The first major revision of the nation's pesticide control law in a decade is headed for President Reagan's desk with praise from lawmakers and lukewarm support from environ-mentalists.

"After 10 years we've seen a major breakthrough," Agriculture Committee Chairman Patrick J. Leahy, D-Vt., said at a news conference Wednesday following Senate approval on a voice vote.The measure cleared the House last week, and sponsors expected no problem with the administration over the measure, which would accelerate safety reviews of potentially hazardous chemicals sprayed on crops.

The bill, designed to speed the banning of pesticides too dangerous for use, would set a nine-year deadline for finishing Environmental Protection Agency reviews of some 600 active pesticide ingredients.

Completion of the work would not come until the year 2024 at the present pace, according to the General Accounting Office.

The bill also would take a sizeable financial load off taxpayer shoulders and hand it to pesticide manufacturers. Most government indemnities to companies for banned chemicals would be phased out. The industry would pay for the safety reviews as well as a large portion of storage and disposal costs.

The measure also would reauthorize for three years the 1947 Federal Insecticide, Fungicide and Rodenticide Act, which got its last face lift in 1978. Since then, a decade of efforts to speed up the safety reviewing process has produced nothing more than political snarls.

Environmentalists have been calling for tightened pesticide controls for more than two decades amid evidence that some of the 2.6 billion pounds a year of chemicals sprayed on crops can cause cancer, birth defects and other health problems. Eventually, the pesticides find their way to American dinner tables.

Lawmakers did not paint the bill as a full-scale answer to the pesticide issue. Missing was any effort to cope with the problem of pesticide contamination of groundwater, which provides the basic drinking supply for an estimated 113 million Americans.

Seventy-three pesticides have been reported in groundwater in 34 states, the Capitol Hill-based U.S. Public Interest Research Group reported recently after examining EPA records. The agency says it is now trying to determine the extent of contamination with a nationwide survey.