Epidemiology • Volume 25, Number 4, July 2014 Letters
cohort and case-control studies) to: (1) better understand health effects (and mechanisms) potentially associated with electromagnetic fields (EMF), including brain tumors, neurodegenerative, behavioral, and reproductive outcomes; (2) better characterize EMF exposure in the general population; (3) improve integration of EMF and health research into health risk assessment; and (4) underpin risk management policies. GERoNiMO focuses on radiofrequency radiation (from mobile phones and newer communication technologies) and increasingly ubiquitous intermediate frequency fields—alone and in combination with other environmental exposures. We anticipate that GERoNiMO will improve the integration, coherence, and coordination of EMF and health research, leading to improved evidence-based risk estimation, management, and communication. Chelsea Eastman Langer James Grellier Michelle C. Turner Elisabeth Cardis Radiation Programme Centre for Research in Environmental Epidemiology (CREAL) Barcelona, Spain Universitat Pompeu Fabra (UPF) Barcelona, Spain Ciber Epidemiología y Salud Pública (CIBERESP) Madrid, Spain [email protected]
REFERENCES 1. Samet JM, Straif K, Schüz J, Saracci R. Commentary: Mobile Phones and Cancer: Next Steps After the 2011 IARC Review. Epidemiology. 2014;25:23–27. 2. Baan R, Grosse Y, Lauby-Secretan B, et al; WHO International Agency for Research on Cancer Monograph Working Group. Carcinogenicity of radiofrequency electromagnetic fields. Lancet Oncol. 2011;12: 624–626. 3. Cardis E, Armstrong BK, Bowman JD, et al. Risk of brain tumours in relation to estimated RF dose from mobile phones: results from five Interphone countries. Occup Environ Med. 2011;68:631–640. 4. Larjavaara S, Schüz J, Swerdlow A, et al. Location of gliomas in relation to mobile telephone use: a case-case and case-specular analysis. Am J Epidemiol. 2011;174:2–11.
© 2014 Lippincott Williams & Wilkins
Mobile Phones and Cancer Next Steps To the Editors: e welcome the commentary by Samet et al1 and their recommendation for reanalysis of the main case-control studies on radiofrequency electromagnetic fields (the basis of all wireless technology). This reanalysis is something we have also suggested. The authors discuss pros and cons for the IARC classification of radiofrequency electromagnetic fields as “possibly carcinogenic to humans” (group 2B). However, several more recently published articles are either misinterpreted in or omitted from their presentation— for instance, 3 articles published by our research group on meningioma,2 acoustic neuroma,3 and malignant brain tumors.4 Our study and the INTERPHONE study differ in their recruitment of cases and controls, participation rates, and assessment of exposure, but restricting to the same age groups and omitting the use of cordless phones (as in INTERPHONE) gives similar results.5 The Danish cohort study6 was included in the IARC evaluation of radiofrequency electromagnetic fields, with the conclusion that “phone provider, as a surrogate for mobile phone use, could have resulted in considerable misclassification in exposure assessment.” Samet et all write that this was “a study considered by the IARC Working Group” but fail to report the conclusion by the Working Group. Samet et all do not mention the analytic studies we published in 2013, but they do reference an update of the Danish cohort study and Benson et al7—the latter also published in 2013. We have discussed elsewhere the increasing incidence of brain tumors in several countries including Denmark.
W
Copyright © 2014 by Lippincott Williams & Wilkins ISSN: 1044-3983/14/2504-0617 DOI: 10.1097/EDE.0000000000000115
There was a sharp increase in the incidence of brain tumors during 2003–2012 (41% in men and 46% in women). This casts doubt on the findings of both Deltour et al8 on glioma incidence in the Nordic countries during 1997–2008 and the recent report on the Danish cohort study on mobile phone users.6 In summary, we disagree with the way Samet et al1 have chosen to present evidence regarding mobile phones and cancer. We do, however, agree with the authors’ advice on “keeping people well-informed.” In considering the most up-to-date publications, we find increasing evidence of an association between the use of mobile or cordless phones and glioma and acoustic neuroma. Lennart Hardell Michael Carlberg Department of Oncology University Hospital Örebro, Sweden [email protected]
Fredrik Söderqvist Centre for Clinical Research Uppsala University Central Hospital of Västerås Västerås, Sweden
Kjell Hansson Mild Department of Radiation Physics Umeå University Umeå, Sweden
REFERENCES 1. Samet JM, Straif K, Schüz J, Saracci R. Commentary: mobile phones and cancer: next steps after the 2011 IARC review. Epidemiology. 2014;25:23–27. 2. Carlberg M, Söderqvist F, Hansson Mild K, Hardell L. Meningioma patients diagnosed 2007– 2009 and the association with use of mobile and cordless phones. Environ Health. 2013;12:60. 3. Hardell L, Carlberg M, Söderqvist F, Hansson Mild K. Pooled analysis of case-control studies on acoustic neuroma diagnosed 1997-2003 and 2007-2009 and use of mobile and cordless phones. Int J Oncol. 2013;43:1036–1044. 4. Hardell L, Carlberg M, Söderqvist F, Mild KH. Case-control study of the association between malignant brain tumours diagnosed between 2007 and 2009 and mobile and cordless phone use. Int J Oncol. 2013;43:1833–1845. 5. Hardell L, Carlberg M, Hansson Mild K. Re-analysis of risk for glioma in relation to mobile telephone use: comparison with the results of the Interphone international case-control study. Int J Epidemiol. 2011;40:1126–1128.
