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Two distinct views of the roles and responsibilities of epidemiologists have emerged in a decades-long debate: one keeps professional practice constrained to science; the other adds active participation in public health policymaking. In defense of the narrower view are several claims: that epidemiologists lack expertise in policymaking; that advocating policy adversely affects scientific objectivity; that the limits of epidemiologic science work against translating results into policy; and that participation in policy can bring on personal attacks. In this study, each claim is addressed. Epidemiologists already participate fully in educational, research funding, and editorial policymaking and thereby have an experiential foundation in some of the basics of policymaking. Policymaking can enhance scientific objectivity because it requires not only the use but more importantly the improvement of empirical methods. Finally, the comforts of professional life are not the primary yardsticks of our responsibilities. Arguments in favor of active involvement in public health policymaking are presented. Epidemiologists have been mixing science and policymaking for a long time and there is a strong sense that the benefits of public stewardship outweigh the risks. The American College of Epidemiology's Ethics Guidelines support this view. Active participation in public heath policymaking will, however, require curriculum changes in graduate training programs. With additional training and a broader recognition that public health policymaking is an appropriate professional pursuit, epidemiologists can look to a bright and challenging future in the science and practice of public health. [ABSTRACT FROM AUTHOR]

Causation is an essential concept in epidemiology, yet there is no single, clearly articulated definition for the discipline. From a systematic review of the literature, five categories can be delineated: production, necessary and sufficient, sufficient-component, counterfactual, and probabilistic. Strengths and weaknesses of these categories are examined in terms of proposed characteristics of a useful scientific definition of causation: it must be specific enough to distinguish causation from mere correlation, but not so narrow as to eliminate apparent causal phenomena from consideration. Two categories-production and counterfactual-are present in any definition of causation but are not themselves sufficient as definitions. The necessary and sufficient cause definition assumes that all causes are deterministic. The sufficient-component cause definition attempts to explain probabilistic phenomena via unknown component causes. Thus, on both of these views, heavy smoking can be cited as a cause of lung cancer only when the existence of unknown deterministic variables is assumed. The probabilistic definition, however, avoids these assumptions and appears to best fit the characteristics of a useful definition of causation. It is also concluded that the probabilistic definition is consistent with scientific and public health goals of epidemiology. In debates in the literature over these goals, proponents of epidemiology as pure science tend to favour a narrower deterministic notion of causation models while proponents of epidemiology as public health tend to favour a probabilistic view. The authors argue that a single definition of causation for the discipline should be and is consistent with both of these aims. It is concluded that a counterfactually-based probabilistic definition is more amenable to the quantitative tools of epidemiology, is consistent with both deterministic and probabilistic phenomena, and serves equally well for the acquisition and the application of scientific knowledge. [ABSTRACT FROM AUTHOR]

Although Salvadoreans are the fourth largest group of Hispanics in the United States, little is known about their cancer knowledge, attitudes, and practices. There are no publications assessing cancer knowledge among Salvadorean men. In this cross-sectional survey, information was gathered from 706 immigrant Salvadorean men in Washington, D.C. The majority of these men knew that smoking causes cancer and that some cancers can be cured if detected early. However, the men in this survey had inadequate knowledge about symptoms of cancer and early detection methods. The most important predictor of cancer screening among older participants was enrollment in health insurance plans. Our study suggests that Salvadorean men would participate in cancer screening efforts if they had access to medical care. Educational programs to increase awareness of cancer and availability of preventive services may help prevent cancer in this population. [ABSTRACT FROM AUTHOR]

Keywords:Character, education, ethics, philosophy, public health, scientific misconduct, virtues [ABSTRACT FROM PUBLISHER]

Background: Two recent accounts of the use of causal criteria make opposite claims: that criteria should be used more often to avoid bias in assessments of weak associations and, in direct contrast that criteria are scientifically invalid. [ABSTRACT FROM PUBLISHER]

Women's magazines are an important source of health information. To evaluate the relevancy of articles in these publications to known disease risks, seven women's magazines were reviewed to assess their coverage of colon cancer, the third leading cause of cancer mortality in U.S. women. Specifically, the amount of coverage devoted to colon cancer as well as the presentation of issues in the prevention, risks, treatment, diagnosis and genetics of colon cancer were recorded. Twenty articles were published on colon cancer in these magazines during the years 1987-1995. Compared to five other cancers that also affect women, colon cancer was the focus of the fewest articles in the seven magazines analyzed. [ABSTRACT FROM AUTHOR]

This is the second part of a two part glossary on terms used in public health ethics. This glossary focuses on terms related to the professional practice of epidemiology and public health. [ABSTRACT FROM AUTHOR]

OBJECTIVES: This study examined the quality of recent reviews in epidemiology. METHODS: All 1995 issues of 7 widely read epidemiology journals were searched to identify reviews. RESULTS: Twenty-nine reviews were identified. Methodology was not specified or incomplete for literature searches in 79% of reviews; the same was true for inclusion criteria in 83% and for combining studies in 62%. More than 60% of the reviews were not methodologically systematic. CONCLUSIONS: There is a need to improve the quality of review papers in epidemiology. If systematic methodology were followed more frequently, epidemiologic science and its application could be improved. [ABSTRACT FROM AUTHOR]

