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81-690: Devra Lee Davis (born June 7, 1946) is an American epidemiologist , toxicologist , and author of three books about environmental hazards. She was founding director of the Center for Environmental Oncology at the University of Pittsburgh Cancer Institute , and is a former professor of epidemiology at University of Pittsburgh Graduate School of Public Health . She has served on several governmental and non-governmental organizations, conducting research and advocacy into effects of pesticides, asbestos, and wireless radiation on human health, especially cancers. Davis

162-521: A conflict of interest due to funding from companies who make products suspected of causing harm. James Huff, associate director for chemical carcinogenesis of the National Institute of Environmental Health Sciences , called it "exhaustively researched and deftly written, illuminat[ing] more of the truth about chemicals and cancer and the relatively simple means of preventing or reducing cancer burdens." Epidemiologist Richard Clapp called

243-601: A "crusader in the fight over cell phone safety". She claims that radiation from mobile phones and WiFi pose health risks including increases in cancer, but her claims are disputed by other cancer researchers and organizations including the US National Cancer Institute and Cancer Council Australia . She claims much research that finds no effects is industry-funded and biased. She summarized her research into health effects of cell phones in her 2010 book, Disconnect: The Truth about Cell Phone Radiation, What

324-437: A causal association does not exist in general. Conversely, it can be (and is in some circumstances) taken by US courts, in an individual case, to justify an inference that a causal association does exist, based upon a balance of probability . The subdiscipline of forensic epidemiology is directed at the investigation of specific causation of disease or injury in individuals or groups of individuals in instances in which causation

405-580: A commissioner with the International Commission on Non-Ionizing Radiation Protection , who called the views of Davis "a fringe position that is not supported by science." Davis claims that radiation from 5G wireless technology poses health risks, and BBC Radio 4 has called Davis one of the most influential scientists in 5G-opposition movements. An excerpt of a lecture by Davis was used by new-age conspiracy promoter Sacha Stone in his 2020 film 5G Apocalypse: Extinction Event . In 2021,

486-498: A health system responds to current population health issues but also how a health system can be managed to better respond to future potential population health issues. Examples of organizations that use population-based health management that leverage the work and results of epidemiological practice include Canadian Strategy for Cancer Control, Health Canada Tobacco Control Programs, Rick Hansen Foundation, Canadian Tobacco Control Research Initiative. Each of these organizations uses

567-521: A lesser extent, basic research in the biological sciences. Major areas of epidemiological study include disease causation, transmission , outbreak investigation, disease surveillance , environmental epidemiology , forensic epidemiology , occupational epidemiology , screening , biomonitoring , and comparisons of treatment effects such as in clinical trials . Epidemiologists rely on other scientific disciplines like biology to better understand disease processes, statistics to make efficient use of

648-867: A member of the Board of Scientific Counselors of the US National Toxicology Program . Davis founded the International Breast Cancer Prevention Collaborative Research Group, an organization dedicated to exploring the causes of breast cancer. As senior adviser to the US Assistant Secretary for Health, Davis claimed that extra doses of estrogen -like compounds in the environment may increase the quantities of hormone some women receive to dangerous levels and can cause serious illness. Davis served five years as

729-491: A nonprofit with the goal of promoting awareness of environmental issues it believes are linked to cancer. The EHT campaigns for safer cell phone use, and has challenged research that finds no links between cellular phones and cancer, advocated for more research into the effects of wireless radiation on children, and called on the US federal government to reassess its safety guidelines for wireless technology . Davis has been called

810-787: A population (endemic). The term "epidemiology" appears to have first been used to describe the study of epidemics in 1802 by the Spanish physician Joaquín de Villalba  [ es ] in Epidemiología Española . Epidemiologists also study the interaction of diseases in a population, a condition known as a syndemic . The term epidemiology is now widely applied to cover the description and causation of not only epidemic, infectious disease, but of disease in general, including related conditions. Some examples of topics examined through epidemiology include as high blood pressure, mental illness and obesity . Therefore, this epidemiology

891-520: A population-based health management framework called Life at Risk that combines epidemiological quantitative analysis with demographics, health agency operational research and economics to perform: Applied epidemiology is the practice of using epidemiological methods to protect or improve the health of a population. Applied field epidemiology can include investigating communicable and non-communicable disease outbreaks, mortality and morbidity rates, and nutritional status, among other indicators of health, with

