Downloaded from http://oem.bmj.com/ on June 8, 2015 - Published by group.bmj.com
Editorial (Hot topic)
Challenges for occupational epidemiology in the 21st century: observations and opportunities David H Wegman The 2014 International Epidemiology in Occupational Health (EPICOH) meeting in Chicago, USA, focused on the theme: ‘Challenges for Occupational Epidemiology in the 21st Century’. These are exciting times and with them come no end to challenges faced by occupational epidemiology. And participants eagerly engaged in vigorous discussion on a number of current concerns with both wisdom and wit. Ultimately each individual must decide what challenges are most important and how best to address those selected for first order attention. Nonetheless, some overview of challenges could prove worthwhile and so six general areas are provided as a focus for consideration. ▸ Concentrating on important problems ▸ Acting on what we find ▸ Advancing occupational disease and injury surveillance ▸ Relying on worker self-reports ▸ Looking at data ▸ Addressing health disparities
CONCENTRATING ON THE IMPORTANT PROBLEMS We always run the risk of studying what we know how to study rather than investigating important problems. We must try our best to tackle broad issues and not restrict ourselves to narrow expressions or concerns. To paraphrase Walter Holland1: Overall the number of conditions and environments studied by occupational epidemiologists needs to be expanded and we must not hesitate to press for resources to investigate and control conditions of little concern to political or commercial interests, but which are of importance to our workers and our societies. Funding for our studies is increasingly difficult but the more important the problem the more likely we can gain the attention of potential funders. It is likely that each of us has a somewhat different view of what are the important problems. One that deserves priority attention is the impact of climate change on the global workforce. There is a Correspondence to David H Wegman, Department of Work Environment, University of Massachusetts Lowell, 1 University Avenue Lowell, MA 01854, USA; [email protected]
remarkably diverse mix of occupational sectors that will bear the consequences of climate change.2 The numbers of workers potentially affected certainly is in the millions, and will include (at least): emergency responders, workers in construction, utilities, demolition, cleanup, landscaping, agriculture, forestry, wildlife management, along with postal delivery, warehousing, heavy industry and many manufacturing settings. This work is performed in both urban and rural settings and is carried out both indoors and outdoors. Exposures for these workers will not just be extremes of temperature but those extremes combined with chemical exposures, heavy demanding work and long work hours. They will also include other consequences of climate change such as severe weather events, air pollution and infectious and zoonotic diseases. Climate change is also expected to increase employment in what are already the most hazardous occupations mentioned. Significant human-induced climate change is already occurring and workers are already suffering the impacts of these changes. The politics of addressing climate change are remarkable, and solutions are complicated by the economic implications of altering our current trajectory. Therefore, it is all the more important that we place a high priority on developing, and communicating broadly, the evidence for the consequences of climate change on the full range of workers affected. There are, of course, a number of other important problems that could benefit from our attention. Among these are: ▸ The adverse health consequences of intermittent and long-term unemployment; ▸ The role of work in causing or exascerbating depression or other mental health conditions; ▸ The consequences of exposures to more and more exotic materials especially in poorly regulated environments; ▸ The automation of white collar and service jobs; ▸ The aging workforce in developed nations and the consequences of replacement migration on work in developed and developing nations.
And sometimes an important problem will find us. This can happen if we make it a point to stay alert and open to the significance of unexpected events that occur in our environments. Some of our colleagues at this meeting are actively seeking answers to one such event. A number of years ago sugar cane workers began to notice an unusual number of workmates dying of chronic kidney disease. Not too long after, clinicians in these areas noted an increase in cases of end-stage renal disease along with an increased need for dialysis and an increase in mortality. When the problem started to overwhelm the health services they called for help. Since the mid-1990s investigations have documented a deeply troubling epidemic among working age (mostly) males of chronic kidney disease, not explained by hypertension or diabetes. The majority of cases appear related to work, especially on sugar cane plantations. Understanding why remains complicated. Advances will depend very much on well-designed field epidemiology studies paired with careful environmental and laboratory investigations! At this time the leading hypotheses concern heat and dehydration, pesticides or possibly a combination.3 Less likely but not easily dismissed hypotheses include heavy metals, leptospirosis, non-steroidal anti-inflammatory drugs, high fructose drinks and population susceptibility due to genetic traits, early nutrition or problems in adolescent health. It is easy to see how important creative epidemiological study design and analysis will be in arriving at the ultimate explanation to this epidemic.
