Asbestos detection limits

In the past, filters made from asbestos were employed in the preparation of wines, beers, and other items consumed by humans, and asbestos concentrations in these materials ranged Ifom 1 to 10 MFL (Cunningham and Pontefract 1973). Analysis of 47 brands of sake purchased in Japan from 1983 to 1985 indicated that asbestos concentrations in sake ranged Ifom less than the detection limit (7.8x10 MFL) to 196MFL(Oginoetal. 1988). 

The purpose of this chapter is to describe the analytical methods that are available for detecting, measuring, and/or monitoring asbestos, its metabolites, and other biomarkers of exposure and effect to asbestos. 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 ERA 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. 

For the analysis of asbestos fibers in air, a sample of air is drawn through a filter by a vacuum pump (usually at a flow-rate of around 1-2 L/minute), and the fibers retained on the filters are examined microscopically. The sensitivity of the methods depends on the volume of air drawn through the filter and the microscopic method employed. In the workplace, where PCM is the standard method, the theoretical detection limit for a short-term sample (15 minutes) is around 0.04 PCM f/mL, but may be reduced to 0.001 f/mL using an 8-hour sample (NIOSH 1976). In practice, such low detection limits are not readily achievable, and measured values below 0.1 PCM 17mL should not usually be considered reliable (ASTM 1988). Sensitivity of TEM methods for ambient or indoor air are usually around 0.1-1 ng/m. ... 

During the analyses background counts were carried out on a certain number of blank filters of each batch used and, when they exceeded 10 percent of the sample counts, the number of blank fibre count was subtracted from the total number of fibre counts found for the samples. The minimum detectable concentration of asbestos fibres varies with the volume of the liquid passed through the filter, which depends on the amount of the background particles present in the liquid. For the experimental conditions of this study the detection limit (SEM counts) typically ranged from 0.03 MFL to 0.08 MFL. 

If these materials are weighed and were detected from within a 1 kg sample of soil, then it is possible to calculate (using density correction factors) a result that can be expressed as a percentage weight-to-weight of asbestos in soil. Using this method, it is possible to achieve a detection limit of between 0.001 and 0.01% w/w (10-100 mg/kg), depending upon the sample matrix. 

The CIPE plan called for a remediation of asbestos-containing materials in the Etemit and in the ILVA steelwork factories. Ninety percent of the buildings, squares, and sites were cleared of asbestos by March 4,2000. During the remediation activities, and in coordination with the local Health Unities (ASL)), a series of control samples were collected. 915 samples were analyzed to evaluate the presence of aerially dispersed asbestos fibers in nearby locations. No values exceeding WHO limits were detected. 1044 samples and analyses from the Etemit site and 56 from the ILVA site were also collected to monitor fiber dispersion inside the area of the operations. 

Asbestos fibers have also been measured in urine (see Section 7.1), and limited data indicate that above average exposures in the workplace (Finn and Hallenbeck 1984) and through drinking water (Cook and Olson 1979) can be detected by this means. However, only a tiny fraction of inhaled or ingested fibers is... 

The effect of this new policy will be the development, whenever possible, of quantitative RELs that are based on human and/or animal data, as well as on the consideration of technological feasibility for controlling workplace exposures to the REL. Under the old policy, RELs for most carcinogens were non-quantitative values labeled lowest feasible concentration (LFC). [Note There are a few exceptions to LFC RELs for carcinogens (e.g., RELs for asbestos, formaldehyde, benzene, and ethylene oxide are quantitative values based primarily on analjdical limits of detection or technological feasibility). Also, in 1989, NIOSH adopted several quantitative RELs for carcinogens from OSHA s permissible exposure limit (PEL) update.]... 

Although the percentage of asbestos in the vermiculite may be below the limit normally treated as asbestos, the elevated levels detected upon disturbance indicate that asbestos precautions will be necessary to protect the workers performing removal and to prevent contamination of the rest of the building or home. These precautions include ... 

Chest radiographs are limited with respect to sensitivity and specificity in the detection of mild or early asbestosis (Fig. 3.1.4.). Among individuals with asbestosis confirmed by histopathological findings, 15-20% had no radiographic evidence of parenchymal fibrosis (Kipen et al. 1987), similar to the proportion of other interstitial lung diseases that present with normal chest films (Epler et al. 1978). More recent studies have shown that between 5% (Paris et al. 2004) and 30% (Lee et al. 2003) of subjects with documented asbestos exposure and pulmonary... 

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