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972-422: A prospective study, and confounders are more easily controlled for. However, they are more costly, and there is a greater chance of losing subjects to follow-up based on the long time period over which the cohort is followed. Cohort studies also are limited by the same equation for number of cases as for cohort studies, but, if the base incidence rate in the study population is very low, the number of cases required

1053-402: A random sample from the original population at risk. This has as a consequence that the control group can contain people with the disease under study when the disease has a high attack rate in a population. A major drawback for case control studies is that, in order to be considered to be statistically significant, the minimum number of cases required at the 95% confidence interval is related to

1134-648: A reasoned explanation for its determination that its guidelines adequately protect against the harmful effects of exposure to radiofrequency radiation unrelated to cancer." In 1975 Davis married Richard D. Morgenstern, an economist with Resources for the Future and former Environmental Protection Agency official. They have two children. Her father died from multiple myeloma in 1984, and her mother from stomach cancer in 2003. Davis told The New York Times Magazine that, although she decided to devote herself to cancer research shortly after her father's death, his illness

1215-445: A unique disease process different from any other individual ("the unique disease principle"), considering uniqueness of the exposome (a totality of endogenous and exogenous / environmental exposures) and its unique influence on molecular pathologic process in each individual. Studies to examine the relationship between an exposure and molecular pathologic signature of disease (particularly cancer ) became increasingly common throughout

1296-399: A university student, which inspired her interest in epidemiology . She completed a PhD in science studies at the University of Chicago as a Danforth Foundation graduate fellow in 1972, and in 1982 earned a Master of Public Health degree in epidemiology at Johns Hopkins University as a National Cancer Institute senior post-doctoral fellow . In the late 1970s, as a policy advisor for

1377-399: Is a core component, that is unified with management science to provide efficient and effective health care and health guidance to a population. This task requires the forward-looking ability of modern risk management approaches that transform health risk factors, incidence, prevalence and mortality statistics (derived from epidemiological analysis) into management metrics that not only guide how

1458-428: Is based upon how the pattern of the disease causes change in the function of human beings. The Greek physician Hippocrates , taught by Democritus, was known as the father of medicine , sought a logic to sickness; he is the first person known to have examined the relationships between the occurrence of disease and environmental influences. Hippocrates believed sickness of the human body to be caused by an imbalance of

1539-479: Is beyond the domain of the science of epidemiology. Epidemiology has its limits at the point where an inference is made that the relationship between an agent and a disease is causal (general causation) and where the magnitude of excess risk attributed to the agent has been determined; that is, epidemiology addresses whether an agent can cause disease, not whether an agent did cause a specific plaintiff's disease. In United States law, epidemiology alone cannot prove that

1620-483: Is disputed or is unclear, for presentation in legal settings. Epidemiological practice and the results of epidemiological analysis make a significant contribution to emerging population-based health management frameworks. Population-based health management encompasses the ability to: Modern population-based health management is complex, requiring a multiple set of skills (medical, political, technological, mathematical, etc.) of which epidemiological practice and analysis

1701-537: Is famous for his investigations into the causes of the 19th-century cholera epidemics, and is also known as the father of (modern) Epidemiology. He began with noticing the significantly higher death rates in two areas supplied by Southwark Company. His identification of the Broad Street pump as the cause of the Soho epidemic is considered the classic example of epidemiology. Snow used chlorine in an attempt to clean

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1782-499: Is in the term inference . Correlation, or at least association between two variables, is a necessary but not sufficient criterion for the inference that one variable causes the other. Epidemiologists use gathered data and a broad range of biomedical and psychosocial theories in an iterative way to generate or expand theory, to test hypotheses, and to make educated, informed assertions about which relationships are causal, and about exactly how they are causal. Epidemiologists emphasize that

1863-418: Is increasing recognition that a wide range of modern data sources, many not originating from healthcare or epidemiology, can be used for epidemiological study. Such digital epidemiology can include data from internet searching, mobile phone records and retail sales of drugs. Epidemiologists employ a range of study designs from the observational to experimental and generally categorized as descriptive (involving

1944-404: Is reduced by  1 ⁄ 2 . Although epidemiology is sometimes viewed as a collection of statistical tools used to elucidate the associations of exposures to health outcomes, a deeper understanding of this science is that of discovering causal relationships. " Correlation does not imply causation " is a common theme for much of the epidemiological literature. For epidemiologists, the key

