Risk Assessments Developed Under Regulatory Guidelines:

          Regulatory agencies such as the U.S. Environmental Protection Agency (USEPA) and the California Environmental Protection Agency (Cal/EPA) Office of Environmental Health Hazard Assessment (OEHHA) develop risk assessments for specific chemicals and other substances.  The purpose of these regulatory risk assessments is to provide a basis for comparing the relative potential risks of different chemicals and evaluating the potential need for prophylactic or other public health protective measures.  The regulatory risk assessments for all chemicals and other substances are developed using the same general guidelines and default procedures designed to maximize regulatory comparability and not the accuracy of specific chemical assessments.

          Regulatory risk assessments are not designed to determine actual risks.  They do not provide actual risks either for the general population or for specific individuals.

Federal and state regulatory agencies provide risk assessment guidelines designed to result in upper-bound characterizations of human health and ecological risks.  Thus, regulatory risk assessments provide hypothetical upper-bound characterizations of risk and do not provide actual risks for the general population or for specific individuals or even unbiased estimates of actual risks for the general population or for specific individuals.

An "upper bound" is a number designed to be bigger than the actual number it is bounding.  For example, the batting average for a really good baseball player may be in the 300's and occasionally even in the low 400's. Hence, the number 2,000 is an upper bound on a baseball player's batting average because 2,000 is definitely bigger than a baseball player's batting average.  Because a batting average cannot possibly exceed 1,000, another upper bound on a baseball player's batting average is 1,000.  Hence, there can be more than one upper bound, and an upper bound may even exceed the realm of possibility (e.g., 2,000 for a batting average).  Upper bounds may also be designed to exceed the true number with a high probability but not with certainty.  For example, 500 is an upper bound on a baseball player's batting average that exceeds the player's true batting average with a high probability.  The precise numerical value of that "high probability" may be unknown and often is unknown.  Furthermore, even if 500 were an upper bound, it would not mean that all baseball players would have a batting average of 500 or that a specific baseball player's actual batting average would be 500.

Regulatory agencies insist on upper-bound characterizations that are biased toward overestimating any real risks.  The regulatory agency's goal is to err on the side of health protection by going to great lengths to avoid underestimation of the magnitude of the risk to the public.  In pursuit of this goal, risk assessments developed under regulatory guidelines result in upper-bound risk characterizations that may greatly overestimate the risks and are not intended to be construed as real risks or accurate estimates of actual risks. 

The upper-bound human cancer potency used in regulatory risk assessments were developed by regulatory agencies primarily for screening or comparison purposes and were not intended to be used in characterizations of actual risk.  If an upper-bound risk characterization is calculated according to regulatory guidelines, and it is less than a specified screening level, then the real risk is expected to be below that screening level with reasonable certainty and no regulatory action is required.  On the other hand, if an upper-bound risk characterization exceeds a specified screening level, then that only means that further regulatory scrutiny is required.  It does not mean any real risks exceed that screening level.

The upper-bound human cancer potencies used by regulatory agencies are usually based on upper-bound risk characterizations that were developed  primarily for screening or comparison purposes and were not intended to be used in characterizations of actual risk.  If an upper-bound risk characterization is calculated according to regulatory guidelines, and it is less than a specified screening level, then the real risk is expected to be below that screening level with reasonable certainty and no regulatory action is required.  On the other hand, if an upper-bound risk characterization exceeds a specified screening level, then that only means that further regulatory scrutiny is required.  It does not mean any real risks exceed that screening level.