The Massachusetts House last night unanimously approved a bill designed to increase the penalties on those who drive under the influence of alcohol.

The Safe Roads Act, if approved by the Senate and governor, would toughen the existing laws on drunk driving, which went into effect in 1982.

Officials said the most important part of the act, sponsored by Rep. L. Salvatore F. DiMasi (D-North End), concerns the breathalyzer test. The new bill stipulates that any driver whose blood measures at least .1 percent alcohol on the breath test would receive an automatic suspension of his driver's license.

A first offender would receive a 60-day suspension; a second offender, a 90-day suspension; and a multiple offender, an 120-day suspension, said Maryanne C. Calia, a staffer on the house's Committee on Criminal Justice.

Unlike the current law, the new bill would make a .10 measurement a crime, said Jonathan Robbins, a spokesman for the Executive Office of Public Safety. He said a .10 on the breathalyzer test means that a person is impaired, regardless of size.

Under the present drinking law, measuring .10 is "usually not enough to arrest someone. You'd have to blow a .10 and be seen weaving around," Robbins said.

In addition, the new bill would stiffen the penalty for refusing to take the test from a 90-day suspension to a 150-day suspension.

Calia said that under the new bill if someone refused to take the test it would be admitted as evidence in court. Currently, if someone refuses to take the test, it may not be mentioned in the court case.

Officials said that the harsher penalties imposed for refusing to take the breathalyzer test will act as an incentive for people to take the test and thus make it easier to convict a person of drunk driving. "Before, it was harder to convict a person if he would not take the test. The new bill would close that loophole," Calia said.

"It seems to me that someone is concealing something if he refuses to take the test," said Rep. Peter A. Vellucci (D-Cambridge).

The Safe Roads Bill comes after many years of combatting drunken drivers, said officials. Robbins said that state and local police have organized extra patrols and road blocks inorder to "get the drunk driver off the road beforehe kills someone." There was a 12 percent drop offatalities attributed to drunk drivers between1984 and '85, Robbins said.

"Society is saying we're sick of carnage on thehighways caused by drunken drivers, especially themultiple offenders," Robbins said. He said that ifapproved, the new bill will make it easier toconvict chronic offenders. "With the new bill,Massachusetts will become one of the tougheststates in the nation to drunken drivers," he said."What we're going after now is the hard-coremultiple offender."

The new bill increases the minimum jail termfor second offenders from seven to 14 days andproposes a 6-month mandatory jail term for drunkdrivers who cause serious bodily injury. No suchprovision currently exists, said Calia.

The new bill also proposes a change in thevehicular homicide rules. Whereas the offensecurrently results in imprisonment from two and onehalf years to 10 years, the new bill stipulates a10-year license revocation for the first vehicularhomicide and a permanent revocation for asubsequent offense.

In addition, under the new bill, a personconvicted of drunken driving would be required tohave at least a six-week alcohol treatmentprogram