Is some level of radiation "good for you"?

Question

"With the terrible earthquake and resulting tsunami that have devastated Japan, the only good news is that anyone exposed to excess radiation from the nuclear power plants is now probably much less likely to get cancer."

This is a direct quote from US right-wing pundit Ann Coulter's blog on 3/16/2011. She references a NY Times report from 2001 that claims an "increasing number" of scientists (who she fails to name) seem to think there may be a degree of exposure which can offer health benefits.

"They theorize," the Times said, that "these doses protect against cancer by activating cells' natural defense mechanisms."

She seems to be referencing an idea known as hormesis, which is a phenomenon by which low level exposure to something that is normally toxic at higher or prolonged levels of exposure may have positive health effects.

Obviously, there is documented evidence that radiation can be used to treat cancer, but is there any evidence that uncontrolled, accidental environmental exposure can yield benefits?

Is there documented scientific evidence that this claim is valid, or even plausible?

Have any studies been done specifically evaluating the benefits of radiation released in nuclear accidents?

How would such benefits weigh against the known hazards and risks of radiological exposure?

Answer 1

(Note: I don't know who Ann Coulter is. I can, however, comment on the generic claim that radiation is "good for you".)

There is empirical evidence that suggests that low to medium amounts of absorbed gamma radiation boosts immunity and resilience to ailments such as heart disease, though it may (or may not) increase rates of cancer. It has been suggested and that the reduction in the probability of death from other diseases offsets the increased probability of death from cancer.

The reference I found on this is Lawrence Solomon's opinion piece in the Financial Times: Low exposure to the Nagasaki atomic blast resulted in longer lifespans, which states:

The tens of thousands more distant from Ground Zero [of Nagasaki and Hiroshima], and who received lower exposures to radiation, did not die in droves. To the contrary, and surprisingly, they outlived their counterparts in the general population who received no exposure to radiation from the blasts.

and

The only evidence that exists as to the health of humans who have been irradiated at low levels points to a benefit, not a harm. Difficult though it may be to overcome the fear of radiation that has been drubbed into us since childhood, there is no scientific proof whatsoever to view the radiation emitted from the Fukushima plant as dangerous to the Japanese population

These findings are supported by (and reference) the paper "Mortality of A-bomb Survivors in Nagasaki and Hiroshima", by M. MINE, S. HONDA, Y. OKUMURA, H. KONDO, K. YOKOTA and M. TOMONAGA, Atomic Bomb Disease Institute, Nagasaki Univ., Sch. Med., Nagasaki 852-8523, JAPAN. This paper states:

From the analysis of LSS’s population, RERF, lower relative risk of mortality from non-cancerous disease than control was observed for a dose range, 0.06-0.49Gy, when city was not adjusted. But when city was adjusted, lower relative risk was not observed. Although the number of subjects analyzed in Nagasaki University was smaller than that of LSS’s population, we have obtained the lower relative risk of mortality from noncancerous disease for male at a range of low doses.

These correlate with my undergraduate studies in physics and later work as a health and safety worker for Atomic Energy of Canada Limited (AECL). In undergrad I recall hearing that Marie Curie and her husband wore on their arms slabs of radium and/or uranium because they were under the impression that the radiation these materials emitted boosted immunity. As a worker for AECL at a nuclear power plant, it was commonly accepted that people working at the nuclear power plant on average lived longer than the general population and had lower rates of cancer (Submission of Dr. Patrick Moore, Chairman & Chief Scientist Greenspirit Strategies Ltd. To The U.S. Nuclear Regulatory Commission Public Hearing on Potential Environmental Impacts From a License Renewal of Indian Point Nuclear Power Plant, dated September 19, 2007). From that reference:

A 2004 Columbia University Study of 35,000 respondents concluded that “…nuclear power plant workers in the United States…live longer and have significantly lower cancer rates compared to the general population.”

While it doesn't seem to be the study being referred to above (as the sample sizes are different), there is a 2004 study from Columbia University: "Analysis of the Mortality Experience amongst U.S. Nuclear Power Industry Workers after Chronic Low-Dose Exposure to Ionizing Radiation", which states:

The cohort displays a very substantial healthy worker effect, i.e. considerably lower cancer and noncancer mortality than the general population. Based on 26 and 368 deaths, respectively, positive though statistically nonsignificant associations were seen for mortality from leukemia (excluding chronic lymphocytic leukemia) and all solid cancers combined, with excess relative risks per sievert of 5.67 [95% confidence interval (CI)22.56, 30.4] and 0.506 (95% CI 22.01, 4.64), respectively. These estimates are very similar to those from the atomic bomb survivors study, though the wide confidence intervals are also consistent with lower or higher risk estimates. A strong positive and statistically significant association between radiation dose and deaths from arteriosclerotic heart disease including coronary heart disease was also observed in the cohort, with an ERR of 8.78 (95% CI 2.10, 20.0).

