WHY RANK CHEMICALS BASED ON TOXICITY AND PERSISTENCE?
Ranking systems that take into account toxicity and persistence provide a better indicator of the potential environmental hazards of a chemical than toxicity alone. While they may not completely capture differences in exposure potential across chemicals, these ranking systems do penalize chemicals that resist degradation or bioaccumulate through the food chain. Such chemicals are likely to present long term chemical management problems (and unwanted environmental surprises), so they should be priorities for use reduction or elimination. While better indicators of exposure potential would improve priority-setting even more, such indicators require significant amounts of data and environmental modeling and are currently unavailable for most chemicals in widespread use.
