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Uroboros Glass' facility between the Fremont Bridge and Interstate 5.

(Google Streetview)

This post has been updated to clarify the status of Harriet Tubman Middle School.

A second Portland company on Monday voluntarily suspended using cadmium to make colored glass, days after state environmental regulators released a map showing high concentrations of the carcinogenic metal were found nearby.

Uroboros Glass, which manufactures colored glass used in art, sits on the fringe of one of two cadmium hotspots in Portland. Federal scientists studying metal concentrations found in tree moss made the discovery last year, detecting levels of cadmium that far exceeded state safety targets.

"We don't feel like it's really clear that we're the responsible party, but since we use cadmium we'd rather be on the safe side," said Eric Lovell, Uroboros' president. "Even if we were emitting all that cadmium by ourselves, it's hard to figure out why it'd concentrate a half-mile away."

A map of two cadmium air pollution hotspots in Portland released Friday. The Oregonian has added the location of a second glass manufacturer, Uroboros Glass, which announced it was suspending cadmium use in its glass.

A map released Friday by the Oregon Department of Environmental Quality shows two hotspots for cadmium pollution in Portland.

The largest is in Southeast Portland, where the agency said it believes another manufacturer, Bullseye Glass, was responsible. Bullseye announced last week it was immediately suspending use of cadmium and another metal, arsenic, which was also detected in high concentrations.

The other hotspot sits between Interstate 5 and the Fremont Bridge. The cause isn't clear. Uroboros isn't as centrally located in the nearby hotspot as Bullseye Glass is in the Southeast Portland one.

Sarah Armitage, a state air toxics specialist, said last week two glass companies were close to the northern hotspot: Uroboros and National Engravers Inc., formerly known as Ostrom Glass. She said the state didn't know whether either was responsible.

National Engravers' building sits closer to the center of the northern hotspot than Uroboros. But company owner Gary Tinker said the two-employee company doesn't use heavy metals. It etches glass for trophies inside an enclosed cabinet.

"We're just a simple trophy manufacturer," Tinker said. "I'm not involved in anything hazardous - thank God."

Uroboros doesn't use arsenic, but it has used cadmium for years, Lovell said. The metal is used to make red, orange and yellow glass. The Department of Environmental Quality contacted the company in 2009 after air monitoring at nearby Harriet Tubman Middle School found unusually high cadmium levels. The school later closed, but is being used this year to house students from the Faubion School.

Lovell said his company compared its cadmium use to the days when the Tubman monitor found high levels. Some days, Uroboros had melted cadmium. But many days, the monitor detected cadmium when the company hadn't used it. No clear correlation was established.

Uroboros is consulting with an environmental company to see whether air models would project its emissions to drift west toward the center of the hotspot. Lovell said that would surprise him. After working at the site at 2139 N. Kerby Ave. for 30 years, he said, "the wind comes at us from that direction almost all the time."

The Department of Environmental Quality hasn't announced any plans to monitor the air nearby, but has said it would investigate.

The company's emissions aren't monitored, Lovell said, because it doesn't use enough cadmium to need an air pollution permit.

State environmental regulators are participating in a community forum Tuesday from 5 p.m. to 9 p.m. at the Cleveland High School cafeteria, 3400 S.E. 26th Avenue, Portland, OR 97202. More information is here.

Correction: This post was updated to clarify that Harriet Tubman Middle School is housing students from Faubion School this year. It had been closed.

-- Rob Davis

rdavis@oregonian.com

503.294.7657