In a letter to base residents dated April 6, 75th Air Base Wing Commander Scott Chambers said one home in which troubling high levels of the potentially dangerous chemical compound were found has been vacated and will remain so "until the PCBs can be removed."

Health effects associated with PCB exposure include acne-like skin conditions in adults and neurobehavioral and immunological changes in children, according to the national Centers for Disease Control.

Hill first found the chemicals, which once were used as coolants and lubricants but which have been banned since 1977, during routine soil testing in December and January while doing routine testing in preparation for a renovation of about 50 duplex-style housing units.

In a more comprehensive round of testing of surface soil samples in the same housing area, including several taken at the location in which the highest PCB concentrations were first discovered, officials were unable to replicate the earlier levels. But in his letter to residents, Chambers said a third round of testing had revealed "the highest levels of PCBs in the soil we have seen since we began our sampling effort."

He called that discovery "a source of concern" but noted that the high-level sample came from a single source and that most of the other samples taken in the area have shown much smaller concentrations.

"Your safety and health is my number one priority," Chambers added.

The state Department of Environmental Quality is monitoring the continuing analysis. About 100 families live in the area being analyzed.

mlaplante@sltrib.com