It's called the "sniff test," and it represents perhaps the ultimate form of the government's sticking its nose into private industry's business.

But this time it's not private industry objecting to the procedure. It's the owners of the noses.

The noses, about 1,700 of them, belong to federal or federally designated grain inspectors, who check and grade loads of wheat, barley, rye, flaxseed and corn for mold, weevils, animal filth or "unknown foreign substances." When they check the grain, inspectors are supposed to immerse their noses in a grain sample--a time-honored method of detecting contaminants.

For several years, labor union safety experts have argued that sniff tests expose inspectors to unhealthy quantities of grain dust and toxic pesticides.

But many people familiar with the procedure contend that there is no mechanical substitute quite as discerning as the human nose. Agriculture Department officials recently have proposed allowing grain to be sifted and aired out before inspection to reduce that risk.

But the American Federation of Government Employes and the American Federation of State, County and Municipal Employes, which represent the inspectors, contend that their members won't be protected unless the grain is pretested to check pesticide levels.

At public hearings held three years ago by the Occupational Safety and Health Administration, witnesses testified that acute exposure to pesticides and fumigants have sent some inspectors to the hospital briefly with such symptoms as headaches and nausea.

Lewis Lebakken Jr., the USDA official fielding comments on the agency's proposal, said yesterday that the unions' joint comment was one of only two negative comments on the agency proposal. The other, he said, was a complaint that the sifting and airing of grain would make the inspections less thorough. He said he did not know when a final rule would be published. Comments are being analyzed at the agency's Kansas City office.