RADIATION EXPOSURE POTPOURRI Ray Copes, MD, MSc Director, Environmental and Occupational Health Public Health Ontario Associate Professor, University of Toronto

Objectives 1)Quick Review – The EMS. What sources contribute to population exposure to ionizing radiation? How many radiation agents have been reviewed by IARC and what are their ratings? 2) Radon – How risky is radon? What are we doing about it? 3) Do cell phones cause cancer? How can you reduce exposure to RF?

Electro Magnetic Spectrum

Ionizing vs. Non-ionizing effects

Average Annual Ionizing Radiation Dose to US Residents from Upton, 2010 SourceDose (mSv)% of Total Radon1.931 Cosmic0.274 Terrestrial0.284 Internal0.397 Total Natural X-ray Dx2.439 Nuclear Med0.813 Consumer Products0.12 Occup, Nucl, Misc0.05<1 Total Artificial3.3554

Radiation agents reviewed in the International Agency for Research on Cancer’s (IARC) monograph series from Samet Agent Group IARC Monograph Volume No. Year Ultraviolet radiation140, , 1992 Radon-222 and its decay products143, , 2001 Ultraviolet radiation A (NB: Overall evaluation upgraded from 2B to 2A with supporting evidence from other relevant data) 2A Ultraviolet radiation B (NB: Overall evaluation upgraded from 2B to 2A with supporting evidence fromother relevant data) 2A Ultraviolet radiation C (NB: Overall evaluation upgraded from 2B to 2A with supporting evidence from other relevant data) 2A Solar radiation X- and Gamma ( γ )-Radiation Radium-224 and its decay products Radium-226 and its decay products Radium-228 and its decay products Radioiodines, short-lived isotopes, including iodine-131, from atomic reactor accidents and nuclear weapons detonation (exposure during childhood) Radionuclides, α -particle-emitting, internally deposited (NB: Specific radionuclides for which there is sufficient evidence for carcinogenicity to humans are also listed individually as Group 1 agents) Radionuclides, β -particle-emitting, internally deposited (NB: Specific radionuclides for which there is sufficient evidence for carcinogenicity to humans are also listed individually as Group 1 agents) Magnetic fields (extremely low-frequency)2B Magnetic fields (static) Classification of carcinogenic hazards to humans: Group 1: Carcinogenic to humans. Group 2A: Probably carcinogenic to humans. Group 2B: Possibly carcinogenic to humans. Group 3: Not classifiable as to carcinogenicity to humans. Group 4: Probably not carcinogenic to humans.

Radon Worth getting excited about?

Increase in lung cancer risk per 100 Bq m-3 increase in measured radon concentration in 13 European case-control studies Source: Darby et al [28]. 8

Risk of Developing Radon Related Lung Cancer Copes R, Scott J CMAJ 2007;177: ©2007 by Canadian Medical Association

. Copes R, Scott J CMAJ 2007;177: ©2007 by Canadian Medical Association

What About Workplaces? Care taken with definition of ‘dwellings’ OSH regulator has jurisdiction ‘Normal occupancy’ set at 4 hours/day Some workplaces may have more than 200 Bq/m3 At grade or below, also consider potential contribution from water in unusual work settings (e.g. hatcheries) Some dwellings are work places and worker exposure will be reduced as well as residents (e.g. schools)

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What is being done? Health Canada cross country survey year 2 complete not yet released Federal sector buildings being tested Provincial interest ‘variable’ (e.g. BC school testing) Resources available for homeowners to test and remediate at their expense Little concerted pressure or publicity Burden of illness not widely appreciated even by PH staff Second only to smoking as preventable cause of lung cancer Estimated 5-10% of lung ca. radon attributable.

Does cell phone use cause cancer? May 2011 IARC meeting, 30 scientists 14 countries to assess carcinogenicity of RF electromagnetic fields. Frequency 30kHz-300GHz. Sources: cell phones, cordless phones, Bluetooth, amateur radio, dielectric and induction heaters, pulsed radar, broadcast antennas, medical applications. The ‘hazard’ isn’t new, the applications are. Does one apply the Precautionary Principle to new hazards or new applications?

RF Exposures Workers –highest exposures are near field Public – Use of transmitters held close to the body, can give greater dose to brain than work exposures Exposures from cell phone base stations, TV, radio, Bluetooth are all orders of magnitude lower than cell phones New 3G phones emit 100 times less RF than GSM phones For energy deposition to brain, cell phone use is unique

Ionizing vs. Non-ionizing effects

Exposure Standards for RF Based on tissue heating as mechanism for adverse effects Canadian (Safety Code 6) and international stds (ICNIRP) similar Critics argue limits set on tissue heating are not stringent enough Regulatory bodies argue lack of consistency in research with non-thermal end points and whether there is link to ‘adverse’ effects on health. Despite proliferation of wireless technologies, measurements done in community settings are typically small fraction of current limits

Evidence for Carcinogenicity of RF? Time trend, case-control, cohort studies Time trend – surveillance data have not indicated evidence of increase in gliomas or other tumours of interest potentially linked to cell phone use While some interpret as reassuring, this is a relatively insensitive indicator of risk IARC considered one cohort and 5 case-control studies

Cell Phone studies Danish cohort – 257 gliomas in 420,095 subscribers between 1982 and 1995, subscriber incidence close to national average. INTERPHONE glioma cases, 2972 controls OR 0.81 (95% CI ) for ever versus never users For highest decile of exposure OR 1.40 (95% CI ) Suggestion of increased risk for ipsilateral and temporal lobe tumours (where RF dose would be greatest) Hardell -pooled analysis based on cases ascertained up to OR glioma >1 year of use 1.3 (95% CI ) increasing to 3.2 (95% CI ) for >2000h use Ipsilateral use assoc w/ higher risk, cordless phones similar Sato – some evidence ipsilateral risk of acoustic neuroma

Animal Studies 40 studies assessing RF incl 7 2-year rodent bioassays Increase in total tumours in 1 of 7 chronic bioassays 2/12 studies with tumour prone animals showed increase cancer incidence 1/18 studies using initiation-promotion protocol 4/6 co-carcinogenesis studies showed increase in cancer after exposure RF and a known carcinogen

Conclusion? Inconsistencies across studies; recall, selection bias possible; inadequate observations to meet latency Findings cannot be dismissed as reflecting bias alone. Human evidence ‘limited’, animal evidence ‘limited’ IARC Classification 2B ‘possibly carcinogenic’ supported by ‘large majority’ of the working group. This is based on exposure from cell phone use. “In reviewing studies that addressed the possible association between environmental exposure to RF-EMF and cancer, the working group found the available evidence insufficient for any conclusion”.

Reducing RF Exposure Cell phone use dominates exposures Can reduce exposure through: - reducing use -texting -selection of phone with lower SAR -use of speaker, headset -avoid use where there is weak signal Unclear whether this reduces risk of adverse effects Potential for exposure reduction in other settings less clear, although using wireless laptops on desk rather than lap may also be effective

Lessons? Pressure to do ‘premature epidemiology’. Easy to ignore pretty good epidemiology when outrage is low. Discomfort with uncertainty. Tension between ‘Precaution’ versus adoption of beneficial (to whom?) new technologies. Controversy fueled by increased access to information and misinformation. Internet can serve as an ‘amplifier’ of minority or fringe views. Lack of public trust in regulators and experts.

Thank you Questions?