates there's some systemic effect" on the entire body, Hertz-Picciotto said.
Her group looked at 1,133 children from two regions of the Czech Republic where coal is used widely. The researchers matched growth history of children from their medical records at birth and at 36 months with information collected from household surveys completed by their parents.
Just over 10 percent of the households relied on coal for heating or cooking (of those, about a fifth also used other fuels, such as wood). By age 3, children raised in coal-burning households were about 1.3 cm shorter on average than those raised in homes heated by other fuels, the researchers found. The difference was slightly greater for boys (1.34 cm). Children exposed to both coal and cigarette smoke at home were about 0.8 inches (2.09 cm) shorter by age 3 than those exposed to neither pollutant.
The effect of exposure to indoor coal smoke held even after the researchers accounted for several known influences on physical development in early childhood, such as breastfeeding, parental education -- which reflects the wealth of a household -- and whether the child was born prematurely.
Hertz-Picciotto said she and her colleagues might not have been able to account fully for the effects of economic conditions or household nutrition on childhood development. Even so, she doesn't think socioeconomic status skewed the findings.
Although coal smoke contains many potentially harmful chemicals, such as mercury, arsenic and polycyclic aromatic hydrocarbons, experts said they don't know precisely how these substances might retard growth in children.
One explanation is that the hazardous chemicals could interfere with cells in the growth plates -- areas at the ends of long bones, such as the leg femurs, where the tissue is still expanding -- said Len Horovitz, a lung specialist at Lenox Hill Hospital in New York City who was familiar with the latest research. The substances may also disrupt hormones that regulate proper growth.
"Air pollution is not a good thing, whether indoor or outdoor," Horovitz told Reuters Health. "Cleaner indoor and outdoor air is a mandate that we have seen coming and needs to be addressed."
SOURCE: http://bit.ly/f82bzq Archives of Pediatric & Adolescent Medicine, online February 7, 2011.