Population at risk

Dose—response relationships are useful for many purposes in particular, the following if a positive dose—response relationship exists, then this is good evidence that exposure to the material under test is causally related to the response the quantitative information obtained gives an indication of the spread of sensitivity of the population at risk, and hence influences ha2ard evaluation the data may allow assessments of no effects and minimum effects doses, and hence may be valuable in assessing ha2ard and by appropriate considerations of the dose—response data, it is possible to make quantitative comparisons and contrasts between materials or between species. 

Cross-comparing the risks of various activities is difficult because of the lack of a common basis of comparison, however Cohen and Lee, 1979 provide such a comparison on the basis of loss of life expectancy. Solomon and Abraham, 1979 used an index of harm in a study of 6 occupational harms - three radiological and three nonradiological to bracket high and low estimates of radiological effects. The index of harm consists of a weighting factor for parametric study the lost time in an industry and the worker population at risk. The conclusions were that the data are too imprecise for firm conclusions but it is possible for a radiation worker under pessimistic health effects assumptions to have as high index of harm as the other industries compared. 

Some animal studies indicate that dietary exposure to methyl parathion causes decreased humoral and cellular responses (Shtenberg and Dzhunusova 1968 Street and Sharma 1975). A more recent, well-designed animal study that included a battery of immuno/lymphoreticular end points showed few effects at the nonneurotoxic doses tested (Crittenden et al. 1998). No adequate studies are available in humans to assess the immunotoxic potential of methyl parathion. Therefore, studies measuring specific immunologic parameters in occupationally exposed populations are needed to provide useful information. Further studies are also needed to investigate the mechanism for methyl parathion-induced immunotoxicity since this information would help to identify special populations at risk for such effects. 

The potential severity of anaphylaxis during anesthesia underscores the interest of developing a rational approach to reduce its incidence by identifying potential risk factors before surgery. Recommendations concerning the identification of population at risk of peroperative anaphylaxis, who would benefit from preoperative investigation, have been proposed [10]. 

Specific Clinical Features of Anesthesia Induced Anaphylaxis 183 Population at Risk... 

Globally, undernutrition is widespread, leading to impaired growth, defective immune systems, and reduced work capacity. By contrast, in developed countries, there is often excessive food consumption (especially of fat), leading to obesity and to the development of cardiovascular disease and some forms of cancer. Deficiencies of vitamin A, iron, and iodine pose major health concerns in many countries, and deficiencies of other vitamins and minerals are a major cause of iU health. In developed countries, nutrient deficiency is rare, though there are vulnerable sections of the population at risk. Intakes of minerals and vitamins that are adequate to prevent deficiency may be inadequate to promote optimum health and longevity. 

Prior to routine screening of blood products in the early 1990s, the primary route of transmission of the HCV was blood transfusions, when the risk was 0.02% per unit transfused. Since then, the risk has decreased significantly (0.001% per unit transfused).13 Today, intravenous drug users utilizing contaminated paraphernalia are responsible for most HCV transmission. Other populations at risk for acquiring HCV are listed in Table 21-1. Approximately 10% of the individuals infected with HCV have no identifiable risk factors. 

The clinical scenario and the severity of the volume abnormality dictate monitoring parameters during fluid replacement therapy. These may include a subjective sense of thirst, mental status, skin turgor, orthostatic vital signs, pulse rate, weight changes, blood chemistries, fluid input and output, central venous pressure, pulmonary capillary wedge pressure, and cardiac output. Fluid replacement requires particular caution in patient populations at risk of fluid overload, such as those with renal failure, cardiac failure, hepatic failure, or the elderly. Other complications of IV fluid therapy include infiltration, infection, phlebitis, thrombophlebitis, and extravasation. 

