Studies have shown that the central nervous system of children is particularly sensitive to lead. Some of the most damaging neuropsychological effects of lead poisoning of young children include learning disabilities, reduced psychometric intelligence and behavioral disorders. These effects have been associated with chronic low-level exposure to lead and are believed to be irreversible.
Nriagu's study measured the rate of lead emission in a laboratory setting using a flux chamber. The lead released as candle fume was collected in nitric acid and analyzed by means of an atomic absorption spectrometer. In addition to measuring emission rates, he calculated concentration levels of lead in the air in an enclosed space after one hour and then again, for five hours.
"The half-life of lead in air obviously would make a difference in terms of it being inhaled. A recent study has shown that particles emitted by candles during a normal burn are sub-micron in size and should remain suspended in the atmosphere for some time. Even if a particle is deposited after only a short trajectory through the atmosphere, it adds to the lead burden in the house dust. Airborne lead represents a hazard in more ways than one," Nriagu said.
House dust is widely recognized as a primary route of childhood lead exposure through hand-to-mouth activities.
"Assuming that only 50 percent of the lead released is deposited in an area
measuring 12 feet by 15 feet (such as a living room), we estimate that the
loading of the lead to house dust will exceed the U.S. EPA guideline of 100
micrograms per square
Contact: Amy Reyes
University of Michigan