OCCUPATIONAL DOSE ASSESSMENT

Individual dose assessment requires radiological data on all external and internal sources contributing to occupational and non-occupational radiation exposure (Steinhausler and Pohl, 1983). This is of particular importance in the case of low level Rn-d exposure, as man is always exposed to Rn-d at varying levels through all stages of life, e.g. at school, home or work. The resulting lifetime risk from this chronic exposure is influenced by the latent... 

SC 46-10 Assessment of Occupational Doses from Internal Emitters SC 46-11 Radiation Protection During Special Medical Procedures SC 46-13 Design of Facilities for Medical Radiation Therapy SC 57 Dosimetry and Metabolism of Radionuclides SC 57-2 Respiratory Tract Model SC 57-9 Lung Cancer Risk SC 57-10 Liver Cancer Risk SC 57-14 Placental Transfer SC 57-15 Uremium... 

The need for aggregate and cumulative non-occupational exposure assessments, and lower reference doses for all assessments, means that some pesticides will fail lower-tier risk assessments and without more refined exposure data they might even fail higher-tiered assessments. For example, in North America many of the residential uses of the OPs have been discontinued as a result of the aggregate risk assessments. As a result, there has been increased emphasis on gathering better toxicology and exposure data to reduce the conservatisms that are contained in the current system. 

This chapter illustrates probabilistic approaches to residential and occupational exposnre assessment and their incorporation into aggregate and cumulative assessments of exposure, dose and risk. 

The USACHPPM is responsible for providing bioassay support. Specimens for bioassay are collected at medical treatment facilities by occupational health professionals and sent to USACHPPM for analysis and dose assessments. 

The pharmaceutical industry uses PET studies of receptor occupancy to determine the proper doses of new radiopharmaceuticals in Phase I and II clinical trials. Receptor occupancy is assessed in those receptors upon which the new drug acts. An early example was the use of C-carfentanil to measure the duration of blockade of opiate receptors by the drug nalmifene, compared to naloxone. 

A.26. Records of occupational radiation doses. Inspection personnel should selectively review records of individual occupational doses, including internal and external doses. Activities should be observed to ensure that procedural and management controls are effective. This includes controls for radiation areas and contamination areas as well as inspection of activities for internal and external dosimetry. Exposures of personnel that result in the operator s reference levels for effective doses or intakes being exceeded should be noted. Records of radiation protection training and retraining should be assessed. 

AR559 8.19 Occupational radiation dose assessment in light-water reactor power plants Design stage... 

For screening purposes, the dose rate is usually measured above undisturbed soil for large scale radioactive contamination of the environment, and models apphed for dose assessment for the critical group should be simple and conservative and no account should be taken of any reduction in the dose rate in urban areas or for occupation indoors. 

Where occupational exposures due to can occur, a routine monitoring programme may be based on direct thyroid measurement or on indirect monitoring of urine or workplace samples. The choice of monitoring method will depend on factors such as the availability of instrumentation locally (since the isotope is short lived) and the relative costs of the analyses, as well as on the sensitivity that is needed (see Section 3). Although direct measurement of activity in the thyroid provides the basis for the most accurate dose assessment, other methods may provide adequate monitoring and may be better suited to particular circumstances. 

The present Safety Guide addresses the assessment of exposure due to intakes of radionuchdes in the workplace. Snch intakes can occur via a number of pathways whenever unsealed soirrces are present, and the monitoring of workers and the workplace in such situations is an integral part of ar occupational radiation protection programme. The assessment of exposure due to intakes depends critically upon knowledge of the biokinetics of the radionuclides, and the present Safety Guide reflects the major changes over the past decade in international practice in internal dose assessment. 

While occupational hygiene measurements always measure only the concentrations of chemical compounds present in the occupational environment, i.e., the potential dose, the analysis of biological specimens predominantly reflects the body burden. Furthermore, biological monitoring is always limited to assessment of individual exposure. Personal occupational hygiene sampling takes into consideration only some of the individual factors, e.g., working... 

Personal exposure Predictions of exposure of occupants to airborne contaminants for risk assessment, inhaled doses, or time-integrated concentration values. 

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. 

Assess patients for improvement of anxiety symptoms and for return to baseline occupational, social, and interpersonal functioning. With effective treatment, the patient should have no or minimal symptoms of anxiety or depression. While drug therapy is being initiated, evaluate patients more frequently to ensure tolerability and response. Increase the dose in patients exhibiting a partial response after 2 to 4 weeks on an antidepressant or 2 weeks on a benzodiazepine. Individualize the duration of treatment because some patients require up to one year of treatment.27... 

Pyrethroid insecticides are rapidly metabolized to their inactive acids and alcohol components, which are excreted primarily in urine. A small portion of the absorbed compounds is excreted unchanged. Occupational exposure to pyrethroid insecticides can be assessed by measuring intact compounds or their metabolites in urine. Biological indicators of internal dose in exposed subjects are reported in Table 7. Due to their rapid metabolism, determination of blood concentrations can only be used to reveal recent high-level exposures. 

There is a growing need to better characterize the health risk related to occupational and environmental exposure to pesticides. Risk characterization is a basic step in the assessment and management of the health risks related to chemicals (Tordoir and Maroni, 1994). Evaluation of exposure, which may be performed through environmental and biological monitoring, is a fundamental component of risk assessment. Biomarkers are useful tools that may be used in risk assessment to confirm exposure or to quantify it by estimating the internal dose. Besides their use in risk assessment, biomarkers also represent a fundamental tool to improve the effectiveness of medical and epidemiological surveillance. 

From previous studies we found that a single measurement of the average concentration of radon over periods of days, repeated in different seasons, is adequate to assess the exposure and radiation dose of the occupants of buildings (George and Breslin, 1980 ... 

A survey of the radon concentrations in a representative sample of more than 2000 dwellings in the UK has been completed and provisional results are now available. On average, concentrations are 29% lower in bedrooms than in living areas. The mean radon concentration weighted for room occupancy is 22 Bq m 3. Assuming an equilibrium factor of 0.35 and a mean occupancy of 75%, the mean annual exposure in UK homes is assessed as 0.08 Working Level Months (WLM) and the mean annual effective dose equivalent as 0.43 mSv. 

The dangerous properties of acute toxicity, irritation, corrosivity, sensitisation, repeated-dose toxicity and CMR are evaluated in terms of their potential toxic effects to workers, consumers and man exposed indirectly via the environment, based on the use for each stage in the lifecycle of the substance from which exposure can occur. Risk assessment is also required if there are reasonable grounds for concern for potential hazardous properties, e.g., from positive in vitro mutagenicity tests or structural alerts. The risk assessment involves comparing the estimated occupational or consumer exposure levels with the exposure levels at which no adverse effects are anticipated. This may be a quantitative risk assessment, based on the ratio between the two values, or a qualitative evaluation. The principles of human health risk assessment are covered in detail by Illing (a.30) and more briefly in Chapter 7 of (73). 

Exposure Assessment. What is the dose or the level of exposure of humans to the chemical agent This question must be asked in the context of a given policy for controlling the uses and dissemination into the environment of a chemical agent. This control policy might be the present situation, a possible new regulatory policy, or a policy that a chemical manufacturer or distributor could choose to impose on his product. It Is usually appropriate to assess the exposure of specific groups of people, Which may depend on occupation, life style, purchases and uses of certain products, etc. 

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