Whether this is the study referred to or not, it supports the conclusion asserted in the paper.

All that being said, there are significant deleterious effects from significant radiation exposure. For example, while the Curies strapped radioactive materials to their arms on the basis that it benefitted their immunity, they suffered significantly for it (Marie Curie: Pioneering Physicist By Elizabeth R. Cregan, p. 17).

While gamma radiation is, on the above basis, understood to have some benefits, the effects of beta and alpha radiation as are known to be quite destructive to cell tissue. While these forms of radiation are less common to be exposed to and easier to protect against than gamma radiation, I strongly doubt they've any positive effect at reducing the risk of cancer. The one known exception may be exposure to Iodine-131, a beta particle emitter, because it collects in the thyroid. While high doses will destroy the thyroid and stop iodine from collecting in the thyroid, low doses will collect there and the beta particles released by the iodine will cause thyroid cancer.

Going back to the claim that those around Fukushima are "much less likely to get cancer" seems overstated. While evidence supports the existence of certain health benefits, and the evidence is mixed about whether exposure to radiation increases or decreases risk of cancer, I feel it's reasonably clear from the evidence we have at present is that the risk of cancer wouldn't be "much less likely", as claimed.

As well, on whether cells have a natural defence mechanism when exposed to low or medium doses of radiation: I don't know of any studies, nor do I have any other knowledge or information, that would support such a conclusion. That being said, I think it's perfectly plausible that cells could have such an ability.

I hope that's helpful.

Answer 2

Ann Coulter's piece does cites sources and she has some valid points, but she also clearly has a bias. She even downplays Chernobyl, making it sound like there were no deaths due to radiation (she acknowledges 30 deaths, but blames it on the explosion).

What is Radiation Hormesis? (Source)

The linear no-threshold (LNT) hypothesis basically says:

Radiation exposure is harmful at all exposure levels

The Threshold model implies:

no effects of radiation up to certain level

The Hormetic model shows

beneficial effects at low levels of exposure as it drops below ZEP (Zero-Equivalent Point)

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Explanation for Radiation Hormesis:

Because the protective and reparative mechanisms are working at a higher level than they would in the absence of radiation exposure, mutations (both those caused by radiation and those that occur spontaneously) are found and repaired or destroyed. Thus, the whole-organism response to low-level radiation exposure in the radiation hormesis paradigm is a state of improved health when compared with that in the absence of radiation exposure.

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Examples of Epidemiological Studies:

• China: The cancer mortality rate was lower in the high-background group, but this difference was statistically significant only in the 40- to 70-y age group (i.e., those who had the greatest lifelong exposure to high background levels of radiation)

• India: inverse correlation between background radiation levels and cancer incidence and mortality

• Cosmic radiation at high altitudes: The cancer death rate was lower in the high-altitude group.

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Examples of Experimental Studies:

• Very low doses of X-rays can cause human lymphocytes to become less susceptible to ionizing radiation

• Decreased deletion mutation in radioadapted human lymphoblasts

• Low-dose ionizing radiation decreases the frequency of neoplastic transformation

• The suppression of metastases and the change in host immune response after low-dose total-body irradiation in tumor-bearing rats

• A review of certain low-level ionizing radiation studies in mice and guinea pigs

• Evidence for Radiation Hormesis After In Vitro Exposure of Human Lymphocytes to Low Doses of Ionizing Radiation

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But Radiation Hormesis remains a controversial subject.

According to this (2001):

The LNT hypothesis has been adopted by every national and international body that offers radiation protection recommendations or interprets scientific data.

These include, but are not limited to, the National Council on Radiation Protection and Measurements (NCRP), the International Commission on Radiological Protection (ICRP), the National Academy of Sciences (NAS) Biological Effects of Ionizing Radiation (BEIR) Committees, the International Atomic Energy Agency (IAEA), and the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR).

But The U.S. Department of Energy has a Low Dose Radiation Research Program

[The] Program has been studying the biological effects of very low doses of ionizing radiation in relevant experimental systems for a decade. Program research has contributed significantly to the body of scientific understanding needed to inform public debate and future regulatory decision making.

which some proponents of Radiation Hormesis view as a "first step" toward acceptance of this hypothesis.

Answer 3

There's quite an exhaustive takedown of this claim by biologist P.Z. Myers on his blog Pharyungula.

The paper he relies on is

Calabrese EJ (2008) Hormesis: Why it is important to toxicology and toxicologists. Environmental Toxicology and Chemistry 27(7):1451-1474.

