Tim Connor
Editorial Director
Northwest Environmental Education Foundation


MEMO

Date: February 8, 1999

From: Tim Connor
Editorial Director
Northwest Environmental Education Foundation.
1016 S. Buena Vista Drive
Spokane, WA 99224-2204

timconnor@igc.org.
ph. (509) 838-4580, or (509) 363-0121
fax (509) 624-9188.

To: Distribution

Re: The Hanford Thyroid Disease Study and the Case for Medical Monitoring

In the wake of the first pronouncements about the "negative" results of the Hanford Thyroid Disease Study (HTDS), the assumption is that the inability of the HTDS researchers to connect thyroid disease to Hanford radiation emissions spells doom for the Hanford Medical Monitoring Program (HMMP).

Even if one accepts the suspect dosimetry and statistical wizardry that enabled the Fred Hutchinson researchers and the CDC to dismiss any Hanford connection, there is one inalterable reality that won't go way. The medical results on the HTDS study population revealed much more thyroid disease than expected. Indeed, one of the most profound ironies here is that the HTDS analysis could have found a very strong, statistically significant correlation between Hanford radiation and thyroid disease with far FEWER thyroid casualties than were actually observed by the HTDS investigators. What they found, instead, was a surprising amount of thyroid carnage (and mortality) but no clear dose response pattern to directly implicate Hanford iodine-131.

My conclusion from this is that rather than undermining the case for the Hanford Medical Monitoring Program, the results of the HTDS actually make the strongest case for implementing it, and particularly that part of the HMMP that will have the most public health benefit--the blood test screening for thyroid disease and, particularly, hypothyroidism.

In an earlier memo on this topic I noted with some degree of cynical unamusement that the pronouncements by the Fred Hutchinson Cancer Research Center investigators that there is no link between Hanford exposures and thyroid disease don't pass the giggle test. Given the latest national incident rates for the age group studied (mostly white people, mostly between the ages of 50 and 55) we would have expected to find a third of a cancer. All told, the HTDS doctors found at least 20, with 12 being diagnosed for the first time as a result of the HTDS clinical work up.

To be sure, the finding of this many cancers has to be discounted, somewhat, by the act of looking so thoroughly for them. Still, using more conservative lifetime cancer incidence rates for thyroid cancer, one would have expected (based on 1994 incidence trends) that 11 of the 1,748 women in this cohort would have developed thyroid cancer in their lifetimes. The HTDS found that 13 of them already have, or have had, thyroid cancer. Because this age group is essentially at the middle of the period in their lives where most thyroid cancer materializes, it is plausible that the ultimate lifetime thyroid cancer incidence among women in the HTDS cohort will be double that which we would expect from a random selection of women in this age group. This would hold even if we make the rather conservative assumption that no additional Hanford-related thyroid cancers occur in this group.

The HTDS investigators offer no explanation for why the thyroid cancer incidence in this cohort is so high. They're just adamant that they see no evidence (based on their dose-response analysis) that Hanford radioiodine is the causative factor. (Incidentally, my new alternative hypothesis for this apparent large excess in thyroid cancer among past and present Eastern Washingtonians is that all were of child-bearing age during the reign of former Governor Dixy Lee Ray. And for those of you who don't think I'm kidding, I am kidding. On the other hand, neither the investigators at the Fred Hutchinson center or their sponsors at the Centers for Disease Control are kidding.)

Before the Hanford Thyroid Disease Study was declassified and released last month, the main argument against going forward with the Hanford Medical Monitoring Program was that the palpations and ultrasounds used to look for neoplasms would ultimately result in a significant number of unnecessary thyroidectomies and that few, if any, cancer deaths would be avoided. As some of you know, I'm one of those who thinks that it is still responsible and ethical to go forward even with this part of the HMMP, especially if adjustments can be made in the protocal with regard to the use of diagnostic ultrasounds.

Still, no sound argument has been advanced by the Institute of Medicine or anyone else for why the blood test screening part of the HMMP should not proceed. These tests would allow the diagnosis of thyroiditis, hypothyroidism, hyperthyroidism, and hyperparathyroidism without touching a single neck.

