What could be more American than a glass of milk? Cow's milk, that is. In light of this common perception, the time is long overdue to add the milk mustache to that ever-growing list of American myths. Human beings are not designed to drink any milk except human milk (only during infancy, of course). As you'll see below, consuming dairy products—milk, cheese, yogurt, sour cream, ice cream, etc.—is not green and it's not healthy.
It's also a nightmare for the cows themselves. Here's a little of how the folks at GoVeg describe it: "The 9 million cows living on dairy farms in the United States spend most of their lives in large sheds or on feces-caked mud lots, where disease is rampant. Cows raised for their milk are repeatedly impregnated. Their babies are taken away so that humans can drink the milk intended for the calves. When their exhausted bodies can no longer provide enough milk, they are sent to slaughter and ground up for hamburgers."
The first four are environmental reasons to avoid milk.