Environmental epidemiology

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Environmental epidemiology is a branch of epidemiology concerned with determining how environmental exposures impact human health. [1] This field seeks to understand how various external risk factors may predispose to or protect against disease, illness, injury, developmental abnormalities, or death. These factors may be naturally occurring or may be introduced into environments where people live, work, and play.

Contents

Scope

The World Health Organization European Centre for Environment and Health (WHO-ECEH) claims that 1.4 million deaths per year in Europe alone are due to avoidable environmental exposures. [2] Environmental exposures can be broadly categorized into those that are proximate (e.g., directly leading to a health condition), including chemicals, physical agents, and microbiological pathogens, and those that are distal (e.g., indirectly leading to a health condition), such as socioeconomic conditions, climate change, and other broad-scale environmental changes. Proximate exposures occur through air, food, water, and skin contact. Distal exposures cause adverse health conditions directly by altering proximate exposures, and indirectly through changes in ecosystems and other support systems for human health. [3]

Environmental epidemiology research can inform government policy change, risk management activities, and development of environmental standards. Vulnerability is the summation of all risk and protective factors that ultimately determine whether an individual or subpopulation experiences adverse health outcomes when an exposure to an environmental agent occurs. Sensitivity is an individual's or subpopulation's increased responsiveness, primarily for biological reasons, to that exposure. [4] Biological sensitivity may be related to developmental stage, [5] pre-existing medical conditions, acquired factors, and genetic factors. Socioeconomic factors also play a critical role in altering vulnerability and sensitivity to environmentally mediated factors by increasing the likelihood of exposure to harmful agents, interacting with biological factors that mediate risk, and/or leading to differences in the ability to prepare for or cope with exposures or early phases of illness. Populations living in certain regions may be at increased risk due to location and the environmental characteristics of a region. [6]

History

Acknowledgement that the environment impacts human health can be found as far back as 460 B.C. in Hippocrates' essay On Airs, Waters, and Places. [7] In it, he urges physicians to contemplate how factors such as drinking water can impact the health of their patients. Another famous example of environment-health interaction is the lead poisoning experienced by the ancient Romans, who used lead in their water pipes and kitchen pottery. [8] Vitruvius, a Roman architect, wrote to discourage the use of lead pipes, citing health concerns:

"Water conducted through earthen pipes is more wholesome than that through lead; indeed that conveyed in lead must be injurious, because from it white lead is obtained, and this is said to be injurious to the human system. Hence, if what is generated from it is pernicious, there can be no doubt that itself cannot be a wholesome body. This may be verified by observing the workers in lead, who are of a pallid colour; for in casting lead, the fumes from it fixing on the different members, and daily burning them, destroy the vigour of the blood; water should therefore on no account be conducted in leaden pipes if we are desirous that it should be wholesome. That the flavour of that conveyed in earthen pipes is better, is shewn at our daily meals, for all those whose tables are furnished with silver vessels, nevertheless use those made of earth, from the purity of the flavour being preserved in them" [9]

Generally considered to be one of the founders of modern epidemiology, John Snow conducted perhaps the first environmental epidemiology study in 1854. He showed that London residents who drank sewage-contaminated water were more likely to develop cholera than those who drank clean water. [10]

U.S. government regulation

Throughout the 20th century, the United States Government passed legislation and regulations to address environmental health concerns. A partial list is below.

Table of Selected U.S. Laws Relating to Environmental Health
LawYearBrief Description
Federal Food, Drug, and Cosmetic Act 1938Created the U.S. Food and Drug Administration (FDA)
Federal Insecticide, Fungicide, and Rodenticide Act 1947 Pesticide users and manufacturers must register with the EPA; pesticides must not cause unreasonable harm
Federal Water Pollution Control Act 1948 1977Also known as the Clean Water Act, set water quality standards
Clean Air Act 1955,

