We live in an industrialized world and there remains significant concern about e

Question

We live in an industrialized world and there remains significant concern about environmental exposures and public health. One of the key components of environment epidemiology is exposure assessment. Describe an idealized study design that allows you to both assess the level of exposure to an important environmental pollutant and conduct an epidemiological investigation of the general public for a specific disease in the following scenario

Scenario: Air pollution from coal fire station and lung cancer

Explain the choice of epidemiological study design needed to conduct the investigation. If your study includes control groups describe them. How would you measure exposure and give examples of what you would measure. This should include both measures of the environment and biological measures (biomarkers). Indicate how you would collect the samples and how many collections would occur. Give a list of several potential toxins of concern in the scenario. It is difficult to measure every possible exposure ie measure all types of air pollutants from this source – so choose up to three toxins/pollutants to measure – what are the basis for your choices. Describe the age range you would be interested in studying and why. Describe any confounders that you think maybe of interest, and this should include what you know about how environmental justice (EJ) issues. Describe how issues around EJ may modify the observation(s) of the study. The study should not focus on occupational events, bur rather on populations near the coal burning station.

Explanation / Answer

Introduction: Since coal fired power plants poses health hazard to the nearby communities as well as to the environment. It has resulted in diseases like asthma, lung cancer, acute lower respiratory infection and chronic obstructive pulmonary disease.The burning of coals can produce pollutants like sulphur dioxide, nitrogen oxide, particulate matter, mercury. For the study we will use the hospitalization data for various respiratory disease caused by the coal fired power plants.

Methods: In this method we collected hospital discharge data for diseases like the lung cancer, chronic obstructive pulmonary disease, acute lower respiratory infection, asthma. This data included age. sex, race. ethnicity and ZIP code of the current residence of the patients. We collected this data from the New York state. The analysis was restricted to white and black African American since they account for >95% hospitalizations. The population age was divided into 8 groups(0,1-2, 3-5, 6-9,10-24, 25-49, 50-74 and >=75 years. In order to control population density the ZIP codes whose populations were greater than 1000 persons/mi2 were classified as urban and whose populations were less than 1000 persons/mi2 were classified as rural.

Exposure assessment: For the study a list of all existing electric generators and operating power plants present in the New York state from year 1990-2008 were obtained which also includes information on location, energy source, operating period. Since the proximity to waste sites also increases the hospitalization rates of the patients. To mitigate the confounding effect, the ZIP code was classified into 4 groups-'fuel only' which did not contain waste sites and have one or more generators which use coal, oil, solid waste, landfill gas, natural gas as energy source during the time period 1990-2008, 'waste only' which contains only waste sites, 'fuel and waste' which contains both and 'clean' which contains none. For the study, MHI was used a proxy measure of social economic status which is another confounder in the study. MHI was restricted to the year 2000.

Statistical analysis: The hospitalization rate was calculated per 100,000 person years as the number of discharges divided by the total number of population residing during the year 1990-2008 in each category of ZIP codes. The rate ratio of hospitalization was calculated for the 'waste only', 'fuel only', 'fuel-waste' and the 'clean' sites were used as the common referrent exposure group. Covariate patterns were formed that controlled age, sex, race, ethnicity, MHI and exposure.

Results: After adjusted for age, sex, household income and rural/urban residence there were considerable increase of about 11%, 15% and 17% for asthma, ARI and COPD respectively among population having age>10 years living near fuel power compared to that population with no power plants.

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