ACTING ON WHAT WE FIND Most will agree that we have tended to engage much of our intellectual energy in research and research methods related to disease aetiology. Some have argued that this is appropriate—that our responsibility is to place our findings at the door of colleagues in public health practice and of decisionmakers, letting them use, or not, the findings as they see fit. These views regard epidemiological research and public health practice not only as distinct activities, which they are, but also as essentially independent, which they are not. We must match our success in the study of disease aetiology by putting equal intellectual effort into the design of intervention studies and the assessment of intervention efficacy. In this regard one priority is to develop study design equivalents to the randomised clinical trial, the gold standard for our clinical colleagues.
Wegman DH. Occup Environ Med November 2014 Vol 71 No 11
739
Downloaded from http://oem.bmj.com/ on June 8, 2015 - Published by group.bmj.com
Editorial (Hot topic) Second, we must engage in the public policy process. In doing so we must be transparent about inevitable biases both personal and those related to our research. Furthermore, we must learn how to communicate the dilemma all scientists face; the better we characterise the scientific problems and answer the questions that we pose, the more we open areas for further study. To be committed to the public’s health we must simultaneously follow promising lines of inquiry while taking maximum advantage of what is presently known to advocate for the control or elimination of disease.
OCCUPATIONAL DISEASE AND INJURY SURVEILLANCE We need to face the fact that much of the world operates on the assumption that ‘If it’s not counted, it didn’t happen!’ Surveillance is a necessity for estimating burden and for monitoring long-term progress in reducing hazardous exposures and work-related injuries and illnesses. Without good surveillance data we are at a loss to know whether our national or regional intervention programmes make a difference and why they do or do not. We epidemiologists have not devoted sufficient attention to advance the field of surveillance. The intellectual capital of academic epidemiologists is needed to create new surveillance models and methods to advance this work. To go beyond the common employer-based systems we need to seek ways to include non-employer-based data sources such as hospital and other medical data systems as well as national or regional population-based exposure and health surveys.4 5 We should also explore the adaptation of general public health data sets for surveillance of work-related health problems thereby supplementing information not available through traditional data sources.
WORKER SELF-REPORTS We live in an exciting age with rapid developments and increasing sophistication in the use of biomarkers and genetic markers applied both to exposure and to health outcomes. These exciting developments should not distract us from the ever-present need to explore and refine worker self-reports as valid measures of exposures and of illness. Self-reports are too often presented, if at all, with an apology for their use. And there is, of course, a proper concern with recall bias. However, by emphasising careful development and validation of instruments used in the systematic collection of self-reports, 740
these will continue to have an essential place in epidemiology studies.6 Developments in exposure biomonitoring will contribute to efforts to improve exposure assessment but we will always need to rely on self-reports as essential to characterise variations between individuals and over time when estimating long-term or lifetime exposures. Attention to methods and instruments that improve the accuracy and completeness of selfreported exposure requires our ongoing engagement. Symptom reports have the advantage of directing attention to the type of experience that leads most individuals to seek medical attention in the first place. Symptoms can: ▸ Provide the earliest evidence of abnormality; ▸ Often correlate well with objective findings; ▸ Contribute to a more complete picture of illness than objective tests alone; ▸ May be the abnormality, one that cannot be determined by objective measures. With proper attention to the science of psychophysics and with proper use of health measurement scales, valid reports of symptoms can be collected with relative ease, with little expense and with noninvasive measures.
