Space radiation may increase risk of cancer


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Using mice and models, scientists have concluded that humans who spend long periods in space, exposed to its radiation, will have a 3% higher risk for cancer.

A team led by researchers at Colorado State University and Frederick National Laboratory for Cancer Research, which is part of the National Institutes for Health, used a novel approach to test assumptions in a model used by NASA to predict these health risks. Based on the NASA model, the team found that astronauts will have more than a three percent risk of dying of cancer from the radiation exposures they will receive on a Mars mission. That level of risk exceeds what is considered acceptable. [emphasis mine]

And how did they come to this conclusion?

…For the study, Weil and first author Dr. Elijah Edmondson, a veterinary pathologist and researcher based at the Frederick National Laboratory for Cancer Research in Maryland, used a unique stock of genetically diverse mice, mimicking a human population. Mice were divided into three groups with the first group receiving no radiation exposure and the other two receiving varying levels of exposure.

Edmondson, who conducted the research while completing a veterinary residency in pathology at CSU, said that for this type of research project, genetic variability is crucial. “Humans are very genetically diverse,” he explained. “You want to model that when it’s appropriate and feasible to do so.”

Weil said although the research team saw different tumor types, similar to humans, but the heavy ions did not cause any unique types of cancer. They also saw differences by sex. In humans, women are more susceptible to radiation-induced cancers than men; one of the main reasons is that women live longer, allowing sufficient time for cancer to develop. In assessing the cancer risk between male and female mice in the study, scientists said the findings parallel human data.

Edmondson said the study validates the NASA model to measure cancer risks for humans from space radiation.

In a sense, this study is junk. First, it discovers the obvious (radiation increases your chances of getting cancer). Second, it is too model-dependent, so assigning any precise percentage to that increase in humans is absurd, especially when based on a sample comprised of mice.

Third, and most important, it completely forgets the reality that life is risk, exploration is dangerous, and to do great things you need to take greater chances. That NASA concludes these questionable numbers are unacceptable means that NASA will never send humans anywhere beyond Earth orbit. Ever.

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9 comments

  • David Birchler

    I believe that 3% increased risk of getting cancer, not necessarily mortality, was an arbitrary number decided upon many years ago.

    Not to minimize the need to deal with radiation issues, but the chances of loss of crew would likely be higher than that, and the cost of both would still be worth it.

    Of course, we’re not doing the microgravity or radiation shielding research we need to in the environments we’re supposedly designing for. SpaceX launch prices should allow programs to perform inexpensive, comprehensive, useful testing, but the industry at large is still operating programs as if launch costs many times more.

  • john hare

    My risks of getting killed in a construction accident are far more than a 3% over a chair warrior somewhere. I’m going to work when I can and the chair warriors can go jump.

  • Andrew-Winter

    ummm.

    Radiation is radiation. Doesn’t matter if it’s in space or not. Exposure to ionizing radiation has been a known carcinogen for just about ever. I mean ever since the Atomic Bomb studies of victims of Hiroshima and Nagasaki were done in the late 1940s.

    It’s all about the dosage. You get hit without the protection of an atmosphere or some kind of structure, by the radiation release of even a minor Solar Flare, while in orbit or on the moon, you don’t worry about cancer. You worry about surviving the next hour and a half. The chances are you won’t.

  • commodude

    My intro to my advanced training class at Ft. Sill was a Vietnam Vet telling us that, as a group, our life expectancy in combat with a peer power was roughly 1.5 seconds after the radio(s) we were operating were keyed. None of us walked out of training or requested another MOS.

    You manage risk, you acknowledge risk, mitigate it, and move forward. You don’t run away from risk, and you cannot eliminate risk. LIFE is a risky endeavor.

  • pzatchok

    3% is less than the chance of a smoker getting lung cancer.

    Now many people are willing to risk smoking?

  • Edward

    Andrew-Winter wrote: “Radiation is radiation.

    Not really. Different kinds of radiation do different kinds of damage. In addition, some kinds of radiation is dangerous if ingested but is much safer if external.

  • Mike Borgelt

    Also depends on the time over which the exposure and exposure rate happens. More junk science. There is no evidence for the LNT model.

  • Rose

    Simulated deep space radiation exposure studies are done using an accelerator which generates the energetic heavy ions (HZE ions) of galactic cosmic rays (GCR). Such facilities are few and expensive to operate, so they will condense a year and a half of exposure into hours.

    This particular paper notes that the mice were exposed to Si and Fe HZE at the Brookhaven National Laboratories accelerator, but while indicating dose, it does not appear to state exposure rate or duration.

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