1977

Created National Ambient Air Quality Standards (NAAQS) for environmental and public health protection
Solid Waste Disposal Act 1965Specified standards for municipal and industrial waste disposal
Occupational Safety and Health Act 1970Created worker protections standards and established the National Institute for Occupational Safety and Health (NIOSH)
Toxic Substances Control Act 1976Allowed the EPA to regulate chemicals, including the ability to ban substances that are shown to harm humans
Comprehensive Environmental Response, Compensation, and Liability Act 1980 1986Also known as Superfund, it taxes chemical and petroleum industries to fund clean-up of hazardous waste sites
Indoor Radon Abatement Act1988Funded radon clean-up and research programs
Food Quality Protection Act 1996Amended the Federal Insecticide, Fungicide, and Rodenticide Act to include a requirement that pesticides have reasonable certainty that they do not cause human harm

Precautionary principle

The precautionary principle is a concept in the environmental sciences that if an activity is suspected to cause harm, we should not wait until sufficient evidence of that harm is collected to take action. [11] It has its roots in German environmental policy, and was adopted in 1990 by the participants of the North-Sea Conferences in The Hague by declaration. [12] In 2000, the European Union began to formally adopt the precautionary principle into its laws as a Communication from the European Commission. [13] The United States has resisted adoption of this principle, citing concerns that unfounded science could lead to obligations for expensive control measures, especially as related to greenhouse gas emissions. [12]

Investigations

Observational studies

Environmental epidemiology studies are most frequently observational in nature, [14] meaning researchers look at people's exposures to environmental factors without intervening and then observe the patterns that emerge. This is due to the fact that it is often unethical or unfeasible to conduct an experimental study of environmental factors in humans. [15] For example, a researcher cannot ask some of their study subjects to smoke cigarettes to see if they have poorer health outcomes than subjects who are asked not to smoke. The study types most often employed in environmental epidemiology are: [14]

Estimating risk

Epidemiologic studies that assess how an environmental exposure and a health outcome may be connected use a variety of biostatistical approaches to attempt to quantify the relationship. Risk assessment tries to answer questions such as "How does an individual's risk for disease A change when they are exposed to substance B?," and "How many excess cases of disease A can we prevent if exposure to substance B is lowered by X amount?." [16]

Some statistics and approaches used to estimate risk are: [14]

Ethics

Environmental epidemiology studies often identify associations between pollutants in the air, water, or food and adverse health outcomes; these findings can be inconvenient for polluting industries. Environmental epidemiologists are confronted with significant ethical challenges because of the involvement of powerful stakeholders who may try to influence the results or interpretation of their studies. Epidemiologic findings can sometimes have direct effects on industry profits. Because of these concerns, environmental epidemiology maintains guidelines for ethical practice. The International Society for Environmental Epidemiology (ISEE) first adopted ethics guidelines in the late 1990s. The guidelines are maintained by its Ethics and Philosophy Committee, one of the earliest, active, and enduring ethics committees in the field of epidemiology. Since its inception in 1991, the Committee has taken an active role in supporting ethical conduct and promulgating Ethics Guidelines for Environmental Epidemiologists.  The most recent Ethics Guidelines were adopted in 2023. [17]

Bradford Hill factors

To differentiate between correlation and causation, epidemiologists often consider a set of factors to determine the likelihood that an observed relationship between an environmental exposure and health consequence is truly causal. [16] In 1965, Austin Bradford Hill devised a set of postulates to help him determine if there was sufficient evidence to conclude that cigarette smoking causes lung cancer. [18]

The Bradford Hill criteria are:

  1. Strength of association
  2. Consistency of evidence
  3. Specificity
  4. Temporality
  5. Biological gradient
  6. Plausibility
  7. Coherence
  8. Experiment
  9. Analogy

These factors are generally considered to be a guide to scientists, and it is not necessary that all of the factors be met for a consensus to be reached. [16]

See also

Related Research Articles

The precautionary principle is a broad epistemological, philosophical and legal approach to innovations with potential for causing harm when extensive scientific knowledge on the matter is lacking. It emphasizes caution, pausing and review before leaping into new innovations that may prove disastrous. Critics argue that it is vague, self-cancelling, unscientific and an obstacle to progress.

