Discussion- Precautionary Principle

The environmental controversy for this week revolved around the use of paper or plastic bags, and whether the consumer should have to pay for them. Plastic bags are thought to harm the environment, and thus raise several different issues. Along with this issue comes the "precautionary principle." This principle does not directly involve the plastic bag debate, but follows similar arguments. The "precautionary principle" states that all new chemicals and technologies should be assumed to be harmful until proven otherwise and that all commercial products that are suspected of being harmful must be removed from the market until studies can demonstrate that they are safe. Advocates of the principle argue that when dealing with chemicals and technologies, it is better to be safe than sorry. Critics reply that nothing is absolutely safe and that the precautionary principle is unrealistic and would seriously hinder the development of needed drugs, pesticides and other products. Furthermore, the costs of thoroughly testing all controversial chemicals and technologies to prove their "safety" would be prohibitive.
What do you think of these statements? With whom do you agree or disagree and why?