A cancer-causing chemical used to seal pavement, paring lots and driveways is showing up in dust in American homes, and at alarming levels, claims a new study.

The class of chemicals, polycyclic aromatic hydrocarbons or PAH, are a significant component in coal tar. Coal tar is a waste product of steel manufacturing. One of the principal PAH chemicals, benzo[a]pyrene, has long been regarded as a deadly carcinogen.

A study commissioned by the United States Geological Survey compared house dust from 23 ground-floor apartments in Austin — 11 with coal tar-sealed parking lots and 12 coated with other substances, or not sealed at all. The study found that dust in the apartments next to the coal-tar-sealed lots had  pollution levels 25 times higher, on average, than the other lots.

More than half the apartments with the coal tar-sealed lots had dust with levels of PAHs that would increase the risk of cancer if ingested by preschoolers, the researchers said. The dust inside several suburban homes in the Austin area were also examined and found to contain benzo[a]pyrene thousands of times the level that would trigger a cleanup at a toxic-waste site.

Children are at greatest risk to these kinds of chemicals because they have a higher metabolic rate, they get a bigger dose per pound of body weight, their organs are still developing and they play on or near floors where carpets concentrate and retain toxins. Emerging evidence also suggests that babies exposed to PAHs while in the womb may be more prone to asthma and other ailments and may have lowered IQs.

Source: InvestigateWest