nuclear-news

The News That Matters about the Nuclear Industry Fukushima Chernobyl Mayak Three Mile Island Atomic Testing Radiation Isotope

Nuclear Power Plants: Tritium is a lot more hazardous than they say

tests for statistical significance have been misused in epidemiological studies on cancers near nuclear facilities. These in the past have often concluded that such effects do not occur or they downplayed any effects which did occur. In fact, copious evidence exists throughout the world – over 60 studies – of raised cancer levels near NPPs.

Most (>75%) of these studies found cancer increases but because they were small, their findings were often dismissed as not statistically significant. In other words, they were chucked in the bin marked “not significant” without further consideration.

Just as people were misled about tobacco smoking in previous decades, perhaps we are being misled about raised cancers near NPPs nowadays.

The Hazards of Tritium, Dr Ian Fairlie, March 13, 2020

Summary

Nuclear facilities emit very large amounts of tritium, 3H, the radioactive isotope of hydrogen.  Much evidence from cell/animal studies and radiation biology theory indicates that tritium is more hazardous than gamma rays and most X-rays. However the International Commission on Radiological Protection (ICRP) continues to underestimate tritium’s hazard by recommending  a radiation weighting factor (wR) of unity for tritium’s beta particle emissions.  Tritium’s exceptionally high molecular exchange rate with hydrogen atoms on adjacent molecules makes it extremely mobile in the environment. This plus the fact that the most common form of tritium is water, ie radioactive water, means that, when tritium is emitted from nuclear facilities, it rapidly contaminates all biota in adjacent areas. Tritium binds with organic matter to form organically bound tritium (OBT) with long residence times in tissues and organs making it more radiotoxic than tritiated water (HTO). Epidemiology studies indicate increases in cancers and congenital malformations near nuclear facilities. It is recommended that nuclear operators and scientists should be properly informed about tritium’s hazards; that tritium’s safety factors should be strengthened; and that a hazard scheme for common radionuclides be established.

Contents

  1. Overview
  2.  The Multiple Hazards of Tritium
  3. Molecular Exchange
  4. How are we exposed to tritium?
  5. Organically Bound Tritium
  6. Longevity of OBT in the Environment
  7. How do we estimate tritium risks?
  8. Epidemiology
  9. The Abuse of Statistical Significance Tests
  10. Recommendations
  11. References…….

Tritium is the radioactive isotope of hydrogen with a half life of 12.3 years. It decays through the emission of a beta particle with a maximum energy of 18.7 keV and an average energy of 5.7 keV (Okada, 1993). The mean free path of tritium’s decay beta particle in tissue is about 0.6 µm, the diameter of a human chromosome. It exists in nature mainly as elemental tritium (HT) and as radioactive water (HTO). The biological half-life of HTO in humans is about 10 days but this can be shortened by forced diuresis. The biological half-lives of OBT depend on the atom (eg C, N, and P) to which the tritium is bound and the longevity of its organic molecule, eg DNA and RNA are strongly conserved. In areas remote from nuclear facilities, background levels of tritium in water are about two to five becquerels (Bq) per litre mainly as the residue from atmospheric atomic bomb tests in the 1950s and 1960s.

In the latter half of the 20th century, tritium was often regarded as a “weak” nuclide. This attitude changed after the publication of the CERRIE report on internal emitters in 2004, as tritium is the most commonly experienced internal emitter.  The CERRIE report resulted in major reports on tritium by radiation safety agencies in the UK (AGIR, 2008), Canada (CNSC, 2010a; 2010b) and France (ASN, 2010). In addition, the French Institute de Radioprotection et de Sûreté Nucléaire published six reports on tritium (IRSN, 2010a; 2010b; 2010c; 2010d; 2010e; 2010f). In particular, these reports noted that tritium exposures resulted in internal radiation doses which were difficult to estimate and contained large, possibly very large, uncertainties which could render them unreliablThe most comprehensive report on tritium was published by the UK Government’s senior Advisory Group on Ionising Radiation (AGIR, 2008). This strongly recommended that tritium’s hazard (ie, its Relative Biological Effectiveness or RBE) should be doubled. A draft report by the US EPA (2006) recommended its RBE should be increased by a factor of 2.5. Other scientists (Fairlie, 2008; Fairlie, 2007a; Fairlie, 2007b; Melintescu et al, 2007; Makhijani et al, 2006) have presented evidence for even larger increases in tritium’s radiotoxicity.

