AUGUSTA — Gov. John R. McKernan on Thursday vetoed a bill that had been hailed by environmentalists and labor groups as a means to curb the use and release of toxic chemicals in the workplace.

An attempt to override the toxics veto collapsed in the House, but advocates of another vetoed bill, seeking to restrict state investments linked to Northern Ireland, won more than enough votes to override. They applauded as the 104-38 tally was announced and the bill moved to the Senate which was to consider it Friday.

McKernan said the toxics bill would have put costly and burdensome reporting requirements on small businesses, forcing them to develop plans to reduce use of chemicals without regard for their toxicity, and would have forced large companies to reduce emissions of 308 chemicals that were not regulated by the Department of Environmental Protection.

“Before we impose such burdensome requirements on Maine businesses, we must compile the information that is needed about the cost of meeting such goals,” McKernan said in his veto message. “Moreover, we have yet to determine whether there are mechanisms or techniques for industries to comply with these reduction requirements.”

McKernan also turned down proposals to repeal the planned “homestead exemption” tax break and to require state-supervised safety inspections at large industrial or commercial facilities that abruptly replace more than half of their workers. Both vetoes were sustained.

McKernan said the goal of reducing the use of toxics and hazardous waste was laudable, but he said the bill that had been passed by the Legislature was not responsible legislation.

McKernan submitted another bill that would address only the reduction of hazardous waste, but the Democratic majority in the House refused to consider it.

McKernan said in his toxic-bill veto message that he was directing the DEP and the Maine Emergency Management Agency to investigate and report on toxic use and emissions in industrial facilities to decide whether more restrictions on toxics were needed to protect the health and safety of Maine people.

Sen. Judy C. Kany, D-Waterville, Senate chairman of the Energy and Natural Resources Committee, said another bill was being prepared with the same general goals of voluntarily reducing the use of toxic chemicals and the production of hazardous waste, and requiring reduction in the release of chemicals into the environment.

“Perhaps more than any other bill in the last several years, this is important to the state’s future,” said Kany. “This is more important than recycling. I’m surprised he (McKernan) didn’t understand the need for it. I thought he wanted a reputation as an environmental governor.”

After a brief debate, the House voted 84-60 to overturn the toxic bill veto, but that fell short of the necessary two-thirds majority, so the veto was sustained without its being debated in the Senate.

Rep. Michael Michaud, D-East Millinocket, House chairman of the Energy and Natural Resources Committee, argued on behalf of the toxic-reduction bill, which had been promoted by a diverse collection of environmental, labor and public-health groups.

“People are sick in Maine, especially of lung disease, in mill towns around the state,” said Michaud. “Companies that use these poisonous chemicals should be planning to reduce their use of them.”

The Maine Chamber of Commerce and Industry had fought tooth and nail against the toxic-use reduction bill, saying, among other things, that it could give state regulators the power to force production changes on business.

Jack Dexter, president of the state organization, said it was difficult for industry to even measure, much less reduce, the amount of chemicals that were lost into the environment in production — paint that evaporated or spilled while a ship was painted, for example.

The Northern Ireland bill, which is similar to one that McKernan vetoed two years ago, calls for the state and the state-employee pension fund to withdraw investments from American companies that do not adopt a set of non-discriminatory policies known as the MacBride Principles.

McKernan said the MacBride Principles, which include a call for increased job opportunities for minority Catholics in Northern Ireland, are “not at issue in my decision.” Rather, he said he has “serious reservations” about using the pension money “to promote any campaign of social policy in other nations,” especially one that he said lacks strong support from the people it is supposed to help or from the international community.

McKernan’s veto of the homestead exemption bill was sustained in the Senate, with an override supported by only 16 of the 33 senators who voted — less than the required two-thirds majority.

The bill would have shifted money earmarked for the homestead exemption, which is designed to directly reduce Maine residents’ property taxes, to the municipal revenue-sharing program, which benefits towns and cities.