The Senate, in a surprise move yesterday voted to exempt small businesses employing about 10 million workers from federal occupational safety and health regulations.

The action, denounced as "tragically shortsighted" by a spokesman for the Occupational Safety and Health Administration, constitutes one of the most serious moves to trim back the reach of OSHA since it was created eight years ago.

Under the proposal, advanced by Sen. Deway F. Bartlett (R-Okla), businesses with 10 or fewer fulltime employes would be exempted from OSHA regulations if they are in industries with an injury-illness rate of less than 7 percent. The Bartlett proposal was approved on a voice vote after opponents failed, 42 to 51, to table it.

OSHA has moved on its own to exempt small business from federal reporting requirements, but has retained minimum workplace standards and investigatory powers.

Congressional and administration sources estimated that 3 million or more small business might be exempt under Bartlett's proposal. OSHA estimated the number of workers who would be affected at 9.5 million, while the Senate Human at 11.7 million.

Barlett's proposal was adopted as an amendment to legislation authorizing Small Business Administration programs for the next fiscal year, and now goes to a conference with the House, which passed the SBA bill without the OSHA provision.

OSHA has been heavily criticized by members of Congress in the past for its treatment of small businesses, but has largely escaped unscathed, with only an exemption for small agricultural operations. Recently OSHA has attempted to improve its image by concentrating on high-hazard industries and dropping so-called "nitpicking" rules.

Bartlett said his intention was "only to provide relief to those small businesses which are burdened most by the plethoza of OSHA regulations but which have compiled the best records so far as occupational health and safety are concerned."

However, Human Resources Committee Chairman Harrison A. Williams Jr. (D-N.J.) said the proposal would deny equal protection from job hazards to workers simply because they work for small businesses, and would permit a hazardous workplace to exist simply because it is part of a generally safe industry.

OSHA spokesman Frank Greer said Bureau of Labor Statistics figures upon which the hazard assessment would be made, are insufficiently precise to isolate safe or hazardous work places and would not focus on health risks like cancer that do not cause symptoms immediately.