BPA and the Precautionary Principle

On Morning Edition this morning, NPR spent several minutes covering the issue of BPA and the Precautionary Principle. The story does a good job of capturing the tension between the need to protect public health and the complexities of interpreting the precautionary principle. Guest on the program, Ted Schettler defines the Precautionary Principle as such "When there are credible threats of harm from some proposed activity, precautionary action should be taken even if some cause-and-effect relationships are not fully understood."

And there is the rub. How do we establish the point at which the evidence of risk from correlational research is sufficient to justify government regulation of some product or activity? The situation is obviously complicated by the fact that the product or activity in question may be very profitable to an industry or the activity might be very popular among many voters.