There is a fundamental disagreement between industry officials and environmentalists over when to ban chemicals that appear to be dangerous to humans. This conflict was played out recently in the Maine Legislature when lawmakers considered a bill to ban brominated flame retardants (BFRs). The chemicals, used to treat upholstery cushions, mattresses and the plastic casings around electronic components to make them flame resistant, have been found in human breast milk and are known to harm brain development in laboratory animals.

If lawmakers want, as industry officials have suggested, to wait until there is definitive evidence that BFRs harm humans, they should not enact LD 1790. If they want to take the more cautious approach of limiting the use of these chemicals before human problems caused by BFRs are documented, they should take a closer look at this legislation, sponsored by freshman Rep. Hannah Pingree of North Haven, and preliminarily endorsed by the Natural Resources Committee.

In this instance, just the consideration of a ban may have an effect. That’s because the European Union and other states have already banned some of the chemicals and others are considering following suit. As a result, some manufacturers have already switched to alternative flame retardants for some of their merchandise.

Rep. Pingree’s legislation, as it stands after some revisions, would phase out three types of BFRs by 2008. By then, the industry may have decided to make the switch on its own. If that is the case, the Maine Department of Environmental Protection would advise the Legislature that the rule is no longer necessary. Either way, Maine citizens win.

The United States is the largest manufacturer and user of BFRs. Studies have found the chemicals in the breast milk of nursing mothers in the United States at concentrations 10 to 100 times higher than in European countries. In laboratory tests, young mice exposed to BFRs had stunted brain development if the exposure occurred at a critical juncture in brain growth.

Such experiments do not mean the chemicals are harmful to humans, industry spokesmen say. “There have been animal studies, but you cannot extrapolate those findings out to human beings,” Peter O’Toole of the Bromine Science and Environmental Forum said earlier this year. It is illegal and unethical to expose humans to toxic chemicals to determine the consequences of such exposure. So scientists routinely test products, medicines and carcinogens on animals as a proxy for humans.

There is also disagreement about what types of BFRs should be banned. Lawmakers and industry officials largely agreed that compounds called penta and octa should be phased out and the only U.S. manufacturer of these compounds already plans to do so. Industry officials maintain that the compound called deca is safe and that no state action should be taken until the U.S. Environmental Protection Agency decides on a ban. Deca, which dominates the BFR market, has been found in the environment and has been shown to break down into other forms including penta, which is more dangerous.

Maine lawmakers will soon have to sort through these competing views and determine which course to follow. Caution should prevail.