Purpose: The American College of Epidemiology (ACE) held its 2022 Annual Meeting, September 8-11, with a conference theme of 'Pandemic of Misinformation: Building Trust in Epidemiology'. The ACE Ethics Committee hosted a symposium session in recognition of the global spotlight placed on epidemiology and public health due to the COVID-19 crisis. The ACE Ethics Committee invited previous Chairs of the Ethics Committee and current President of the International Epidemiological Association to present at the symposium session. This paper aims to highlight the ethical challenges presented during the symposium session., Methods: Three speakers with diverse backgrounds representing expertize from the fields of ethics, epidemiology, public health, clinical trials, pharmacoepidemiology, statistics, law, and public policy, covering perspectives from the U.S., Europe, and Southeast Asia were selected to present on the ethical challenges in epidemiology and public health applying a global theme. Dr. D. Weed presented on 'Causation, Epidemiology and Ethics'; Dr. C.M. Pandey presented on the 'Ethical Challenges in the Practice of Digital Epidemiology'; and Dr. J. Acquavella presented on 'Departures from Scientific Objectivity: A Cause of Eroding Trust in Epidemiology.', Results: The collective goal to improve the public's health was a mutually shared theme across the three distinct areas. We highlight the common ethical guidance and principle-based approaches that have served epidemiology and public health in framing and critical analysis of novel challenges, including autonomy, beneficence, justice, scientific integrity, duties to the profession and community, and developing and maintaining public trust; however, gaps remain in how best to address health inequalities and the novel emergence and pervasiveness of misinformation and disinformation that have impacted the health of the global community. We introduce an ethical framework of translational bioethics that places considerations of the social determinants of health at the forefront., Conclusions: The COVID-19 pandemic required an expedited public health response and, at the same time, placed the profession of epidemiology and public health, its system, and structures, under the microscope like never before. This article illustrates that revisiting our foundations in research and practice and orienting contemporary challenges using an ethical lens can assist in identifying and furthering the health of populations globally., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Causal assessments in epidemiology are a complex process due to the many methods involved. The general scientific method lords over the process joined by study designs and statistical methods. Other methods include those that evaluate quality and bias along with the research synthesis methods such as the systematic narrative review, meta-analysis, and the criteria-based methods. When different investigators apply these methods to the same evidence and come up with different causal assessments, as described in the review by Goodman et al. in this issue, a key question becomes, how can the differences be explained? A prime candidate involves different methodologic choices. A deeper question emerges from this same situation: are the methods used for causal assessments reliable? Reliability is a hallmark of scientific practice. The methods used to make claims about causality should be reliable. Given the complexity of the causal assessment process, an objective evaluation of reliability is challenging but clearly worth the effort. Fortunately, Hill's criterion of analogy, much maligned in epidemiology, provides a clue. This commentary explores the issue of the reliability of causal claims using the Goodman et al. systematic review as its foil along with the claims by EPA, IARC, and ATSDR about the relationship between perchloroethylene and non-Hodgkin lymphoma, the claims Goodman et al. believe are wrong., (© 2022 The Author. Published by Elsevier Inc.)

To examine the extent to which a consensus exists in the scientific community regarding the relationship between exposure to paraquat and Parkinson's disease, a critical review of reviews was undertaken focusing on reviews published between 2006 and the present that offered opinions on the issue of causation. Systematic searches were undertaken of scientific databases along with searches of published bibliographies to identify English language reviews on the topic of paraquat and Parkinson's disease including those on the broader topic of environmental and occupational risk factors for Parkinson's disease. Of the 269 publications identified in the searches, there were twelve reviews, some with meta-analyses, that met the inclusion criteria. Information on methods used by the reviewers, if any, and source of funding was collected; the quality of the reviews was considered. No author of any published review stated that it has been established that exposure to paraquat causes Parkinson's disease, regardless of methods used and independent of funding source. A consensus exists in the scientific community that the available evidence does not warrant a claim that paraquat causes Parkinson's disease. Future research on this topic should focus on improving the quality of epidemiological studies including better exposure measures and identifying specific mechanisms of action. Future reviews of emerging evidence should be structured as systematic narrative reviews with meta-analysis if appropriate., (Copyright © 2021 The Author(s). Published by Elsevier B.V. All rights reserved.)

Metaphors have had an important role to play in the theory and practice of epidemiology. Some well-known examples include "black boxes," the "web of causation," "shoe-leather epidemiology," the "ivory tower" and the ubiquitous "gold standard." Metaphors like these do not replace methods or principles but rather like memes can spark a creative response and thoughtful reflection. In this paper, I bring to the attention of epidemiologists a metaphor that originated forty years ago in a paper describing and explaining measures of disease incidence. The authors wrote about a "sea of population time" to represent how incident disease events-specifically, incidence density measures- occur in the two-dimensional space of person-time. A "sea of population time" or "sea of person time" seems ideally suited as a metaphor for creative and thoughtful development in epidemiology. The vast and varied characteristics of oceans provide a plethora of ideas that can potentially help us to think more deeply about the role and responsibilities of epidemiologists. As an example, consider the notion that epidemiologists' journey across this sea in their methodologically-laden and concept-heavy fishing boats searching for the causes of disease. At the same time, epidemiologists live in the sea itself subject to and thus at risk of all the same diseases that affect human populations. Storms on this imaginary sea could sink our boats causing us to rethink conceptual and methodological frameworks. Here I provide in lyric form examples that explore what might exist behind the sea of person time and on its shores., Competing Interests: The author declares that he has no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2021 The Author.)

