Question 1
Environmental epidemiology is the study of how different environments act as a bearing factor in contributing to or preventing injury, disease or death (Merrill, 2015).
A Natural experiment happens when nature determines which individuals are exposed to the experimental and control factors (Merrill, 2015).
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Descriptive epidemiology is kindred to the distribution and frequency of disease-causing factors as well as disease extenuation and exacerbating factors based on geographical areas (Merrill, 2015).
The odds ratio is a measure that represents the probability that a certain exposure will result in a certain outcome (Merrill, 2015).
Relative risk is the statistical representation of the probability of an event occurring in a group that has been exposed to a factor, against the probability of the same event occurring in a group that hasn’t been exposed (Merrill, 2015).
Question Two: John Snow and the Natural Experiment
John Snow took advantage of a natural event to conduct an experiment on the veracity of the natural experiment process. In 1849, all the water companies of London drew water from the same spot, thus all their water was contaminated with the London sewerage. By the advent of the 1853-54, one of the companies had moved to a site where no contamination was possible (Hajna et al, 2015). Without their knowledge, Londoners who got their water from different companies drew water that was either contaminated or not. John Snow used this natural occurrence as a successful basis for a natural experiment in Cholera.
Question Three: Epidemiology and Environmental Health
Epidemiology enables an understanding of what disease incidences happen to different people under different environmental conditions. This enables the understanding of the relationship between environmental factors and health issues thus enabling control. Epidemiology also enables an understanding of which health risks to anticipate under different weather conditions (Nieuwenhuijsen, 2015). This facilitates planning and preparation for extenuation of health risks caused by environmental factors. The most significant limitation to this lies in the unpredictability of health factors, more so due to human inferences. This creates a lack of plausible control which lowers the reliability and validity of the kindred research (Nieuwenhuijsen, 2015).
Question 4: Ecologic Analysis and Air Pollution
To test the health effects of air pollution using ecologic analysis, researchers need to anticipate an event that will cause air pollution. They will then conduct tests before and after the event to arrive at the specific impact of the event (Nieuwenhuijsen, 2015). This means that the event that causes the pollution is not under the control of the experimenters making it akin to a natural experiment. Rarely is an uncontrolled event clinical, thus it may also have secondary forms of pollution and environmental impacts. For example, a factory explosion may cause air pollution but at the same time cause a leakage of gamma rays. It will be difficult for researchers to differentiate between effects of air pollution and gamma rays from a health perspective.
Question 5
Sir Percival Pott was able to establish a clear correlation between the advent of cancer and professional affiliation of sufferers. This enabled a connection between certain cancers and certain environmental conditions affiliated to different working conditions. The contribution, therefore, gave a foundation for the study of the causes of different environmental-factor caused cancers and their prevention (Nieuwenhuijsen, 2015).
Question Six
Sir Austin Bradford Hill used statistics to establish a relationship between cause and outcome in disease. Using cigarette smoking and lung cancer, Hill came up with a 9 component causal-effect relationship test (McDonald & Strang, 2016). These components are strength, consistency, specificity, temporarily, biological gradient, plausibility, coherence, experiment, and analogy. The satisfaction of these components could statistically tie a cause to a disease outcome.
Question 7: Epidemiologic Triangle
The epidemiologic triangle or triad, relates to contagious diseases and how they spread or exist in a relationship through a combination of three factors (Merrill, 2015). These factors are the host, the vector and the right environment for the survival of the disease-causing pathogen. In environmental health, the epidemiologic triangle can be used to establish a means or avenue for eliminating a pathogen or preventing further spread thereof (Merrill, 2015). This can be done by picking the most effective and efficient point of attack amongst the three points of the triangle.
Question 8: Analytical Versus Descriptive Epidemiology
Analytical epidemiology (AE) deals with the “what” of the disease what of the disease while descriptive epidemiology (DE) deals with the where, when and to what extent of the disease (Merrill, 2015). AE is therefore incisive about the nature of the disease as well as its risk and exacerbation factors. On the other hand, DE deals with the geographical distribution related factors. For example, in the case of a cholera outbreak, AE will deal with what caused the cholera outbreak and what risk factors led to its advent and exacerbation or mitigation. On the other hand, DE will deal with which area or segments of the populace were affected the most or less and why.
References
Hajna, S., Buckeridge, D. L., & Hanley, J. A. (2015). Substantiating the impact of John Snow’s contributions using data deleted during the 1936 reprinting of his original essay On the Mode of Communication of Cholera. International Journal of Epidemiology , 44 (6), 1794-1799
McDonald, R., & Strang, J. (2016). Are take ‐ home naloxone programmes effective? Systematic review utilizing application of the Bradford Hill criteria. Addiction , 111 (7), 1177-1187
Merrill, R. M. (2015). Introduction to epidemiology . Burlington, Massachusetts: Jones & Bartlett Publishers
Nieuwenhuijsen, M. J. (Ed.). (2015). Exposure assessment in environmental epidemiology . New York: Oxford University Press, USA
