Parents who inhale coal smoke at home may put their babies at increased risk of birth defects, Chinese researchers say.
Zhiwen Li and colleagues at the Peking University Health Science Center in Beijing found that the odds of having malformations of the brain and spine known as neural tube defects are 60 percent higher for children whose mothers inhaled coal smoke than for the children of unexposed mothers.
A 2004 report by the World Health Organization estimated that 90 percent of rural households worldwide use coal and biomass fuel (such as wood, charcoal and dung) for cooking and heating. While coal is relatively inexpensive compared to other energy sources, there are known health risks associated with breathing coal smoke, including lung cancer and other respiratory diseases.
"The indoor air pollution caused by coal and biomass burning at home is a major public health concern, especially given the very large numbers of households that rely on these fuels" said Dr. Beate Ritz, an epidemiologist at the University of California, Los Angeles, who was not involved in the new study.
Coal smoke contains many chemicals known to cause health problems, including arsenic, carbon monoxide and lead. Coal smoke has many similarities to cigarette smoke, explained Kirk Smith, a professor of global environmental health at the University of California, Berkeley.
Some 70 percent of Chinese households rely on coal or biomass fuels and coal use in particular has tripled in the past 20 years, note the Peking University researchers in the American Journal of Epidemiology.
They focused on four rural counties in Shanxi Province in China, where many residents use coal for cooking and heating their homes and where the rate of 10 to 20 cases of neural tube defects for every 1,000 births in some counties represents one of the highest in the world.
For comparison, the U.S. rate of neural tube defects, which include spina bifida, a paralyzing deformation of the spine, is about 1 in 1,000 births.
The researchers collected information on coal use and other exposures for parents of 610 infants with neural tube defects and 837 healthy infants. Overall, nearly 90 percent of infants with neural tube defects lived in a house that used coal for cooking, compared to just over 80 percent of infants without the defects.
Infants were also more likely to have neural tube defects the higher their mothers' exposure to coal smoke, which is often a good indicator of a link between an apparent cause and an effect.
Nonetheless, the study does not prove that exposure to burning coal produced the birth defects, merely that there is some association between the two.
Smith said the results of the study do provide further evidence that coal causes significant health problems and should be replaced by other fuel sources. "Coal can't be burned cleanly...it should be banned from all household use," he told Reuters Health.
Advocating biomass fuel as an alternative, Smith pointed to the potential benefits of "taking a dirty non-renewable fuel and substituting a clean renewable fuel." Biomass can be burned cleanly in a special stove that costs as little as $80, Smith explained, which may prevent future health problems for millions of people.