Personal sampling techniques

Ethylene oxide is sold as a high purity chemical, with typical specifications shown ia Table 14. This purity is so high that only impurities are specified. There is normally no assay specification. Proper sampling techniques are critical to avoid personal exposure and prevent contamination of the sample with trace levels of water. A complete review and description of analytical methods for pure ethylene oxide is given ia Reference 228. 

TTie ability of the ventilation system to protect the worker efficiently can readily be determined by personal samples. The PIMEX method (see Chapter 12) can be used to determine the worker s exposure during various work phases. The capture efficiency as well as the supply air fraction can be measured using tracer gas techniques. Simple evaluation is carried out visually with smoke tube or pellet tests. Daily system evaluation is recommended using airflow or static pressure measurements at appropriate parts of the system. The air velocities, turbulence intensities, air temperature, mean radiant temperature, and air humidity should also be measured to provide an assessment ol thermal comfort. 

However, Fraser et al. (1998) noted that this canister sampling technique may underestimate the methyl-naphthalenes. Thus, their methylnaphthalenes/naph-thalene ratios were lower than those obtained by Arey et al. (1989a) using Tenax-GC solid adsorbent. This may be due to significant adsorption of the methyl isomers to the canister (Arey, personal communication). Zielinska and co-workers (1996) evaluated measurement methods for VOCs up to C2() emitted from motor vehicles and reported that C8-Cl2 hydrocarbons were more stable on the Tenax cartridge than in canisters. Similar problems with canister sampling for organics are discussed in Chapter ll.A.4e. 

A method for sampling and analysis of the metallic dusts and fumes is necessary to assess the exposure of workers to these dusts. Personal sampling devices are used to collect samples from the work-place atmosphere in a representative manner. The samples are then analyzed by convenient analytical techniques such as atomic absorption spectroscopy. 

Collection of airborne particulates in workplace atmospheres can be achieved effectively by a variety of filtering media which are amenable to use with personal sampling devices. Extraction of the particulates from the filters with suitable solvents results in solutions which may then be analyzed by the developed analytical technique. 

Passive samplers are not useful to monitor peak concentrations, but offer a convenient way to regard for example, long term exposure of persons in an indoor environment. A more detailed description of the passive sampling technique is given in Chapter 3. 

There are several future trends for the development of passive sampling techniques. The first is the development of devices that can be used to monitor emerging environmental pollutants. Recently, attention has shifted from hydrophobic persistent organic pollutants to compounds with a medium-to-high polarity, for example, polar pesticides, pharmaceuticals, and personal care products.82 147148 Novel materials will need to be tested as selective receiving phases (e.g., ionic liquids, molecularly imprinted polymers, and immunoadsorbents), together with membrane materials that permit the selective diffusion of these chemicals. The sample extraction and preconcentration methods used for these devices will need to be compatible with LC-MS analytical techniques. 

Exposure assessment is done under the strong assumptions that (1) an adequate model for exposure calculation is on hand and (2) sufficient data about all influential exposure factors are available. The calculation is a prognosis about the expected level of exposure or the burden. Direct methods of exposure assessment, such as personal sampling (air, radiation), duplicate studies (nutrition) and human biomonitoring, provide information on a measurement level. The exposure assessors and the risk managers should balance the reasons for using prognostic techniques instead of direct exposure measurement methods. Both should anticipate critical questions about the validity of the exposure assessment technique in the course of public risk communication. Questions heard by the authors from concerned persons include, for example ... 

In the development of an analytical method, it may be assumed that it must be usable over a range of concentrations from about 10% (25% at minimum) of the limit value to 300% of the Hmit value. For practical control of workplaces, several sampling techniques are available. In principle, one can distinguish between active and passive, personal, and stationary sampling techniques. 

For the determination of the median shift concentration, which allows for direct comparison with the occupational exposure level (OEL-value), several sampling techniques are available. The most commonly used method is, Personal Air Sam-... 

Indirect analytical methods have a high significance for personal exposure measurements in regard to ha2ardous chemicals at workplaces. Though most indirect methods are based on active sampling techniques, passive sampling devices have also been developed. 

The personal samples on the chest and back allow an estimate of pesticide exposure based on the standard technique of extrapolating from patch to total body region. The standard method only considers unprotected regions of the body to be exposed. In this case, only the head and neck of the workers are unprotected, and in four of six cases face shields were worn. Thus, beyond a comparison of head and neck exposure for workers 1 and 2, it is not clear how the patch technique could be applied in this study. Later in this paper the patch data will be employed to make this comparison. These... 

Occupational skin diseases health and safety precautions Acrylonitrile personal protective equipment Control of lead air sampling techniques and strategies Control of lead outside workers Control of lead pottery and related industries Control of exposure to polyvinyl chloride dust Control of exposure to talc dust Atmospheric pollution in car parks Benzidine based dyes. Health and safety precautions Probable asbestos dust concentrations at construction premises Work with asbestos cement Work with asbestos insulating board Ozone health hazards and precautionary measures Occupational exposure limits (updated yearly)... 

Suppose the sampling technique makes it equally likely that any person or point is chosen when a random selection is made. Then p is the probability that the response is yes or inside the curve. Assign a numerical value of 1 to yes or inside the curve. Assign 0 to the complement. The average (the expected value) for the entire population is ... 

It is most appropriate to consult an IH when selecting personal protective equipment for a specific use such as which gloves are best for use with certain chemicals and which respirator should be used for exposure to a specific chemical. The IH is the only one who has the training and experience to determine the risk for exposure, the environmental sampling that is needed, the sampling techniques to use, and the controls that should be in place to prevent further exposure. 

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