www.epidem.com | 617
Epidemiology • Volume 25, Number 4, July 2014
Letters
6. Frei P, Poulsen AH, Johansen C, Olsen JH, Steding-Jessen M, Schüz J. Use of mobile phones and risk of brain tumours: update of Danish cohort study. BMJ. 2011;343:d6387. 7. Benson VS, Pirie K, Schüz J, Reeves GK, Beral V, Green J; Million Women Study Collaborators. Mobile phone use and risk of brain neoplasms and other cancers: prospective study. Int J Epidemiol. 2013;42:792–802. 8. Deltour I, Auvinen A, Feychting M, et al. Mobile phone use and incidence of glioma in the Nordic countries 1979-2008: consistency check. Epidemiology. 2012;23:301–307.
The authors respond:
W
e write in response to 2 letters1,2 concerning our recent commentary in Epidemiology (“Mobile phones and cancer: next steps after the 2011 IARC review”).3 We concur with the reasoned call by Cardis and colleagues1 for a strategic research agenda that will address critical uncertainties related to any risks of exposure to radiofrequency electromagnetic radiation, and we note that such research agendas have been regularly developed by, for instance, WHO and the European Commission. We were pleased to learn about the just-funded GERoNiMO initiative that takes a broad, interdisciplinary approach in a 5-year project (geronimo.crealradiation.com). Hardell et al2 offer concerns about the completeness of coverage of the literature in the commentary. We wrote our commentary3 explicitly to address issues raised by the release of IARC Monograph 102,4 and we did not develop a full systematic review of publications since the 2011 2B classification. The 3 publications by the Hardell group5–7 were published after we submitted our manuscript for publication; however, their results remain incompatible with incidence time trends based on the highquality Nordic population-based cancer registries.8 All available reports from the studies by Hardell and colleagues were considered in Monograph 102.4
The authors report no conflicts of interest. Copyright © 2014 by Lippincott Williams & Wilkins ISSN: 1044-3983/14/2504-0618 DOI: 10.1097/EDE.0000000000000109
618 | www.epidem.com
Readers of our commentary should recognize its specific purpose: to review key issues raised by the release of the IARC classification.4 We touch on topics that are critical for not only IARC but also scientists who carry out research on any topic that is controversial, challenging, and of societal importance. There is a wide range of views on the possible risks of radiofrequency electromagnetic radiation and approaches to exposure management, and open discussion on these topics is needed. EPIDEMIOLOGY has provided a venue for this discussion, and we thank the authors of the 2 letters1,2 for their comments. Jonathan M. Samet Department of Preventive Medicine Keck School of Medicine of USC Institute for Global Health University of Southern California Los Angeles, CA [email protected]
Kurt Straif Section of IARC Monographs International Agency for Research on Cancer Lyon, France
Joachim Schüz Section of Environment and Radiations International Agency for Research on Cancer Lyon, France
Rodolfo Saracci International Agency for Research on Cancer Lyon, France
REFERENCES 1. Langer CE, Grellier J, Turner MC, Cardis E. Mobile phones and cancer: next steps [letter]. Epidemiology. 2014;25:616–617. 2. Hardell L, Carlberrg M, Söderqvist F, Hansson Mild K. Mobile phones and cancer: next steps [letter]. Epidemiology. 2014;25:617–618. 3. Samet JM, Straif K, Schüz J, Saracci R. Commentary: mobile phones and cancer: next steps after the 2011 IARC review. Epidemiology. 2014;25:23–27. 4. International Agency for Research on Cancer. IARC Monographs on the Evaluation of Carcinogenic Risks to Human. NonIonizing Radiation, Part 2: Radiofrequency Electromagnetic Fields. Vol. 102. Lyon, France: International Agency for Research on Cancer; 2013. 5. Carlberg M, Söderqvist F, Hansson Mild K, Hardell L. Meningioma patients diagnosed 2007–2009 and the association with use of mobile and cordless phones: a case–control study. Environ Health. 2013;12:60.