LOOKING AT DATA We need to remain attentive to the consequences of the easy use of models particularly those that assume some form of linearity in an unknown dose–response relationship. Do these models and assumptions permit us to see, or are they ultimately misrepresenting, the truth? Approaches to modelling that relax these constraints certainly are beginning to address this concern. However, we must continue to pay attention to the importance of describing and reflecting on our data carefully before exploring models. Thoughtful consideration of well-displayed data tables and figures is undervalued. And this extends to the reports of our research. Readers are too often frustrated by publications of well-designed studies that present very limited detail about the actual data before providing the findings associated with final models. Simple approaches to data analysis deserve a place in any publication and appropriately stratified data should accompany any presentation of models that adjust for covariates. For example, increasing attention is paid to the impact of work on an aging workforce. Many studies could inform understanding but
this requires care to report more than age-adjusted analyses in our studies of aetiology or intervention effectiveness.
HEALTH DISPARITIES AND INEQUITY In this age of deregulation and the dominance of the market economy many countries are experiencing increasing disparity, certainly we are in the USA. In the workplace these developments are reflected in ▸ Wide-spread reduction in job security along with a rise in work without contracts or benefits; ▸ Intermittent periods of employment and unemployment; ▸ Increased hours of work when working; ▸ Much less attention to the quality of work and work environments. As epidemiologists our roles must include using our knowledge and skills to draw attention to the consequences of these developments by supplying evidence of the impact of current work practices on an increasingly vulnerable workforce. Equally important, those of us in the developed world need to take responsibility to track and describe the impact of the export of hazardous materials, equipment and jobs. The tragedies in Bangladesh associated with the manufacture of garments for Benetton, JC Penny, Walmart and others show the result of moving manufacturing away from better-regulated settings.7 And there are also the consequences of exporting toxic materials judged unsafe in one country for free use in another. 1,2-Dibromo-3-chloropropane was banned from use in the USA in the 1980s but a decade later was shown to contribute to male infertility in banana workers in Costa Rica.8 And, concerning collaborations with our colleagues in developing nations, there is need for epidemiologists to put their best talents to work on appropriate exposure assessment approaches for even well-known chemical, physical and biological hazards in developing nations. Tools and techniques are needed that provide valid, timely and affordable assessments critical to target and assess interventions.
CLOSING There is no end to the challenges we will face over the 21st century. These comments are intended to stimulate the reader to identify the challenges most relevant along with the choice of what problems are most important to address. Remember, we can make a difference.
Wegman DH. Occup Environ Med November 2014 Vol 71 No 11
Downloaded from http://oem.bmj.com/ on June 8, 2015 - Published by group.bmj.com
Editorial (Hot topic) Acknowledgements This editorial is based on a dinner address at the 24th International Epidemiology in Occupational Health (EPICOH) Conference, June 24-27, 2014, Chicago, IL. Thoughtful review was provided by Anthony Robbins, Christer Hogstedt, Gregory Wagner and Lawrence Fine.
Occup Environ Med 2014;71:739–741. doi:10.1136/oemed-2014-102487
REFERENCES 1
Competing interests None. Provenance and peer review Commissioned; internally peer reviewed.
2
3
To cite Wegman DH. Occup Environ Med 2014;71:739–741. Received 6 August 2014 Accepted 10 September 2014 Published Online First 17 September 2014
5
4
Holland WW. What should be the concerns of epidemiology? Int J Epidemiol 1999;5(Suppl 1): 1009–11. Schulte PA, Chun H. Climate change and occupational safety and health: establishing a preliminary framework. J Occup Environ Hyg 2009;6:542–54. Correa-Rotter R, Wesseling C, Johnson RJ. CKD of unknown origin in central America: the case for a mesoamerican nephropathy. Am J Kidney Dis 2014;63:506–20. Souza K, Davis L, Shire J. Occupational and enviornmental health surveillance. In: Levy BS, Wegman DH, Baron SL, Sokas RK, eds. Occupational and environmental health recognizing and preventing disease and injury. 6th edn. New York: Oxford Univ Press, 2011:55–68.