The above reports drew attention to tritium’s various properties which mark it out as an unusually hazardous radionuclide. These include

  • its relatively long half-life of 12.3 years,
  • its mobility and cycling as radioactive water in the biosphere,
  • its multiple pathways to man,
  • its ability to swap instantaneously with H atoms in adjacent materials,
  • its comparatively high relative biological effectiveness (RBE) of 2 to 3,
  • its propensity to bind with cell constituents to form organically-bound tritium (OBT) with heterogeneous distribution in humans, and
  • the short range of its beta particle meaning that its damage depends crucially on its location within cellular molecules, including DNA
  • in its oxide form, tritium is generally not detected by commonly-used survey instruments (Okada et al, 1993), and
  • in its elemental form, tritium diffuses through most containers, including those made of steel, aluminium, concrete and plastic.See for example, https://www.ianfairlie.org/news/continued-radioactive-emissions-from-old-closed-nuclear-reactors/
In sum, tritium presents numerous challenges to conventional dosimetry and health risk assessment. However several very recent reports have indicated little awareness of these problems with tritium.  ………

How are we exposed to tritium?

Let’s examine what actually happens when tritium is emitted from nuclear facilities whether as water vapour or as elemental tritium. It travels via multiple environmental pathways (vapour plumes, rivers, crops etc) to reach humans. Human intakes occur via

  • skin absorption,
  • inhalation of contaminated water vapour, and
  • ingestion of contaminated food and water

When tritium enters the body, it is readily taken up through exchange mechanisms by metabolic reactions and by cellular growth. Over 60 percent of the body’s atoms are hydrogen atoms, and every day about five per cent of these are egaged in metabolic reactions and cell proliferation. The result is that a proportion of the tritium taken in is fixed to lipids, carbohydrates, proteins and nucleoproteins such as DNA and RNA. This is organically bound tritium (OBT) and is discussed further below.

These unusual properties suggest that tritium should be regarded as hazardous by radiation protection authorities. Unfortunately this is not the case. Tritium’s unusual properties are not at all recognised by the ICRP and national authorities which take their lead from the ICRP. Unfortunately, no international hazard index for radionuclides exists at present although one has been proposed (Kirchner, 1990).

Another controversy exists over the ICRP’s continued recommendation of a radiation weighting factor (wR) for tritium of 1 despite copious evidence (Fairlie, 2007a) that it should be doubled or trebled. This debate has lasted for more than sixty years.

It should be borne in mind that the ICRP, despite its title, is not an official body but a voluntary one. In the past, its scientific interpretations have been criticised (eg Shrader-Frechette, 1985). Although it has adopted a more open appearance in recent years, when it comes to crunch issues such as collective dose, internal dosimetry, and the RBE for tritium, it remains principally concerned with protecting the interests of its members rather than those of the general public. It appears that non-scientific considerations play a part in the ICRP’s policies on tritium, particularly as regards nuclear weapons production plants in the past, nuclear power facilities at present and proposed fusion facilities in future.

Organically Bound Tritium (OBT)

OBT is non-uniformly distributed and is retained for longer periods than tritiated water. ICRP dosimetric models for tritium assume the opposite – that tritium is homogenously distributed in the tissues/organs as tritiated water (HTO) and is quickly excreted. The problem is that exposures from OBT are generally higher than those from HTO. The longer people are exposed to tritiated water emissions, the higher their levels of OBT become until, in the case of exposures lasting years, equilibria are established between HTO and OBT levels. Again ICRP dosimetric models assume the opposite: only single exposures are considered so that their estimates of OBT levels remain low………

Longevity of OBT in the Environment

Eyrolle-Boyer et al (2014) have suggested that raised OBT levels can persist in the environment for several decades following HTO releases. They found that terrestrial biomass pools which had been contaminated by the global atmospheric fallout of tritium from nuclear weapons testing in the 1950s and 1960s constituted a significant delayed source of OBT, resulting in an apparent increase in OBT levels compared to HTO levels. This finding explains OBT/HTO ratios greater than 1 observed in areas not affected by radioactive releases. This finding also supports the findings by Ichimasa (1995) of long-term raised OBT levels near the Chalk River nuclear plant in Canada following chronic tritium releases………

How do we estimate tritium risks?

