The real killers

The biggest cause of lead pollution may be incinerated waste, not vehicles

Published: Monday 15 March 1999

 Smog over New York: incinerat (Credit: usis)the conventional notion that vehicles are the main cause of atmospheric lead pollution may be wrong, according to new evidence gathered by us researchers. A recent study shows that the primary source of lead pollution in New York City is actually incinerated waste rather than leaded gasoline.

The findings may spur a rethink of the causes of urban pollution, and its impact on environmental policies around the world, particularly in developing countries such as China where the incineration of solid waste is on the increase.

The study also questions the assumption that the introduction of unleaded gasoline resulted in falling atmospheric and blood lead levels in the 1970s and 1980s. Some experts feel that this may be due to the fact that after unleaded gasoline was introduced in the us , pollution shifted from vehicles to incinerated waste. However in India the scenario may be different. The quality of gasoline used is very poor. Thus, vehicles continue to be the primary cause of lead pollution

Researchers from Columbia University, Rensselaer Polytechnic Institute and the New York Department of Environmental Conservation examined sediments from New York's Central Park lake. Such sediments provide a profile of the city's atmospheric make-up dating back to 100 years.

The study showed that the amount of lead released into the atmosphere reached a peak from the late 1930s to the early 1960s, decades before the highest levels were recorded from leaded gasoline emissions. The peak coincides with the massive expansion of incinerator operations in the city, say the researchers.

Even when leaded gasoline emissions peaked around 1970, the sediments clearly show that they only 'contributed a relatively small fraction of the total lead deposited at the site'. Lead researcher Steven Chillrud of Columbia University said: "Solid waste combustion has been underestimated as a source of atmospheric lead and other contaminants." High atmospheric levels of zinc, tin, cadmium, antimony and possibly silver are also primarily caused by municipal waste burning, he added.

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