Societal issues in a context of radiation protection

Transcription

1 Societal issues in a context of radiation protection Dr Patrick Smeesters Vice-chair BVS/ABR, UCL, EC Art 31, Belgium Challenges for the Radiological Protection for the next 50 years Symposium BVS/ABR 50 th anniversary Brussels, 8-10 April 2013 P. Smeesters 8-10 April

2 Challenges for the Radiological Protection for the next 50 years: societal issues at a glance Strategies of doubt and the lost credibility of the experts Dominant medical paradigm: limits and misuses of the evidence-based approach Lack of precautionary attitude in scientific research Scientific reductionism and mechanistic vision of the world: increasing gap with society P. Smeesters 8-10 April

3 Societal issues: an illustration The 100 msv case frequently presented as a level of concern for radiation effects on human health, under this level the possibility of any health effect is purely hypothetic. P. Smeesters 8-10 April

4 Some statements Académie Nationale de Médecine (Fr; rapport 2005):»les études épidémiologiques disponibles ne décèlent aucun effet pour des doses inférieures à 100 msv, soit qu il n en existe pas, soit que la puissance statistique des enquêtes ait été insuffisante pour les détecter Une relation linéaire décrit convenablement la relation entre la dose et l effet cancérogène pour les doses supérieures à 200 msv où on a pu la tester». Position statement of the Health Physics Society (2010): below 5 10 rem ( msv) (which includes occupational and environmental exposures), risks of health effects are either too small to be observed or are nonexistent P. Smeesters 8-10 April

5 Purely hypothetic? Either not observable or nonexistent? Is this true? P. Smeesters 8-10 April

6 In utero irradiation BEIR VII: «Studies of prenatal exposure to diagnostic X-rays have, despite longstanding controversy, provided important information on the existence of a significantly increased risk of leukaemia and childhood cancer following diagnostic doses of mgy in utero» P. Smeesters 8-10 April

7 Childhood thyroid cancer FDA (2001); «FDA has concluded from the Chernobyl data that the most reliable evidence supports a significant increase in the risk of childhood thyroid cancer at exposure of 5 cgy or greater.» P. Smeesters 8-10 April

8 New data: Kendall 2013 (Leukemia) A record-based case-control study of natural background radiation and the incidence of childhood leukaemia and other cancers in Great Britain during : cases - 12% ERR (95% CI 3, 22) of childhood leukaemia per msv of cumulative red-bone-marrow dose from gammaradiation supports the extrapolation of high dose-rate risk models to protracted exposures at natural background exposure levels. P. Smeesters 8-10 April

9 γ-h2ax foci in T-lymphocytes Control sample 0.5 Gy in vitro P. Smeesters 8-10 April

10 Comparison of γ-h2ax foci induced in vivo in pediatric patients versus in vitro irradiation Dashed line: LNT extrapolation from in vitro 0.5 Gy P. Smeesters 8-10 April

11 New data: Pearce 2012 (Lancet) Radiation exposure from CT scans in childhood and risk of leukaemia and brain tumours: Retrospective study (based on NHS UK): patients < 22 y with CT ( ); cancers Relative risk of leukaemia for patients who received a cumulative dose of about 50 mgy: 3 18 (95% CI ) Relative risk of brain cancer for cumulative dose of about 60 mgy: 2.82 ( ) Linear dose response; supports LSS extrapolations P. Smeesters 8-10 April

12 Solid Cancer Incidence among Japanese Atomic Bomb Survivors ( ) (from Preston et al., Radiat Res 2007; 168: 1-64) P. Smeesters 8-10 April

13 DDREF issue (DOSE AND DOSE RATE EFFECTIVENESS FACTOR) DDREF: reduction of risk coefficient at low dose and dose rate LSS: quasi-linear dose-response for solid cancers (means DDREF ~ 1) ICRP (current regulation + 103): DDREF: 2 BEIR VII (central estimate): DDREF: 1.5 (LSS DDREF) ( ) Art 31 GoE (Art 31 Sem. 2006): From a Radiation Protection point of view, a DDREF of 1.5 seems to be more justified P. Smeesters 8-10 April

14 Radiation-induction of cancer : overall judgment (U 2000) On the basis of the current evidence : no threshold; cancer risk rising as a function of dose; various patterns: L and LQ «the most scientifically defensible approximation» P. Smeesters 8-10 April

15 BEIR VII and current ICRP: position regarding LNT Support U 2000 conclusions BEIR VII conclusion: The committee concludes that current scientific evidence is consistent with the hypothesis that there is a linear, no threshold dose-response relationship between exposure to ionizing radiation and the development of cancer in humans. P. Smeesters 8-10 April