In the assessment of risks from tritium releases, aerial emissions are more important than liquid discharges for two reasons. First, the key parameter in estimating radiation doses to local people is the nuclide concentration in environmental materials. Contrary to what many think, air emissions result in higher environmental concentrations than water discharges. The reason is dilution: ………

When assessing risks, it is considered preferable to use radioactivity instead of radiation, in other words we should use tritium’s Bq emissions and intakes and concentrations instead of Sv doses. At least, radioactivity can be physically measured whereas radiation doses are estimates. The radioactivity approach has been used by other scientists (eg Osborne, 2002)

Air concentrations of tritium will vary considerably over time as spikes in tritium emissions regularly occur. Pulsed tritium emissions could result in heavy labelling of cells being formed in the embryos and fetuses of nearby pregnant women at that particular moment. This fear was expressed by Professor Edward Radford in his 1979 testimony to the Ontario Government’s Select Committee on Ontario Hydro Affairs: Hearings on The Safety of Ontario’s Nuclear Reactors,  See http://www.ccnr.org/tritium_2.html#scoha] July 10 1979.This provides the basic mechanism for the hypothesis explaining the large observed increases in leukemia in subsequent children born near nuclear reactors (Fairlie, 2014).

Local people living near nuclear facilities can be exposed to tritium via

  • drinking tritiated liquids, and ingesting foodstuffs contaminated with tritiated water vapour, e.g. from local markets and fruit stalls
  • inhaling tritium gas and tritiated water vapour, and
  • skin absorption of tritiated water vapour

In fact, local people could have high intakes of tritium, so that, ideally, their tritium concentrations should be measured using urine analyses for HTO and non-invasive bioassays, such as nail clippings and hair clippings, for OBT. Unfortunately this is almost never done among members of the public.

Yardstick for tritium in drinking water

To use radioactivity (measured in Bq) as a measure of risk, we need a yardstick for safe levels in drinking water, which is constructed as follows…………

Conclusion   I have argued that tests for statistical significance have been misused in epidemiological studies on cancers near nuclear facilities. These in the past have often concluded that such effects do not occur or they downplayed any effects which did occur. In fact, copious evidence exists throughout the world – over 60 studies – of raised cancer levels near NPPs. This is discussed in my scientific article in 2014 on a hypothesis to explain cancers near NPPs. Most (>75%) of these studies found cancer increases but because they were small, their findings were often dismissed as not statistically significant. In other words, they were chucked in the bin marked “not significant” without further consideration. I conclude by asking open-minded scientists and observers to reconsider their views about the above 60+ studies and the misleading COMARE reports showing raised cancer levels near NPPs. Just as people were misled about tobacco smoking in previous decades, perhaps we are being misled about raised cancers near NPPs nowadays.

Recommendations

It is recommended that

  1. a limit of 20 becquerels per litre (Bq/L) for drinking water
  2. Urine tests and non-invasive bioassay tests should be carried out on volunteers living nearby to ascertain HTO/OBT levels.
  3. Local residents should be advised to avoid consuming locally-grown foods and water from local wells.
  4. Local women near NPPs intending to have a family, and families with babies and young children should consider moving elsewhere. It is recognised this recommendation may cause concern but it is better to be aware of the risks to babies and young children than be ignorant of them.
  5. Employees and their spouses, especially young workers, should be informed about the hazards of tritiuStatistical significance in epi study findings should not be arbitrarily used to dismiss positive findings.
  6. Statistical significance in epi study findings should not be arbitrarily used to dismiss positive findings.
  7.   A hazard index of radionuclides should be established.

March 19, 2020 - Posted by | radiation, Reference, secrets,lies and civil liberties, spinbuster

No comments yet.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: