Radiation Risks Low Dose Linearity Data, Science, Regulation and Liability

1. Radiation RisksLow Dose LinearityData, Science, Regulation and Liability Talk at Association of Physicists in Medicine San Diego 10:00 a.m. Monday, August 11th, 2003 by Richard Wilson Mallinckrodt Research Professor of Physics Harvard University

2. We should start withDataThen use theory (Science)to fill in gapsDecide on Aims of RegulationDiscuss Science Policy to meet these aimsAddress implementation

3. DATA comes fromSocietal MistakesAtom Bomb (RERF)Excessive medical exposuresindustrial exposuresanimal dataDo they fitenvironmental observations?

6. These were follow up to 1990.A threshold at 0.1 Sv (= 10 Rems) is possibleDose was in < a second.Less effect if dose spread in timeDRRF = 10 (animals)3 (Techa River and Mayak)2 NCRP and ICRP

13. Techa River (Kossenko); Sr 90 dose50 leukemias observed102 expected from RERF29 backgroundMAYAK workersearly period (Koshurnikova)“Leukemia” mortality1/3.5 RERF

17. Could the effect at low doses be worse than linear?It was so claimed for the Hanford workersby Mancuso Stewart and KnealebutLook at the DATA

22. Acute Effects Characteristics • One dose or dose accumulated in a short time KILLS • 1/10 the dose repeated 10 times DOES NOT KILL

23. LINEARITYAT LOW DOSESIS USUAL!! Walking blindfold across Michigan Avenue is safe: (Risk (R) = 0) IF THERE ARE NO CARS! The risk (R) increases roughly in proportion to the number of cars.

24. CHRONIC EFFECTS including CANCER Characteristics A dose just sub-acute can give effects if repeated. Usually not all people affected - dose response is flatter

28. Low dose linearity is common in societal risks • Contrast Acute and Chronic Effects • Radiation Cancers look like other cancers • 30% of people get cancer These are enough to set LINEARITY as the DEFAULT (but only for that cancer)

29. Some believe in a beneficial effect or radiation at low dosescf. Low doses of alcohol reduce risk of stroke.High doses give cancer and narcosisThis is controversial but cannot be excludedNo one knows at low doses

30. Logical StepsDATAScientific Interpretation:APS/ANS/HPS/AAPMScience policyUNSCEAR/ICRP/NCRPMFederal RegulatorsDOD/DOE/NRC/EPA/OMBState RegulatorsPublic ConcernCourts (toxic tort cases)Plaintiff’s Bar/ALF/etc

31. Legitimate aims (RW)Doses to be less than acute dosesWorker Risk comparable to other worker risksPublic Exposure no larger than accepted fluctuation in BackgroundCost per life in all cases $200,000 per person Sv (Public)$2,000 per person Sv (worker) Establish “de minimis” levels 10 (0.1Sv/yr)Any Firm Limits enough to avoid Legal Liability

32. ALARA dates from 1928Originally:“No one should be exposed without expectation of benefit” (Implicit risk-benefit analysis)Doses must be reduced:As Low As Practicable (ALAP)As Low As Reasonably Achievable (ALARA)As Low As Reasonably Practicable (ALARP)(note word change without change in understanding)

33. Assumed whole body dose effects (risk)~ 1965 1 fatal cancer per 10,000 Man - Rems~ 1991 1 fatal cancer per 2,500 Man-Rems per 25 Person-Sv Recommended Dose Limits (ICRP; NCRP similar)When? Public Workers ~1965 500 mR/yr 5 R/yr(expected public average 170 mR/yr)~1991 (guidance) 100 mR/yr 5 R/yr~ 1991 500 mR/5yr 5 R/yr 10 R/5 yr‘91 NCRP 1R x ageNote that if a large group of workers received the maximum, effects would just be detectable (above background) at age 80

34. Conservatisms Theory for low doses (<10 rems in RERF) Dose Rate Response Factor = 2 (data on leukemia says 3; animal data range to 10) Cost to reduce a risk used as a minimum not a maximum ‘de Minimis” guidelines used as regulation

35. Radiation Risk should be comparable to other Occupational RisksAnnual Risk per 100,000Actual(av over all workers):All Industries 7manufacturing 3Coal mining 24Maximum (theory): ICRP 5 yr av. 80 but average worker gets about 1/5 of ICRP maximum

36. What Dose Parameter?Average over 1/4 to full lifetimeWhy regulate over 1/4 year?What about contract workers? Worker should control his exposurePublic? Liability for LawsuitsRemember old rule: Average over public is what matters most

37. Be Prepared!If someone sues you:Have all data and justification readyHelp stop frivolous lawsuits

38. No. 98-56157 In the Supreme Court of the United StatesJOE KENNEDY, et al. Plaintiffs-Appellantsv.SOUTHERN CALIFORNIA EDISON COMPANY and COMBUSTION ENGINEERINGOn Writ of Certiorari to the United States Court of Appeals for the First CircuitBRIEF OF AMICI CURIAEROBERT K. ADAIR, BRUCE N. AMES, D. ALLAN BROMLEY, PATRICIA A. BUFFLER, BERNARD COHEN, BERNARD GITTELMAN, SHELDON LEE GLASHOW, MICHAEL GOUGH, RONALD HART, DUDLEY HERSCHBACH, LAWRENCE LITT, A. ALAN MOGHISSI, RODNEY W. NICHOLS, ROBERT V. POUND, NORMAN RAMSEY, JOSEPH P. RING, FREDERICK SEITZ, EDWARD THORNDIKE, LYNN H. VERHEY and JAMES D. WATSONIN SUPPORT OF DEFENDANTS-APPELLEES' MOTION FOR REHEARING AND REHEARING EN BANC

39. Kennedy worked at San Onofre Nuclear plantSome workers brought “fuel fleas” homeKennedy claimed his wife got Leukemia from a fuel flea he brought home.No evidence he brought one homeUncontroverted evidence that the maximum dose from the largest possible fuel flea gave a risk of 10-7(Probability of Causation 10-5) 3 week trial Appeal originally allowed by 3 judge panel.The appeal was reversed, and the plaintiffs blamed it on ALF!(Where was AAPM? Health Physics Society? NCRPM)

40. My website:http://phys4.harvard.edu/~wilson/Page on radiation references/resource_letter.htmlpages on Russian Chernobyl dataradiation/radiation_and_risk.htmlTecha Riverpublications/pp747/techa_cor.htmWilson and CrouchRisk Benefit AnalysisRiskad.html