2025-584: Is the chief executive officer of the board, and exercises the executive and administrative functions of the board. The current board members as of September 24, 2024: The USCSB has investigated many of the most devastating industrial chemical accidents in the U.S. since its inception in 1998. It is known for its highly detailed and technically oriented post mortem analyses of individual incidents, as well as its transparent public relations practices. The latter include at length reconstructions of an incident, alongside root cause analysis and subsequent recommendations

2106-525: Is the founder and president of the Environmental Health Trust, a non-profit organization which argues that mobile devices, WiFi, 5G, and other radio-frequency systems pose a health risk to humans and the environment . She has been called a "crusader in the fight over cell phone safety" and believes that radio frequencies could cause cancer. Such claims have been challenged by critics as being bereft of credible arguments. Devra Lee Davis

2187-521: Is typically determined using DNA from peripheral blood leukocytes. Since the 2000s, genome-wide association studies (GWAS) have been commonly performed to identify genetic risk factors for many diseases and health conditions. While most molecular epidemiology studies are still using conventional disease diagnosis and classification systems, it is increasingly recognized that disease progression represents inherently heterogeneous processes differing from person to person. Conceptually, each individual has

2268-439: Is used to describe the intersection of Host , Agent , and Environment in analyzing an outbreak. Case-series may refer to the qualitative study of the experience of a single patient, or small group of patients with a similar diagnosis, or to a statistical factor with the potential to produce illness with periods when they are unexposed. The former type of study is purely descriptive and cannot be used to make inferences about

2349-788: The Environmental Law Institute , Davis began publishing articles examining links between environmental chemicals and cancer. Davis was appointed resident scholar at the National Research Council of the National Academy of Sciences in 1989. In 1990, she led a study published in The Lancet along with National Institute for Environmental Health Sciences director David Hoel, British census director John Fox , and World Health Organization statistician Alan Lopez , examining cancer rates in

2430-476: The " one cause – one effect " understanding is a simplistic mis-belief. Most outcomes, whether disease or death, are caused by a chain or web consisting of many component causes. Causes can be distinguished as necessary, sufficient or probabilistic conditions. If a necessary condition can be identified and controlled (e.g., antibodies to a disease agent, energy in an injury), the harmful outcome can be avoided (Robertson, 2015). One tool regularly used to conceptualize

2511-459: The "who, what, where and when of health-related state occurrence". However, analytical observations deal more with the 'how' of a health-related event. Experimental epidemiology contains three case types: randomized controlled trials (often used for a new medicine or drug testing), field trials (conducted on those at a high risk of contracting a disease), and community trials (research on social originating diseases). The term 'epidemiologic triad'

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2592-515: The 2000s. However, the use of molecular pathology in epidemiology posed unique challenges, including lack of research guidelines and standardized statistical methodologies, and paucity of interdisciplinary experts and training programs. Furthermore, the concept of disease heterogeneity appears to conflict with the long-standing premise in epidemiology that individuals with the same disease name have similar etiologies and disease processes. To resolve these issues and advance population health science in

2673-504: The 2010s. By 2012, it was recognized that many pathogens' evolution is rapid enough to be highly relevant to epidemiology, and that therefore much could be gained from an interdisciplinary approach to infectious disease integrating epidemiology and molecular evolution to "inform control strategies, or even patient treatment." Modern epidemiological studies can use advanced statistics and machine learning to create predictive models as well as to define treatment effects. There

2754-679: The Battle Against Pollution , describes how environmental toxins are linked to cancers and other health problems. She provides accounts of the 1948 Donora smog in her hometown, the 1952 Great Smog of London , and other events. She also criticizes industry interests who dismiss evidence they dislike as "junk science." The book was a finalist for that year's National Book Award for Nonfiction . Public health philosopher Kristin Shrader-Frechette praised it as "the best book on public health and environmental pollution of

2835-596: The CSB's investigative function be completely independent of the rulemaking, inspection, and enforcement authorities of the Environmental Protection Agency and Occupational Safety and Health Administration . Congress recognized that board investigations would identify chemical hazards that were not addressed by those agencies. Also similarly to the NTSB, the CSB performs "investigations [that] identify

