When parents think about their children's exposure to environmental risks, they might think of lead, pesticides or grass pollens. In fact, the greatest environmental exposure for most children is television. They spend more time watching television than in any other wakeful activity, and it affects their health and well-being in significant ways. For too long parents and even pediatricians have asked: "Is television good or bad?" Television is inherently neither; it's time to move beyond such black or white thinking. Television is a tool. Whether it is good or bad for children depends on what they watch and how they watch it. Used carefully for children older than 2, TV need not have untoward effects at all. According to recent studies, it even can exert a positive influence. By and large, however, it is not being used carefully. By and large, parents are clueless about the content and consequences of the media-saturated world their children inhabit. Content is the critical factor in the effects of TV on children. Watching "Sesame Street" or the Discovery Channel is not the same as watching "Grey's Anatomy" or "Desperate Housewives." Yet, 95 percent of American children watch programs that are produced for more mature audiences. This trend is a cause for concern when you consider that children, who use media to learn about culture, typically lack the knowledge and experience to recognize what is unrealistic.