From: psonnenfeld**At_Symbol_Here**EARTHLINK.NET
Subject: Re: [DCHAS-L] Health risk assessment
Date: Wed, 24 Dec 2014 22:11:52 -0800
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: 12854786.1419487913285.JavaMail.root**At_Symbol_Here**

Some of the "issues" associated with HRAs, specifically for benzene include:

* Which dispersion model is being used?
* Is the meteorological data modeled or based upon actual field data (did you set up a local weather station with a data logger)?
* Are the benzene emissions periodic "excursions" or is the rate of release reasonable constant?
* How many collection stations were established in the community and how long did they operate
* When the emissions data was crunched did the HRA look at both juvenile and adult receptors? (In other words, what is the population age structure of the human receptor population)
* Is the neighborhood composed of "permanent" residents versus a "transient" community (the receptors don't stay in the area long enough to receive chronic exposures)?

Respectfully yours,


-----Original Message-----
From: "jtarr**At_Symbol_Here**"
Sent: Dec 24, 2014 3:52 PM
Subject: Re: [DCHAS-L] Health risk assessment

Ralph Stuart:

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.

Jim Tarr

> On December 23, 2014 at 5:06 AM Ralph Stuart 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
> rstuartcih**At_Symbol_Here**

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