The regulatory struggle has gone on all fall, with the grain handling and flour milling industries tugging the Occupational Safety and Health Administration one way and labor unions pulling the other. At issue is OSHA's upcoming proposal to prevent explosions in the nation's 15,000 grain elevators.

This week, OSHA moved in labor's direction, circulating a second draft of its proposed grain elevator safety standard with a new requirement that operators clean up immediately if the grain dust gets as deep as an eighth of an inch. That provoked a lobbyist for the National Grain and Feed Association to drop by the office of OSHA rulewriter Thomas Seymour two days later to register his objection.

In theory, the rule they are wrangling over doesn't even exist. But in fact, such negotiations go on throughout government daily.

Although formal procedures for evaluating evidence and comments don't take effect until a rule is published, what appears in the Federal Register seldom comes as a surprise to those who care deeply about it.

"Oftentimes regulations that are written have a lot of flaws in them because the people writing them are not familiar with the industry they're attempting to regulate," said Tom Klevay of the Millers' National Federation. "Circulating the drafts early can possibly eliminate some technical errors.

"Once it's published some of the more controversial areas can be argued in further detail--the miscellaneous stuff that is less meaningful will be taken care of already."

But since it's easier to get a draft changed than a formal proposal, all sides want OSHA to tailor the whole draft to their liking before it is published.

That explained the optimism of AFL-CIO safety expert Debbie Berkowitz as she talked of the latest version, and the more sober tones of James Maness of the grain and feed group and Klevay of the millers' federation.

Labor unions have waged a campaign for a standard that would require grain dust to be kept under a specific level. Loose dust in elevators can act like gunpowder, magnifying small fires or explosions into lethal blasts. The more dust in the air, the bigger the blast.

In the last five years, 132 explosions have killed 108 people and injured 310, according to Berkowitz, whose colleagues favor a more restrictive standard limiting accumulations to 1/64th of an inch.

Industry trade groups counter that no level of dust is safe and setting unrealistic cleanup requirements could lead to a rash of "nuisance citations." "Our basic philosophy is that it's extremely difficult to establish a number that dictates safety in the facility," said Maness.

OSHA's original draft, circulated three months ago, focused on controlling potential ignition sources--cigarettes, loose wiring and overheated machinery. It set no minimum dust level, in part because officials feared they could not defend a minimum level in court when studies showed no level was safe.

In addition, preliminary figures by the accounting firm examining the rule's economic impact indicated that clean-up costs would be unacceptably high if a low minimum dust level were established.

When Berkowitz and her colleagues got wind of that, they offered up information on other ways the dust could be cleaned up that reduced the cost estimates substantially. "There are less expensive ways to do things we might not have known about earlier," said one OSHA aide who requested anonymity. So OSHA's draft this week contained a provision for an "action level" of one-eighth of an inch of dust.

But if labor won on dust levels, it gave up ground on other fronts. The draft also contained new sections giving smaller elevators an extra three years to meet the standard.