The purpose of this article was to rethink and resurrect Austin Bradford Hill's "criterion" of analogy as an important consideration in causal inference. In epidemiology today, analogy is either completely ignored (e.g., in many textbooks), or equated with biologic plausibility or coherence, or aligned with the scientist's imagination. None of these examples, however, captures Hill's description of analogy. His words suggest that there may be something gained by contrasting two bodies of evidence, one from an established causal relationship, the other not. Coupled with developments in the methods of systematic assessments of evidence-including but not limited to meta-analysis-analogy can be restructured as a key component in causal inference. This new approach will require that a collection-a library-of known cases of causal inference (i.e., bodies of evidence involving established causal relationships) be developed. This library would likely include causal assessments by organizations such as the International Agency for Research on Cancer, the National Toxicology Program, and the United States Environmental Protection Agency. In addition, a process for describing key features of a causal relationship would need to be developed along with what will be considered paradigm cases of causation. Finally, it will be important to develop ways to objectively compare a "new" body of evidence with the relevant paradigm case of causation. Analogy, along with all other existing methods and causal considerations, may improve our ability to identify causal relationships., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The possible relationship between dietary cholesterol and cardiac outcomes has been scrutinized for decades. However, recent reviews of the literature have suggested that dietary cholesterol is not a nutrient of concern. Thus, we conducted a meta-analysis of egg intake (a significant contributor to dietary cholesterol) and risk of coronary heart disease (CHD) and stroke. A comprehensive literature search was conducted through August 2015 to identify prospective cohort studies that reported risk estimates for egg consumption in association with CHD or stroke. Random-effects meta-analysis was used to generate summary relative risk estimates (SRREs) for high vs low intake and stratified intake dose-response analyses. Heterogeneity was examined in subgroups where sensitivity and meta regression analyses were conducted based on increasing egg intake. A 12% decreased risk (SRRE = 0.88, 95% confidence interval [CI], 0.81-0.97) of stroke was observed in the meta-analysis of 7 studies of egg intake (high vs low; generally 1/d vs <2/wk), with little heterogeneity (p-H = 0.37, I 2 = 7.50). A nonstatistically significant SRRE of 0.97 (95% CI, 0.88-1.07, p-H = 0.67, I 2 = 0.00) was observed in the meta-analysis of 7 studies of egg consumption and CHD. No clear dose-response trends were apparent in the stratified intake meta-analyses or the meta regression analyses. Based on the results of this meta-analysis, consumption of up to one egg daily may contribute to a decreased risk of total stroke, and daily egg intake does not appear to be associated with risk of CHD. Key Teaching Points: • The role of egg consumption in the risk of stroke and coronary heart disease has come under scrutiny over many years. • A comprehensive meta-analysis of prospective cohort studies that reported risk estimates for egg consumption in association with CHD or stroke was performed on the peer-reviewed epidemiologic literature through August 2015. • Overall, summary associations indicate that intake of up to 1 egg daily may be associated with reduced risk of total stroke. • Overall, summary associations show no clear association between egg intake and increased or decreased risk of CHD. • Eggs are a relatively low-cost and nutrient-dense whole food that provides a valuable source of protein, essential fatty acids, antioxidants, choline, vitamins, and minerals.

We conducted a systematic review of the epidemiologic literature for glyphosate focusing on non-Hodgkin's lymphoma (NHL) and multiple myeloma (MM) - two cancers that were the focus of a recent review by an International Agency for Research on Cancer Working Group. Our approach was consistent with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for systematic reviews. We evaluated each relevant study according to a priori criteria for study quality: adequacy of study size, likelihood of confounding, potential for other biases and adequacy of the statistical analyses. Our evaluation included seven unique studies for NHL and four for MM, all but one of which were case control studies for each cancer. For NHL, the case-control studies were all limited by the potential for recall bias and the lack of adequate multivariate adjustment for multiple pesticide and other farming exposures. Only the Agricultural Health (cohort) Study met our a priori quality standards and this study found no evidence of an association between glyphosate and NHL. For MM, the case control studies shared the same limitations as noted for the NHL case-control studies and, in aggregate, the data were too sparse to enable an informed causal judgment. Overall, our review did not find support in the epidemiologic literature for a causal association between glyphosate and NHL or MM.

The International Agency for Research on Cancer (IARC) published a monograph in 2015 concluding that glyphosate is "probably carcinogenic to humans" (Group 2A) based on limited evidence in humans and sufficient evidence in experimental animals. It was also concluded that there was strong evidence of genotoxicity and oxidative stress. Four Expert Panels have been convened for the purpose of conducting a detailed critique of the evidence in light of IARC's assessment and to review all relevant information pertaining to glyphosate exposure, animal carcinogenicity, genotoxicity, and epidemiologic studies. Two of the Panels (animal bioassay and genetic toxicology) also provided a critique of the IARC position with respect to conclusions made in these areas. The incidences of neoplasms in the animal bioassays were found not to be associated with glyphosate exposure on the basis that they lacked statistical strength, were inconsistent across studies, lacked dose-response relationships, were not associated with preneoplasia, and/or were not plausible from a mechanistic perspective. The overall weight of evidence from the genetic toxicology data supports a conclusion that glyphosate (including GBFs and AMPA) does not pose a genotoxic hazard and therefore, should not be considered support for the classification of glyphosate as a genotoxic carcinogen. The assessment of the epidemiological data found that the data do not support a causal relationship between glyphosate exposure and non-Hodgkin's lymphoma while the data were judged to be too sparse to assess a potential relationship between glyphosate exposure and multiple myeloma. As a result, following the review of the totality of the evidence, the Panels concluded that the data do not support IARC's conclusion that glyphosate is a "probable human carcinogen" and, consistent with previous regulatory assessments, further concluded that glyphosate is unlikely to pose a carcinogenic risk to humans.

