Science and Values in Radiological Protection

The second workshop of the CRPPH on radiological protection and public health

Vaulx de Cernay, France

30 November - 2 December 2009

Possible questions for 2nd S&V workshop break-out sessions

Taking “What Now?” as the key question of the workshop, perhaps the following background could be taken into account:

Introductory Presentations
These should provide

• Description of the science, and of any changes in scientific knowledge that today provoke new thoughts on how to manage radiological protection as it applies to radon, medical exposures or radiation-induced vascular effects .
• Description of how these three topical areas are currently addressed, in a broad sense and in terms of the “common” national approaches (if there are any), or in terms of any marked differences that are known to exist
• Consideration of how the choices to be made reflect issues at the root of radiological decision-making: considerations of balance (of risks and benefits), of uncertainty (of the scientific understanding of the situation) or of implications (in terms of costs or re-framing if regulatory and practical change is needed).

Breakout sessions
These should discuss, for each topical area:

• Which issues need further elaboration before deciding whether it is necessary or appropriate to change the current approach?
• Identification and discussion of science issues
• what level of effect is being discussed
• what are the uncertainties involved and how well characterized are they
• Identification and discussion of practical issues
• What would a change of regulation impact
• What would be the magnitude of such impacts
• Identification and discussion of value issues
• Balance of risks and benefits
• Precautionary judgment

• What aspects weigh on decisions regarding possible change? What would be the implications of alternative approaches if it were decided to change? What elements are needed before a “tipping point” is reached in terms of feeling that it is time for “significant” change?
• Implications for regulation, industry and health care sector
• Practical implications for application
• Resources
• Need for wide-scale application
• Need for a large number of people to be involved
• Need for a graded, long-term approach
• Significant change of approach
• Very new risk assessment
• Very new management approach
• Education and training implications
• Significant retraining of current radiological protection professionals
• Significant need to alter radiological protection education

An important output of the breakout sessions would be the identification of where, in current policy and application, there is a need for more explicit expression of value judgments and rationale for current choices in protection.

Based on these considerations, the following questions could be used as a starting point for Breakout session discussions:

Radon as public health issue: How to best address this as a public health issue?
Observations today:

1. Many national domestic radon management programmes have not been extremely successful at achieving the results they desired
2. Recent epidemiological studies suggest that radon is a key cause of lung-cancer deaths in both smokers and non-smokers, with statistical significance at exposures levels on the order of 150 Bq/m3.
3. The ICRP and the UNSCEAR seem on the verge of agreeing on exposure conversion factors such that they now agree that the dosimetric benchmark that has been used for radon exposure, i.e. 10 mSv/a, represents approximately 300 – 400 Bq/m3 of Rn-222 (at an equilibrium factor of 0.4).

These observations bring to mind several questions regarding how values are included in radiological protection decision making for the management of radon exposures:

• Is 10 mSv/a still a good dosimetric benchmark for radon exposure?
• If not, what criteria should be used?
• What benchmarks to be used, in terms of activity concentration; e.g. by ICRP Publ.103 recommended 1500 Bq/m3 reference level for worker exposure, and 600 Bq/m3 - reference level for public exposure?
• Should the value of 1000 Bq/m3 continue to be used as an “entry point” at which worker exposure would be subject to occupational exposure protection measures (i.e. dose measuring/assessment and recording, worker health considerations, worker dose limitation, etc.)?

These observations also bring to mind several questions regarding practical aspects of radiological protection for the management of radon exposures:

• Are there national radon exposure management programmes that have achieved their desired results?
• What targets are used for the management of radon exposures?

Medical exposures in diagnostic and screening procedures: How to best balance risks and benefits?
Observations today:

1. Patient exposures from medical use of diagnostic and screening procedures are increasing very rapidly. In some developed countries, per capita medical exposure now exceeds per capita natural background exposure.
2. The radiological protection community sees this as a significant challenge, while the medical community focuses more on the medical benefits that these imaging procedures have brought.

These observations bring to mind several questions regarding how values are included in radiological protection decision making regarding the management of medical exposures, and regarding how exposures can practically be most effectively managed:

• What is the best approach to reconcile the assessment of risks and benefits from medical exposures in the context of implementing an “appropriate” level of radiological protection?
• What national programmes have effectively been implemented to appropriately manage medical exposures?

Radiation-induced vascular effects: How/when should evolving science affect radiological protection policy and practice?
Observations today:

1. New epidemiological evidence suggests that chronic exposure at levels as low as 500 mSv can cause excess risk of stroke and heart disease.
2. Current biological understanding does not reveal any mechanism(s) for this detriment, but studies do not suggest that this is a threshold effect.

These observations bring to mind several questions regarding how values are used in regulatory discussions of the impacts that this new risk might have on radiological protection principles, policy and practice:

• How much additional risk is suggested by these studies?
• What are the implications for detriment and effective dose?
• Is there an evidence sufficiently compelling to require the adoption of a precautionary approach?
• What is the importance of consistency of approach given the precedent in how cancer risk was managed/regulated in absence of complete knowledge?
• How would this additional risk be taken into account in discussions of radiological risk management?
• At what level would additional risk be sufficient to result in changes to the current radiological protection paradigm (i.e. relative risk model and dose/risk curves)?
• At what point would it be appropriate to consider lowering dose limits?
• For workers?
• For the public?