AUGUSTA – The Maine House and Senate soon will debate a pair of bills designed to reduce the volume of mercury dumped in the environment.

Floor debate is likely because both bills come from the Natural Resources Committee with members divided over whether they should pass.

One bill backed by seven of the 13 committee members would require automobile manufacturers to pay for a system to remove mercury switches from cars when they are junked.

Recyclers and junkyards would remove the switches and take them to collection centers, which would pay bounties of at least $1 per switch. The cost to manufacturers to pay for the collection system and payments would be about $1.5 million over a decade, according to the bill’s supporters.

Environmentalists say Maine’s auto fleet carries about 1,500 pounds of mercury in 850,000 mercury switches. Mercury exposure has been linked to nerve, immune system and heart problems.

A separate bill would require the phaseout of all mercury thermostats from residential and commercial buildings by 2006. It was scaled back from a version that called for the phaseout of all products containing mercury.

It is supported by nine members of the Natural Resources Committee.

Competing versions advanced by some committee members seek more studies into the mercury-switch recycling and phaseout plans.

Maine already has enacted a ban on mercury thermometers, which took effect in January.

Most auto manufacturers already have stopped using mercury switches in their models, and electronic thermostats are widely available as an alternative to mercury types.