Of the above conditions, hypothyroidism is the one most clearly associated with radiation exposure to the thyroid and the condition that we would most expect. It is far more common than thyroid cancer and the consequences, in some cases, can be far more severe than thyroid cancer--even fatal.

In justifying its case for the Hanford Medical Monitoring Program, the Agency for Toxic Substances and Disease Registry (ATSDR) reported it expected to find 45 cases of previously undiagnosed cases of hypothyroidism among the first 6,000 people it examined under the HMMP. This is an incidence rate of .75 percent and (because ATSDR was reluctant to forecast additional, radiation-induced cases based on the 10 rad exposure levels needed for HMMP eligibility) the number of hypothyroid cases expected was based on the ambient rate of the disease in a similarly aged population.

Under the Hanford Thyroid Disease Study procedures, 3,441 people (the vast majority of them receiving some exposure from Hanford with a mean dose of 18 rad) were examined. Of the 3,441, 595 were diagnosed with hypothyroidism (an incidence rate of 17.3%) and 146 cases were first time detections (an incidence rate of 4.2%).

Comparing apples to apples here:

The HMMP expected 45 undiagnosed cases among 6,000.

The HTDS found 146 undiagnosed cases among 3,441 actually examined.

What this means for the HTDS has already been commented upon. The investigators see an infirmary overflowing with thyroid disease, but don't see the Hanford connection. In my humble view, it is all the more evidence for why this study was either poorly designed and/or the underlying dose estimates smell of low tide.

But it also means that ATSDR clearly UNDERSTATED--by about four times--the humanitarian, public health benefit of just the hypothyroidism portion of the Hanford Medical Monitoring Program. I don't blame ATSDR for this. I think they've been unfairly hammered unfairly by the Institute of Medicine for their plan and that the hypothyroid detect benefits were purposely conservative (something, incidentally, that IOM gave them zero credit for). What the results from HTDS show is that this program will be much more valuable than ATSDR portrayed, that it is likely to improve the lives of 600 or more people who are currently living with undiagnosed hypothyroidism.

The most disingenuous and destructive effect the Hanford Thyroid Disease Study is likely to have is to further delay, if not entirely derail, the Hanford Medical Monitoring Program. If it happens, we will have the Fred Hutchinson researchers and the CDC program managers to blame for this. As I wrote in my earlier memo, researchers have a God-given right to test hypotheses and to do studies that result in negative or inconclusive findings. The FHCRC team went beyond that, however. They purposely held this study up as sound evidence that not only is Hanford somehow blameless for the thyroid disease that afflicts Hanford downwinders, they also clearly suggested that the results were superior to previous research indicating a connection between I-131 and thyroid disease. {According to USA TODAY, Scott Davis, the lead FHCRC investigator said that he hoped the results of the HTDS will be used to "refine [our] understanding of what the [NTS] doses might have meant."}

The bottom line here is that not only is it premature to accept that the HTDS tells us much of anything about the alleged non-relationship between Hanford exposures and thyroid disease, the study itself has actually provided the best evidence yet that implementing the Hanford Medical Monitoring Program will produce a social benefit that far outweighs the cost.

The only question then becomes whether the program is warranted and that the people served by it, deserve the service. The answer on both counts is emphatically yes.

While it may be a puzzle that the HTDS missed the expected dose response it is only a puzzle. It doesn't undo the basic facts that this population was exposed, against its knowledge and consent, and that it is remains at significantly greater risk for thyroid and other diseases as a result of the exposures. The HTDS doesn't undo any of these basic facts and one hopes, in time, it's anamolous non-conclusion will be put in proper scientific perspective. In the meantime, the case for Hanford Medical Monitoring is, in fact, stronger than it ever has been.

Tim Connor


Tim Connor is a Spokane writer and author of "Burdens of Proof, Science and Public Accountability in the Field of Environmental Epidemiology." Since 1992 he has been a member of the federal Advisory Committee on Energy-Related Epidemiologic Research which advises the Secretary of Health and Human Services on federal radiation research policy and priorities.