We conducted a systematic review and meta-analysis to estimate the potential association between LCω-3PUFAs and prostate cancer (PC). A comprehensive literature search was performed through 2013 to identify prospective studies that examined dietary intakes of long-chain omega-3 polyunsaturated fatty acids (LCω-3PUFA) or blood biomarkers of LCω-3PUFA status and risk of PC. Random-effects meta-analyses were conducted to generate summary relative risk estimates (SRREs) for LCω-3PUFAs and total PC, and by stage and grade. Subgroup analyses were also conducted for specific fatty acids and other study characteristics. Twelve self-reported dietary intake and 9 biomarker studies from independent study populations were included in the analysis, with 446,243 and 14,897 total participants, respectively. No association between LCω-3PUFAs and total PC was observed (SRRE = 1.00, 95% CI: 0.93-1.09) for the dietary intake studies (high vs. low LCω-3PUFAs category comparison) or for the biomarker studies (SRRE of 1.07, 95% CI: 0.94-1.20). In general, most summary associations for the dietary intake studies were in the inverse direction, whereas the majority of summary associations for the biomarker studies were in the positive direction, but all were weak in magnitude. The results from this meta-analysis do not support an association between LCω-3PUFAs and PC.

The potential relationship between red meat consumption and colorectal cancer (CRC) has been the subject of scientific debate. Given the high degree of resulting uncertainty, our objective was to update the state of the science by conducting a systematic quantitative assessment of the epidemiologic literature. Specifically, we updated and expanded our previous meta-analysis by integrating data from new prospective cohort studies and conducting a broader evaluation of the relative risk estimates by specific intake categories. Data from 27 independent prospective cohort studies were meta-analyzed using random-effects models, and sources of potential heterogeneity were examined through subgroup and sensitivity analyses. In addition, a comprehensive evaluation of potential dose-response patterns was conducted. In the meta-analysis of all cohorts, a weakly elevated summary relative risk was observed (1.11, 95% CI: 1.03-1.19); however, statistically significant heterogeneity was present. In general, summary associations were attenuated (closer to the null and less heterogeneous) in models that isolated fresh red meat (from processed meat), adjusted for more relevant factors, analyzed women only, and were conducted in countries outside of the United States. Furthermore, no clear patterns of dose-response were apparent. In conclusion, the state of the epidemiologic science on red meat consumption and CRC is best described in terms of weak associations, heterogeneity, an inability to disentangle effects from other dietary and lifestyle factors, lack of a clear dose-response effect, and weakening evidence over time. KEY TEACHING POINTS: •The role of red meat consumption in colorectal cancer risk has been widely contested among the scientific community.•In the current meta-analysis of red meat intake and colorectal cancer, we comprehensively examined associations by creating numerous sub-group stratifications, conducting extensive sensitivity analyses, and evaluating dose-response using several different methods.•Overall, all summary associations were weak in magnitude with no clear dose-response patterns.•Interpretation of findings from epidemiologic studies investigating diet and health outcomes involves numerous methodological considerations, such as accurately measuring food intake, dietary pattern differences across populations, food definitions, outcome classifications, bias and confounding, multicollinearity, biological mechanisms, genetic variation in metabolizing enzymes, and differences in analytical metrics and statistical testing parameters.

This paper is based on a workshop held in Oslo, Norway in November 2013, in which experts discussed how to reach consensus on the healthiness of red and processed meat. Recent nutritional recommendations include reducing intake of red and processed meat to reduce cancer risk, in particular colorectal cancer (CRC). Epidemiological and mechanistic data on associations between red and processed meat intake and CRC are inconsistent and underlying mechanisms are unclear. There is a need for further studies on differences between white and red meat, between processed and whole red meat and between different types of processed meats, as potential health risks may not be the same for all products. Better biomarkers of meat intake and of cancer occurrence and updated food composition databases are required for future studies. Modifying meat composition via animal feeding and breeding, improving meat processing by alternative methods such as adding phytochemicals and improving our diets in general are strategies that need to be followed up., (Copyright © 2014. Published by Elsevier Ltd.)

Background: Assessment of design heterogeneity conducted prior to meta-analysis is infrequently reported; it is often presented post hoc to explain statistical heterogeneity. However, design heterogeneity determines the mix of included studies and how they are analyzed in a meta-analysis, which in turn can importantly influence the results. The goal of this work is to introduce ways to improve the assessment and reporting of design heterogeneity prior to statistical summarization of epidemiologic studies., Methods: In this paper, we use an assessment of sugar-sweetened beverages (SSB) and type 2 diabetes (T2D) as an example to show how a technique called 'evidence mapping' can be used to organize studies and evaluate design heterogeneity prior to meta-analysis.. Employing a systematic and reproducible approach, we evaluated the following elements across 11 selected cohort studies: variation in definitions of SSB, T2D, and co-variables, design features and population characteristics associated with specific definitions of SSB, and diversity in modeling strategies., Results: Evidence mapping strategies effectively organized complex data and clearly depicted design heterogeneity. For example, across 11 studies of SSB and T2D, 7 measured diet only once (with 7 to 16 years of disease follow-up), 5 included primarily low SSB consumers, and 3 defined the study variable (SSB) as consumption of either sugar or artificially-sweetened beverages. This exercise also identified diversity in analysis strategies, such as adjustment for 11 to 17 co-variables and a large degree of fluctuation in SSB-T2D risk estimates depending on variables selected for multivariable models (2 to 95% change in the risk estimate from the age-adjusted model)., Conclusions: Meta-analysis seeks to understand heterogeneity in addition to computing a summary risk estimate. This strategy effectively documents design heterogeneity, thus improving the practice of meta-analysis by aiding in: 1) protocol and analysis planning, 2) transparent reporting of differences in study designs, and 3) interpretation of pooled estimates. We recommend expanding the practice of meta-analysis reporting to include a table that summarizes design heterogeneity. This would provide readers with more evidence to interpret the summary risk estimates.

