Thorium-232 is the only weekly radioactive element found in the Lynas waste product.
Thorium-232 decay produces only alpha particles which can be stopped by a piece of thin paper and cannot penetrate even the outer layer of the human skin, whereas potassium-40 in our normal diet produces the highly dangerous gamma and beta rays from all the 3 types of beta decay, i.e. electron emission, electron capture and positron emission.
A typical 5.5 MeV alpha particle can be expected to travel less than 0.005cm in body fluids.
THE LONGER THE HALF-LIFE OF THE SUBSTANCE THE LESS IS THE RADIOACTIVITY and as such the less dangerous it is.
As a simple analogy, if it takes 14,000,000,000 years for half of a house to be burnt, there is no chance of anybody getting hurt. But if it takes only 14 minutes for half of the house to be burnt down, a lot of people will be injured or killed.
Thorium-232 which is the only significant radioactive element found in the Lynas waste has an incredibly long half-life of 14 bilion years and as such is much less radioactive than the Potassium -40 whose half-life only 1.25 billion years.
Comparison of Radioactivity in Bq (number of atoms decaying in 1 second)
Pure Thorium = 4,080 Bq/gm
Pure Potassium-40 = 254,000 Bq/gm
Naturally Occurring Potassium (3 different isotopes) in our body and food = 31.825 Bq/gm
Artificially created Plutonium-238 = 634,000,000, 000 Bq/gm (1/2 life = 87.7 years)
Lynas Rare Earth Waste = 6 Bq/gm
It has been estimated that in the worst case scenario, the radiation risk from the Lynas plant is only 0.002 mSv/yr.
In Ramsar, Iran, the naturally occurring radiation is extremely high at 260 mSv/yr. This is 13,000,000% higher than the expected worse case scenario in Kuantan.
And the people in Ramsar, Iran have been found to be healthier and live longer than the rest of the Iranians! There is also no increase in the number of cancer cases.
In the south western area of Kerala state in India, the Thorium-232 in the soil is as high as 4,000 parts per million as compared to the Lynas waste which has only 1,650 parts per million.
And studies have shown that the population which have been living all their lives in these areas, do not have a higher incidence of cancer and their blood and tissues do not have a significant increase in the level of Thorium.
We are exposed to radiation all our lives. In fact we get 4,400 Bq of radiation from the Pottasium-40 with a further 3,000 Bq from Carbon-14 which forms part of our body tissues.
There is no way we can escape completely from radiation. Even outer space is full radiation. The only way we can escape from all radiation is to leave this universe! Or jump into Kuantan River and be eaten by the crocodiles.
Come to think about it, this would not work either as human body as well as crocodile’s body have their own intrinsic radioactivity!
Thorium-232 in Clay Soil Cannot Get into Body Tissues
Thorium-232 is strongly bound (adsorbed) by soil especially clay soil. The Thorium concentration in the clay particles is about 5,000,000% higher than in the water between the clay particles.
So, it cannot be leached out by water and pollute the rivers. Even if the clay soil is washed into the rivers and sea it will not do any harm as the thorium will still be strongly attached (adsorbed) to the clay and will not dissolve into the water.
When ingested there is insignificant absorption of the Thorium because of this strong bond between the clay particles and the thorium. Practically all the Thorium will be excreted in the faeces with the clay.
Even when Thorium-232 is in the gut, it cannot do any significant harm as a typical 5.5 MeV alpha particle can be expected to travel less than 0.005 cm in body fluids, or much less in the semi-solid faeces.
That may be why, there is not a single well documented case of accidentally or environmentally ingested or inhaled Thorium-232 included cancer in the intestines.
Because of its mass, Thorium-232 particles are very heavy and has great difficulty to get airborne.
Normally these particles get airborne only when they are very small and the only ones that can deep into the lungs are those which are about 1 to 2 micron in diameter.
These fine particles are only found in the mines and experimental nuclear plants where powerful machines are used or where there is combustion. The chance of inhaling 1 to 2 micron sized thorium particles in the Kuantan air is practically non-existent.
All lung disorders are associated with prolonged exposure in the mines or Thorium refining plants where the above conditions are present.
Thorium-232 produces only alpha rays (gamma rays from daughter isotopes are significant) which cannot pass through even a thin piece of paper or the surface of the skin.
If you have a lump of pure Thorium-232, all you need to do is to wrap it up newspaper and that will stop all the alpha radiation from getting out!
Since alpha radiation cannot go far, even if you have a huge pile of Lynas waste, the external radiation would not increase by much because only the tiny percentage of Thorium-232 atoms directly on the surface of the pile will be able to radiate out their alpha particles. Those just below the surface will remain inside the pile and be converted to the simple helium gas.
The radiation of 6 Bq/gm from the weakly radioactive Thorium-232 in the Lynas waste is so low that even AIEA do not consider it significant and as such can be transported without any special permission.
Moreover, Thorium-232 is not a Carcinogen (cancer causing agent) if inhaled or ingested according to the International Agency for Research on Cancer IARC.
Thorium-232 is considered to be carcinogen only IF ADMINISTERED INTRAVENOUSLY AS A COLLOIDAL DESPERSION OF THORIUM-232 DIOXIDE.
It was claimed that over 20 years study in one of the largest rare earth mine, the Bayun Obo mine has shown that inhalation Thorium has proven to cause lung cancer. The number of miners in 2001 were 6,983 of which 3016 were exposed to dense dust in the mine.
After correcting for the heavy smoking, there was an excess of 10 cases of lung cancer in workers who had worked for about 30 years or so in the mine.
