Drive around your neighborhood and count the number of “blacktop” driveways – they look innocent enough, right? In fact, they may be just fine, that is, if they are sealed with an asphalt product. But many driveways are sealed with coal tar, which contains hazardous chemicals that can raise your lifetime risk of cancer and contaminate soil and water.
Coal tar sealants contain polycyclic aromatic hydrocarbons, or PAHs, which volatilize into the air (which is why you smell a strong odor in a newly paved parking lot), and wear off and break down into tiny particles that can be tracked indoors on shoes, blown into our homes through screens or washed into surface waters. Scientists with the U.S. Geological Survey (USGS) found these sealants account for about half of the PAHs found in urban lakes.
Many cities and states have banned coal tar sealants and big box stores and national hardware store chains have stopped selling them. But until they are gone for good, you can make sure you are not inadvertently putting them on your driveway by only buying a product with a “coal tar free” logo or asking your contractor to show you the product’s MSDS sheet. Check to see if it contains this CAS number for coal tar: 65996-93-2.
Or go blacktop-free and use pavers or stone. A river stone driveway is beautiful, completely porous, let’s the rain through to recharge groundwater, doesn’t contribute to storm water runoff and supplies children with material for toy dump trucks and is an easy source of stones for forcing paperwhite bulbs!