Background: Evidence maps are a new method that systematically characterize the range of research activity in broad topic areas and are used to guide research priority setting, systematic reviews, and meta-analyses., Objective: We expanded evidence mapping methods by demonstrating their usefulness as a tool for organizing epidemiologic research on sugar-sweetened beverage (SSB) intake and health outcomes: obesity, type 2 diabetes, metabolic syndrome, and coronary heart disease/stroke., Design: We performed a search of the PubMed, Scopus, and Cochrane databases and a hand search of references. Studies selected were reviews and longitudinal studies (intervention and cohort) published between 1 January 1966 and 31 October 2012., Results: We identified and mapped 77 studies (18 review and 59 primary research articles); most of the research focused on obesity (n = 47). For all outcomes, >30% (n = 18) of the primary research studies we identified were not referenced in published reviews. We found considerable variability among primary research studies of SSBs and the 4 health outcomes in terms of designs, definitions of SSBs, and definitions of outcomes, which renders these studies difficult to interpret collectively. For example, we counted 14 different definitions of weight/obesity in 29 observational cohort studies, and ≤6 studies reported the use of the same outcome measure., Conclusions: Establishing field standards in the study of SSB intake and health outcomes would facilitate interpretation across research studies and thereby increase the utility of systematic reviews/meta-analyses and ultimately the efficiency of research efforts. Rapid publication of new data suggests the need for regular updates and caution when reading reviews.

Multivitamin-multimineral (MVM) supplements are the most frequently used dietary supplements in the United States, with one third or more of the population using at least one daily. However, the health-related implications of MVM use are unclear. Thus, we systematically reviewed and summarized the prospective studies of MVM supplementation and all-cause and cause-specific mortality, as well as cardiovascular disease (CVD) and cancer incidence, to critically evaluate the current evidence on this topic. We included studies of generally healthy adult populations that evaluated multivitamin (the most commonly used dietary supplement) and/or multimineral supplement use or simultaneous use of 3 or more vitamins and minerals. We did not evaluate individual supplements. A total of 12 cohort studies and 3 primary prevention randomized controlled trials met our inclusion criteria. The majority of the studies were conducted in the United States (n = 11), and the remaining were conducted in European countries (n = 3) and Japan (n = 1). Although between-study methodological variation was present, most relative risks hovered closely around or slightly below the null value. No clear patterns of associations by study country, gender, smoking status, or frequency of use were observed. Based upon the available scientific evidence to date, supplementation with MVMs does not appear to increase all-cause mortality, cancer incidence or mortality, or CVD incidence or mortality and may provide a modest protective benefit.

The methodological quality of published reviews of nutrition and cancer (2008-2009) and of the carcinogenicity of acrylamide (1999-2009) was systematically assessed. Each review was examined with respect to four characteristics: whether the purpose of the review was explicitly stated, whether a methods section (detailing the methods used to "weigh" the evidence) was included, whether "weight of evidence" methods were described elsewhere in the paper (e.g., in the discussion), and finally, whether references to recognized "weight of evidence" methods were included. In this study, ninety per cent of a systematically selected sample of recent reviews on nutrition and cancer published in 2008-2009 and 74% of reviews on acrylamide on cancer published in 1999-2009 were found to be methodologically troublesome or frankly unsound. Failure of peer review and editorial oversight are possible explanations, suggesting a broad lack of concern about this issue in the scientific community. If peer reviewers in the nutrition and cancer community do not require "weight of evidence" methods, then these methods may not appear in the published reviews. Similarly, if journal editors (or editorial policies) do not require methods sections in literature reviews, then these sections may not appear. The prerogative of the author(s) seems the most likely determinant of whether a systematic approach is used or not in nutrition and cancer reviews.

Objective: To systematically evaluate epidemiologic studies on pesticides and colon cancer and rectal cancer in agricultural pesticide applicator populations using a transparent "weight-of-evidence" (WOE) methodological approach., Methods: Twenty-nine (29) publications from the Agricultural Health Study (AHS) and 13 additional epidemiologic studies were identified that reported data for pesticide applicators and/or specific pesticide compounds and colorectal, colon, or rectal cancer. The AHS evaluated pesticide applicators as well as dose-response associations for specific pesticide compounds, whereas the large majority of non-AHS evaluated applicators but did not analyze specific compounds or dose-response trends. This WOE assessment of 153 different pesticide-outcome pairs emphasized several key evidentiary features: existence of statistically significant relative risks, magnitude of observed associations, results from the most reliable exposure assessments, and evidence of convincing dose-response relationships (i.e., those monotonically increasing, with statistically significant trend tests)., Results: Occupation as a pesticide applicator or pesticide application as a farming-related function was not associated with increasing the risk of colon or rectal cancer. Deficits of colon or rectal cancer were observed across most studies of pesticide applicators. After applying the WOE methodology to the epidemiologic studies of specific pesticide compounds and colon or rectal cancer, a number of pesticide-outcome pairs were identified and evaluated further based on positive statistical associations. Of these, only two-aldicarb and colon cancer and imazethapyr and proximal colon cancer-appears to warrant further discussion regarding a possible causal relationship, although the epidemiologic data are limited. For the remainder, a lack of a clear dose-response trend, inconsistencies in associations between exposure metrics and comparison groups, imprecise associations, variable participation rates for analyses of specific compounds, and the reliance upon data from one study (the AHS) limit interpretation regarding risk., Conclusion: The available epidemiologic evidence does not support a causal relationship between occupation as a pesticide applicator or specific pesticide exposures and colon or rectal cancer.

