Correction: Asphalt has much, much less PAH than coal tar sealers

On our story on the hazards of coal tar driveway sealers on page 19 of the April 16 Independent, there was a mistake in the figures on the PAH in asphalt-based driveway sealers.
The correction is for the fourth paragraph, in which we stated that asphalt-based driveway sealers contain 0 – 1% PAHs. The correct figures are 0.005 – 0.01%, about one-thousandth of the concentration of PAHs found in coal tar-based sealers.
Thanks to Dr. David Wilson for straightening that out for us. We regret the error.
We asked Dr. Wilson to explain, in 25 words or less, just what PAH is. He said 33 words are what he needed: “Polycyclic aromatic hydrocarbons (PAHs) are chemicals composed of joined rings of carbon atoms with attached hydrogens. They are common in substances containing coal tar. Many can cause cancer, birth defects, and genetic mutations.”
Dr. Wilson added: “For further information, see the Wikipedia article on polycyclic aromatic hydrocarbons … which, while not an organic chemistry text, is pretty good.”
— Rosemary K. Otzman, Editor