Is indoor pollution a growing problem or are we simply looking for it more, or better equipped to monitor it now than in the past?

The answer: All of the above. There's no doubt that the energy crisis of the 1970s--which resulted in more tightly sealed offices and homes, sacrificing ventilation for heating and cooling efficiency--exacerbated the indoor pollution problem, says Buckley. Greater reliance on construction materials that emit gases such as formaldehyde may also be a contributing factor.

At the same time, gains have been made, says Buckley. Levels of benzene added to gasoline have been cut in half, perhaps reducing the amount of this gas that penetrates living and working spaces. Carbon tetrachloride, once found in many spot removers and shown to be a carcinogen in animals, is being or has been phased out.

What's clear is that we as a society are probably more conscious of the environmental contaminants and the health problems they can cause.

One factor is the methodology. "It's really [extending] the limits of what we can measure," says Buckley. With state-of-the-art mass spectrometry, researchers can detect individual molecules of a chemical. But the problem is, what does that mean? Is a molecule harmful? "Is it enough to pose a health risk?" asks Buckley.

As an example, Buckley refers to the growing use of chemicals called brominated flame-retardants, used to coat mattresses, kids pajamas, and many consumer electronics. Relatively little is known about their toxicity, although they are similar in structure to PCBs, says Buckley. What is potentially alarming is that their chemical structure indicates that they persist in the body for a long time. A recent Swedish study showed levels of the compounds in breast milk rose exponentially over a 25-year period. The rub is that these flame-retardant chemicals are not regulated by EPA or anywhere in the world, says Buckley.

"We're beginning to understand that there are other effects of chemicals we haven't tested for before," says Thomas Burke, co-director of the Risk Sciences and Public Policy Institute at the School of Public Health. For example, researchers now suspect that some chemicals may cause subtle changes in immunity, reproduction, and cognition. They are investigating links between environmental exposures and attention deficit disorder, Parkinson's disease, Alzheimer's disease, and auto-immune diseases such as lupus.

Pesticides are one example. "In the past, we felt that the effects to the user were small (except for poisonings)," says Burke. "But now we're becoming more sophisticated at understanding subtle effects in unborn children and the development of the brain."

"So is the sky falling? No," says Burke. "But there is a lot in consumer products we don't know about. I think it is very important that we know more." -MH