It is important in defining any analysis scheme that the analysis elements be consistent in scope, scale, and detail with each other and with the purposes of the analysis. Thus details of cohort exposure in microenvironments can provide valuable information on populations at risk if, in fact, pollutant concentrations are functions of micro-environments. It appears that micro-environments are clearly important in carbon monoxide (CO) exposure analysis because automobile generated CO concentrations are highly correlated with automobile usage patterns. It is not clear that ozone exposures are so correlated. Ozone commonly exists in "clouds" that are large compared to any one micro-environment, but drift over an area large compared to their size in the course of their formation and decay. 

The US Army, which for several years has had responsibilities for renovating contaminated tracts of land, has developed a conceptual framework that can accommodate a variety of decisionmaking processes and models to respond to the question, "How clean is clean " This approach focuses on determining acceptable pollutant residue levels as goals for remedial action. It recognizes that potential land use, courses of remedial action, the nature and extent of contamination, and the population at risk are all considerations that may affect those goals. 

Special populations at risk of high exposure to tetraethyl lead include workers at hazardous waste sites and those involved in the manufacture and dispensing of tetraethyl lead (Bress and Bidanset 1991). Recreational drug sniffers of leaded gasoline are also at risk (Edminster and Bayer 1985). 

As noted by Goldsmith, medical technologies do not inherently increase health care costs. Their effects are broad-based and complex. Advances in medical technology may influence (1) the population at risk, (2) the cost of each treatment, (3) the risk of complications, (4) clinical incomes or hospital revenue, (5) the need for additional treatment, and/or (6) patients quality of life (Goldsmith, 1994). The pharmacoeconomics of an intervention are particularly important when the intervention is a therapeutic breakthrough (leads to better patient outcomes), is relatively expensive compared... 

Incidence rate. The rate of occurrence of new cases of a disease, adverse reaction, or other event in a given population at risk (e.g., the incidence of disease A is Y patients per year per 100,000 population). 

The incidence of adverse symptoms cannot be determined, since the number of people ingesting the substance (population at risk) is not known. 

Cataldo, A.M., Hamilton, D.J., Barnett, J.L., Paskevich, P.A., and Nixon, R.A., 1996, Properties of the endosomal-lysosomal system in the human central nervous system disturbances mark most neurons in populations at risk to degenerate in Alzheimer s disease. J. Neurosci. 16 186-199... 

Diseases associated with marine seafood toxins appear to have high attack rates. An attack rate is the proportion of a well-defined population that develops a disease over a specific period of time (where the numerator is the number of new cases during that period and the denominator is the size of the population at risk, e.g., the number of people who ate a contaminated food at the start of the time period of interest) (Goodman and Peavy, 1996). Physicians therefore need to ask about disease cases among people sharing the same seafood meal. 

The prevention and treatment of opportunistic infections (OIs) in the ART era is still an important component of HIV care in RLS for three major reasons. First of all, many individuals present with life threatening OIs as the first indication of HIV infection. The proportion of the population at risk for HIV infection that is aware of its HIV serostatus is considerably very low. Secondly, whereas over the last two years access to ART has improved greatly, ART coverage in RLS is still less than 25% of the ART eligible population. 

First, the carcinogenic effects of radiation and chemicals are expressed as an increase in the age-spedfic incidence of particular neoplasms. Depending on the survival of the population at risk, the final cumulative incidence of neoplasms in the population may, or may not, be increased. 

In order to determine the effective dose of a given agent to the population at risk, evaluators need to take into account such variables as the duration and intensity of exposure, the age distribution of exposed persons at the time of their exposure, their sex, state of disease or health, and the estimated concentrations of the agent and its metabolic derivatives in various tissues of the body. Also, insofar as possible, the mode of action of the agent should be characterized in order to enable selection of the appropriate dose-incidence model for use in risk estimation. 

Tolerance Distribution Model. This model assumes that each member of the population at risk has an individual tolerance below which no response will be produced and that these tolerances vary in the members of the population according to some probability distribution (F). The probability distribution is also assumed to involve parameters of location (a) and scale (0 > 0) and can be generally denoted by F (a + 0 log z), where z is the tolerance level to a particular toxic agent. The probability, P(d), that a random individual will suffer a response from a dose, d, is P(d) = F (a + 0 log d) = dF(x). 

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