Environmental Health Science Student Forum

24/01/2020

Case series

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 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 cases control studies or prospective studies. A cases control study would involve matching comparable controls without 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 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.

24/01/2020

Epidemiologists employ a range of study designs from the observational to experimental and generally categorized as descriptive, 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, 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 as a tool.

Observational studies have two components, descriptive and analytical.
Descriptive observations pertain to 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 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' is used to describe the intersection of Host, Agent, and Environment in analyzing an outbreak.

24/01/2020

Continuation on EPIDEMIOLOGY

Epidemiology, literally meaning "the study of what is upon the people", is derived fromGreek epi, meaning 'upon, among', demos, meaning 'people, district', and logos, meaning 'study, word, discourse', suggesting that it applies only to human populations. However, 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" a population (endemic).[4] The term "epidemiology" appears to have first been used to describe the study of epidemics in 1802 by the Spanish physician Villalba 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 disease, but of disease in general, and even many non-disease, health-related conditions, such as high blood pressure, depression and obesity.
Therefore, this epidemiology is based upon how the pattern of the disease causes change in the function of everyone.

24/01/2020

Lecture on EPIDEMIOLOGY
Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in defined populations.

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 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 the data and draw appropriate conclusions, social sciences to better understand proximate and distal causes, andengineering for exposure assessment.

24/01/2020

The Toxicology and Environmental Health Information Program (TEHIP)
is a comprehensive toxicology and environmental health web site, that includes open access to resources produced by US government agencies and organizations, and is maintained under the umbrella of the Specialized Information Service at the United States National Library of Medicine. TEHIP includes links to technical databases, bibliographies, tutorials, and consumer-oriented resources. TEHIP is responsible for the Toxicology Data Network (TOXNET),an integrated system of toxicology and environmental health databases including the Hazardous Substances Data Bank, that are open access,
i.e. available free of charge.

24/01/2020

Environmental health addresses all human-health-related aspects of the natura.environment and the built environment. Environmental health concerns include:

Air quality, including both ambient outdoor air and indoor air quality, which also comprises concerns about environmental to***co smoke.BiosafetyDisaster preparedness and response.Climate change and its effects on health.ENVIRONMENTAL racism wherein certain groups of people can be put at higher risk for environmental hazards, such as air, soil, and water pollution. This often happens due to marginalization, economic and political processes, and ultimately, racism. Environmental racism disproportionately affects different groups globally, however generally the most marginalized groups of any given region/nation.
Food safety, including in agriculture,transportation, food processing, wholesale and retail distribution and sale.
Hazardous materials management, including hazardous waste management, contaminated site remediation, the prevention of leaks from underground storage tanks and the prevention of hazardous materials releases to the environment and responses to emergency situations resulting from such releases.
Housing, including substandard housing abatement and the inspection of jails and prisons. Childhood lead poisoning prevention. Land use planning, including smart growth.
Liquid waste disposal, including city waste water treatment plants and on-site waste water disposal systems, such as septic tank systems and chemical toilets. Medical waste management and disposal. Noise pollution control.

24/01/2020

Five basic disciplines generally contribute to the field of environmental health:environmental epidemiology, toxicology, exposure science, environmental engineering, and environmental law. Each of these disciplines contributes different information to describe problems and solutions in environmental health, but there is some overlap among them.

Environmental epidemiology studies the relationship between environmental exposures (including exposure to chemicals, radiation, microbiological agents, etc.) and human health. Observational studies, which simply observe exposures that people have already experienced, are common in environmental epidemiology because humans cannot ethically be exposed to agents that are known or suspected to cause disease. While the inability to use experimental study designs is a limitation of environmental epidemiology, this discipline directly observes effects on human health rather than estimating effects from animal studies.
Toxicology studies how environmental exposures lead to specific health outcomes, generally in animals, as a means to understand possible health outcomes in humans. Toxicology has the advantage of being able to conduct randomized controlled trials and other experimental studies because they can use animal subjects. However there are many differences in animal and human biology, and there can be a lot of uncertainty when interpreting the results of animal studies for their implications for human health.
Exposure science studies human exposure to environmental contaminants by both identifying and quantifying exposures. Exposure science can be used to support environmental epidemiology by better describing environmental exposures that may lead to a particular health outcome,identify common exposures whose health outcomes may be better understood through a toxicology study, or can be used in a risk assessment to determine whether current levels of exposure might exceed recommended levels.

23/01/2020

Environmental health has been defined in a 1999 document by the [World Health Organization] (WHO) as: Those aspects of the human health and disease that are determined by factors in the environment. It also refers to the theory and practice of assessing and controlling factors in the environment that can potentially affect health.

Environmental health as used by the WHO Regional Office for Europe, includes both the direct pathological effects of chemicals, radiation and some biological agents, and the effects (often indirect) on health and well being of the broad physical, psychological, social and cultural environment, which includes housing, urban development, land use and transport.

As of 2016 the WHO website on environmental health states "Environmental health addresses all the physical, chemical, and biological factors external to a person, and all the related factors impacting behaviours. It encompasses the assessment and control of those environmental factors that can potentially affect health. It is targeted towards preventing disease and creating health-supportive environments. This definition excludes behaviour not related to environment, as well as behaviour related to the social and cultural environment, as well as genetics.

The WHO has also defined environmental health services as "those services which implement environmental health policies through monitoring and control activities. They also carry out that role by promoting the improvement of environmental parameters and by encouraging the use of environmentally friendly and healthy technologies and behaviors. They also have a leading role in developing and suggesting new policy areas.

The term environmental medicine may be seen as a medical specialty, or branch of the broader field of environmental health.
Terminology is not fully established, and in many European countries they are used interchangeably.

23/01/2020

Environmental health is the branch of public health concerned with all aspects of thenatural and built environment affecting human health. Environmental health is focused on the natural and built environments for the benefit of human health. The major subdisciplines of environmental health are:environmental science; environmental and occupational medicine, toxicology andepidemiology.

Other terms referring to or concerning environmental health are environmental public health, public health protection, and environmental health protection.

23/01/2020

23/01/2020

ENVIRONMENTAL HEALTH SCIENCE STUDENT FORUM