AW: [ RadSafe ]" EPA Tritium Risk Plan May Force Tighter NuclearPlant Controls "

[Rainer.Facius at dlr.de]

“Carcinogenesis following HTO intake appears to be strongly dependent upon dose rate.”

Philippe,

this reminds us of the paper by Gregoire and Cleland last year paper:

Conclusions: The idea that the dose rate may have a significant impact on health effects of ionizing radiations is not new, but has always been considered as a parameter in models based on integrated dose. The novel approach in this paper is to consider the primary relevant parameter as an average of dose rate over a time period of one day. This is an argument to revise the whole philosophy in radioprotection, and place regulatory limits on specific locations instead of annual limits relevant to individual persons. 

Gregoire O, Cleland M.
Novel approach to analyzing the carcinogenic effect of ionizing radiations 
International Journal of Radiation Biology 82#1(2006)13-19

Best regards, Rainer

Dr. Rainer Facius
German Aerospace Center
Institute of Aerospace Medicine
Linder Hoehe
51147 Koeln
GERMANY
Voice: +49 2203 601 3147 or 3150
FAX:   +49 2203 61970

-----Ursprüngliche Nachricht-----
Von: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] Im Auftrag von Philippe J. Duport
Gesendet: Mittwoch, 20. Juni 2007 16:43
An: John R Johnson; Franta, Jaroslav; Radsafe (E-mail)
Betreff: RE: [ RadSafe ]" EPA Tritium Risk Plan May Force Tighter NuclearPlant Controls "

Radsafers

Follow-up on John Johnson’s comments:

Carcinogenesis following HTO intake appears to be strongly dependent upon dose rate.  Yamamoto et al exposed mice to chronic ingestion of HTO starting at 10 weeks of age.  They show fairly clear thresholds at or below 12 mGy/day.  I think Myers et al conducted their experiments at doses total doses of about 1 to 3 Gy, delivered in one intraperitoneal injection; the total dose was delivered in a few days and the dose rate was fairly high immediately after the injection.  The difference in dose rates may explain the difference between Yamamoto's and Myers's results.   

Reference:  Yamamoto, O., Seyama, T., Itoh, H., and Fujimoto, N. (1998) Oral administration of tritiated water (HTO) in mouse. III: Low dose-rate irradiation and threshold dose-rate for radiation risk.  Int J Radiat Biol, 73:535-541.

Philippe Duport

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On Behalf Of John R Johnson
Sent: June 20, 2007 10:13
To: Franta, Jaroslav; Radsafe (E-mail)
Subject: Re: [ RadSafe ]" EPA Tritium Risk Plan May Force Tighter Nuclear Plant Controls "

Radsafers

It is "well known" that tritium and other radionuclides that emit low energy electrons and photons have a higher risk per unit dose than the "standard" 
250 kVp X-rays, but than so does lower energy X-rays, and higher energy electons and photons have lower risks. We did a large animal experiment at CRNL to test this.

See

INDUCTION OF MAMMARY TUMOURS IN RATS BY X‑RAYS AND TRITIUM BETA‑RAYS

D.K. Myers, N.J. Gragtmans, J. R. Johnson, L.D. Johnson, and A.R. Jones

Published in the proceedings of an international symposium on The Effects of Low‑Level Radiation with Special Regard to Stochastic and Non‑Stochastic Effects, jointly organized by the International Atomic Energy Agency and the World Health Organization, IAEA‑SM‑266/12P (1983) 653.

and

AN EXPERIMENT DESIGNED TO MEASURE THE RBE OF TRITIUM FOR THE INDUCTION OF MYELOID LEUKEMIA IN ANIMALS

J. R. Johnson, D.K. Myers, and N.J. Gragtmans

Radiation Protection Dosimetry 16 Nos. 1‑2 (1986) 161‑164, AECL‑9339.


The ICRP, NCRP, etc have decided that a single radiation weighting factor of unity is adaquate to represnt the risk from all this radiation, given the large uncertainty in the risk.

Is there new information that is "leading" the EPA to change this titium weighting factor?

***************
John R Johnson, PhD
CEO, IDIAS, Inc.
Vancouver, B. C.
Canada
(604) 222-9840
idias at interchange.ubc.ca



----- Original Message -----
From: "Franta, Jaroslav" <frantaj at aecl.ca>
To: "Radsafe (E-mail)" <radsafe at radlab.nl>
Sent: Wednesday, June 20, 2007 6:10 AM
Subject: [ RadSafe ] " EPA Tritium Risk Plan May Force Tighter Nuclear Plant Controls "


