Wednesday, January 24, 2007

NAS on radon

In response to a statement by one IPBiz reader, another IPBiz reader commented:

Radon is not a "bogus" issue. In fact, more data exists about the risk of human exposure to radon than nearly any other airborne chemical. The National Academy of Sciences last looked at the issue in 1999, examining all available studies, and concluded radon causes over 20,000 deaths a year in the United States. There is no serious debate in the scientific community about the risk of radon. So why not test your home?

There are several issues raised by the comment of the commenting IPBiz reader:

#1. IPBiz itself was talking about Mayor Gilmore's placement of a radon detection cannister on a table on the first floor. IPBiz notes that that is not the right place to look for radon, a gas which is significantly heavier than air. IPBiz also notes that solid-phase daughter products (e.g., the long-lived lead daughter) can be the significant problem.

#2. An IPBiz reader (not IPBiz) raised the bogus issue, and now further states:
Please note, that the respondent did not say if tobacco related lung cancer was "subtracted out" in the BIER-VI data. (After all, it is the largest lung cancer source.) The respondent did not describe the model, how it subtracted out the data.

I will admit, that if the K factor is truly equal to 1 for underground male smoking miners, as well as 3 year olds in non-smoking homes, then maybe the extrapolation from the high dose of miners, to the lower doses in homes, has some validity. So all the "art" is in the statistics for deaths by lung cancer for children in non-smoking homes...and I'll bet that number is very low. (In other words, one is subtracting two big numbers, and then parsing the residual among all other groups.

Lastly, in BIER-IV, (or its critics), there were concerns about nonlinear effects, radon PLUS smoking being more damaging than the sum of radon and smoking. (For instance, the radon daughters being bound to smoke particles in the lungs.) "The committee selected a linear-nonthreshold relationship..." means the assessment never proved it, they assumed it. It would appear they have no evidence for linearity at low doses.

I'd buy a junk science detector, before I bought a radon detector.

#3. The commenting IPBiz reader invoked an NAS study, and NAS studies are not necessarily deemed reliable references at IPBiz [below and in papers published by LBE]. The commenting IPBiz reader suggests that the 1999 study was the last NAS study on the topic ["last looked at the issue in 1999", which is untrue], but, in the following, consider what is, and is not in, the 1999 NAS report.

The statement of the EPA on the matter is as follows:

--The National Research Council has published the report, entitled: "Health Effects of Exposure to Radon: BEIR VI, Committee on Health Risks of Exposure to Radon (BEIR VI)". This report by the National Academy of Sciences (NAS) is the most definitive accumulation of scientific data on indoor radon. The report confirms that radon is the second leading cause of lung cancer in the U.S. and that it is a serious public health problem. The study fully supports EPA estimates that radon causes about 15,000 lung cancer deaths per year.--

The executive summary of the 1999 NAS report includes the following:

This National Research Council's report of the sixth Committee on Biological Effects of Ionizing Radiations (BEIR VI) addresses the risk of lung cancer associated with exposure to radon and its radioactive progeny.


Risk models, which mathematically represent the relationship between exposure and risk, have been developed and used to assess the lung-cancer risks associated with indoor radon. For example, the precursor to this committee, the BEIR IV committee, developed one such model on the basis of statistical analysis of data from 4 epidemiologic studies of underground miners. The BEIR IV model has been widely used to estimate the risk posed by indoor radon. Since the 1988 publication of the BEIR IV report, substantial new evidence on radon has become available: new epidemiologic studies of miners have been completed, existing studies have been extended, and analysis of the pooled data from 11 principal epidemiologic studies of underground miners has been conducted involving a total of 68,000 miners and to date, 2,700 deaths from lung cancer.

Radon itself does not directly cause lung cancer but alpha particles from radon progeny directly damage target lung cells to cause cancer.


Physical and biologic differences between the circumstances of exposures of male miners working underground and of men, women, and children in their homes could lead to differing doses at the same exposures. The committee estimated the value of a dimensionless parameter, termed the "K factor" in prior reports, that characterizes the comparative doses to lung cells in homes and mines for the same exposure. Using a model to estimate the dose to the cells in the lung, and incorporating new information on the input parameters of the model, the committee found that the doses per unit exposure in mines and homes were essentially the same. Thus, K is calculated to be about 1 for men, women and children (age 10 years), and slightly above K = 1 for infants (age 1). Consequently, a value of 1 was used in making the risk projections.