Wegman DH. Occup Environ Med November 2014 Vol 71 No 11
6
7
8
IOM (Institute of Medicine) and National Research Council. Evaluating occupational health and safety research programs: framework and next steps. Washington, DC: The National Academies Press, 2009:97–8. Wegman DH. Investigations into the use of symptom reports for studying toxic epidemics. In: Rantanen J, ed. New epidemics in occupational health (Proceedings of the International Symposium on New Epidemics in Occupational Health) People and Work Research Reports #1. Helsinki: Finnish Institute of Occupational Health, 1994:124–38. Burke J. Bangladesh factory collapse leaves trail of shattered lives. The Guardian 6 June 2013. http:// www.theguardian.com/world/2013/jun/06/bangladeshfactory-building-collapse-community (accessed 4 Aug 2014). Thrupp LA. Sterilization of workers from pesticide exposure: the causes and consequences of DBCPinduced damage in Costa Rica and beyond. Int J Health Serv 1991;21:731–57.
741
Downloaded from http://oem.bmj.com/ on June 8, 2015 - Published by group.bmj.com
Challenges for occupational epidemiology in the 21st century: observations and opportunities David H Wegman Occup Environ Med 2014 71: 739-741 originally published online September 17, 2014
doi: 10.1136/oemed-2014-102487 Updated information and services can be found at: http://oem.bmj.com/content/71/11/739
These include:
References Email alerting service
Topic Collections
This article cites 4 articles, 0 of which you can access for free at: http://oem.bmj.com/content/71/11/739#BIBL Receive free email alerts when new articles cite this article. Sign up in the box at the top right corner of the online article.
Articles on similar topics can be found in the following collections Air pollution, air quality (178) Other exposures (830)
Notes
To request permissions go to: http://group.bmj.com/group/rights-licensing/permissions To order reprints go to: http://journals.bmj.com/cgi/reprintform To subscribe to BMJ go to: http://group.bmj.com/subscribe/
Editorial (Hot topic)
Challenges for occupational epidemiology in the 21st century: observations and opportunities David H Wegman The 2014 International Epidemiology in Occupational Health (EPICOH) meeting in Chicago, USA, focused on the theme: ‘Challenges for Occupational Epidemiology in the 21st Century’. These are exciting times and with them come no end to challenges faced by occupational epidemiology. And participants eagerly engaged in vigorous discussion on a number of current concerns with both wisdom and wit. Ultimately each individual must decide what challenges are most important and how best to address those selected for first order attention. Nonetheless, some overview of challenges could prove worthwhile and so six general areas are provided as a focus for consideration. ▸ Concentrating on important problems ▸ Acting on what we find ▸ Advancing occupational disease and injury surveillance ▸ Relying on worker self-reports ▸ Looking at data ▸ Addressing health disparities
CONCENTRATING ON THE IMPORTANT PROBLEMS We always run the risk of studying what we know how to study rather than investigating important problems. We must try our best to tackle broad issues and not restrict ourselves to narrow expressions or concerns. To paraphrase Walter Holland1: Overall the number of conditions and environments studied by occupational epidemiologists needs to be expanded and we must not hesitate to press for resources to investigate and control conditions of little concern to political or commercial interests, but which are of importance to our workers and our societies. Funding for our studies is increasingly difficult but the more important the problem the more likely we can gain the attention of potential funders. It is likely that each of us has a somewhat different view of what are the important problems. One that deserves priority attention is the impact of climate change on the global workforce. There is a Correspondence to David H Wegman, Department of Work Environment, University of Massachusetts Lowell, 1 University Avenue Lowell, MA 01854, USA; [email protected]