6. Hardell L, Carlberg M, Söderqvist F, Mild KH. Pooled analysis of case-control studies on acoustic neuroma diagnosed 1997-2003 and 2007-2009 and use of mobile and cordless phones. Int J Oncol. 2013;43:1036–1044. 7. Hardell L, Carlberg M, Söderqvist F, Mild KH. Case-control study of the association between malignant brain tumours diagnosed between 2007 and 2009 and mobile and cordless phone use. Int J Oncol. 2013;43:1833–1845. 8. Deltour I, Auvinen A, Feychting M, et al. Mobile phone use and incidence of glioma in the Nordic countries 1979-2008: consistency check. Epidemiology. 2012;23:301–307.
Further Refinements to the Organizational Schema for Causal Effects To the Editor: n the January 2014 issue of Epidemiology, Gatto et al1 provided a valuable organizational schema for epidemiologic causal effects. Using the potential outcomes framework, they illuminated the distinguishing characteristics of various causal effects and clarified their interpretation. Here, we highlight the significance of the fact that the notion of confounding can be defined with respect to both marginal distributions of potential outcomes and a specific effect measure.2,3 Let A denote a binary exposure of interest (1 = exposed, 0 = unexposed) and Y, a binary outcome (1 = outcome occurred, 0 = outcome did not occur). Then, we let Ya (ω) denote the potential outcomes for individual ω if, possibly contrary to fact, there had been interventions to set A to a. As a result, persons can be classified into 4 response types, ie, doomed (type 1), causal (type 2),
I
The authors report no conflicts of interest. Supplemental digital content is available through direct URL citations in the HTML and PDF versions of this article (www.epidem.com). This content is not peerreviewed or copy-edited; it is the sole responsibility of the authors. Copyright © 2014 by Lippincott Williams & Wilkins ISSN: 1044-3983/14/2504-0618 DOI: 10.1097/EDE.0000000000000114
© 2014 Lippincott Williams & Wilkins
cohort and case-control studies) to: (1) better understand health effects (and mechanisms) potentially associated with electromagnetic fields (EMF), including brain tumors, neurodegenerative, behavioral, and reproductive outcomes; (2) better characterize EMF exposure in the general population; (3) improve integration of EMF and health research into health risk assessment; and (4) underpin risk management policies. GERoNiMO focuses on radiofrequency radiation (from mobile phones and newer communication technologies) and increasingly ubiquitous intermediate frequency fields—alone and in combination with other environmental exposures. We anticipate that GERoNiMO will improve the integration, coherence, and coordination of EMF and health research, leading to improved evidence-based risk estimation, management, and communication. Chelsea Eastman Langer James Grellier Michelle C. Turner Elisabeth Cardis Radiation Programme Centre for Research in Environmental Epidemiology (CREAL) Barcelona, Spain Universitat Pompeu Fabra (UPF) Barcelona, Spain Ciber Epidemiología y Salud Pública (CIBERESP) Madrid, Spain [email protected]
REFERENCES 1. Samet JM, Straif K, Schüz J, Saracci R. Commentary: Mobile Phones and Cancer: Next Steps After the 2011 IARC Review. Epidemiology. 2014;25:23–27. 2. Baan R, Grosse Y, Lauby-Secretan B, et al; WHO International Agency for Research on Cancer Monograph Working Group. Carcinogenicity of radiofrequency electromagnetic fields. Lancet Oncol. 2011;12: 624–626. 3. Cardis E, Armstrong BK, Bowman JD, et al. Risk of brain tumours in relation to estimated RF dose from mobile phones: results from five Interphone countries. Occup Environ Med. 2011;68:631–640. 4. Larjavaara S, Schüz J, Swerdlow A, et al. Location of gliomas in relation to mobile telephone use: a case-case and case-specular analysis. Am J Epidemiol. 2011;174:2–11.
