Health effects risks

Risk is the likelihood that an individual will develop a specified adverse health effect. Risk can be characterized in quantitative terms, such as the probability of the adverse health effect or the MOE. 

The exposure pattern, or chain of relationships between radioactivity in agricultural products and radiation dose and health effects (risk) in humans, is schematically presented in Fig. 3.1. The actual radionuclides present in some phosphate fertilizers (including by products and wastes) contribute to the radiation exposure of a population (Fisher et al., 1979 Fitzgerald and Sensitaffar, 1978 Phillip et al., 1978). 

Risk Assessment - The use of available information to evaluate and estimate exposure to a substance(s) and its consequent adverse health effects. Risk assessment consists of one or more of the following four elements ... 

Contents Include epidemiologic study designs, disease duster studies, surveillance, exposure assessment laboratory practices, biological markers, human health effects, risk assessment ethics, and pokey and law. 

Schlesinger RB, Cassee F (2003) Atmospheric secondary inorganic particulate matter the toxicological perspective as a basis for health effects risk assessment. Inhal Toxicol 15 197-235... 

For radiation doses <0.5 Sv, there is no clinically observable iacrease ia the number of cancers above those that occur naturally (57). There are two risk hypotheses the linear and the nonlinear. The former implies that as the radiation dose decreases, the risk of cancer goes down at roughly the same rate. The latter suggests that risk of cancer actually falls much faster as radiation exposure declines. Because risk of cancer and other health effects is quite low at low radiation doses, the iacidence of cancer cannot clearly be ascribed to occupational radiation exposure. Thus, the regulations have adopted the more conservative or restrictive approach, ie, the linear hypothesis. Whereas nuclear iadustry workers are allowed to receive up to 0.05 Sv/yr, the ALARA practices result ia much lower actual radiatioa exposure. 

Another way to evaluate risks is to calculate the sensitivity of the total risk estimates to changes in assumptions, frequencies, or consequences. Risk analysts tend to be conservative in their assumptions and calculations, and the cumulative effect of this conservatism may be a substantial overestimation of risk. For example, always assuming that short-term exposure to chemical concentrations above some threshold limit value will cause serious injury may severely skew the calculated risks of health effects. If you do not understand the sensitivity of the risk results to this conservative assumption, you may misallocate your loss prevention resources or misinform your company or the public about the actual risk. 

A basic tenet of risk communication is that people have a right to participate in decisions that affect their lives. The goal of risk communication should be to inform the community about the risks and potential health effects of your activities and to involve the public in developing solutions to any related problems. 

EPA must first make determinations about which contaminants to regulate. These determinations are based on health risks and the likelihood that the contaminant occurs in public water systems at levels of concern. The National Drinking Water Contaminant Candidate List (CCL), published March 2, 1998, lists contaminants that (1) are not already regulated under SDWA (2) may have adverse health effects (3) are known or anticipated to occur in public water systems and (4) may require regulations under SDWA. Contaminants on the CCL are divided into priorities for regulation, health research and occurrence data collection. 

Microbial Contaminants For microbial contaminants that may present public health risk, the MCLG is set at zero because ingesting one protozoa, virus, or bacterium may cause adverse health effects. EPA is conducting studies to determine whether there is a safe level above zero for some microbial contaminants. So far, however, this has not been established. 

Nonemergency medical care should be arranged for hazardous waste site personnel who are experiencing health effects resulting from an exposure to hazardous substances. Off-site medical care should make sure that any potential job-related symptoms or illnesses are evaluated in the context of the employee s exposure. Off-site medical personnel should investigate and treat non-job-related illnesses that may put the employee at risk because of task requirements [1]. 

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. 

Primary emphasis is often placed on the frequently occurring initiators, but they may not present the largest public health risk. To gain a perception of the relative importance of various initiators, Table 6.3-6 from Taylor et al, (1986) shows an ordering of the accident initiators for Indian Point 3 by Inspection Importance (Section 2.8.2) which considers both frequency of occurrence and health effects based on of one or more latent fatalities. 

The harmful effects of industrial emissions are not confined to the workers but extend beyond the plant boundary line. Chemically-induced diseases among workers exposed to industrial chemicals are a warning sign of the risks to which a larger population is also being exposed usually the chemical hazards are in principle similar in the occupational and general environment. However, occasionally environmental exposures can be qualitatively different from the occupational environment and may also cause deleterious health effects in the general population. 

Provides information on how levels of exposure of hazardous chemicals affect human health. Covers levels of exposure to hazardous chemicals below which no adverse health effects are expected to occur in various segments of the human population. The reference dose and carcinogenicity assessments on IRIS can sen>e as guides in e >aluating potential health hazards and selecting response to alleviate a potential risk to human health. Hours 8 00 a.m. to 4 40 p.m. EST, Monday - Friday. 

Since 1970 tlie field of healtli risk assessment Itas received widespread attention witliin both tlie scientific and regulatoiy committees. It has also attracted tlie attention of the public. Properly conducted risk assessments have received fairly broad acceptance, in part because they put into perspective the terms to. ic, Itazard, and risk. Toxicity is an inlierent property of all substances. It states tliat all chemical and physical agents can produce adverse healtli effects at some dose or under specific exposure conditions. In contrast, exposure to a chemical tliat lias tlie capacity to produce a particular type of adverse effect, represents a health hazard. Risk, however, is tlie probability or likelihood tliat an adverse outcome will occur in a person or a group tliat is exposed to a particular concentration or dose of the hazardous agent. Tlierefore, risk can be generally a function of exposure and dose. Consequently, healtli risk assessment is defined as tlie process or procedure used to estimate tlie likelihood that... 

Dose-Response Evaluation The process of quantitatively evaluating toxicity information and characterizing the relationship between the dose a contaminant administered or received, and the incidence of adverse health effects in the exposed population. From a quantitative dose-respoiise relationship, toxicity values can be derived that are used in the risk characterization step to estimate the likelihood of adverse effects occurring in humans at different exposure levels. 

Risk characterization is lire process of estimating llie incidence of a health effect under the various conditions of human or animal exposure described in lire exposure assessment. It is performed by combining the exposure (see Cliapter 12) and dose response (see Cluipter 11) assessments. The summary effects of the uncertainties in lire preceding steps should also be described in lliis step. 

A risk estimate indicates the likelihood of occurrence of the different types of health or enviromiiental effects in exposed populations. Risk assessment should include both human healtli and environmental evaluations (i.e., impacts on ecosystems). Ecological impacts include actual and potential effects on plants and animal (otlier than domesticated species). The numbers produced from the risk characterization, representing tlie probability of adverse health effects being caused, must be evaluated. 

Accidental release, toxics Short duration exposure yields low cancer risk non-cancer health effects of much greater concern. 

National Academy of Science. (1999). Health Effects of Exposure to Radon BEIR VI, Committee on Health Risks of Exposure to Radon. Washington, DC National Academy Press. 

Minimal Risk Eevel Review. The Minimal Risk Level Workgroup considers issues relevant to substance-specific minimal risk levels (MRLs), reviews the health effects database of each profile, and makes recommendations for derivation of MRLs. 

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