Background: Medical and public health decisions are informed by reviews, which makes the quality of reviews an important scientific concern., Objective: We systematically assessed the quality of published reviews on sugar-sweetened beverages (SSBs) and health, which is a controversial topic that is important to public health., Design: We performed a search of PubMed and Cochrane databases and a hand search of reference lists. Studies that were selected were published reviews and meta-analyses (June 2001 to June 2011) of epidemiologic studies of the relation between SSBs and obesity, type 2 diabetes, metabolic syndrome, and coronary heart disease. A standardized data-abstraction form was used. Review quality was assessed by using the validated instrument AMSTAR (assessment of multiple systematic reviews), which is a one-page tool with 11 questions., Results: Seventeen reviews met our inclusion and exclusion criteria: obesity or weight (16 reviews), diabetes (3 reviews), metabolic syndrome (3 reviews), and coronary heart disease (2 reviews). Authors frequently used a strictly narrative review (7 of 17 reviews). Only 6 of 17 reviews reported quantitative data in a table format. Overall, reviews of SSBs and health outcomes received moderately low-quality scores by the AMSTAR [mean: 4.4 points; median: 4 points; range: 1-8.5 points (out of a possible score of 11 points)]. AMSTAR scores were not related to the conclusions of authors (8 reviews reported an association with a mean AMSTAR score of 4.1 points; 9 reviews with equivocal conclusions scored 4.7 points; P value = 0.84). Less than one-third of published reviews reported a comprehensive literature search, listed included and excluded studies, or used duplicate study selection and data abstraction., Conclusion: The comprehensive reporting of epidemiologic evidence and use of systematic methodologies to interpret evidence were underused in published reviews on SSBs and health.

The relationship between red meat consumption and colorectal cancer (CRC) has been the subject of scientific debate. To estimate the summary association between red meat intake and CRC and to examine sources of heterogeneity, a meta-analysis of prospective studies was conducted. Thirty-four prospective studies of red meat and CRC were identified, of which 25 represented independent nonoverlapping study populations. Summary relative risk estimates (SRREs) for high versus low intake and dose-response relationships were calculated. In the high versus low intake meta-analysis, the SRRE was 1.12 (95% CI: 1.04-1.21) with significant heterogeneity (P=0.014). Summary associations were modified by tumor site and sex. The SRREs for colon cancer and rectal cancer were 1.11 (95% CI: 1.03-1.19) and 1.19 (95% CI: 0.97-1.46), respectively. The SRREs among men and women were 1.21 (95% CI: 1.04-1.42) and 1.01 (95% CI: 0.87-1.17), respectively. The available epidemiologic data are not sufficient to support an independent and unequivocal positive association between red meat intake and CRC. This conclusion is based on summary associations that are weak in magnitude, heterogeneity across studies, inconsistent patterns of associations across the subgroup analyses, and the likely influence of confounding by other dietary and lifestyle factors.

Transparency and documentation of the decision process are at the core of a credible risk assessment and, in addition, are essential in the presentation of a weight of evidence (WoE)-based approach. Lack of confidence in the risk assessment process (as the basis for a risk management decision), beginning with evaluation of raw data and continuing through the risk decision process, is largely because of issues surrounding transparency. There is a critical need to implement greater transparency throughout the risk assessment process, and although doing so will not guarantee the correctness of the risk assessment or that all risk assessors come up with the same conclusions, it will provide essential information on how a particular conclusion or decision was made, thereby increasing confidence in the conclusions. Recognizing this issue, the International Life Sciences Institute Health and Environmental Sciences Institute convened a multisector committee tasked with discussing this issue and examining existing guidance and recommendations related to transparency in risk assessment. The committee concluded that transparency is inextricably linked to credibility: credibility of the data, credibility of the risk assessment process, and credibility of the resulting decision making. To increase this credibility, existing guidance concerning criteria elements of transparency related to the risk assessment process must be more widely disseminated and applied, and raw data for studies used in human health and environmental risk assessment must be more widely available. Finally, the decision-making process in risk management must be better documented and a guidance framework established for both the process itself and its communication to the public.

Meta-analysis is an important method in the practice of occupational epidemiology, with a legitimate, but limited role to play in causal inference. Meta-analysis provides an assessment of consistency-one of several classic causal criteria-through tests of heterogeneity and an assessment of differences across studies. It can also provide an increase in the precision of effect estimates, including the precision of dose response relationships. Causal inference, however, involves much more: a complete assessment of the classic causal criteria, for example. Causal claims, therefore, should not emerge from meta-analyses as such. A recent meta-analysis of epidemiological studies of benzene exposure and non-Hodgkin lymphoma (NHL), however, does exactly that. Using studies from a previous narrative review in which the authors made no causal claim, the same authors performed a meta-analysis and concluded that it represented new evidence that benzene causes NHL. Despite a lack of consistency (i.e., significant heterogeneity), weak associations, no evidence of dose-response, no effort to provide an assessment of biological plausibility, and no new epidemiological evidence, the authors, nevertheless, changed their conclusion from association to causation. By using case study as an illustrative platform, this commentary provides cautionary and critical comments about the use of meta-analysis and causal inference in occupational epidemiology., (2010 Elsevier Inc. All rights reserved.)

