Self-interest has an important effect with the desire for free trade because the level of skill demonstrated by workers depends directly on their wages. So unskilled workers continue to receive lower and lower wages through the demand for free trade and the demand for quality workers. As labor standards rise, unskilled workers find fewer and fewer jobs, so they obviously oppose free trade. Environmental concerns stem from environmentalists' belief that free trade would stimulate economic growth and harm the environment. Coughlin goes on to say that people were worried about jobs in the US due to the lack of international environmental standards and this caused gratuitous skepticism.