While the effect of hormesis is real:

Hormesis refers to a biphasic dose response curve. That is, when exposed to a toxic agent at very low doses, you may observe an initial reduction in deleterious effects; as the dose is increased, you begin to see a dose-dependent increase in the effects. The most likely mechanism is an upregulation of cellular defenses that overcompensates for the damage the agent is doing. This is real (I told you there's a grain of truth to what she wrote), and it's been observed in multiple situations.

However, there is one important caveat: (my emphasis)

However, the key thing to note about hormetic effects is that they only apply at low dosages. Low dosages tend to be where the damaging effects are weakest, anyway, and where the data are also the poorest. The US government recommendations for radiation exposure are based on a linear no threshold model in which there is no hormesis to reduced effects at low concentrations for a couple of reasons. One is methodological. The data we can get from high exposures to toxic agents tends to be much more robust and consistent, and we do see simple relationships like a ten-fold increase in dose produces a ten-fold increase in effect, whereas at low doses, where the effects are much weaker, variability adds so much noise to the measurements that it may be difficult to get a repeatable and consistent relationship. So the strategy is to determine the relationships at high doses and extrapolate backwards.

As a consequence:

In the low dosage regime, these responses get complicated at the same time the data gets harder to collect. This is why it's a bad idea to base public policy on the weakest information.

He continues to give a very simple example explaining the idea behind hormesis, before coming to his damning conclusion:

Here in Minnesota in the winter we get very snowy, icy conditions. If I'm driving down the road and I sense a slippery patch, what I will immediately do is become more alert, slow down, and drive more carefully — I will effectively reduce my risk of an accident on that road because I detected ice. This does not in any way imply that ice reduces traffic accidents. Again, with the way Ann Coulter's mind works, she'd argue that what we ought to do to encourage more responsible driving is to send trucks out before a storm to hose the roads down with water instead of salt.

Ann Coulter is blithely ignoring competent scientists' informed recommendations to promote a dangerous complacency in the face of a radiation hazard. She's using a childish, lazy interpretation of a complex phenomenon to tell people lies.

Answer 4

There's the famous case of the Hiroshima and Nagasaki survivor that died at the age of 93, although the cause of death was stomach cancer. It's hard to tell if the radiation exposure made him live longer or promoted his well-being in another way. However, it did appear to cause many radiation-related illnesses over the course of his life:

The blasts deprived him of the hearing in his left ear, but Yamaguchi's family said he was in relatively good health for most of his life. In later years he battled acute leukaemia, cataracts and other radiation-related ailments.

Relating to this, mice can be made immune to the effects of radiation by switching off a related inhibitory pathway that controls nitric oxide, so perhaps some people have similar control over the DNA damage caused by radiation. Also, conditions such as hyperthyroidism and cancer can be treated with radiation therapy (although this is extremely targeted).

Additionally, there's work done by Dr Ron Mitchel, Researcher Emeritus at the Atomic Energy of Canada Limited who presented evidence that cells are adapted to use protective mechanisms against low doses of radiation that are actually beneficial.

These studies included examinations of yeast, cells from mice, deer and humans as well as frogs in the natural environment that suggest low doses of radiation primes cells so that they are protected against the effects of exposure to large doses. One study performed on cancer-prone mice, for example, showed that exposure to 1, 10 or 100 milligrays (mGy) actually cut their incidence of cancer by 3 or 4-fold.

He goes on to say that this work could be used for sparing healthy tissue when treating cancer with radiation therapy. The work is presented on his website, and includes scientific data.

Answer 5

This is an open question.

There are at least three competing theories:

1. the health impact of ionising radiation (IR) is linear, with no lower threshold dose. This is known as the LNT (Linear No Threshold) model.
2. there is a threshold dose below which there is no effect.
3. there is a threshold below which there is a beneficial effect.

Each has their advocates. LNT is used as the cautious response to the uncertainties. The epidemiological evidence is complicated by several factors: difficulties in measuring the actual exposure received by very large numbers of people; and other things which affect health that correlate with radiation exposure.

So, for example, Cohen 1995 found evidence against LNT:

no potential explanation for the discrepancy other than failure of the linear-no threshold theory for carcinogenesis from inhaled radon decay products could be found

However, various bodies have come to the conclusion that LNT is the right model to use, including UNSCEAR, the United Nations Scientific Committee on the effects of Ionizing Radiations, and the US Environmental Protection Agency, which found:

Underlying the risk models is a large body of epidemiological and radiobiological data. In general, results from both lines of research are consistent with a linear, no-threshold dose (LNT) response model in which the risk of inducing a cancer in an irradiated tissue by low doses of IR is proportional to the dose to that tissue.