remarkably diverse mix of occupational sectors that will bear the consequences of climate change.2 The numbers of workers potentially affected certainly is in the millions, and will include (at least): emergency responders, workers in construction, utilities, demolition, cleanup, landscaping, agriculture, forestry, wildlife management, along with postal delivery, warehousing, heavy industry and many manufacturing settings. This work is performed in both urban and rural settings and is carried out both indoors and outdoors. Exposures for these workers will not just be extremes of temperature but those extremes combined with chemical exposures, heavy demanding work and long work hours. They will also include other consequences of climate change such as severe weather events, air pollution and infectious and zoonotic diseases. Climate change is also expected to increase employment in what are already the most hazardous occupations mentioned. Significant human-induced climate change is already occurring and workers are already suffering the impacts of these changes. The politics of addressing climate change are remarkable, and solutions are complicated by the economic implications of altering our current trajectory. Therefore, it is all the more important that we place a high priority on developing, and communicating broadly, the evidence for the consequences of climate change on the full range of workers affected. There are, of course, a number of other important problems that could benefit from our attention. Among these are: ▸ The adverse health consequences of intermittent and long-term unemployment; ▸ The role of work in causing or exascerbating depression or other mental health conditions; ▸ The consequences of exposures to more and more exotic materials especially in poorly regulated environments; ▸ The automation of white collar and service jobs; ▸ The aging workforce in developed nations and the consequences of replacement migration on work in developed and developing nations.
And sometimes an important problem will find us. This can happen if we make it a point to stay alert and open to the significance of unexpected events that occur in our environments. Some of our colleagues at this meeting are actively seeking answers to one such event. A number of years ago sugar cane workers began to notice an unusual number of workmates dying of chronic kidney disease. Not too long after, clinicians in these areas noted an increase in cases of end-stage renal disease along with an increased need for dialysis and an increase in mortality. When the problem started to overwhelm the health services they called for help. Since the mid-1990s investigations have documented a deeply troubling epidemic among working age (mostly) males of chronic kidney disease, not explained by hypertension or diabetes. The majority of cases appear related to work, especially on sugar cane plantations. Understanding why remains complicated. Advances will depend very much on well-designed field epidemiology studies paired with careful environmental and laboratory investigations! At this time the leading hypotheses concern heat and dehydration, pesticides or possibly a combination.3 Less likely but not easily dismissed hypotheses include heavy metals, leptospirosis, non-steroidal anti-inflammatory drugs, high fructose drinks and population susceptibility due to genetic traits, early nutrition or problems in adolescent health. It is easy to see how important creative epidemiological study design and analysis will be in arriving at the ultimate explanation to this epidemic.
ACTING ON WHAT WE FIND Most will agree that we have tended to engage much of our intellectual energy in research and research methods related to disease aetiology. Some have argued that this is appropriate—that our responsibility is to place our findings at the door of colleagues in public health practice and of decisionmakers, letting them use, or not, the findings as they see fit. These views regard epidemiological research and public health practice not only as distinct activities, which they are, but also as essentially independent, which they are not. We must match our success in the study of disease aetiology by putting equal intellectual effort into the design of intervention studies and the assessment of intervention efficacy. In this regard one priority is to develop study design equivalents to the randomised clinical trial, the gold standard for our clinical colleagues.
Wegman DH. Occup Environ Med November 2014 Vol 71 No 11
739
Downloaded from http://oem.bmj.com/ on June 8, 2015 - Published by group.bmj.com
Editorial (Hot topic) Second, we must engage in the public policy process. In doing so we must be transparent about inevitable biases both personal and those related to our research. Furthermore, we must learn how to communicate the dilemma all scientists face; the better we characterise the scientific problems and answer the questions that we pose, the more we open areas for further study. To be committed to the public’s health we must simultaneously follow promising lines of inquiry while taking maximum advantage of what is presently known to advocate for the control or elimination of disease.