<span class="mw-page-title-main">Epidemiology</span> Study of health and disease within a population

Epidemiology is the study and analysis of the distribution, patterns and determinants of health and disease conditions in a defined population.

The science of epidemiology has matured significantly from the times of Hippocrates, Semmelweis and John Snow. The techniques for gathering and analyzing epidemiological data vary depending on the type of disease being monitored but each study will have overarching similarities.

<span class="mw-page-title-main">Environmental health</span> Public health branch focused on environmental impacts on human health

Environmental health is the branch of public health concerned with all aspects of the natural and built environment affecting human health. In order to effectively control factors that may affect health, the requirements that must be met in order to create a healthy environment must be determined. The major sub-disciplines of environmental health are environmental science, toxicology, environmental epidemiology, and environmental and occupational medicine.

An environmental factor, ecological factor or eco factor is any factor, abiotic or biotic, that influences living organisms. Abiotic factors include ambient temperature, amount of sunlight, air, soil, water and pH of the water soil in which an organism lives. Biotic factors would include the availability of food organisms and the presence of biological specificity, competitors, predators, and parasites.

Environmental medicine is a multidisciplinary field involving medicine, environmental science, chemistry and others, overlapping with environmental pathology. It can be viewed as the medical branch of the broader field of environmental health. The scope of this field involves studying the interactions between environment and human health, and the role of the environment in causing or mediating disease. This specialist field of study developed after the realisation that health is more widely and dramatically affected by environmental factors than previously recognized.

Indicator bacteria are types of bacteria used to detect and estimate the level of fecal contamination of water. They are not dangerous to human health but are used to indicate the presence of a health risk.

<span class="mw-page-title-main">Disease burden</span> Impact of diseases

Disease burden is the impact of a health problem as measured by financial cost, mortality, morbidity, or other indicators. It is often quantified in terms of quality-adjusted life years (QALYs) or disability-adjusted life years (DALYs). Both of these metrics quantify the number of years lost due to disability (YLDs), sometimes also known as years lost due to disease or years lived with disability/disease. One DALY can be thought of as one year of healthy life lost, and the overall disease burden can be thought of as a measure of the gap between current health status and the ideal health status. According to an article published in The Lancet in June 2015, low back pain and major depressive disorder were among the top ten causes of YLDs and were the cause of more health loss than diabetes, chronic obstructive pulmonary disease, and asthma combined. The study based on data from 188 countries, considered to be the largest and most detailed analysis to quantify levels, patterns, and trends in ill health and disability, concluded that "the proportion of disability-adjusted life years due to YLDs increased globally from 21.1% in 1990 to 31.2% in 2013." The environmental burden of disease is defined as the number of DALYs that can be attributed to environmental factors. Similarly, the work-related burden of disease is defined as the number of deaths and DALYs that can be attributed to occupational risk factors to human health. These measures allow for comparison of disease burdens, and have also been used to forecast the possible impacts of health interventions. By 2014, DALYs per head were "40% higher in low-income and middle-income regions."

Molecular epidemiology is a branch of epidemiology and medical science that focuses on the contribution of potential genetic and environmental risk factors, identified at the molecular level, to the etiology, distribution and prevention of disease within families and across populations. This field has emerged from the integration of molecular biology into traditional epidemiological research. Molecular epidemiology improves our understanding of the pathogenesis of disease by identifying specific pathways, molecules and genes that influence the risk of developing disease. More broadly, it seeks to establish understanding of how the interactions between genetic traits and environmental exposures result in disease.

Genetic epidemiology is the study of the role of genetic factors in determining health and disease in families and in populations, and the interplay of such genetic factors with environmental factors. Genetic epidemiology seeks to derive a statistical and quantitative analysis of how genetics work in large groups.

Environmental social science is the broad, transdisciplinary study of interrelations between humans and the natural environment. Environmental social scientists work within and between the fields of anthropology, communication studies, economics, geography, history, political science, psychology, and sociology; and also in the interdisciplinary fields of environmental studies, human ecology and political ecology, social epidemiology, among others.