© 2014 Lippincott Williams & Wilkins
Mobile Phones and Cancer Next Steps To the Editors: e welcome the commentary by Samet et al1 and their recommendation for reanalysis of the main case-control studies on radiofrequency electromagnetic fields (the basis of all wireless technology). This reanalysis is something we have also suggested. The authors discuss pros and cons for the IARC classification of radiofrequency electromagnetic fields as “possibly carcinogenic to humans” (group 2B). However, several more recently published articles are either misinterpreted in or omitted from their presentation— for instance, 3 articles published by our research group on meningioma,2 acoustic neuroma,3 and malignant brain tumors.4 Our study and the INTERPHONE study differ in their recruitment of cases and controls, participation rates, and assessment of exposure, but restricting to the same age groups and omitting the use of cordless phones (as in INTERPHONE) gives similar results.5 The Danish cohort study6 was included in the IARC evaluation of radiofrequency electromagnetic fields, with the conclusion that “phone provider, as a surrogate for mobile phone use, could have resulted in considerable misclassification in exposure assessment.” Samet et all write that this was “a study considered by the IARC Working Group” but fail to report the conclusion by the Working Group. Samet et all do not mention the analytic studies we published in 2013, but they do reference an update of the Danish cohort study and Benson et al7—the latter also published in 2013. We have discussed elsewhere the increasing incidence of brain tumors in several countries including Denmark.
W
Copyright © 2014 by Lippincott Williams & Wilkins ISSN: 1044-3983/14/2504-0617 DOI: 10.1097/EDE.0000000000000115
There was a sharp increase in the incidence of brain tumors during 2003–2012 (41% in men and 46% in women). This casts doubt on the findings of both Deltour et al8 on glioma incidence in the Nordic countries during 1997–2008 and the recent report on the Danish cohort study on mobile phone users.6 In summary, we disagree with the way Samet et al1 have chosen to present evidence regarding mobile phones and cancer. We do, however, agree with the authors’ advice on “keeping people well-informed.” In considering the most up-to-date publications, we find increasing evidence of an association between the use of mobile or cordless phones and glioma and acoustic neuroma. Lennart Hardell Michael Carlberg Department of Oncology University Hospital Örebro, Sweden [email protected]
Fredrik Söderqvist Centre for Clinical Research Uppsala University Central Hospital of Västerås Västerås, Sweden
Kjell Hansson Mild Department of Radiation Physics Umeå University Umeå, Sweden
REFERENCES 1. Samet JM, Straif K, Schüz J, Saracci R. Commentary: mobile phones and cancer: next steps after the 2011 IARC review. Epidemiology. 2014;25:23–27. 2. Carlberg M, Söderqvist F, Hansson Mild K, Hardell L. Meningioma patients diagnosed 2007– 2009 and the association with use of mobile and cordless phones. Environ Health. 2013;12:60. 3. Hardell L, Carlberg M, Söderqvist F, Hansson Mild K. Pooled analysis of case-control studies on acoustic neuroma diagnosed 1997-2003 and 2007-2009 and use of mobile and cordless phones. Int J Oncol. 2013;43:1036–1044. 4. Hardell L, Carlberg M, Söderqvist F, Mild KH. Case-control study of the association between malignant brain tumours diagnosed between 2007 and 2009 and mobile and cordless phone use. Int J Oncol. 2013;43:1833–1845. 5. Hardell L, Carlberg M, Hansson Mild K. Re-analysis of risk for glioma in relation to mobile telephone use: comparison with the results of the Interphone international case-control study. Int J Epidemiol. 2011;40:1126–1128.
www.epidem.com | 617
Epidemiology • Volume 25, Number 4, July 2014
Letters
6. Frei P, Poulsen AH, Johansen C, Olsen JH, Steding-Jessen M, Schüz J. Use of mobile phones and risk of brain tumours: update of Danish cohort study. BMJ. 2011;343:d6387. 7. Benson VS, Pirie K, Schüz J, Reeves GK, Beral V, Green J; Million Women Study Collaborators. Mobile phone use and risk of brain neoplasms and other cancers: prospective study. Int J Epidemiol. 2013;42:792–802. 8. Deltour I, Auvinen A, Feychting M, et al. Mobile phone use and incidence of glioma in the Nordic countries 1979-2008: consistency check. Epidemiology. 2012;23:301–307.