OCCUPATIONAL DISEASE AND INJURY SURVEILLANCE We need to face the fact that much of the world operates on the assumption that ‘If it’s not counted, it didn’t happen!’ Surveillance is a necessity for estimating burden and for monitoring long-term progress in reducing hazardous exposures and work-related injuries and illnesses. Without good surveillance data we are at a loss to know whether our national or regional intervention programmes make a difference and why they do or do not. We epidemiologists have not devoted sufficient attention to advance the field of surveillance. The intellectual capital of academic epidemiologists is needed to create new surveillance models and methods to advance this work. To go beyond the common employer-based systems we need to seek ways to include non-employer-based data sources such as hospital and other medical data systems as well as national or regional population-based exposure and health surveys.4 5 We should also explore the adaptation of general public health data sets for surveillance of work-related health problems thereby supplementing information not available through traditional data sources.
WORKER SELF-REPORTS We live in an exciting age with rapid developments and increasing sophistication in the use of biomarkers and genetic markers applied both to exposure and to health outcomes. These exciting developments should not distract us from the ever-present need to explore and refine worker self-reports as valid measures of exposures and of illness. Self-reports are too often presented, if at all, with an apology for their use. And there is, of course, a proper concern with recall bias. However, by emphasising careful development and validation of instruments used in the systematic collection of self-reports, 740
these will continue to have an essential place in epidemiology studies.6 Developments in exposure biomonitoring will contribute to efforts to improve exposure assessment but we will always need to rely on self-reports as essential to characterise variations between individuals and over time when estimating long-term or lifetime exposures. Attention to methods and instruments that improve the accuracy and completeness of selfreported exposure requires our ongoing engagement. Symptom reports have the advantage of directing attention to the type of experience that leads most individuals to seek medical attention in the first place. Symptoms can: ▸ Provide the earliest evidence of abnormality; ▸ Often correlate well with objective findings; ▸ Contribute to a more complete picture of illness than objective tests alone; ▸ May be the abnormality, one that cannot be determined by objective measures. With proper attention to the science of psychophysics and with proper use of health measurement scales, valid reports of symptoms can be collected with relative ease, with little expense and with noninvasive measures.
LOOKING AT DATA We need to remain attentive to the consequences of the easy use of models particularly those that assume some form of linearity in an unknown dose–response relationship. Do these models and assumptions permit us to see, or are they ultimately misrepresenting, the truth? Approaches to modelling that relax these constraints certainly are beginning to address this concern. However, we must continue to pay attention to the importance of describing and reflecting on our data carefully before exploring models. Thoughtful consideration of well-displayed data tables and figures is undervalued. And this extends to the reports of our research. Readers are too often frustrated by publications of well-designed studies that present very limited detail about the actual data before providing the findings associated with final models. Simple approaches to data analysis deserve a place in any publication and appropriately stratified data should accompany any presentation of models that adjust for covariates. For example, increasing attention is paid to the impact of work on an aging workforce. Many studies could inform understanding but
this requires care to report more than age-adjusted analyses in our studies of aetiology or intervention effectiveness.
HEALTH DISPARITIES AND INEQUITY In this age of deregulation and the dominance of the market economy many countries are experiencing increasing disparity, certainly we are in the USA. In the workplace these developments are reflected in ▸ Wide-spread reduction in job security along with a rise in work without contracts or benefits; ▸ Intermittent periods of employment and unemployment; ▸ Increased hours of work when working; ▸ Much less attention to the quality of work and work environments. As epidemiologists our roles must include using our knowledge and skills to draw attention to the consequences of these developments by supplying evidence of the impact of current work practices on an increasingly vulnerable workforce. Equally important, those of us in the developed world need to take responsibility to track and describe the impact of the export of hazardous materials, equipment and jobs. The tragedies in Bangladesh associated with the manufacture of garments for Benetton, JC Penny, Walmart and others show the result of moving manufacturing away from better-regulated settings.7 And there are also the consequences of exporting toxic materials judged unsafe in one country for free use in another. 1,2-Dibromo-3-chloropropane was banned from use in the USA in the 1980s but a decade later was shown to contribute to male infertility in banana workers in Costa Rica.8 And, concerning collaborations with our colleagues in developing nations, there is need for epidemiologists to put their best talents to work on appropriate exposure assessment approaches for even well-known chemical, physical and biological hazards in developing nations. Tools and techniques are needed that provide valid, timely and affordable assessments critical to target and assess interventions.
