Glossary of Environmental and Occupational Health
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- Exposure pathway
- The physical course a pollutant takes from the source to a subject.
- Exposure Route
- Way a substance enters the body
- Exposure assessment
- The study of distribution of determinants of substances or factors affecting human health:
- 3 components of exposure assessment
- 1)design of the study
3)interpretation of the data
- is referred to the exposure after uptake of the body.
- A substance or factor affecting human health (adversely or beneficially). In Occupational or Environmental Epidemiology- generally contact with a substance through and environmental medium and surface of the human body.
- Source-receptor models
- Include the routes and pathways of exposure and a helpful in understanding how people are exposed.
- 3 possible exposure routes for humans
- 1. inhalation through respiratory system
2. ingestion through gastrointestinal system
3. absorption through the skin.
- 3 dimensions of exposure
- 1. Duration (ie, hours or days)
3. Frequency (ie, times per week)
[can be used as an exposure index in an epidemiological stdy. i.e., exposures that cause acute effects, the short term concentration is generally the most relevant exposure index.] NOTE: these can be combined such as duration x concentration = cumulative exposure.
- Within and between subject exposure variability
- Exposure generally varies from day to day for any subject and from subject to subject.
Can be estimated with repeated exposure measurements
- 2 main approaches to obtaining exposure estimate(s) for a population
- 1. Individual (ie every member of a population is monitored either once or repeatedly.
2. Exposure grouping population is split into smaller subpopulations or "exposure groups" based on determinants of exposure & group or ecological estimates are obtained for each exposure group.
- Pros & Cons of expert and self-assessment methods
- Pro: easiest and cheapest, generally.
Con: Can suffer due to lack of objectivity and knowledge, and may introduce bias.
- More objective way to assess exposure
- - Measurement.
ex: Levels of outdoor pollution assessed by ambient air monitors.
ex: Levels of substance into body can be estimated by biomonitoring.
- Deterministic Modeling
- One of two types of modeling - in which the models describe the relationship between variables mathematically on the basis of knowledge of the physical, chemical, and or biological mechanisms governing these relationships.
- Stochastic Modeling
- One of two types of modeling - statistical relationships are modeled between variables.
- The degree to which a measurement or an estimate represents the true value of what is being measured
- Deviation of results or inferences from the truth, or processes leading to such deviation; any trend in the design, collection, analysis, interpretation, publication or review of data that can lead to conclusions that are systematically different from the truth.
- Limit of Detection (LOD)
- The minimum concentration of an analyte, in a given matrix and with a specific method, that statistically is significantly greater than zero, that is, the lowest concentration that can be measured with a certain degree of confidence
- The degree of variability in a measurement or estimate, estimated, for example, by the standard error of measurements or the standard deviation in a series of replicate measures
- The ability of a study to demonstrate statistically significant effects, which is determined by a number of factors including study design, magnitude of effect, and sample size.
- The degree of stability exhibited when a mesurement is repeated under identical conditions - the degree to which the results obtaind by measurement procedure can be replicated.
- A test or measurement is repeatable if the results are identical or closely similar each time it is conducted
- A procedure is said to be robust if it is not very sensitive to departures from assumptions or variations in the conditions or practices under which it was set up
- Index of the performance of a diagnostic tool, for ex, for questionnaires: the proportion of truly exposed people in the population who are identified as exposed by the questionnaire.
- Index of the performance of a diagnostic tool, for ex, for questionnaires: teh proportion of truly non-exposed people in the population who are identified as non-exposed by the questionnaire.
- An expression of the degree to which a measurement measures what it purports to measure.
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