Monitoring around Hanford's tanks of highly radioactive wastes may be inadequate to protect workers from potentially toxic chemicals released from the tanks, a state investigation concluded.

Too little is known about what chemicals are in the vapors, and monitoring equipment may be inadequate for some chemicals, according to a letter sent Friday to Energy Secretary Spencer Abraham. It was signed by Washington Gov. Gary Locke and Attorney General Christine Gregoire.

"Data regarding chemical constituents and vapors within the tanks is incomplete, the data is not managed in a manner that allows a comprehensive assessment of the waste composition and the data lacks recognized quality assurance," the letter said.

The state started an investigation in response to a report released by the Government Accountability Project, or GAP. It showed a significant increase in the number of workers at Hanford reporting exposure to vapors from the tanks as work has progressed to empty nearly all liquid wastes from the tanks.

The massive underground tanks holding wastes from the past production of plutonium at Hanford vent vapors through filters to the atmosphere.

Some workers have reported nosebleeds, sore throats, dizziness and increased heart rates after breathing different mixes of up to 1,200 chemicals in the tanks, according to the watchdog group GAP.

The state is recommending that workers in the fields, or "farms," where the tanks are buried wear scuba-style, supplied-air systems until more is known. DOE also is investigating.

The state is recommending a thorough analysis by trained industrial hygienists or toxicologists to understand worker exposure issues, said Sheryl Hutchison, spokeswoman for the state Department of Ecology.

CH2M Hill Hanford Group, which operates the tank farm for DOE, began temporarily requiring workers in the older, single-shell tank farms to wear the supplied-air equipment in April. Earlier, it had banned the use of supplied air systems, saying they limited workers' vision and made them more likely to trip.

DOE also should require that data used to analyze chemical vapors is managed better, according to the state. "It's not apples to apples," making it difficult to use to assess worker risk, Hutchison said.

Workplace monitoring and characterization of chemicals in the tanks is based on chemical data that is "sparse or incomplete and of questionable accuracy," said a report accompanying the letter. The report was prepared by the state Department of Ecology.

Data is stored in numerous unconnected databases by various contractor organizations, making a comprehensive assessment of the composition of tank waste difficult, the report said.

A central database is available to contractors, but the data is minimal, lacks adequate quality assurance and is limited to a handful of the chemicals that may be present in the tanks, the report found.

Insufficient data exists regarding the gases trapped within the tank wastes to identify what potentially toxic chemicals might be in the data, according to the report. The state also could not determine whether enough was known about how vapors might disperse when wastes are disturbed as tanks are emptied.

The report was critical of monitoring that measured the total amount of organic vapors from the tanks without determining specific types. Some Hanford tanks may contain organic compounds that are toxic at very low levels, the report concluded.

CH2M Hill has maintained that workers may have had unpleasant symptoms, particularly from ammonia in the vapors, but have not had permanent damage to their health.

Work is stopped in the tank farms when chemicals are detected at levels far below allowable industrial standards, according to CH2M Hill.

Company officials had not seen the letter and report Monday and could not comment, said spokesman Bryan Kidder. DOE's Office of River Protection also had not received the report Monday, said spokesman Eric Olds.

In addition to the Department of Ecology's assessment of chemical vapors, the Washington State Department of Health looked at whether the vapors included radioactive particles from the tanks. It concluded that none of the radiation exposures at the tank farms in 2002 and 2003 were due to vapors.

Twenty-one workers were contaminated with radiation from the tanks. The maximum dose to a worker was 188 millirems to the skin and 28 millirems internally. DOE has a standard of 5,000 millirems per year for workers.