CLOSING There is no end to the challenges we will face over the 21st century. These comments are intended to stimulate the reader to identify the challenges most relevant along with the choice of what problems are most important to address. Remember, we can make a difference.
Wegman DH. Occup Environ Med November 2014 Vol 71 No 11
Downloaded from http://oem.bmj.com/ on June 8, 2015 - Published by group.bmj.com
Editorial (Hot topic) Acknowledgements This editorial is based on a dinner address at the 24th International Epidemiology in Occupational Health (EPICOH) Conference, June 24-27, 2014, Chicago, IL. Thoughtful review was provided by Anthony Robbins, Christer Hogstedt, Gregory Wagner and Lawrence Fine.
Occup Environ Med 2014;71:739–741. doi:10.1136/oemed-2014-102487
REFERENCES 1
Competing interests None. Provenance and peer review Commissioned; internally peer reviewed.
2
3
To cite Wegman DH. Occup Environ Med 2014;71:739–741. Received 6 August 2014 Accepted 10 September 2014 Published Online First 17 September 2014
5
4
Holland WW. What should be the concerns of epidemiology? Int J Epidemiol 1999;5(Suppl 1): 1009–11. Schulte PA, Chun H. Climate change and occupational safety and health: establishing a preliminary framework. J Occup Environ Hyg 2009;6:542–54. Correa-Rotter R, Wesseling C, Johnson RJ. CKD of unknown origin in central America: the case for a mesoamerican nephropathy. Am J Kidney Dis 2014;63:506–20. Souza K, Davis L, Shire J. Occupational and enviornmental health surveillance. In: Levy BS, Wegman DH, Baron SL, Sokas RK, eds. Occupational and environmental health recognizing and preventing disease and injury. 6th edn. New York: Oxford Univ Press, 2011:55–68.
Wegman DH. Occup Environ Med November 2014 Vol 71 No 11
6
7
8
IOM (Institute of Medicine) and National Research Council. Evaluating occupational health and safety research programs: framework and next steps. Washington, DC: The National Academies Press, 2009:97–8. Wegman DH. Investigations into the use of symptom reports for studying toxic epidemics. In: Rantanen J, ed. New epidemics in occupational health (Proceedings of the International Symposium on New Epidemics in Occupational Health) People and Work Research Reports #1. Helsinki: Finnish Institute of Occupational Health, 1994:124–38. Burke J. Bangladesh factory collapse leaves trail of shattered lives. The Guardian 6 June 2013. http:// www.theguardian.com/world/2013/jun/06/bangladeshfactory-building-collapse-community (accessed 4 Aug 2014). Thrupp LA. Sterilization of workers from pesticide exposure: the causes and consequences of DBCPinduced damage in Costa Rica and beyond. Int J Health Serv 1991;21:731–57.
741
Downloaded from http://oem.bmj.com/ on June 8, 2015 - Published by group.bmj.com
Challenges for occupational epidemiology in the 21st century: observations and opportunities David H Wegman Occup Environ Med 2014 71: 739-741 originally published online September 17, 2014
doi: 10.1136/oemed-2014-102487 Updated information and services can be found at: http://oem.bmj.com/content/71/11/739
These include:
References Email alerting service
Topic Collections
This article cites 4 articles, 0 of which you can access for free at: http://oem.bmj.com/content/71/11/739#BIBL Receive free email alerts when new articles cite this article. Sign up in the box at the top right corner of the online article.
Articles on similar topics can be found in the following collections Air pollution, air quality (178) Other exposures (830)
Notes
To request permissions go to: http://group.bmj.com/group/rights-licensing/permissions To order reprints go to: http://journals.bmj.com/cgi/reprintform To subscribe to BMJ go to: http://group.bmj.com/subscribe/
