The Seante voted yesterday to block until May 1 the Carter administration's tough new rules for controlling cotton dust in mills and textile plants.

It also voted to instruct Health, Education and Welfare Secretary Joseph A. Califano Jr. to cut $2 billion from his department's spending by reducting waste, fraud and misuse of programs.

The votes came as the Senate debated the $56.5 billion appropriations bill for HEW and the Department of Labor.

Tha new cotton-dust rules, the subject of a bitter internal adminsitration struggle, were put into effect, Sept. 4, but the amendment, sponsored by J. Bennet Johnson Jr. (D-La.) delays them until May 1. The rules were issued to limit workers' exposure to cotton dust, which can cause crippling "brown lung" disease.

Johnston said the delay will give congressional committees more time for study of cotton-dust dangers and will prevent implementation of new requirements that could cost the cotton inudstry up to $2.6 billion and raise the price of cotton from 44 to 61 cents a pound.

Johnston, stating that the cotton industry, which includes 90,000 farms growing cotton and 160,000 related jobs, could be economically crippled by the new regulations, at first proposed to block the new rules for the fiscal year beginning Oct. 1.

When other senators objected, a compromise of May 1 was reached.

The amendment, which is not in the House bill, was another attack on the Occupational Safety and Health Administration is the Labor Department.The agency has said 35,000 workers are suffering from crippling "brown lung" and 150,000 others have less severe symptoms of the disease. The Labor Department estimates the cost of compliance at $656 million.

Under the Sept. 4 rules, the existing limit of 1,000 micrograms of cotton dust per cubic meter of air in mills and other cotton processing plants would eventually be reduced to 200 from mills, 700 for weaving establishments and 500 for other places where workers are exposed to the dust. Johnston said the new standards are 7 1/2 times more severe than those in effect in West Germany.

Sen. Wendell H. Ford (D-Ky.), who represents a leading tobacco state, sought to cut out $4.5 million asked by Califano for his antismoking campaign, but withdrew the amendment after opposition from Sen. Birch Bayh (D-Ind.) and others. As a compromise, senators said Califano will be instructed to use the $4.5 million for smoking-information programs focused on children.

The senate also accepted an OSHA amendment by Bob Dole (R-Kan.). which provides that a business shall not be fined for any violation of OSHA work-safety rules involving any industry if it had consulted before hand with state work-safety experts and had made a good-faith effort to found there. This provision would apply only to non serious, nonwillful and nonrepeated violations.

Debate on the bill, including a highly controversial antiaboration amendment, continues today.

The amendment instructing Califano to try to cut $2 billion in waste from his department was offered by Sen. Harry F. Byrd (Ind.-Va.). The bill's floor manager, Sen. Warren G. Magnuson (D-Wash.), made clear that the $2 billion is not an absolute figure, but only a goal to be reached if Califano finds it possible to eliminate that much waste and fraud.

The House voted a similar amendment, with $1 billion as a goal. The language makes clear that the cut is not intended to reduce legitimate Social Security, welfare and Medicaid payments or to slash authorized allotments to states for education, health and welfare.