2916-661: The EHT and other groups filed a lawsuit asserting the Federal Communications Commission (FCC) failed to consider new scientific evidence when deciding in 2019 not to update its safety guidelines for cellular phone and cellular tower radiation, which had not been updated since 1996. The U.S. Court of Appeals for the District of Columbia ruled in favor of the EHT and plaintiffs, finding the FCC "failed to provide

2997-570: The Industry Has Done to Hide It, and How to Protect Your Family . She has cited the World Health Organization 's 2011 classification of wireless radiation as a Class 2B agent ("Possibly Carcinogenic to Humans") . Critics of Davis have accused her of " cherry-picking " evidence and misrepresenting the studies upon which her conclusions were drawn, while the EHT has been accused of promoting low quality sources. Davis

3078-560: The OR, a RR greater than 1 shows association, where the conclusion can be read "those with the exposure were more likely to develop the disease." Prospective studies have many benefits over case control studies. The RR is a more powerful effect measure than the OR, as the OR is just an estimation of the RR, since true incidence cannot be calculated in a case control study where subjects are selected based on disease status. Temporality can be established in

3159-522: The Trump administration proposed shutting down the CSB as part of the 2019 United States federal budget which ultimately would not occur. The board consists of five members who are appointed by the president with the advice and consent of the Senate. The terms of office are five years. The president designates one of the members as chairperson, again with the advice and consent of the Senate. The chairperson

3240-500: The United States, Japan, and several European countries, concluding "all forms of cancer are increasing in persons over age 54 except lung and stomach" and "the changes in cancer other than lung are so great and rapid that their causes demand intensive investigation." The paper reignited debate between prominent epidemiologists over how to interpret cancer trends: Bruce Ames , Richard Doll , and Richard Peto , among others argued

3321-407: The assessment of data covering time, place, and person), analytic (aiming to further examine known associations or hypothesized relationships), and experimental (a term often equated with clinical or community trials of treatments and other interventions). In observational studies, nature is allowed to "take its course", as epidemiologists observe from the sidelines. Conversely, in experimental studies,

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3402-477: The board has made; unusually for a governmental agency, they are often attended by a video form safety report, with careful narration and high quality computer graphics. Their videos are narrated by Sheldon Smith. The agency publishes its videos on a public YouTube channel, which as of August 2024 has over 341,000 subscribers. The CSB's videos have been lauded for their quality, with experts encouraging their use in teaching process safety fundamentals. In

3483-476: The book "a welcome addition to the struggle to correct the imbalance" between curative and preventative research, while science writer Fred Pearce wrote it "is a rattling good read and raises vital issues that remain relevant today." In a positive review, science journalist Dan Fagin called Davis "her generation's strongest advocate of the idea that synthetic chemicals are a seriously under-recognized cause of cancer." Medical historian Peter Keating, however, found

3564-424: The book "largely unoriginal" and poorly organized. Epidemiologist Peter Boyle wrote that "devotees of conspiracy theories and aficionados of gossip and innuendo will be drawn towards this book like wasps to a juicy piece of meat" and discussed how the book suggested that the link between tobacco and cancer was used to distract from other possible sources. In 2007 Davis founded the Environmental Health Trust (EHT),

3645-414: The case control study. However, the point estimate generated is the relative risk (RR), which is the probability of disease for a person in the exposed group, P e  =  A  / ( A  +  B ) over the probability of disease for a person in the unexposed group, P u  =  C  / ( C  +  D ), i.e. RR  =  P e  /  P u . As with

3726-429: The causation of the disease. Case-control studies are usually faster and more cost-effective than cohort studies but are sensitive to bias (such as recall bias and selection bias ). The main challenge is to identify the appropriate control group; the distribution of exposure among the control group should be representative of the distribution in the population that gave rise to the cases. This can be achieved by drawing

3807-427: The cause-and-effect hypothesis and none can be required sine qua non ." Epidemiological studies can only go to prove that an agent could have caused, but not that it did cause, an effect in any particular case: Epidemiology is concerned with the incidence of disease in populations and does not address the question of the cause of an individual's disease. This question, sometimes referred to as specific causation,

3888-587: The conditions and circumstances which led up to the event and to identify the cause or causes so that similar events might be prevented." Congress gave the CSB a unique statutory mission and provided in law that no other agency or executive branch official may direct the activities of the board. Following the successful model of the National Transportation Safety Board and the Department of Transportation , Congress directed that