In analytical chemistry, biomonitoring is the measurement of the body burden of toxic chemical compounds, elements, or their metabolites, in biological substances. Often, these measurements are done in blood and urine. Biomonitoring is performed in both environmental health, and in occupational safety and health as a means of exposure assessment and workplace health surveillance.

The Bradford Hill criteria, otherwise known as Hill's criteria for causation, are a group of nine principles that can be useful in establishing epidemiologic evidence of a causal relationship between a presumed cause and an observed effect and have been widely used in public health research. They were established in 1965 by the English epidemiologist Sir Austin Bradford Hill.

Irva Hertz-Picciotto, is an environmental epidemiologist best known for her studies of autism. She is Professor and Chief, Division of Environmental and Occupational Health, Department of Public Health Sciences, at the University of California, Davis (UC-Davis). In addition, she is on the Research Faculty of the MIND Institute at UC-Davis; is Deputy Director of the UC-Davis Center for Children's Environmental Health; and is on the faculty of the Center for Occupational and Environmental Health of the Universities of California at Berkeley, Davis, and San Francisco. Hertz-Picciotto serves on the advisory board of the anti-toxic chemical NGO Healthy Child, Healthy World.

<span class="mw-page-title-main">Nutritional epidemiology</span> Field of medical research on disease and diet

Nutritional epidemiology examines dietary and nutritional factors in relation to disease occurrence at a population level. Nutritional epidemiology is a relatively new field of medical research that studies the relationship between nutrition and health. It is a young discipline in epidemiology that is continuing to grow in relevance to present-day health concerns. Diet and physical activity are difficult to measure accurately, which may partly explain why nutrition has received less attention than other risk factors for disease in epidemiology. Nutritional epidemiology uses knowledge from nutritional science to aid in the understanding of human nutrition and the explanation of basic underlying mechanisms. Nutritional science information is also used in the development of nutritional epidemiological studies and interventions including clinical, case-control and cohort studies. Nutritional epidemiological methods have been developed to study the relationship between diet and disease. Findings from these studies impact public health as they guide the development of dietary recommendations including those tailored specifically for the prevention of certain diseases, conditions and cancers. It is argued by western researchers that nutritional epidemiology should be a core component in the training of all health and social service professions because of its increasing relevance and past successes in improving the health of the public worldwide. However, it is also argued that nutritional epidemiological studies yield unreliable findings as they rely on the role of diet in health and disease, which is known as an exposure that is susceptible to considerable measurement error.

Molecular pathological epidemiology is a discipline combining epidemiology and pathology. It is defined as "epidemiology of molecular pathology and heterogeneity of disease". Pathology and epidemiology share the same goal of elucidating etiology of disease, and MPE aims to achieve this goal at molecular, individual and population levels. Typically, MPE utilizes tissue pathology resources and data within existing epidemiology studies. Molecular epidemiology broadly encompasses MPE and conventional-type molecular epidemiology with the use of traditional disease designation systems.

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Occupational epidemiology is a subdiscipline of epidemiology that focuses on investigations of workers and the workplace. Occupational epidemiologic studies examine health outcomes among workers, and their potential association with conditions in the workplace including noise, chemicals, heat, or radiation, or work organization such as schedules.

Environmental risk transition is the process by which traditional communities with associated environmental health issues become more economically developed and experience new health issues. In traditional or economically undeveloped regions, humans often suffer and die from infectious diseases or of malnutrition due to poor food, water, and air quality. As economic development occurs, these environmental issues are reduced or solved, and others begin to arise. There is a shift in the character of these environmental changes, and as a result, a shift in causes of death and disease.