> Comments welcome:
>
>
> EPA Tritium Risk Plan May Force Tighter Nuclear Plant Controls Energy 
> Washington Week, Vol. 4, No. 25, 20 June 2007
>
> EPA is considering a substantial increase in its estimates of the 
> risks posed by human exposure to tritium, a controversial byproduct of 
> nuclear power generation, in a move that could prompt nuclear 
> regulatory agencies to tighten their risk-based approaches for 
> regulating radiological releases from nuclear power plants.
>
> However, sources say any effort by EPA to tighten the risk estimates 
> for tritium would likely prompt opposition from the industry and 
> nuclear regulators, who fear it would complicate industry efforts to 
> present nuclear power as an alternative to coal-fired generation under 
> any future climate change regime.
>
> Informed sources say EPA is weighing whether to double the 
> effectiveness factor it assigns for tritium, a risk estimate figure 
> used in setting contamination and cleanup standards that represents a 
> given radionuclide's potential to damage the human body. EPA and other 
> federal regulators generally set this factor at 1.7 for tritium and similar radionuclides.
>
> However, recent scientific findings from the International Commission 
> on Radiological Protection and evidence accumulated by the National 
> Institute for Occupational Safety and Health (NIOSH) have led some EPA 
> regulators to consider increasing that factor to 2 or higher, the sources say.
>
> Tritium is an isotope of hydrogen that produces relatively low levels 
> of radiation. Nuclear power plants release tritium in water and steam 
> discharges. Regulators in several instances have also dealt with 
> tritium leaks from nuclear facilities in the form of contaminated water.
> Consequently the task of estimating the health risks associated with 
> tritium is a highly contentious issue among nuclear experts, industry 
> and environmentalists.
>
> Observers say increasing the effectiveness factor for tritium could 
> result in risk assessments that suggest human exposure to tritium is 
> more harmful, thereby giving federal regulators grounds to tighten 
> tritium containment and release standards at nuclear power plants, 
> research laboratories and places where nuclear fuel is stored. 
> Additionally, a key activist source says the increased risk figures 
> could encourage more severe federal enforcement actions should 
> regulators discover tritium leaking at a nuclear facility.
>
> Increasing the effectiveness factor for tritium would have little to 
> no impact on EPA's radiation standards because the risk associated 
> with tritium would still be within already regulated levels, which are 
> based on calculated doses, the sources add. Nevertheless, the move 
> could spur regulators in other agencies -- such as the NRC and the 
> DOE-- to adopt a similar risk assessment approach, the sources say.
>
> Sources say EPA efforts to tighten its risk estimates would likely 
> prompt opposition from NRC and the industry, in part because it could 
> stifle efforts to build as many as 27 new nuclear reactors in the 
> United States over the next few years.
>
> Nuclear industry officials are hoping for a so-called "renaissance" 
> for nuclear power nationwide, arguing in part that the plants provide 
> increased energy supplies without increasing harmful greenhouse gas 
> emissions that contribute to climate change.
>
> However, environmentalists and Democrats are calling for stricter 
> safety and environmental controls on the industry before new plants 
> can be built.
>
> News that EPA is eyeing an increase in the tritium effectiveness 
> factor could bolster anti-nuclear activists and prompt opposition from 
> NRC and industry.
>
> The expected growth in the nuclear energy sector, an informed federal 
> source says, is one reason NRC would likely resist any effort to 
> increase the risk factors connected to tritium. "The other agencies 
> would try to stop it,"
> the
> source says. "Not under this administration, it'll never make it through."
>
> A radiological protection expert agrees, saying such an increase in 
> tritium effectiveness factor could "make the NRC mad."
>
> An NRC source downplays the significance of increasing the 
> effectiveness factor for tritium, saying the agency would have to 
> formulate its own technical opinion on the factor before adopting it. 
> The source also takes issue with the suggestion that the factor could 
> impact power plant standards, noting that new plants tend to use the 
> most current methods to ensure radiation exposures remain well below 
> regulated levels. A nuclear industry source agrees, noting that the 
> deliberative nature of setting radiation standards could mean that any 
> regulatory change may be years in the making.
>
> One informed source cautions that it is "not a foregone conclusion" 
> that increasing the factor will lead to stricter tritium regulations 
> because those rules are most often based on specific dose 
> calculations. However, an expert with a nuclear watchdog group 
> suggests the increased factor would translate into tougher standards 
> and regulators "would have to do something to undercut that" in their 
> risk calculations for it to not have a significant impact.
>
> But despite potential efforts to block tighter risk factors for 
> tritium, the federal source notes that EPA is slated to begin a review 
> of its water contaminant limits for radionuclides in 2009. Increasing 
> the effectiveness factor, the source adds, could encourage agency 
> regulators to impose stricter maximum contaminant level (MCL) limits, 
> which the agency also uses to set cleanup standards, during this 
> review. The tritium MCL is currently set at 20,000 picocuries per 
> liter of water, roughly 4 millirems of exposure per year.
>
> EPA has already seen pressure from nuclear watchdog groups to impose 
> significantly stricter water standards for plutonium in the pending 
> review.
>
> EPA is also in the midst of a Science Advisory Board panel review 
> examining the agency's risk approach to radiation that will likely 
> prompt the agency to adjust its risk calculations for many 
> radionuclides. A nuclear watchdog group has repeatedly urged the panel 
> to increase the effectiveness factor for tritium to 3 or higher, 
> citing several studies arguing it should be raised. A source with one 
> group says the panel will soon receive formal written comments 
> advocating such an increase.
>
> The panel's most recent draft report, released Feb. 23, says tritium 
> is among several issues the National Academy of Sciences most recent 
> report evaluating radiation risks, which is the basis on the panel's 
> work, did not address. EPA has a "need to derive a basis for risk 
> estimates" for it, the report says.
>
> The report also suggests EPA's effectiveness factor for tritium could 
> be increased as the agency adopts its proposed radiation risk methods 
> based on the NAS report. In its discussion of the risks associated 
> with low-energy photons and electrons, the report says "an 
> effectiveness factor for these low energy radiations in the range of 2 
> to 2.5 seems reasonable." The report includes the chemical symbol for 
> tritium, 3H, among the particles that would fall within that category.
>
> Additionally, tritium will likely be at issue in a June 21 meeting 
> between officials with the NRC and the nuclear industry focused on a 
> voluntary industry initiative begun last year to boost groundwater 
> protection standards at power plants. The initiative was prompted by 
> concerns over tritium leaks at several nuclear facilities.
>
> However, the nuclear industry contends such leaks are not dangerous to 
> public health and are generally contained within the facility in question.
> The radiological protection expert adds that concerns over tritium 
> leaks would be better addressed by ensuring it is contained at a site, 
> rather than increasing the risk factors associated with it. The source 
> points out that NRC and the nuclear industry itself closely monitor 
> tritium to ensure leaks and other unintentional releases are 
> prevented.
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