3969-445: The data and draw appropriate conclusions, social sciences to better understand proximate and distal causes, and engineering for exposure assessment . Epidemiology , literally meaning "the study of what is upon the people", is derived from Greek epi  'upon, among' demos  'people, district' and logos  'study, word, discourse', suggesting that it applies only to human populations. However,

4050-497: The disease to the cases in the series. A prospective study would involve following the case series over time to evaluate the disease's natural history. The latter type, more formally described as self-controlled case-series studies, divide individual patient follow-up time into exposed and unexposed periods and use fixed-effects Poisson regression processes to compare the incidence rate of a given outcome between exposed and unexposed periods. This technique has been extensively used in

4131-612: The epidemiologist is the one in control of all of the factors entering a certain case study. Epidemiological studies are aimed, where possible, at revealing unbiased relationships between exposures such as alcohol or smoking, biological agents , stress , or chemicals to mortality or morbidity . The identification of causal relationships between these exposures and outcomes is an important aspect of epidemiology. Modern epidemiologists use informatics and infodemiology as tools. Observational studies have two components, descriptive and analytical. Descriptive observations pertain to

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4212-771: The era of molecular precision medicine , "molecular pathology" and "epidemiology" was integrated to create a new interdisciplinary field of " molecular pathological epidemiology " (MPE), defined as "epidemiology of molecular pathology and heterogeneity of disease". In MPE, investigators analyze the relationships between (A) environmental, dietary, lifestyle and genetic factors; (B) alterations in cellular or extracellular molecules; and (C) evolution and progression of disease. A better understanding of heterogeneity of disease pathogenesis will further contribute to elucidate etiologies of disease. The MPE approach can be applied to not only neoplastic diseases but also non-neoplastic diseases. The concept and paradigm of MPE have become widespread in

4293-571: The field and advanced methods to study cancer, a disease with patterns and mode of occurrences that could not be suitably studied with the methods developed for epidemics of infectious diseases. Geography pathology eventually combined with infectious disease epidemiology to make the field that is epidemiology today. Another breakthrough was the 1954 publication of the results of a British Doctors Study , led by Richard Doll and Austin Bradford Hill , which lent very strong statistical support to

4374-481: The founding director of the Center for Environmental Oncology at the University of Pittsburgh Cancer Institute (UPCI). In 2009, she stepped down to become professor in the Department of Epidemiology at the University of Pittsburgh Graduate School of Public Health . She has authored over 200 scientific papers as well as three books. Davis' 2002 book, When Smoke Ran Like Water: Tales of Environmental Deception and

4455-405: The four humors (black bile, yellow bile, blood, and phlegm). The cure to the sickness was to remove or add the humor in question to balance the body. This belief led to the application of bloodletting and dieting in medicine. He coined the terms endemic (for diseases usually found in some places but not in others) and epidemic (for diseases that are seen at some times but not others). In

4536-458: The general population of patients with that disease. These types of studies, in which an astute clinician identifies an unusual feature of a disease or a patient's history, may lead to a formulation of a new hypothesis. Using the data from the series, analytic studies could be done to investigate possible causal factors. These can include case-control studies or prospective studies. A case-control study would involve matching comparable controls without

4617-576: The last 30 years." Science writer Fred Pearce in New Scientist called Davis a "a hero with a nose for trouble" and drew comparisons to Rachel Carson , the author of Silent Spring . Other writers have compared and Davis and Carson, both in their styles and themes of writing and their small town Pennsylvania upbringings. Epidemiologist Bert Brunekreef wrote the book is "at its best when describing how commercial interests have harassed well known environmental health scientists in attempts to downplay

4698-575: The link between tobacco smoking and lung cancer . In the late 20th century, with the advancement of biomedical sciences, a number of molecular markers in blood, other biospecimens and environment were identified as predictors of development or risk of a certain disease. Epidemiology research to examine the relationship between these biomarkers analyzed at the molecular level and disease was broadly named " molecular epidemiology ". Specifically, " genetic epidemiology " has been used for epidemiology of germline genetic variation and disease. Genetic variation

