The likelihood of former and some current Hanford workers getting cancer or leukemia is being looked at in a 14-nation study.

That study is expected to be completed in 2000, and takes a statistical step forward from a similar 1994 study, said Jack Fix, a Pacific Northwest National Laboratory staff scientist speaking at a Hanford health conference in Richland.

About 175 people attended the conference Wednesday and Thursday, which featured several sessions on public health, workers' health and ecological health matters pertaining to Hanford.

The conference was coordinated by the University of Washington and was sponsored by a number of agencies, schools and organizations interested in Hanford.

In one session, Fix discussed a 1994 study by the International Agency for Research on Cancer at several nuclear-related sites in England, Canada and the United States to look for links between radiation exposure, and cancer and leukemia.

The sample of 95,673 workers -whose medical records stretch from the 1940s to the late 1980s -contained 5,976 who died of cancer and 119 who died of leukemia.

The study showed no association between radiation exposure and the cancer deaths.

But the same study showed more people receiving higher radiation doses died of leukemia, but a direct cause-and-effect could not be firmly established.

Also, the sample of 119 leukemia victims was small and presented statistical reliability problems.

So now the International Agency for Research on Cancer is conducting a second similar study on about 500,000 workers in nuclear fields spread across 14 countries - a much larger statistical sample. That is expected to be done in 2000, said Fix, who is on the project's dosimetry committees.

Hanford workers were included in both studies. Also at the conference, Roger Dirkes, PNNL's project manager for surface environmental surveillance, discussed which radioactive substances from Hanford appear in greater amounts downstream from the site compared with upstream readings.

Radioactivity in the Columbia River could come from upstream of Hanford; come from Hanford but dissipate or decay quickly; or flow south from the site.

PNNL's observations in 1996 noted four radioactive substances from Hanford that have flowed south to Richland or McNary Dam - all in tiny concentrations.

Iodine 129 and tritium from Hanford have been found in samples near Richland. But those substances were in concentrations that were tiny fractions of state water quality limits, Dirkes said.

Meanwhile, strontium 90 and cobalt 60 were found in tiny amounts on fine silts collected near McNary Dam. No state limits have been set on these substances in river silt.

None of these substances has increased in concentrations over the past several years Dirkes said, noting they are decaying.

PNNL and other agencies tracking contaminants in the river are keeping an eye on the subterranean radioactive substances in central Hanford seeping toward the river, Dirkes said. Estimated travel times range from 20 years to 100 years, giving scientists ample time to prepare to track them if and when they reach the river, he said.