The Maryland Department of Environment is investigating how and why a container of trash from the SCM Chemical Co. plant at Hawkins Point set off radioactivity alarms at the BRESCO incinerator Friday.
The load of trash, which was found to be slightly radioactive, was returned to SCM's property and is being analyzed, said Mike Sullivan, a spokesman for the department.
"We found very low levels of radioactivity -- only one-half of a millirem," Mr. Sullivan said, explaining, "the average X-ray exposure is 20 to 30 millirems, and the health standard is 100 millirems per year. . . . This is not a particularly serious situation."
Mr. Sullivan said the investigators believe some filters that had caught radioactive materials were then thrown out.
But, Mr. Sullivan noted, the chemical plant isn't licensed to generate radioactive trash.
The SCM plant, with about 800 people, turns iron smelting residue into titanium dioxide, an ingredient of white paint, paper and plastics.
The plant does have state permission to use three machines with radioactive measuring devices. But those devices are protected, and shouldn't leak, Mr. Sullivan said. Besides, he said, the devices use cesium, while the radioactivity detected Friday was generated by radium.
The state could fine SCM for generating radioactive trash. But since the kind of radium discovered in the filters is common in nature, it is possible the plant was mistakenly shipped some contaminated ores, Mr. Sullivan said.
Steve Tomczewski, BRESCO plant manager, said the alarm that rang was a "very sensitive" screening device that tests every truck entering the Russell Street facility.
The alarm is tripped only once or twice a year on average, Mr. Tomczewski said.
SCM officials said they were puzzled by the radioactivity, but had hired a firm to survey the plant for radioactivity.
The ores they receive from Canada "have extremely low radioactivity levels," said Donald D. Knapp, SCM's vice president for technology.
The company has been using the ore and the plastic filters for years without a problem, Mr. Knapp said.
Although the container of trash was rejected by BRESCO, Mr. Knapp said SCM could send it to a landfill because the level of radioactivity was so low.