ABSTRACT
Considerable scientific evidence has accumulated in the area of risk assessment. The use of physiologically based pharmacokinetic models and biologically based dose-response models gives the appearance that quite precise estimates of risk can be made. In cancer at least, such precise estimates are misleading to say the least.
The most gigantic gap in knowledge in cancer risk analysis today is cross-species extrapolation. It is indeed a pity that the most elaborate and largest cancer testing facility in the world continues to operate without the benefit of using known human carcinogen positive controls. Without such controls to gauge responses the risk accessor cannot possibly hope to quantitate cancer risk in man from the cancer risk determined in the model.
