You need to clarify what you mean by “confirmed”. The type of risk assessment below are all based on models of exposure and dose (modeling the emission rates to estimate long term exposure rates in the surrounding neighborhood and estimating duration and frequency of exposure for the population at large). The dose response assessments are often based on extrapolations and may have safety factors built in-which causes another source of uncertainty and often not based on . Most HRA do state or should explicitly state the assumptions and sources of uncertainty in the HRA.
The only thing you can “confirm” when assessing risk, is that when EPA administrators say that the air is “safe” (as Christine Whitman did following 9/11), the law suits will follow!.
Here is a better way to pose my questions:
1. An industrial facility, surrounded by neighborhoods a few blocks away, emits a substantial amount of benzene into the air on a routine basis.
2. The responsible air pollution regulatory agency requests the facility operator to conduct a "health risk assessment" related to ambient air benzene exposure in the nearby neighborhoods and the possible risk of cancer caused by benzene exposure in those nearby neighborhoods.
3. The "health risk assessment" is carried out, and the reported risk of cancer caused by benzene exposure amongst the neighbors is found to be one additional case in one million.
My questions are:
1. Have the results of a "health risk assessment" like the one outlined above ever been confirmed by experiment?
2. If the answer to the above question is no, then is the process described above consistent with the scientific method?
3. If the process of "health risk assessment" described above is not consistent with the scientific method, then why don't the authors of "health risk assessment" reports include a statement to that effect in their reports?
I trust the above explanation explains my question in a more understandable way.
> On December 23, 2014 at 5:06 AM Ralph Stuart <rstuartcih**At_Symbol_Here**ICLOUD.COM> wrote:
> >Does anyone know of a "health risk assessment" wherein the results of same have been verified? And if not, is the process of "health risk assessment" consistent with the scientific method?
> Depending on the definitions of the words involved, there are a variety of possible levels of verification that can apply to a "health risk assessment":
> - in individual cases reviewed by medical professionals,
> - at the population level through epidemiological evidence, or
> - at the regulatory level which includes a cost/benefit analysis.
> All of these include a mixture of scientific elements and professional judgement in applying applicable data to the target population of interest. This mixture means that the level of clarity of verification can vary from case to case.
> Perhaps that's helpful.
> - Ralph
> Ralph Stuart
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