But this study cannot exclude crystalline silica (SiO2) in the dust as being the cause of the lung cancers. Silica is a confirmed carcinogen while Thorium by inhalation or investigation is not.
AND MOREVER, KUANTAN PEOPLE ARE NOT RARE EARTH OR THORIUM MINERS!
The rare earth miners in the case of the Lynas Rare Earth Plant are still in a place called Mount Weld in Western Australia!
If there is any long term lung problem, the Australians are the ones who will be getting those problems and not Kuantan people.
Kuantan people are just ordinary traders, office workers, taxi drivers or just hanging around doing nothing in the air conditioned-malls.
It is tantamount to claiming that since workers in the granite quarries and underground tin mines developed severe lung diseases (silicosis) and lung cancer from inhaling dust containing silica (sand), the millions of tons of sand in our beaches should be relocated to somewhere safe or shipped back to..? Australia.
Definite evidence that crystalline silica (Sand, SiO2) is associated with an increased rate of lung cancer led the International Agency for Research on Cancer (IARC) to conclude in 1997 that crystalline silica is known human carcinogen.
There is also a fear that the waste will be dumped all over the place. Unfortunately, the risk also apply to all our factories and plants to be close down so that we can go back to the good old days of tapping rubber and plucking coconuts for the BIG WHITE MAN?
And what about other pollution and/or radiation sources in the environment before Lynas even starts. For example, a 1,000MW coal plant after just 1 year of operation produces 6,000,000 tons of CO2, 44,000 tons of SO2, 22,000 tons of NO2, 320,000 tons of ash containing 400 tons of heavy metals (arsenic, mercury, cadmium, lead, etc.) and, here’s the cicker, including 5 tons of Uranium and 12 tons of Thorium from which the radon gas of both decay chains are out the chimney and into our air… and we are building TWO of these now to add to those we already have on the peninsula.
3. External Threat
Thorium-232 produces only alpha rays (gamma rays from daughter isotopes are insignificant) which cannot pass through even a thin piece of paper or the surface of the skin.
Even a giant lump of Thorium-232 containing material will radiate alpha particles only from the tiny amount of Thorium-232 atoms on it’s surface as all the alpha particles produced by those inside the lump cannot penetrate even a couple of centimeters, so even if we have a small mountain of material containing Thorium-232, it makes not much difference.
A simple newspaper wrapping would stop all alpha radiation from a lump of Thorium-232.
Well, the reason is obvious. But, I find great difficulty in explaining to the layman the reason why when an element with an extremely long half-life that decays into isotopes with very short half-life, there is minimal accumulation of the short half-life isotopes and as such do not build up into large enough quantity to pose any significant hazard.
I will try to explain by this simple analogy. If there are 2 million people waiting outside a stadium and 1 million people managed to get into stadium after 14,000,000,000 years (half-life of Thorium-232), it means that you will see only one person getting into the stadium every 14,000 years.
But once in the stadium the half-life of the new person (half-life of Radon-220 from the Thorium-232 decay chain is only 55 seconds) is so short when compared with those outside (Thorium-232) that he has left the stadium almost immediately. Getting in is extremely fast!
Since only 1 person gets into the stadium every 14,000 years, if you look into the stadium you will see it as empty most of the time! It is just like trying to fill up a bucket by a slow, slow drop by drop drip and the bucket has a big hole at the bottom. If you look into the bucket you will see practically little or no water in it.
Since the Lynas waste product has only 6 Bq/gm of radioactivity, the chance of detecting any significant amount of radon gas is pretty slim indeed.
4. Unnatural Routes of Entry
The only way Thorium can gain entry into the body is by injection. In the past where huge doses of 25 cc to 50 cc of 25% solution of Thorium dioxide (Thorotrast) was injected into the vein for contrast radiological studies, a very small number of patients were believed to have developed cancers 20 to 30 years later. Even with these extremely high unnatural doses, there was no acute toxity.
In the south of the state of Karala in India the soil contains as much as 4,000 ppm (parts of Thorium per million). Studies have shown that there is little or accumulation of Thorium-232 in the inhabitants.
The Lynas waste contains only 1,650 ppm.
Over the last 40 years since I developed a special interest in nuclear medicine and particle physics, I have not come across any well documented and well proven report of any human being severely injured or killed by accidental or environmental inhalation or ingestion of Thorium-232.
We need to compare this with the 15,000 people murdered in the USA every year and the 2 to 3 million people killed by Malaria worldwide yearly!
So if Thorium cannot enter the body in significant amount by ingestion or inhalation and alpha rays do not pose an external threat, what’s all the big fuss about the Lynas rare earth plant?
It should also be noted that Australians are delighted that a company called Arafura is building a huge Rare Earth Processing Plant costing over A$1 Billion in Whyalla in South Australia.
This plant is expected to produce over 1,000 high paying jobs for the Australians.
Arafura must be hoping that we are stupid enough to stop Lynas and stop competing with them.
Remember the Tin slag from the Eastern Semelting and Straits Trading in Penang? These, which contain the tantalum and monazite ore, and the monazite ore, can be more than 3,700% more radioactive than the Lynas waste.
And these radioactive tin slag were used to fill up the old Penang Stadium and the roads in Penang. A lot of these already been stolen and sold off at a huge profit, but a lot still remains in the roads in Butterworth and Penang island.
The people in Penang have not developed Cancer so far as a result of these slag!
By: Dato’ Dr. Looi Hoong Wah,
FAMM, MB. ChB (Manchester), MRCS (England), MRCP (UK), MRCP (London)