Kirk R. Smith links cooking with biomass to low birth weight

A study of babies born to mothers cooking with wood, dung, or straw has confirmed early reports of an association between household use of biomass cooking fuels and reduced birth weight.
 
COEH faculty member Kirk R. Smith, working with an international research team at the East-West Center in Honolulu, analyzed demographic, socioeconomic, and health information for a random sample of mothers in Zimbabwe who had given birth in the years 1993-98. Unlike babies born in most developing countries, those in Zimbabwe routinely have their weights measured at birth. In all, the researchers analyzed 3,559 births.
 
Results of the analysis showed that babies born to mothers cooking with biomass fuel weighed about six ounces (175 grams) less than babies whose mothers were using propane, natural gas, or electricity.
 
An earlier study of women and newborns in Guatemala had found that babies born to mothers using wood fuels weighed less than those whose mothers cooked with gas or electricity. Similar results have been found for mothers exposed to active and passive tobacco smoke.
 
The study in Zimbabwe, to be published in the Annals of Epidemiology, provides further evidence that cooking with unprocessed biomass fuels, which produces a large number of air pollutants that are hazardous to health, especially respiratory health, can also increase the risk of adverse pregnancy outcomes. Low birth weight (below 2,500 grams or about 5.5 pounds) puts children at risk for childhood ill health and early death.
 
In light of these findings, the researchers called for more investigation to measure the relationship of indoor smoke exposure and birth weight more directly.
 
Smith's research group at UC Berkeley is piloting methods in their Guatemala research for doing such direct measurement. "If we know how much impact a certain level of indoor air pollution has on birthweight," Smith explained, "it will be possible, for example, to decide whether building a chimney will help, or whether that won't reduce levels enough to make a difference."
 
Mishra V, Dai Z, Smith KR, Mika L (2004) Maternal exposure to biomass smoke and reduced birth weight in Zimbabwe. Annals of Epidemiology, in press. Summary