The authors respond:
W
e write in response to 2 letters1,2 concerning our recent commentary in Epidemiology (“Mobile phones and cancer: next steps after the 2011 IARC review”).3 We concur with the reasoned call by Cardis and colleagues1 for a strategic research agenda that will address critical uncertainties related to any risks of exposure to radiofrequency electromagnetic radiation, and we note that such research agendas have been regularly developed by, for instance, WHO and the European Commission. We were pleased to learn about the just-funded GERoNiMO initiative that takes a broad, interdisciplinary approach in a 5-year project (geronimo.crealradiation.com). Hardell et al2 offer concerns about the completeness of coverage of the literature in the commentary. We wrote our commentary3 explicitly to address issues raised by the release of IARC Monograph 102,4 and we did not develop a full systematic review of publications since the 2011 2B classification. The 3 publications by the Hardell group5–7 were published after we submitted our manuscript for publication; however, their results remain incompatible with incidence time trends based on the highquality Nordic population-based cancer registries.8 All available reports from the studies by Hardell and colleagues were considered in Monograph 102.4
The authors report no conflicts of interest. Copyright © 2014 by Lippincott Williams & Wilkins ISSN: 1044-3983/14/2504-0618 DOI: 10.1097/EDE.0000000000000109
618 | www.epidem.com
Readers of our commentary should recognize its specific purpose: to review key issues raised by the release of the IARC classification.4 We touch on topics that are critical for not only IARC but also scientists who carry out research on any topic that is controversial, challenging, and of societal importance. There is a wide range of views on the possible risks of radiofrequency electromagnetic radiation and approaches to exposure management, and open discussion on these topics is needed. EPIDEMIOLOGY has provided a venue for this discussion, and we thank the authors of the 2 letters1,2 for their comments. Jonathan M. Samet Department of Preventive Medicine Keck School of Medicine of USC Institute for Global Health University of Southern California Los Angeles, CA [email protected]
Kurt Straif Section of IARC Monographs International Agency for Research on Cancer Lyon, France
Joachim Schüz Section of Environment and Radiations International Agency for Research on Cancer Lyon, France
Rodolfo Saracci International Agency for Research on Cancer Lyon, France
REFERENCES 1. Langer CE, Grellier J, Turner MC, Cardis E. Mobile phones and cancer: next steps [letter]. Epidemiology. 2014;25:616–617. 2. Hardell L, Carlberrg M, Söderqvist F, Hansson Mild K. Mobile phones and cancer: next steps [letter]. Epidemiology. 2014;25:617–618. 3. Samet JM, Straif K, Schüz J, Saracci R. Commentary: mobile phones and cancer: next steps after the 2011 IARC review. Epidemiology. 2014;25:23–27. 4. International Agency for Research on Cancer. IARC Monographs on the Evaluation of Carcinogenic Risks to Human. NonIonizing Radiation, Part 2: Radiofrequency Electromagnetic Fields. Vol. 102. Lyon, France: International Agency for Research on Cancer; 2013. 5. Carlberg M, Söderqvist F, Hansson Mild K, Hardell L. Meningioma patients diagnosed 2007–2009 and the association with use of mobile and cordless phones: a case–control study. Environ Health. 2013;12:60.
6. Hardell L, Carlberg M, Söderqvist F, Mild KH. Pooled analysis of case-control studies on acoustic neuroma diagnosed 1997-2003 and 2007-2009 and use of mobile and cordless phones. Int J Oncol. 2013;43:1036–1044. 7. Hardell L, Carlberg M, Söderqvist F, Mild KH. Case-control study of the association between malignant brain tumours diagnosed between 2007 and 2009 and mobile and cordless phone use. Int J Oncol. 2013;43:1833–1845. 8. Deltour I, Auvinen A, Feychting M, et al. Mobile phone use and incidence of glioma in the Nordic countries 1979-2008: consistency check. Epidemiology. 2012;23:301–307.
Further Refinements to the Organizational Schema for Causal Effects To the Editor: n the January 2014 issue of Epidemiology, Gatto et al1 provided a valuable organizational schema for epidemiologic causal effects. Using the potential outcomes framework, they illuminated the distinguishing characteristics of various causal effects and clarified their interpretation. Here, we highlight the significance of the fact that the notion of confounding can be defined with respect to both marginal distributions of potential outcomes and a specific effect measure.2,3 Let A denote a binary exposure of interest (1 = exposed, 0 = unexposed) and Y, a binary outcome (1 = outcome occurred, 0 = outcome did not occur). Then, we let Ya (ω) denote the potential outcomes for individual ω if, possibly contrary to fact, there had been interventions to set A to a. As a result, persons can be classified into 4 response types, ie, doomed (type 1), causal (type 2),
I
The authors report no conflicts of interest. Supplemental digital content is available through direct URL citations in the HTML and PDF versions of this article (www.epidem.com). This content is not peerreviewed or copy-edited; it is the sole responsibility of the authors. Copyright © 2014 by Lippincott Williams & Wilkins ISSN: 1044-3983/14/2504-0618 DOI: 10.1097/EDE.0000000000000114
© 2014 Lippincott Williams & Wilkins