References

  1. ↑ Merrill, Ray M. (2008). Environmental epidemiology : principles and methods. Sudbury, Mass.: Jones and Bartlett Publishers. pp. 8–9. ISBN   9780763741525. OCLC   163589221.
  2. ↑ "Ostrava Declaration on Environment and Health" (PDF). World Health Organization. Archived from the original (PDF) on April 30, 2019. Retrieved December 5, 2018.
  3. ↑ Slikker, William Jr., Chang, Louis W., Handbook of Developmental Neurotoxicology, p. 460, 1998, Academic Press, ISBN   0080533434, google books
  4. ↑ Balbus, John M; Catherine Malina (January 2009). "Identifying vulnerable subpopulations for climate change health effects in the United States". Journal of Occupational and Environmental Medicine. 51 (1): 33–37. doi:10.1097/JOM.0b013e318193e12e. ISSN   1536-5948. PMID   19136871. S2CID   24177750.
  5. ↑ Grandjean, Phillipe (2015). Only one chance : how environmental pollution impairs brain development--and how to protect the brains of the next generation. Oxford: Oxford University Press. ISBN   9780199985388. OCLC   817736465.
  6. ↑ "Ripple Effects: Population and Coastal Regions". PRB. Retrieved 2023-10-19.
  7. ↑ Hippocrates (1881). On Airs, Waters, and Places. London: Wyman and Sons.
  8. ↑ Boulakia, Jean David C. (1972). "Lead in the Roman World". American Journal of Archaeology. 76 (2): 139–144. doi:10.2307/503857. ISSN   0002-9114. JSTOR   503857.
  9. ↑ Pollio, Vitruvius (1999). Vitruvius : Ten Books on Architecture. Rowland, Ingrid D. (Ingrid Drake), Howe, Thomas Noble, 1949-, Dewar, Michael (Michael J.). New York: Cambridge University Press. ISBN   978-0521553643. OCLC   39523557.
  10. ↑ Snow, John (1855). On the Mode of Communication of Cholera (2nd ed.). London: John Churchill.
  11. ↑ Kriebel, David; Tickner, Joel; Epstein, Paul; Lemons, John; Levins, Richard; Loechler, Edward L.; Quinn, Margaret; Rudel, Ruthann; Schettler, Ted (2001). "The Precautionary Principle in Environmental Science". Environmental Health Perspectives. 109 (9): 871–6. doi:10.1289/ehp.01109871. ISSN   0091-6765. JSTOR   3454986. PMC   1240435 . PMID   11673114.
  12. 1 2 Wybe, Douma (1996). The precautionary principle. pp. 65–100. doi:10.1163/9789004189195_003. ISBN   9789004189195. S2CID   2615631.
  13. ↑ "Commission adopts Communication on Precautionary Principle". European Commission. February 2000. Retrieved December 9, 2018.
  14. 1 2 3 "Principles of Epidemiology in Public Health Practice, Third Edition: An Introduction to Applied Epidemiology and Biostatistics". Centers for Disease Control and Prevention. Archived from the original on 2014-10-11. Retrieved December 9, 2018.
  15. ↑ Gordis, Leon (2009). Epidemiology (4th ed.). Philadelphia: Saunders Elsevier. ISBN   9781437700510. OCLC   489073248.
  16. 1 2 3 Introduction to environmental epidemiology. Talbott, Evelyn O., Craun, Gunther F. Boca Raton: Lewis Publishers. 1995. ISBN   978-0873715737. OCLC   31970345.{{cite book}}: CS1 maint: others (link)
  17. ↑ Etzel, Ruth A.; Abbas, Nivine H.; Anastario, Michael P.; Mustapha, Adetoun; Osuolale, Olayinka; Sarkar, Atanu; Soyiri, Ireneous N.; Whaibeh, Emil; Soskolne, Colin L. and the Ethics and Philosophy Committee (September 17, 2023). "Ethics Guidelines for Environmental Epidemiologists" (PDF). Retrieved September 17, 2013.
  18. ↑ Hill, Austin Bradford (1965). "The environment and disease: association or causation?". Journal of the Royal Society of Medicine. 108 (1): 32–37. doi:10.1177/0141076814562718. ISSN   0141-0768. PMC   4291332 . PMID   25572993.

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