The University of Michigan University of Michigan School of Public Health study of candles purchased from stores in southeast Michigan shows that some candles on the market today are made with wicks that have either lead or lead cores that emit potentially dangerous levels of lead into the air.
The study is by Jerome Nriagu, a professor of environmental health sciences, who examined lead emissions from 15 different brands of candles made in the United States, Mexico and China. He also examined the concentration levels of lead that lingered in the air in an enclosed space, such as a room measuring 12 feet by 12 feet and 10 feet high, after one hour and then again for five hours.
Nriagu's study showed that lead emission rates for the candles ranged between 0.5 and 327 micrograms per hour. After burning the candle for one hour, the lead levels in the air of an enclosed space were estimated to range from 0.04 to 13.1 micrograms per cubic meter, which compares to the US Environmental Protection Agency recommendation of 1.5 micrograms per cubic meter for ambient air. After one hour, five of the candles Nriagu tested emitted unsafe levels of lead into the air that measured greater than 1.5 micrograms per cubic meter.
After five hours, the lead levels in an enclosed space ranged from an estimated 0.21 to 65.3 micrograms per cubic meter. Candles produced in China and the United States released the highest levels of lead into the air. Regular exposure to lead in this manner in confined spaces could pose health risks to people with weak immune systems, especially children and the elderly, Nriagu said.
"Lead poisoning remains one of the most serious environmental health diseases in this country and other parts of the world. It affects many organ systems and biochemical processes with the most serious sequelae often occurring in the central nervous, cardiovascular and blood systems," Nriagu said.
Nriagu's findings are consistent with an Australian study due to be published in the journal Science of the Total Environment. In that study, Mike van Alphen of Lead Sense, an independent consultancy in Australia involved in environmental lead testing, lead exposure investigations and consumer product testing, examined a single brand of candle sold in Australia. The candle he examined released up to 1,130 micrograms of lead per hour.
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.
Not all candles are made with wicks that have metallic cores. The practice is primarily used with candles that are needed to burn longer, such as scented or ceremonial candles. A metal core is used to provide rigidity to the wick, which provides an even and slower burn rate, and to reduce the mushrooming at the tip. Since lead and its alloys melt at relatively low temperature, a large fraction of the wick core material is volatilized as the candle is burned.
"Because it is costly and difficult to control lead once it is released to the environment and medical treatment does not fully reverse the health effects, the optimal strategy for minimizing the risk involves the reduction or elimination of exposure in various forms. This study shows that there are still other important domestic sources of lead exposure that have escaped public scrutiny and legislative control. Leaded candles were recently banned in Australia, and we recommend a similar action in this country," Nriagu said.
Written by: University of Michigan
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