The committee selected a linear-nonthreshold relationship relating exposure to risk for the relatively low exposures at issue for indoor radon. This assumption has significant implications for risk projections.

On the basis of the epidemiologic evidence from miners and understanding of the genomic damage caused by alpha particles, the committee concluded that exposure to radon in homes is expected to be a cause of lung cancer in the general population. According to the committee's two preferred risk models, the number of lung-cancer cases due to residential radon exposure in the United States was projected to be 15,400 (exposure-age-duration model) or 21,800 (exposure-age-concentration model). Although these represent the best estimates that can be made at this time, the committee's uncertainty analyses using the constant relative risk model suggested that the number of cases could range from about 3,000 to 33,000.1 Nonetheless, this indicates a public-health problem and makes indoor radon the second leading cause of lung cancer after cigarette-smoking.

The committee's model and general approach to assessing lung-cancer risks posed by indoor radon and cigarette-smoking are subject to considerable uncertainty because of gaps in our scientific knowledge of effects at low levels of exposure.


A 2004 report in Health Physics notes: The large United States county-based study ( Cohen 1995, 2001) in which an inverse relationship has been suggested between residential low-dose radon levels and lung cancer mortality has been reviewed. While this study has been used to evaluate the validity of the linear nonthreshold theory, the grouped nature of its data limits the usefulness of this application. Our assessment of the study's approach, including a reanalysis of its data, also indicates that the likelihood of strong, undetected confounding effects by cigarette smoking, coupled with approximations of data values and uncertainties in accuracy of data sources regarding levels of radon exposure and intensity of smoking, compromises the study's analytic power. The most clear data for estimating lung cancer risk from low levels of radon exposure continue to rest with higher-dose studies of miner populations in which projections to zero dose are consistent with estimates arising from most case-control studies regarding residential exposure.

Note that a BEIR VII report was released in 2005.

The discussion above raises many issues. There is no direct (i.e., autopsy) evidence that radon causes 20,000 deaths per year. This number comes from a model, which derives from data on deaths in miners who were exposed to far more than 4 pC/liter of radon. But let's consider the reliability of other NAS reports, specifically the NAS report on patent reform.

LBE published a footnote which included the following text concerning the "patent grant rate" numbers of Quillen and Webster, and the use thereof in a report by the National Academy of Sciences (NAS):

A post at (topic: internal 3d laser engraving) noted: "The counting scheme generating these numbers is ridiculous." Of the use by the National Academy of Sciences of the Quillen/Webster data, one poster observed: "For whatever reason, the authors of the National Academies of Science and of Engineering choose to manipulate the data to make a point; and they did." While the NAS study utilizes comparisons between countries (as distinct from analyzing how the USPTO is following US rules, which is the issue), one notes patent prosecution in the US differs from foreign offices in so many ways regarding claim interpretation and application of prior art that they are not well suited for comparison, as Robert A. Clarke noted in 85 J. Pat. & Trademark Off. Soc'y [JPTOS] 335 (2003). A poster on a different board observed: Now if the question is how many patents are granted with their original claim set and with no prosecution history estoppel, I'd say the PTO is c! loser to 5-10%. Thus, in the saga of patent grant rate, in the legal world so dominated by the use of proxies, we have a situation in which the one guy at the USPTO and some other guys writing on internet boards were right, and the former General Counsel of a Fortune 100 company, the professor at a top 10 law school, and the National Academy of Sciences (in the April 2004 version of Stephen A. Merrill, Richard C. Levin, and Mark B. Myers, A Patent System for the 21st Century ) were wrong. It is a strange, strange world, and one in which things are not always what they seem to be.

LBE wrote

In the final report by the National Academy of Sciences, the panel did not rely on the numbers of Quillen and Webster, but did rely on a perceived higher grant rate in the US relative to Japan and Europe to infer the presence of a patent quality issue in the United States. The NAS panel did not contemplate the impact of different rules among the US, Japan and Europe.
The patent quality issue served as common ground to involve many players dissatisfied with the patent system to get traction for patent reform, in the body of HR 2795. However, disagreement over the injunction issue among major players killed off 2795. Of course, 2795 was disconnected from the fee diversion issue, which also went nowhere. In the end, the USPTO pretty much ended up where it started.

At no point did the NAS investigate the accuracy of the numbers of Quillen and Webster, or the reliability of the method used to generate them.


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