The approximately one billion gallons of used oil generated in the United States each year comes primarily from lubricating oils motor and transmission oils and from hydraulic and cutting oils used in industry.
The researchers found that selling untreated used oil as an inexpensive fuel, the most common method of managing used oil in the United States, causes significant emissions of heavy metals like lead and zinc.
There are three primary ways of managing used oil: About 14 percent of old oil is re-refined; 11 percent is treated and recycled for heating fuel; and 75 percent is resold, without treatment, as fuel oil to industrial consumers. It's the latter that presents the biggest problem, according to the authors of the new study.
"We have the oil changed in our cars, but what happens after that [oil] is out of sight and out of mind?" asks Bob Boughton, a researcher with the California Department of Toxic Substances Control and lead author of the paper. "Only 10 percent of the more than 100 million gallons of used oil generated each year in California is recycled to produce useful lubricants, just as paper is recycled to produce paper again."
Boughton, along with Arpad Horvath, Ph.D., from the University of California, Berkeley, compared the environmental impacts from each of the three ways of managing used oil, focusing on used oil data from California in 2002.
They found that, while the three ways of handling used oil were equal in their effects on ozone depletion and global warming, emissions from the untreated used oil fuel contained significantly higher levels of zinc, lead, co
Contact: Michael Bernstein
American Chemical Society