INTERVIEWED BY PAUL ARNOLD, BBC, ON 30TH MAY, 2000
To be broadcasted on 14th June, 2000
1) Why did you write the article in Physics Today? What were you wanting to achieve?
A similar paper I presented in 1998, at an International Conference in Warsaw at the occasion of the Centenary of Polonium and Radium Discovery - Its Scientific and Philosophical Consequences. Benefits and Threats for Mankind. The conference was attended by 13 Nobel Prize winners, and the audience was mainly the physicists. I noticed that what I say is new to them, and also that some eminent speakers repeat old mythology, like, for example, that nuclear war will annihilate all life on the Earth. The physicists are the cream of cream among the scientists. Therefore, I decided to reach a wider audience of physicists, and through them to influence the thinking of intellectuals. The Physics Today [Sept. 1999, p.24] was an obvious choice for this aim.
2) What is the basis of your dissatisfaction with LNT?
It is a dubious moral aspect of its applications, and its poor scientific basis. In fact LNT is a policy, not the science. For the past 27 years I was the representative of Poland in the UNSCEAR . Since the very first years of my work in this committee, I was astonished to see that the committee was deeply concerned with trifle problems of no meaning, and the important ones were ignored. For example, in the Cold War years, UNSCEAR was not concerned at all with the lethal consequences of a nuclear attack, but year after year, was diligently collecting the data on radioactive emissions from nuclear power installations all over the world. Thousands of scientists and technicians were providing these data.
>From all the emissions from nuclear power, atmospheric nuclear testing, and Chernobyl accident combined, the average individual global radiation dose in the 1990s was about 0.4% of the average global natural exposure of 2.2 mSv, and a 60,000th fraction of the natural exposure of inhabitants of a city of Ramsar, Iran. No adverse health effects of natural radiation were found in Ramsar, and in a similarly radioactive region of Kerala in India. But in UNSCEAR we were not interested in this lack of radiological harm in Iran or India.
Instead, UNSCEAR was producing estimates of the "risk factor", that is the number of cancers per unit dose, which was supposed to be valid for all doses, and dose rates, even those near the zero dose. This factor, an offspring of LNT, was based on epidemiological data from Hiroshima and Nagasaki, which are not relevant to the normal radiological protection, when people are irradiated with very low doses (about 1 mSv) delivered during long time (a year). In Japan people were irradiated in a fraction of a second with near lethal doses (up to 5000 mSv), at the dose rates more than 1015 (thousand trillions) times higher than encountered in radiological protection. Extrapolating over such a vast span is scientifically not justified.
UNSCEAR also used concept of LNT to conceive the notion of dose commitment and collective dose. This lead to producing staggering values of man Sieverts received by the global population. For example: 200,000 man Sv from power reactors in the next 10,000 years, or 600,000 man Sv from Chernobyl fallout until the end of time in the infinity, or 650,000,000 man Sv from natural radiation in the past 50 years only. UNSCEAR and the radiation protection community were not interested in the social and economic consequences of producing such meaningless, but frightening numbers. These numbers have no biological or medical meaning, because LNT on which they are based is a false assumption. It states that even the lowest, close to zero, radiation dose is detrimental, and can produce a cancer or a hereditary effect. However, no hereditary effects were discovered in the progeny of survivors of Hiroshima and Nagasaki irradiated with high sub-lethal doses.
Also radiation carcinogenesis should no longer be perceived as a straightforward process: one DNA hit, one cell, one cancer. Modern oncological studies demonstrate the complexity of this process, which precludes the use of direct proportionality for estimating the cancers risk. After a total malignant transformation, the cell has to divide some billions of times, before a cancer is formed. Such transformed cells appear to be distant from cancer by so many billions of iterative steps, that their outcome cannot be predicted, as a matter of principle. The notion that radiogenic cancer is caused by simple mutation in one cell is erroneous, and therefore there is no scientific basis for the LNT hypothesis.
3) How good are our bodies at coping with low levels of ionizing radiation? What evidence do you have for this?
