Late in the 1950s, Carson turned her attention to conservation, especially some problems that she believed were caused by synthetic pesticides. The result was the book "Silent Spring" (1962), which brought environmental concerns to an unprecedented share of the American people. Although "Silent Spring" was met with fierce opposition by chemical companies, it spurred a reversal in national pesticide policy, which led to a nationwide ban on DDT and other pesticides. It also inspired a grassroots environmental movement that led to the creation of the U.S. Environmental Protection Agency. Carson was posthumously awarded the Presidential Medal of Freedom by President Jimmy Carter.