4779-403: The main etiological work that brought forward the concept. His concepts were still being considered in analysing SARS outbreak by WHO in 2004 in the context of traditional Chinese medicine. Another pioneer, Thomas Sydenham (1624–1689), was the first to distinguish the fevers of Londoners in the later 1600s. His theories on cures of fevers met with much resistance from traditional physicians at

4860-448: The middle of the 16th century, a doctor from Verona named Girolamo Fracastoro was the first to propose a theory that the very small, unseeable, particles that cause disease were alive. They were considered to be able to spread by air, multiply by themselves and to be destroyable by fire. In this way he refuted Galen 's miasma theory (poison gas in sick people). In 1543 he wrote a book De contagione et contagiosis morbis , in which he

4941-506: The multicausality associated with disease is the causal pie model . In 1965, Austin Bradford Hill proposed a series of considerations to help assess evidence of causation, which have come to be commonly known as the " Bradford Hill criteria ". In contrast to the explicit intentions of their author, Hill's considerations are now sometimes taught as a checklist to be implemented for assessing causality. Hill himself said "None of my nine viewpoints can bring indisputable evidence for or against

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5022-417: The odds of exposure in the cases (A/C) to the odds of exposure in the controls (B/D), i.e. OR = (AD/BC). If the OR is significantly greater than 1, then the conclusion is "those with the disease are more likely to have been exposed", whereas if it is close to 1 then the exposure and disease are not likely associated. If the OR is far less than one, then this suggests that the exposure is a protective factor in

5103-498: The odds ratio by the equation: where N is the ratio of cases to controls. As the odds ratio approaches 1, the number of cases required for statistical significance grows towards infinity; rendering case-control studies all but useless for low odds ratios. For instance, for an odds ratio of 1.5 and cases = controls, the table shown above would look like this: For an odds ratio of 1.1: Cohort studies select subjects based on their exposure status. The study subjects should be at risk of

5184-414: The outcome under investigation at the beginning of the cohort study; this usually means that they should be disease free when the cohort study starts. The cohort is followed through time to assess their later outcome status. An example of a cohort study would be the investigation of a cohort of smokers and non-smokers over time to estimate the incidence of lung cancer. The same 2×2 table is constructed as with

5265-400: The prevailing Miasma Theory of the time, a model of disease in which poor air quality was blamed for illness. This was used to rationalize high rates of infection in impoverished areas instead of addressing the underlying issues of poor nutrition and sanitation, and was proven false by his work. Other pioneers include Danish physician Peter Anton Schleisner , who in 1849 related his work on

5346-640: The prevention of the epidemic of neonatal tetanus on the Vestmanna Islands in Iceland . Another important pioneer was Hungarian physician Ignaz Semmelweis , who in 1847 brought down infant mortality at a Vienna hospital by instituting a disinfection procedure. His findings were published in 1850, but his work was ill-received by his colleagues, who discontinued the procedure. Disinfection did not become widely practiced until British surgeon Joseph Lister 'discovered' antiseptics in 1865 in light of

5427-569: The purpose of communicating the results to those who can implement appropriate policies or disease control measures. US Chemical Safety and Hazard Investigation Board The U.S. Chemical Safety Board is authorized by the Clean Air Act Amendments of 1990 and became operational in January 1998. The Senate legislative history states: "The principal role of the new chemical safety board is to investigate accidents to determine

5508-507: The root causes of chemical incidents and share these findings broadly across industries to prevent future incidents." Following criticism from lawmakers and allegations of mismanagement, the former chairman of the CSB, Rafael Moure-Eraso , resigned in March 2015. He was replaced by Vanessa Allen Sutherland in August 2015. Sutherland resigned with two years left in her five-year term after

5589-402: The same population that gave rise to the cases. The case-control study looks back through time at potential exposures that both groups (cases and controls) may have encountered. A 2×2 table is constructed, displaying exposed cases (A), exposed controls (B), unexposed cases (C) and unexposed controls (D). The statistic generated to measure association is the odds ratio (OR), which is the ratio of

5670-533: The seriousness of, say, the effects of environmental lead on the IQ of children," but found "an alarming number of errors" regarding air pollution. Davis' second book, The Secret History of the War on Cancer , was published in 2007. In it, she argues that medical institutions involved in the " war on cancer " have focused more on cures than on prevention , and that some safety research into environmental toxicity suffers from

