As with so many building and decorating materials (think asbestos insulations and lead paint), certain health concerns have surfaced with the use of concrete and granite as food-preparation services. The concerns are not considered to be dire, and both materials have made the news -- granite for emitting possibly unhealthy levels of radon, and concrete for the heavy metals present in some pigments and finishing materials [sources: CBS, Kolich]. And neither one pulls ahead in terms of environmental health. Both products have to be dug out of the ground, and both have the potential to emit polluting particles into the air and water through the grinding and the sealing processes. Producing the cement for concrete produces a lot of greenhouse gasses. Transporting concrete from, say, Italy to New York produces lots of greenhouse gasses, too. (If you're looking for a truly green countertop, best to look to something like bamboo or recycled aluminum.)
Granite and concrete are both high-quality options. Perhaps granite will wear a bit better. Maybe concrete will finally let you have that LED-embedded countertop that looks like a starry sky. No matter which material you choose, you won't get off cheap. Both granite and concrete are going to run anywhere from $50 to $100 per square foot installed. That price will go up with custom concrete built-ins or high-end, single-slab granite. In the end, it's all about your personal needs. If the idea of countertop maintenance chills you to the bone, you might do better with granite. If you're dying to chop some broccoli on a sparkling night sky, concrete's the only way to go.
For more information on concrete, granite and other countertop materials, look over the links on the next page.