16 Why biologically consistent? P. Smeesters 8-10 April

17 Multistage model of tumorigenesis: Mutational driving force (UNSCEAR 2000) Damage to DNA Failure to correct DNA damage Initiating mutation (most tumours: single target stem-like cell) Promotional growth ( role of cellular environment) Conversion to malignant phenotype (driven by further mutations) Progression: tumour spread (driven by further mutations) P. Smeesters 8-10 April

18 DNA-repair genes, cell-cycle regulation genes (U 2000) Many genes involved in the response to DNA-damage Puzzle not yet assembled Several pathways for DNA-repair: error-prone or «errorfree» (homologous recombination) «Error-free»?: uses template of parental copy but in heterozygotes can copy the bad allele! Loss of heterozygoty! P. Smeesters 8-10 April

19 Cancer-proneness Human genetic disorders affecting DNA-repair genes and cell-cycle regulation genes P. Smeesters 8-10 April

20 Exposure to diagnostic radiation and risk of breast cancer among carriers of BRCA1/2 mutations: retrospective cohort study (Pijpe 2012 GENE-RAD-RISK) In this large European study among carriers of BRCA1/2 mutations, any exposure to diagnostic radiation before the age of 30 was associated with an increased risk of breast cancer. P. Smeesters 8-10 April

21 There is compelling evidence that there are observable effects (well below) under 100 msv, and consistent biological explanations P. Smeesters 8-10 April

22 Why does the 100 msv myth survive? conflicts of interest : lead to strategies of doubt misuse of the evidence-based approach, by focusing only on the avoidance of unjustified causal associations (false positives) and neglecting the possibility of unjustified dismissal of real health effects (false negatives) misunderstanding of the precautionary principle, considered not relevant in science Value judgments: self-censorship, due to the pressure of dominant paradigms and of the peers. P. Smeesters 8-10 April

23 Conflicts of interest National and quasi all international institutions have obvious conflicts of interest. Research depends on its financing and this financing comes often from these institutions. Self-censorship is the easiest way to avoid problems. Scientific independence is a moral duty but also a difficult financial challenge. P. Smeesters 8-10 April

24 Srategies of doubt Alla Yarochinskaya (22 April 1996) «Lies about Tchernobyl are more terrifying than the disaster himself» P. Smeesters 8-10 April

25 Why does the myth survive? conflicts of interest : lead to strategies of doubt misuse of the evidence-based approach, by focusing only on the avoidance of unjustified causal associations (false positives) and neglecting the possibility of unjustified dismissal of real health effects (false negatives) misunderstanding of the precautionary principle, considered not relevant in science Value judgments: self-censorship, due to the pressure of dominant paradigms and of the peers. P. Smeesters 8-10 April

26 Evidence-based approach: current dominant scientific paradigm The almost only concern is to avoid concluding that a causal relationship exists before it is firmly proved (hard evidence). The main dominant concern is: avoid the false positives P. Smeesters 8-10 April

27 Misuse of evidence-based approaches: long term effects in a rapidly moving world For society the main concern of the experts is expected to be the protection of health. When there is scientific plausibility (enough evidence) of the existence of a risk of serious harm, action is needed! Even if there is still uncertainty! The main societal concern is: avoid the false negatives! P. Smeesters 8-10 April

28 The hard evidence-based approach is largely dominant by nuclear experts. It is frequently used as a stategy for delaying decisions as long as «some doubt» exists. (cfr tobacco) P. Smeesters 8-10 April

29 Why does the myth survive? conflicts of interest : lead to strategies of doubt misuse of the evidence-based approach, by focusing only on the avoidance of unjustified causal associations (false positives) and neglecting the possibility of unjustified dismissal of real health effects (false negatives) misunderstanding of the precautionary principle, considered not relevant in science self-censorship, due to the pressure of dominant paradigms and of the peers. P. Smeesters 8-10 April

30 Misunderstanding of the precautionary principle: Precaution in Science is relevant! Although frequently limited to the decision-making processes in situations of uncertainty, the precautionary approach is also relevant and appropriate in science. As underlined in the COMEST report from UNESCO, the precaution approach in science includes: a focus on risk plausibility rather than on hard evidence a responsiveness to the first signals ( early warnings ) a systematic search for surprises ( thinking the unthinkable ), particularly for possible long term effects P. Smeesters 8-10 April

31 Missed early warnings Recent developments regarding the late recognized radiation effects of low to moderate doses on the lens of the eye and on the circulatory system are good illustrations of a lack of vigilance and responsiveness regarding early warnings that were described many years ago. P. Smeesters 8-10 April