This report provides a summary of deliberations conducted under the charge for members of Module B participating in the Naphthalene State-of-the-Science Symposium (NS(3)), Monterey, CA, October 9-12, 2006. The panel's charge was to derive consensus estimates of human exposure to naphthalene under various conditions, cancer incidence plausibly associated with these exposures, and identify quintessential research that could significantly reduce or eliminate material uncertainties to inform human cancer risk assessment. Relying in large part on a commissioned paper [Price, P.S., Jayjock, M.A., 2008. Available data on naphthalene exposures: strengths and limitations, in this issue], exposure levels were estimated for background (0.0001-0.003 microg/m(3)), ambient air (0.001-1.0 microg/m(3)), vehicles (0.003-3.0 microg/m(3)), residences (0.1-10 microg/m(3)), mothball use (on-label: 1-100 microg/m(3); off-label: 10-100 microg/m(3)), and occupational (low: 3-100 microg/m(3); high: 30-1,000 microg/m(3)). There have been few published reports of human cancer associated with naphthalene exposure. Several research projects are suggested that could reduce uncertainty in our understanding of human exposure. Using best scientific judgment, it is reasonably certain that the largest non-occupational exposures to naphthalene are indoor/residential exposures, particularly in households that use naphthalene-based products such as mothballs. However, even the highest of these exposures is likely to fall one or more orders of magnitude below moderate or high-level occupational exposure levels experienced by the few known cohorts exposed occupationally to naphthalene alone or as part of chemical mixtures such as jet fuel.

Purpose: The authors describe an evaluation approach to assess research training that is easy to implement, takes into account individual experience and diversity in research disciplines, and can be adapted to measure various outcomes, depending upon program goals., Method: Using publications as the outcome measure, the authors analyzed data from 66 trainees in the National Cancer Institute's Cancer Prevention Fellowship Program (CPFP) to illustrate this evaluation strategy. For postdoctoral fellows entering the CPFP between 1987 and 1997, the authors considered the three-year period prior to entry in the CPFP (pre-CPFP), the period during training, and the three-year period after completion of the CPFP (post-CPFP). Summary measures for individuals' publications during each of the three time periods were calculated, and the probability of change in total, peer-reviewed, and first-authored publications post-CPFP compared to pre-CPFP was assessed., Results: Compared to pre-CPFP, the CPFP fellows published significantly more total, peer-reviewed, and first-authored publications post-CPFP. Post-CPFP younger individuals published more than older fellows. MDs had a greater increase in publications over time than did PhDs, but both groups had similar overall numbers of publications post-CPFP. Individuals pursuing a master of public health degree during training published more post-CPFP than did those who did not pursue this training in the program., Conclusions: Training programs facing the challenge of evaluating research outcomes will require new evaluation methods that take into account program goals. This easily adaptable, longitudinal evaluation strategy allows for diversity in research disciplines and research experience and can inform programmatic needs and individual progress.

Background: The epidemiologic literature is replete with conceptual discussions about causal inference, but little is known about how the causal criteria are applied in public health practice. The criteria for causal inference in use today by epidemiologists have been shaped substantially by their use over time in reports of the U.S. Surgeon General on Smoking and Health., Methods: We reviewed two classic reports on smoking and health from expert committees convened by the US Surgeon General, in 1964 and 1982, in order to evaluate and contrast how the committees applied causal criteria to the available evidence for the different cancer sites at different time periods. We focus on the evidence for four cancer sites in particular that received detailed reviews in the reports: lung, larynx, esophagus and bladder., Results: We found that strength of association and coherence (especially dose-response, biological plausibility and epidemiologic sense) appeared to carry the most weight; consistency carried less weight, and temporality and specificity were apparently not applied at all in some cases. No causal claim was made for associations with a summary odds ratio of less than 3.0., Conclusion: Our findings suggest that the causal criteria as described in textbooks and the Surgeon General reports can have variable interpretations and applications in practice. While the authors of these reports may have considered evidential factors that they did not explicitly cite, such lack of transparency of methods undermines the purpose of the causal criteria to promote objective, evidence-based decision making. Further empirical study and critical examination of the process by which causal conclusions are reached can play an important role in advancing the practice of epidemiology by helping public health scientists to better understand the practice of causal inference.

"Weight of evidence" (WOE) is a common term in the published scientific and policy-making literature, most often seen in the context of risk assessment (RA). Its definition, however, is unclear. A systematic review of the scientific literature was undertaken to characterize the concept. For the years 1994 through 2004, PubMed was searched for publications in which "weight of evidence" appeared in the abstract and/or title. Of the 276 papers that met these criteria, 92 were selected for review: 71 papers published in 2003 and 2004 (WOE appeared in abstract/title) and 21 from 1994 through 2002 (WOE appeared in title). WOE has three characteristic uses in this literature: (1) metaphorical, where WOE refers to a collection of studies or to an unspecified methodological approach; (2) methodological, where WOE points to established interpretative methodologies (e.g., systematic narrative review, meta-analysis, causal criteria, and/or quality criteria for toxicological studies) or where WOE means that "all" rather than some subset of the evidence is examined, or rarely, where WOE points to methods using quantitative weights for evidence; and (3) theoretical, where WOE serves as a label for a conceptual framework. Several problems are identified: the frequent lack of definition of the term "weight of evidence," multiple uses of the term and a lack of consensus about its meaning, and the many different kinds of weights, both qualitative and quantitative, which can be used in RA. A practical recommendation emerges: the WOE concept and its associated methods should be fully described when used. A research agenda should examine the advantages of quantitative versus qualitative weighting schemes, how best to improve existing methods, and how best to combine those methods (e.g., epidemiology's causal criteria with toxicology's quality criteria).

