The Baltimore Shipyard Study

In a comment on my last post, Sean Estey described a study of Baltimore shipyard workers, some of whom handled radioactive materials. The ones exposed to more radiation were healthier than those exposed to less. The difference in death rate was huge: 25%. This is so large and consistent with other data I doubt it is due to a confounding.

You can read more about this study here and here. If one quarter of all deaths are due to suboptimal stimulation of repair systems, that’s extraordinary news. The study was finished around 1990. The plausibility of such a large benefit should have led to experiments. The observation that people in mountain states (such as Colorado) have less cancer than those in gulf states (such as Alabama) as well as greater radiation exposure suggested to John Cameron, a professor of toxicology, an experiment in which some gulf state residents are exposed to enough radiation to bring their total exposure up to what mountain state residents receive. This has yet to be done.

In a paper about the effects of low-dose radiation, the authors say we should ignore the Baltimore study because of “the healthy worker” effect — the possibility that persons in one exposure group were healthier than those in another exposure group because workers are healthier than non-workers (and fitness for work may have differed between the exposure groups in the Baltimore study). They give three examples to illustrate the healthy worker effect. In these examples, a group in which everyone has a particular job were healthier than the general public, which includes many people without a job. In their examples, the median effect of being in the full-employment group (in which everyone has a job) is a 10% decrease in mortality compared to the general-public group (in which some people don’t have a job because of disability). That should give a good idea of the maximum size of the healthy worker effect — when something is explicitly varied, that’s what happens. The Baltimore study compares person with job to person with job, not person with job to person without job. This suggests that in the Baltimore study, the healthy worker effect was smaller than the effect in the examples, meaning smaller than a 10% reduction. Such an effect cannot explain a 25% reduction.

A comment by Alrenous on my earlier post linked to a 2007 study of people in Taiwan whose apartment building was accidentally contaminated with radioactive materials. By the time of data collection, they had gotten far less cancer (3% of what would have been expected) than the general Taiwan population. A healthy worker effect cannot explain this. Again, the reduction is so great it is unlikely to be due to confounding.

If I could buy something to put under my bed that would expose me to the level of radiation received by people in Colorado, I would.

12 Responses to “The Baltimore Shipyard Study”

  1. PeterW Says:

    Maybe all those trans-Pacific flights are doing you some good.

    Actually, stewardesses and pilots would be two more groups worth looking at.

  2. Robbo Says:

    “If I could buy something to put under my bed that would expose me to the level of radiation received by people in Colorado, I would.”

    Granite chippings ?

  3. Anonymous Says:

    I hate to say this, but maybe the new full body scanners at US airports are actually improving the public’s health?

  4. PeterW Says:

    http://informahealthcare.com/doi/abs/10.1080/09553000601085980

    This study criticized the Taiwan study you cite for neglecting the age distribution of people living in the apartment buildings. They found that once you adjust for age and demographics the cancer incidence went up.

  5. Stego Says:

    In a place called Bad Gastein in Austria and about a hundredfifty years back a bright doctor realised that the miners working the saltmines were a lot healthier than the general populace. Knowing he was unto a good thing he bought the mines – they were on the point of running dry – and starting selling time in the mines by the hour to the – wealthy – unhealthy. The company he founded is still in business today. Back then they thought it must be the highly mineralised air, today it is assumed that the slightly elevated radioactivity in there is the key.
    The good doctor lived to the age of ninety by the way – quite a feat in those times.

  6. Alrenous Says:

    “They found that once you adjust for age and demographics the cancer incidence went up.”

    Well, yeah. 97% reduction in morbidity is way too high to be fully believable. But with separate studies with a similar effect, the question is one of magnitude, not sign.

    From the study:
    “increase risks of developing certain cancers in specific subgroups”

    Shockingly, making your body work harder is not risk-free. Hence Seth’s,

    “The plausibility of such a large benefit should have led to experiments.”

    However, I would also caution against dosing yourself on rads just based on these studies. I symbolize it this way: should those dockworkers expose themselves to even more radiation? So: how do you measure the ideal exposure for yourself as an individual, rather than a population mortality statistic?

  7. PeterW Says:

    @Alrenous

    Yes, the magnitude is different, but so is the *sign*:

    “All cancers combined, all solid cancers combined were shown to exhibit significant exposure-dependent increased risks in individuals with the initial exposure before the age of 30, but not beyond this age.”

  8. Leonardo Says:

    I my lazyness I haven’t read the linked articles of the studies. What kind of radiation do they refer to?

    I would assume that not all radiation are equal.

    Thanks,
    L

  9. Seth Roberts Says:

    Leonardo, they refer to (a) radiation from radioactive materials (e.g., uranium) and (b) cosmic radiation (as a possible reason that people in mountain states get less cancer than people who live by the sea).

  10. Thomas Seay Says:

    Here is a study done on the effects of radon on rhematoid arthritis from people who visited Radon Spas (places that have relatively high levels of radon):
    http://www.radonmine.com/pdf/longterm.pdf

    Here is a link for an actual Radon Health spa in Montana:
    http://www.radonmine.com/

  11. Thomas Seay Says:

    That said, this question of hormetics is very complex. A good case in point is the hormetic effects of resveratrol. At a lower dose, for example, it may be good for heart protection but also conducive to tumor formation. In other words, the biomedical endpoint determines whether some of these substances are “good” or not. They may be “good” for one biomedical endpoint and “bad” for another. Please see this interesting article by one of the leading researchers in hormetics, Calabrese:
    http://www.belleonline.com/newsletters/volume16/vol16-2.pdf

    “The current assessment indicates that low concentrations
    of resveratrol can be potentially beneficial or harmful,
    depending on the endpoint of interest. The data suggest
    that low doses of resveratrol would have the capacity to
    increase the risk of tumor development of a number of
    organs based on its capacity to enhance cell proliferation
    in multiple human tumor cell lines. In contrast, a strong
    case can be made that low doses of resveratrol can be
    significantly cardio-protective. “

  12. Chris Says:

    As a Tokyo resident, I’m encouraged by your post…I really hope it’s true.

    I’m curious though, would you choose to live in a place like Tokyo where there’s higher than normal radiation in the food/water and possibly the air for the possible benefits?