The Post's editorial Sept. 4 suggests that the American Petroleum Institute helped delay issuance of a new benzene standard of 1 ppm (one part benzene to a million parts of air) by arguing before the Supreme Court that the government had failed to prove "that benzene was a significant risk."

The fact is that in our court brief (filed July 30, 1979) the API forthrightly acknowledged that exposures to high levels of benzene are dangerous.

In the brief, the petroleum industry said:

"Because benzene has been exhaustively studied, far more is known about its health effects than most other chemicals. Short-term exposure to high benzene concentrations (over 250 ppm) can result in 'acute' reactions ranging from headache to rapid death at levels of about 20,000 ppm. Long-term exposure to levels above the present 10 ppm standard can produce 'chronic' toxicity, including bone marrow depression, aplastic anemia, pancytopenia and chromosomal changes.

"For many years, there has been evidence (including unsystematic population studies and case reports dating back as far as 1897), that exposure to high benzene concentrations (in excess of 100 ppm) can cause leukemia. None of these studies or reports, however, associated benzene concentrations below 100 ppm with the development of leukemia."

These statements are solid proof that the petroleum industry has long been aware of the need to limit its workers' exposure to benzene. Workers in this industry now, and for more than a decade, have generally been exposed to levels well below the new standard of 1 ppm announced Sept. 1 by the Occupational Safety and Health Administration.

However, the API continues to maintain, as it did during OSHA's 1986 benzene rulemaking proceeding, that there is substantial uncertainty about any health benefit from lowering benzene exposure levels below 10 ppm. Moreover, the API demonstrated during the rulemaking that the risk assessments preferred by OSHA are flawed because they understated historical exposures to benzene and overstated current exposures.

The API agrees with the OSHA finding that "employers who carry out the provisions of the (new) standard conscientiously may have confidence they are protecting their employees, and employees working for such employers can feel confident that they are receiving substantial protection."

WILLIAM F. O'KEEFE

Vice President, American Petroleum Institute

Washington