Preparing junior scientists for careers in the health sciences has become an immense challenge for many reasons, including the emerging demand for multidisciplinary approaches to solving problems in the health sciences. For those choosing careers in hybrid and interdisciplinary fields, the "traditional" postdoctoral training model may not perform well, particularly in light of other problems that plague postdoctoral success. New approaches are required. Using the interdisciplinary field of cancer prevention as an example, the authors describe the Cancer Prevention Fellowship Program (CPFP) of the National Cancer Institute, a three-year postdoctoral program of which the goal is to provide its fellows with a strong foundation in cancer prevention through education, mentored research, and structured professional development training activities that emphasize multidisciplinary approaches and leadership skills. Over time, the CPFP has incorporated the best aspects of the traditional postdoctoral training model with newer training approaches in an effort to overcome existing problems in postdoctoral training and to address the additional complexities inherent in training those who seek careers in interdisciplinary science. Many aspects of the CPFP, including an efficient infrastructure, a dedicated staff, a capacity to provide educational activities, and the provision of rich research opportunities, may translate well to other postdoctoral programs that face similar issues.

The precautionary principle brings a special challenge to the practice of evidence-based public health decision-making, suggesting changes in the interpretative methods of public health used to identify causes of disease. In this paper, precautionary changes to these methods are examined: including discounting contrary evidence, reducing the number of causal criteria, weakening the rules of evidence assigned to the criteria, and altering thresholds for statistical significance. All such changes reflect the precautionary goal of earlier primary preventive intervention, i.e. acting on insufficient evidence, the least amount, or minimum level, of evidence for causation. Evaluating the impact of these changes will be difficult without a careful study of how well the current methods of causal inference work, their theoretical foundations, and the ethical implications of their applications. That research program will be most productive if it is jointly developed by public health professionals trained in the ethics and philosophy and by bioethicists and philosophers trained in the theories, methods, and practice of public health.

Applying the Precautionary Principle to public health requires a re-evaluation of the methods of inference currently used to make claims about disease causation from epidemiologic and other forms of scientific evidence. In current thinking, a well-established, near-certain causal relationship implies highly consistent statistically significant results across many different studies, large relative risk estimates, extensive understanding of biological mechanisms and dose-response relationships, positive prevention trial results, a clear temporal relationship between cause and effect, and other conditions spelled out in terms of the widely-used causal criteria. The Precautionary Principle, however, states that preventive measures are to be taken when cause and effect relationships are not fully established scientifically. What evidentiary conditions, as reflected in the causal criteria, will be certain enough to warrant precautionary preventive action? This paper argues that minimum evidentiary requirements for causation need to be articulated if the Precautionary Principle is to be successfully incorporated into public health practice. Two precautionary changes to criteria-based methods of causal inference are examined: reducing the number of criteria and weakening the rules of inference accompanying the criteria. Such changes point in the direction of identifying minimum evidentiary conditions, but would be premature without better understanding how well current methods of causal inference work.

Epidemiologists and environmental health researchers have a joint responsibility to acquire scientific knowledge that matters to public health and to apply the knowledge gained in public health practice. We examine the nature and source of these social responsibilities, discuss a debate in the epidemiological literature on roles and responsibilities, and cite approaches to environmental justice as reflective of them. At one level, responsibility refers to accountability, as in being responsible for actions taken. A deeper meaning of responsibility corresponds to commitment to the pursuit and achievement of a valued end. Epidemiologists are committed to the scientific study of health and disease in human populations and to the application of scientific knowledge to improve the public's health. Responsibility is also closely linked to reliability. Responsible professionals reliably perform the tasks they set for themselves as well as the tasks society expects them to undertake. The defining axiom for our approach is that the health of the public is a social good we commit ourselves to pursue, thus assuming an obligation to contribute to its achievement. Epidemiologists cannot claim to be committed to public health as a social good and not accept the responsibility of ensuring that the knowledge gained in their roles as scientists is used to achieve that good. The social responsibilities of environmental health researchers are conspicuous in the environmental justice movement, for example, in community-based participatory research. Responsibility is an ethical concept particularly well suited to frame many key aspects of the ethics of our profession.

Epidemiology is a core science of public health, focusing on research related to the distribution and determinants of both positive and adverse health states and events and on application of knowledge gained to improve public health. The American College of Epidemiology (ACE) is a professional organization devoted to the professional practice of epidemiology. As part of that commitment, and in response to concerns for more explicit attention to core values and duties of epidemiologists in light of emerging issues and increased scrutiny of epidemiology, the College developed, adopted, and published a set of Ethics Guidelines. The structure of the ACE ethics guidelines is in four parts: (1) a brief statement of core values and duties of epidemiologists, coupled with the virtues important to professional practice; (2) concise statements of key duties and obligations; (3) exposition of the duties and obligations with more applications; and (4) a brief summary and conclusion. The Guidelines have been published on the ACE website and in the official College journal Annals of Epidemiology. The guidelines contain (and maintain) core elements that define the discipline of epidemiology and its fundamental duties, but they are also intended to be dynamic and evolving, responsive to a changing professional and social environment.