The highest dose we receive from natural radiation, in which all living things are immersed since life began 3.5 billion years ago. At this early time radiation background was some 5 times higher than now, and organisms developed powerful defense mechanisms against such adverse radiation effects as mutation and malignant change. Those effects originate in the cell nucleus, where DNA is their primary target. At its present average global natural dose of about 2.2 mSv per year, natural radiation causes about 5 DNA damages in each cell per year. Natural radiation doses are ranging in various parts of the world between 1 and some 500 mSv per year, what corresponds to about 2 to 1000 DNA damages in each cell per year. However, each mammalian cell suffers about 70 million spontaneous DNA damages per year, caused not by radiation, but by thermodynamic processes and by aggressive free radicals formed by the metabolism of oxygen. Only if armed with a powerful defense system could a living organism survive such a high rate of DNA damage. That evolution proceeded for so long is proof of the effectiveness of living things' defenses against this very tornado of spontaneous DNA damages, and also against natural doses of radiation.
This defense system operates in three steps: PREVENTION (antioxidants), REPAIR OF DAMAGED DNA (enzymes, cell cycle control), and REMOVAL OF DAMAGED CELLS (apoptosis, necrosis, differentiation, immune response). High-dose radiation suppresses activity of this system, resulting in increased metabolic mutations, and in cancer. Low-dose radiation stimulates this system, resulting in fewer metabolic mutations, less cancers, and increased longevity. Such stimulation is sometimes called radiation hormesis. The defense system maintains the integrity of organisms, both during the lifetime of the individual and for thousands of generations. If this system were absent, we all would die of cancer in the first few months of life, or be crippled by hereditary changes. Just because we have this system, ionizing radiation was defined by UNSCEAR as rather feeble, as compared with other noxious agents present in our immediate environment.
4) But isn't there a problem here that hormesis hasn't been related to the known incidence of cancers?
There is epidemiological evidence that radiation hormesis decreases cancer incidence and mortality, and also hereditary effects. This evidence comes from studies of A-bomb survivors in Hiroshima and Nagasaki, of inhabitants of regions with high natural radiation, of effects of residential radon, of medical patients, of nuclear workers, and of inhabitants of region near Techa river, in Urals, contaminated by Soviet atomic weapon industry.
Among the children of parents who survived the atomic bombings of Hiroshima and Nagasaki there were about 4% fewer death than among the children of unexposed parent, 23% less disorders in number of chromosomes (aneuploidy), 29% fewer chromosomal aberrations, and 30% fewer mutations in blood proteins. The older A-bomb survivors in Nagasaki irradiated with doses higher than 10 mSv, have 40% lower rate of mortality from all causes than unexposed inhabitants of this city. In Nagasaki, among the persons irradiated with doses between 10 and 490 mSv cancer death in male survivors was about 40% lower than that in non-irradiated persons. In both Japanese cities mortality due to leukemia was in persons irradiated with doses below100 mSv up to 50% lower than in non-irradiated persons.
In Yangjiang county in China, where annual radiation dose is 5.5 mSv (5 times higher than the limit for population currently recommended by ICRP), cancer and leukemia mortality was about 15% lower than in the adjacent two other counties where radiation dose is 2.1 mSv per year. Leukemia mortality among women was in Yangjiang 60% lower than in these two other counties.
These findings are similar to the earlier ones in the United States, where in regions with high natural radiation dose, mortality due to all malignancies was lower than in regions where radiation is lower by a factor of 2. Similar effect was found there for congenital malformations.
In the United States a study that covers about 90% of the population found that people living in houses with higher radon concentration had a lower lung cancer mortality than those less exposed to radon. Similar observations comes from Germany, China, Japan and other countries.
Several studies of nuclear industry workers exposed to low radiation doses, were carried out in the United Kingdom, the United States, Canada, and Russia. Most of them show a decreased mortality for all causes, and for malignant neoplasms. I wish to mention a study from Atomic Energy Establishment of Canada. Among more than 13,000 employees the mortality from all cancers and from noncancer diseases was less than expected in the general Canadian population, and mortality due to leukemia was only 32% of expected mortality. One may say that this is a "healthy worker effect", but some of these studies that were specifically designed to check this problem, excluded this effect.
Numerous studies on patients irradiated during radiodiagnostic or radiotherapeutic operations show a decrease in lung cancer risk in those irradiated up to about 1500 mSv. Two Canadian studies of female tuberculosis patients subject to multiple x-ray diagnostics, demonstrated decreased breast cancer risk at the dose range between 10 and 1000 mSv. In Sweden many thousands of patients diagnosed with radioactive iodine-131, with an average radiation dose to thyroid gland of 1000 mSv. In the group of patients not suspected of thyroid cancers, and studied many years later, there were 38% fewer thyroid cancers than in normal population.