32 Thinking the unthinkable Recent scientific findings and publications on the health effects of Chernobyl RADIATION PROTECTION NO P. Smeesters 8-10 April

33 Children s morbidity Many claims concerning the health of children in the contaminated territories around Chernobyl, which seem to suffer from multiple diseases and co-morbidities with repeated manifestations (compilation in Yablokov 2009) Reports from international organizations did not give until now much interest: psychosocial But most studies not available in English and not translated! P. Smeesters 8-10 April

34 Children s morbidity: recent initiatives Series of IRSN studies: Rats exposed to 137 Caesium contamination during several months through drinking water (150 Bq/day/animal: comparable with a typical low intake in the contaminated territories) Although the animals tested in theses studies did not show induced clinical diseases, a number of important biological effects were observed on various systems: increase of CK and CK-MG, decrease of mean blood pressure and disappearance of its circadian rhythm; EEG modifications, perturbations of the sleep-wake cycle, neuro-inflammatory response, particularly in the hippocampus, etc P. Smeesters 8-10 April

35 Children s morbidity: recent studies Series of longitudinal studies initiated recently in Ukraine in conjunction with the US University of South Carolina: Stepanova 2008: 1993 to 1998: significant reduction in red and white blood cell counts, platelet counts and haemoglobin with increasing residential soil contamination (cfr Techa River) Svendsen 2010 : 1993 to 1998: spirometry: statistically significant evidence of both airway obstruction and restriction with increasing soil contamination (immune mechanism?) The optimism of the UN reports may be based on too few studies published in English, conducted too soon after the event to be conclusive. P. Smeesters 8-10 April

36 Children s morbidity and internal exposures: thinking the unthinkable For chronic internal exposures, a major underlying issue could be the adequacy of the effective dose as risk indicator. P. Smeesters 8-10 April

37 Studies on embryos: HTO v/ tritiated arginine: factor ! (factor 4 for Sv/Bq!) (EU RIHSS; HPA; livre blanc ASN) P. Smeesters 8-10 April

38 Why does the myth survive? conflicts of interest : lead to strategies of doubt misuse of the evidence-based approach, by focusing only on the avoidance of unjustified causal associations (false positives) and neglecting the possibility of unjustified dismissal of real health effects (false negatives) misunderstanding of the precautionary principle, considered not relevant in science Value judgments: self-censorship, due to the pressure of dominant paradigms and of the peers. P. Smeesters 8-10 April

39 «Purely scientific»? Ethical issues within science Science cannot avoid ethical issues, some of them being deeply imbricated (and often not seen) within the area of the scientific work. For example: value judgements, like on importance of the risk P. Smeesters 8-10 April

40 An inhabitant of Fukushima:» My forefathers legacy» P. Smeesters 8-10 April

41 Holy Land P. Smeesters 8-10 April

42 Holy Land P. Smeesters 8-10 April

43 Value judgments and «reality» Current scientific paradigm: based on a mechanistic vision of the world, considering quantification as the only way for accessing to the reality Holistic vision: articulates hard science observations (and limitations), human sciences, ethics and spirituality, all considered as necessary for understanding the reality and for justifying responsible decision-making (Frederic Lenoir). P. Smeesters 8-10 April

44 Objectivity and the club spirit Science cannot escape from some intrinsic subjectivity. In an attempt to control this, one often appeals to consensus as a guarantee for objectivity. Doing so, one forgets that scientists, coming from the same melting pot, spontaneously favour cognitive consonance and share the same interpretative language, the same paradigm (a whole of reference presuppositions, which are often unconscious). On these grounds, interpretations of reality are not seen by them as subjective and have in their eyes an indisputable value P. Smeesters 8-10 April

45 The stakeholder opening Stakeholder involvement is the appropriate remedy for avoiding club thinking, allowing new views and perspectives to emerge and favouring creative thinking about mechanisms, scenarios or implications. P. Smeesters 8-10 April

46 But Unfortunately stakeholder involvement is currently often just a façade. The invited stakeholders and experts are very few and their opinion often considered as irrelevant and hardly taken into account: the real experts and the others P. Smeesters 8-10 April

47 Conclusion: main challenge for (RP) experts in the next 50 years To change the perception not of the public but of themselves! P. Smeesters 8-10 April

48 «Ce qu il faut à présent, c est réconcilier en nous les deux démarches (science et conscience); non pas nier l une en faveur de l autre, mais faire en sorte que l œil qui scrute, qui analyse et qui dissèque vive en harmonie et en intelligence avec celui qui contemple et vénère «(Hubert Reeves) P. Smeesters 8-10 April