The U.S. Senate unanimously passed a bill yesterday to require tougher safety measures for oil and natural-gas pipelines, hoping to prevent spills and leaks that pollute the environment and sometimes prove deadly. The bill would increase inspections and fines for hazardous accidents and require pipeline operators to disclose more info to government regulators. Still, some safety advocates say the legislation isn’t tough enough. The Senate bill was introduced after a pipeline blast killed three people in Bellingham, Wash., in June 1999, and it was passed shortly after another pipeline explosion killed 12 people in Carlsbad, N.M., last month. Since 1986, there have been more than 5,700 pipeline accidents, killing more than 300 people and spilling 6 million gallons of oil, gas, and other substances. The bill now goes to the House, where its future is uncertain with only 21 working days left in this session of Congress.