15. Hazard Identification Group Exercise: You are part of a public health team that has been sent to a neighbourhood of a city where parents have been complaining of their children experiencing coughing, runny noses, and fevers that won’t go away. The number of children with these symptoms is growing every year; the numbers are 4 times larger than expected. With your team, discuss the possible causes of these symptoms.
16. Childhood Leukaemia in Woburn A 1981 Department of Public Health study confirmed a childhood leukaemia cluster in Woburn, MA. The number of cases was 4 times higher than the national average. Woburn has a 130-year industrial history that resulted in significant local deposition of chemical manufacturing waste.
17. Epidemiology Epidemiology is the basic science of public health. Purpose is to study (1) the distribution of disease in a population, and (2) the determinants of that disease. Concerned with person, place, and time.
21. Unit of Measure 𝐼𝑛𝑐𝑖𝑑𝑒𝑛𝑐𝑒 𝑅𝑎𝑡𝑒= 𝑃𝑒𝑟𝑠𝑜𝑛𝑃𝑙𝑎𝑐𝑒×𝑇𝑖𝑚𝑒 1000 people living in Accra contracted the flu last year. What is the incidence rate?
22. Relative Risk 𝑅𝑒𝑙𝑎𝑡𝑖𝑣𝑒 𝑅𝑖𝑠𝑘 (𝑅𝑅)= 𝐼𝑛𝑐𝑖𝑑𝑒𝑛𝑐𝑒 𝑅𝑎𝑡𝑒 1𝐼𝑛𝑐𝑖𝑑𝑒𝑛𝑐𝑒 𝑅𝑎𝑡𝑒 2 The IR of swine flu when flying with Delta is 2 cases per 1000 people each week. The IR of swine flu on all airlines is 1 case per 1000 each week. What is the RR of getting swine flu when flying with Delta?
23. Woburn MA: person Child diagnosed with leukaemia before 19th birthday. Diagnosed between 1969 and 1989. A resident of Woburn MA at the time of diagnosis.
26. Woburn MA: Relative Risk RR = 9 For those living near contaminated well water relative to all residents of Woburn. Is there a reason for concern?
27. Summary of Epidemiology Studies Advantages Study human populations. Can examine adverse effects associated with exposures to risk factors in real time. Convincing data if studies are conducted correctly. Disadvantages Long time to execute Costly Difficult to establish causality
28. Dose-Response Assessment Determine whether the causative agent can damage human cells/tissues/organs. Studies are typically conducted in laboratories. Fundamental science is toxicology
30. Toxicokinetics What the body does to the chemical. Defined by absorption, distribution, metabolism, and excretion (ADME). Establishes the DOSE in dose-response.
31. Toxicodynamics What the chemical does to the body. Defined by cellular damage, DNA modifications, protein concentration changes, etc. Establishes the RESPONSE in dose-response. Decreased dopamine levels in Parkinson’s disease patients
37. Summary of Toxicology Studies Advantages Highly controlled. Fast results. Can better establish causal relationship between dose and effect. Disadvantages Laboratory conditions Extensive use of animals Questionable relevance to humans
39. Objectives of Exposure Assessment Measure the amount of contaminant in the environment. Record how often humans come into contact with the contaminant. Identify who comes into contact with the contaminant.
45. Summary of Exposure Studies Advantages Quantitative Real-world values Disadvantages High cost of conducting studies (i.e., analytical chemistry) Small number of samples due to intensive nature of studies
46. Risk Characterization Final phase of a risk assessment. Integrates information collected from EPIDEMIOLOGY, TOXICOLOGY, and EXPOSURE ASSESSMENT studies. Qualitative and quantitative conclusions. Synthesizes all the information and recommends actions to prevent diseases from spreading.
47. Risk Characterization for Cr(VI) Clearly there is an association between leukaemia and living where Cr(VI) levels are high. Toxicological studies demonstrate a positive dose-response, suggesting a causal relationship. Exposure studies have measured presence of Cr(VI) levels in drinking water that exceed health standards. All evidence seems to point to the need to reduce Cr(VI) levels in order to prevent childhood leukaemia from occurring.
52. Biological monitoring shows that people are exposed to dangerous levels of mercury.What evidence do you need to evaluate whether or not preventive action should be taken?
