The Unified Community Advisory Board, which discusses groundwater-contamination issues, will discuss the 1,4-dioxane situation and the city's planned cleanup effort at its next meeting. The meeting starts at 5:45 p.m. July 20 in the activity center of El Pueblo Neighborhood Center, 101 W. Irvington Road.
'EXCEEDINGLY LOW' RISK
The risk from drinking the groundwater from a Tucson treatment plant that contains 1,4-dioxane is "exceedingly low" at the levels found there, EPA toxicologist Gerald Hiatt said Wednesday.
Typically, the EPA's goal for groundwater-contamination cleanup is to keep the risk level to between 1 and 100 chances in a million of getting cancer, Hiatt said.
In the Tucson situation, the level of dioxane presents about 3 chances in 1 million of getting cancer, he said. Another way of looking at it: The Tucson level would be expected to cause about three more cases of cancer per 1 million people over a lifetime than would otherwise occur.
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DID YOU KNOW
TCE (trichloroethylene) and TCA (trichloroethane) are industrial solvents that were used to clean airplanes and parts by the Air Force, its contractors and other businesses working mostly in and around Tucson International Airport as long as 50 to 60 years ago. Among them was Hughes Aircraft Co. (now Raytheon Missile Systems).
The chemical 1,4-dioxane was used to stabilize TCE. Dioxane is also used in many products such as shampoos, cosmetics and lotions.
A city treatment plant has been cleaning the TCE and TCA from the water for a number of years but its equipment can't remove the dioxane.