5751-456: The study of adverse reactions to vaccination and has been shown in some circumstances to provide statistical power comparable to that available in cohort studies. Case-control studies select subjects based on their disease status. It is a retrospective study. A group of individuals that are disease positive (the "case" group) is compared with a group of disease negative individuals (the "control" group). The control group should ideally come from

5832-439: The term is widely used in studies of zoological populations (veterinary epidemiology), although the term " epizoology " is available, and it has also been applied to studies of plant populations (botanical or plant disease epidemiology ). The distinction between "epidemic" and "endemic" was first drawn by Hippocrates , to distinguish between diseases that are "visited upon" a population (epidemic) from those that "reside within"

5913-716: The time. He was not able to find the initial cause of the smallpox fever he researched and treated. John Graunt , a haberdasher and amateur statistician, published Natural and Political Observations ... upon the Bills of Mortality in 1662. In it, he analysed the mortality rolls in London before the Great Plague , presented one of the first life tables , and reported time trends for many diseases, new and old. He provided statistical evidence for many theories on disease, and also refuted some widespread ideas on them. John Snow

5994-489: The trends were unimportant: more attributed to better diagnoses and increasing human longevity, while Davis' views gained support from Philip J. Landrigan and biostatisticians such as John C. Bailar and Thomas C. Chalmers . Davis was appointed by President Clinton to the US Chemical Safety and Hazard Investigation Board . In 1997 she was working as a consultant to the World Health Organization and served as

6075-413: The water and removed the handle; this ended the outbreak. This has been perceived as a major event in the history of public health and regarded as the founding event of the science of epidemiology, having helped shape public health policies around the world. However, Snow's research and preventive measures to avoid further outbreaks were not fully accepted or put into practice until after his death due to

6156-637: The work of Louis Pasteur . In the early 20th century, mathematical methods were introduced into epidemiology by Ronald Ross , Janet Lane-Claypon , Anderson Gray McKendrick , and others. In a parallel development during the 1920s, German-Swiss pathologist Max Askanazy and others founded the International Society for Geographical Pathology to systematically investigate the geographical pathology of cancer and other non-infectious diseases across populations in different regions. After World War II, Richard Doll and other non-pathologists joined

6237-459: Was a homemaker. Raised in a Jewish family, as a child she briefly considered becoming a rabbi . At age 14, her family moved to Pittsburgh , where she attended Taylor Allderdice High School . Davis then attended the University of Pittsburgh , where in 1967 she earned a Bachelor of Science degree in physiological psychology and an MA in sociology . She learned of the Donora smog incident as

6318-545: Was born June 7, 1946, in Washington, D.C., to Harry and Jean Langer Davis, and raised in the steel making town of Donora, Pennsylvania , where in 1948 a severe smog event killed 20 people and sickened thousands. Davis was the oldest of four children; her father was a chemist and machinist in the local steel mills , as well as a brigadier general in the Pennsylvania National Guard and her mother

6399-605: Was featured prominently in a controversial 2016 episode of the Australian TV program Catalyst , in which she claimed "every single well-designed study ever conducted finds an increased risk of brain cancer with the heaviest users [of mobile phones]". The episode drew heavy criticism from researchers, and Davis' claims were refuted by public health scholar Simon Chapman , who claims there is no evidence of increase brain cancer rates in Australians, as well as Rodney Croft,

6480-729: Was not the reason for that decision. Epidemiology Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population . It is a cornerstone of public health , and shapes policy decisions and evidence-based practice by identifying risk factors for disease and targets for preventive healthcare . Epidemiologists help with study design, collection, and statistical analysis of data, amend interpretation and dissemination of results (including peer review and occasional systematic review ). Epidemiology has helped develop methodology used in clinical research , public health studies, and, to

6561-668: Was the first to promote personal and environmental hygiene to prevent disease. The development of a sufficiently powerful microscope by Antonie van Leeuwenhoek in 1675 provided visual evidence of living particles consistent with a germ theory of disease . During the Ming dynasty , Wu Youke (1582–1652) developed the idea that some diseases were caused by transmissible agents, which he called Li Qi (戾气 or pestilential factors) when he observed various epidemics rage around him between 1641 and 1644. His book Wen Yi Lun (瘟疫论, Treatise on Pestilence/Treatise of Epidemic Diseases) can be regarded as

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