Exposure analytical methods

The reader is referred to Toxicological Profile for Lead [37] for a comprehensive report on lead, including public health statement health effects summary chemical and physical information production, import, use, and disposal information description of the potential for human exposure analytical methods used in monitoring health effects regulations and advisories a valuable glossary and a comprehensive reference list. The US Center for Disease Control and US Environmental Protection Agency also maintain extensive databases on lead. 

Because of the extreme toxicity of this material and the possibiUty it could be present in failed circuit breakers containing decomposed SF, several studies have been carried out to develop analytical methods and investigate possible ways to minimize environmental exposure. One method capable of determining S2F2Q in the ppb range has been reviewed (123). 

The evaluation phase of industrial hygiene is the process of making measurements on some set of samples which permits a conclusion about the degrees of hazard. Before conducting an evaluation, it is necessary to make a number of choices of what and where to sample, when to sample, how long to sample, how many samples to take, what sampling and analytical methods to use, what exposure criteria to use in the analysis of the data, and how to report the results. These choices as a whole constitute the evaluation plan. The object is to find if one or more workers have an unacceptable probabiUty of being exposed in excess of some estabUshed limit. 

Sensitivity. The sampling and analytical method together should ideally have a limit of detection much less than the exposure limit. Less sensitive methods are stiU usable, however, as long as the limit is easily within the range of the method. 

Operations capable of generating airborne beryUium particulate, such as melting, machining, welding, grinding, etc, are effectively controUed by local exhaust ventilation or other control measures. To assure a safe environment and measure compliance with the OSHA standards, employee exposures should be periodicaUy measured by prescribed air sampling and analytical methods. 

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. 

Sampling and analytical error (SAE) A numerical factor used in analytical methods to account for uncontrollable errors. Its value is taken into consideration in the determination of whether the exposures are within acceptable limits. 

The purpose of this chapter is to describe the analytical methods that are available for detecting, measuring, and/or monitoring methyl parathion, its metabolites, and other biomarkers of exposure and effect to methyl parathion. The intent is not to provide an exhaustive list of analytical methods. Rather, the intention is to identify well-established methods that are used as the standard methods of analysis. Many of the analytical methods used for environmental samples are the methods approved by federal agencies and organizations such as EPA and the National Institute for Occupational Safety and Health (NIOSH). Other methods presented in this chapter are those that are approved by groups such as the Association of Official Analytical Chemists (AOAC) and the American Public Health Association (APHA). Additionally, analytical methods are included that modify previously used methods to obtain lower detection limits and/or to improve accuracy and precision. 

GC/MS has been employed by Demeter et al. (1978) to quantitatively detect low-ppb levels of a- and P-endosulfan in human serum, urine, and liver. This technique could not separate a- and P-isomers, and limited sensitivity confined its use to toxicological analysis following exposures to high levels of endosulfan. More recently, Le Bel and Williams (1986) and Williams et al. (1988) employed GC/MS to confirm qualitatively the presence of a-endosulfan in adipose tissue previously analyzed quantitatively by GC/ECD. These studies indicate that GC/MS is not as sensitive as GC/ECD. Mariani et al. (1995) have used GC in conjunction with negative ion chemical ionization mass spectrometry to determine alpha- and beta-endosulfan in plasma and brain samples with limits of detection reported to be 5 ppb in each matrix. Details of commonly used analytical methods for several types of biological media are presented in Table 6-1. 

Methods to determine the a.i., and/or relevant metabolites in air during or shortly after the application must be submitted unless it can be justified that exposure of operators, workers, or bystanders does not occur. In SANCO/825/00 it is stated that spray drift and particle-associated as well as gaseous substances have to be taken into consideration because both can cause relevant exposure of operators, workers, or bystanders. Therefore, an analytical method must also be submitted for relevant substances with a low vapor pressure (< 10-5 Pa). 

As probabilistic exposure and risk assessment methods are developed and become more frequently used for environmental fate and effects assessment, OPP increasingly needs distributions of environmental fate values rather than single point estimates, and quantitation of error and uncertainty in measurements. Probabilistic models currently being developed by the OPP require distributions of environmental fate and effects parameters either by measurement, extrapolation or a combination of the two. The models predictions will allow regulators to base decisions on the likelihood and magnitude of exposure and effects for a range of conditions which vary both spatially and temporally, rather than in a specific environment under static conditions. This increased need for basic data on environmental fate may increase data collection and drive development of less costly and more precise analytical methods. 

Methods for Determining Biomarkers of Exposure and Effect. Analytical methods with satisfactory sensitivity and precision are available to determine the levels of americium in human tissues and body fluids. However, improved methods are needed to assess the biological effects of americium in tissues. 

Methods for Determining Parent Compounds and Degradation Products in Environmental Media. Analytical methods with the required sensitivity and accuracy are available for quantification of americium, both total and isotopic, in environmental matrices (see Table 7-2). Knowledge of the levels of americium in various environmental media, along with the appropriate modeling (see Chapters 3 and 5), can be used to evaluate potential human exposures through inhalation and ingestion pathways. 

This new analytical method determines the rate constant and activation energy of Kevlar s photooxidative processes. The 0.2 atm of oxygen-18-labelled environment in a solar chamber simulates the air-exposure under sunlight conditions. The technique also allows the radial 0-distribution measurement from the fiber surface toward the fiber center. The data from the accelerated experimental conditions in the solar chamber in an 02-atmosphere are differentiated from the usual daylight exposure effects. 

Polyalphaolefin Hydraulic Fluids. No methods were identified for determining biomarkers of exposure or effect. Nonetheless, the available analytical methods for identifying C15 50 alkanes in biological tissues could be used to determine exposure levels (Ferrario et al. 1985a, 1985b Hesselberg and Seelye 1982). 

The industry task forces (ARTF, ORETF, and others) are generating model protocols, efficient and accurate methods of sample collection, and analytical methods of appropriate detectability for use in field-worker exposure studies. Subsequently, the task forces are conducting field studies that will generate data for inclusion in several generic databases. It is understood that the databases will be the property of the member companies who have financed the work of the task forces. It is hoped, however, that the task forces will see fit to publish their protocols, methods, study designs, and other useful information in a volume like this one so that other scientists working in this discipline may access the information. 

Nowadays, best practice is to combine both modelling and analysis of chemicals for an appropriate assessment of chemical exposure in environmental scenarios. Future research activities should focus on the development of reliable analytical methods at trace level concentrations. 

A number of the previously cited investigators3->2>5 9 have employed UV spectroscopy as an analytical tool for following PC degradation. We have found the measurement of UV spectra of weathered PC films by difference from an unexposed reference sample to be an extremely simple and useful analytical method. This nondestructive analysis allows the repetitive return of a sample to the exposure conditions and thus enables one to essentially perform continuous analyses on the same sample. This technique, of course, will not detect the formation of non-chromophoric products such as aliphatic oxidation products which may form during the degradation. 

Exposure Levels in Environmental Media. Existing studies have not provided data on acrylonitrile levels in typical ambient air. Studies using analytical methods with lower detection limits would be helpful in determining if ambient air is an exposure medium of concern. Because higher levels of... 

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