The Labor Department was petitioned yesterday to move at once to lower the risk of lung cancer for thousands of uranium miners in the West.

The hazard comes from radon daughters -- radioactive decay products of uranium that cling to dust or moisture particles inhaled by miners.

The petition was filed by the nonprofit Health Research Group (HRG), which is financed by Ralph Nader's Public Citizen, and the Oil, Chemical and Atomic Workers International Union. More than 900 OCAW members are among the growing number of uranium miners, currently estimated at 6,000 to 7,000.

The petition asks the Labor Department's Mine Safety and Health Administration (MSHA) to issue an emergency temporary mandatory standard to cut sharply the allowable exposure of miners to radon daughters.

The yardstick for an individual miner is known as a working level month (WLM) -- 173 hours of exposure in a month to a specific amount of radiation in the air of mine.

Under the petition, the allowable annual exposure would be 0.7 WLM. The current allowable exposure is 4 WLM, or 5.7 times as much. That level, the National Institute of Occupational Safety and Health (NIOSH) said in May 1976, "cannot be characterized as safe since the risk of lung cancer would be expected to double after 10-20 years of employment."

NIOSH hasn't formally requested MSHA to rule the 4 WLM standard unsafe, but its conclusion, published in an official bulletin, "constitutes a statement favoring a new standard," HRG director Sidney M. Wolfe said in a letter to Labor Secretary Ray Marshall.

The cause-effect connection between exposure to radon daughters and lung cancer is made "especially clear" by NIOSH and National Cancer Institute studies of 3,366 white uranium miners who had worked in the mines before 1964, Dr. Wolfe said in the letter to Marshall.

The data show that as of the latest followup of the miners through December 1978, the number found to have died of lung cancer was 205. Under normal circumstances, only 40 of the men would have been expected to die of the disease. Thus the number of "excess" deaths was 165, and the relative risk to which the miners were exposed was 5.1 times normal.

In addition followups of 780 American Indian uranium miners showed 11 deaths -- 4.3 times the 2.6 expected deaths.

"Thus, in American uranium miners, there have already been an excess of 173 lung cancer deaths in 4,146 miners, with the number rapidly rising as the latency period between the initial exposure and the present gets longer," Wolfe wrote.

He said the current allowable standard, which figures out to a cumulative exposure of 120 WLM in a 30-year stint in the mines, is "clearly associated with increased lung cancer as admitted by NIOSH and MSHA. Their opinions are based on a number of studies showing increased lung cancer in workers with lifetime exposures of considerably less than 120 WLM."