One of the most recent data showing hormetic effects in humans come from the former Soviet Union. In September 1967, inhabitants of 22 villages along the Techa river in the Eastern Urals were irradiated with high radiation doses of up to 1500 mSv. This was a result of a radioactivity release from a thermal explosion in a Soviet military nuclear facility. About 10,000 people were evacuated and their cancer mortality was studied during the next 30 years. Among those who received doses of about 500 mSv cancer mortality was 28% lower than in non-irradiated control population from the same region. In the 120 mSv group this mortality was 39% lower. The difference from controls was statistically significant.
5) Do you consider there to be a level below which there is no risk?
Yes, I do. At chronic, that is long-term irradiation, with low dose rates, such level is probably similar to doses received by inhabitants of natural high radiation areas. It can be probably near 500 mSv per year.
6) Could you just define for us radiophobia?
It is an irrational fear of all things nuclear, and of even trifle amounts of man-made ionizing radiation, which is a natural component of our environment.
7) How do you think it can be conquered?
Most important factor would be resignation from LNT principle in radiation protection regulations. This is not an easy task, due to "old-boys-fighting-back" effect, bureaucratic stagnancy, and green politicians. Even after changing the regulations, to heal the harm already d one in the public conscience and perception by many decades of anti-radiation and anti-nuclear propaganda, will take a long time. Educational effort should be directed toward young people, and mass media should change their current anti-radiation attitude.
8) If LNT were to be abolished what would you put in its place?
It is not only LNT that should be abolished, but also a principle of "source oriented protection", which should be replaced with "individual oriented protection". The principle of the individual oriented protection is based on the premise that if the risk of harm to the health of the most exposed individual is trivial, than the total risk is trivial - irrespective of how many people are exposed.
Radiation protection should be based on principle of practical thresholds. These thresholds are radiation doses at which a harm cannot be detected. These threshold will be different for various dose rates, and for various effects, such as for example, an increase in cancer incidence, hereditary changes, or acute radiation sickness. The existing range of natural doses, and epidemiological observations of both adverse and beneficial effects of radiation may provide guidance as to the numerical values of these thresholds.
9) Could we just talk about Chernobyl - how has the residual radiation affected the health of the population?
For the simplest answer I would like to quote the most recent UNSCEAR document on Chernobyl of May 11, which I know almost by heart:
"The number of thyroid cancers (1800, until now 1 child died) in individuals exposed in childhood ... is considerably greater than expected based onprevious knowledge. The high incidence and the short induction period are unusual. Other (than radiation) factors may be influencing the risk."
"In addition to the increase in thyroid cancer... no increases in overall cancer incidence or mortality have been observed that could be attributed to ionizing radiation. The risk of leukaemia, one of the main concerns (leukaemia is the first cancer to appear after radiation exposure owing to its short latency time, 2-10 years), does not appear to be elevated, even among the recovery operation workers. Neither is there any proof of other non malignant disorders ... that can be related to ionizing radiation. However, there were widespread psychological reactions to the accident. These are due to fear of the radiation, not due to the radiation doses".
10) Has the cause of the thyroid cancers in children been ascertained?
The increased registration of thyroid cancers in highly contaminated parts of Belarus, Russia and Ukraine is not limited to children. Such increase occurred also in adults. The average radiation doses to thyroid gland from radioactive iodine-131 ranged from 25 to 380 mSv. These doses were not much different from average dose given to Swedish patients (1000 mSv) in which no increase, but rather a decrease of thyroid cancers was detected. It seems that the thyroid doses in the former Soviet Union were too small to cause the thyroid cancers, which also appeared too early (4 years after accident). It seems that not radiation but screening effect is here the main culprit. In normal populations occurs a very high number of hidden thyroid cancers, those with no clinical manifestations, and called the "occult cancers". The incidence of occult cancers in Canada is 6,000 per 100,000 persons, 9,000 in Poland, 13,000 in the United States, and 35,000 in Finland. The greatest incidence that was registered in Gomel region, Belarus was 18 cancers per 100,000 persons. Thus potential for detection of "excess" thyroid cancers, after improving or intensifying the diagnostics, is enormous. I doubt that Chernobyl thyroid cancers are caused by Chernobyl radiation.