There are different types of approaches. Some of the laws of environment come out of the Public Health Committee of the Congress. Public Health Committee tends to claim to protect public health irrespective of cost. The Clean Air Act set one example. On the other hand, Toxic Substance Control Act basically says we have to balance the benefit of new chemicals to society versus their adverse health consequences. This Act comes out of the Commerce Committee not out of the health committee.

Clean Air Act:

http://www.epa.gov/compliance/civil/federal/caa.html

Toxic Substance Control Act:

http://www.epa.gov/compliance/civil/federal/tsca.html