Survey of the Biological Effects of Refractory Ceramic Fibres: Overload and Its Possible Consequences

doi:10.1093/annhyg/meh098

Cited by 20 publications

(3 citation statements)

References 66 publications

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“…However (Brown et al., 2005) the RCF study may have been compromised by overload resulting from use of a test substance that was not representative of that found in the workplace.…”

Section: Animal Studiesmentioning

confidence: 99%

“…It builds upon earlier work (Brown et al., 2005; Mast et al., 2000a; Utell & Maxim, 2010) seeking to understand the relevant toxicological and epidemiological data on this fiber. Briefly, we conclude that there are many similarities between RCF and traditional rock wool 1 …”

Section: Introductionmentioning

confidence: 99%

“…The RCC studies were believed to be the “state of the art” at the time. However, subsequent analysis of these studies concluded that overload was likely (Mast et al., 2000a,b) – chiefly due to a high and non-representative amount of particles in the exposure aerosol (Maxim et al., 1997) – and it was not possible to assess the relative contribution of these particles to the observed response (Brown et al., 2005, references therein). The IARC Working Group acknowledged possible confounding (IARC, 2002, p. 233):

“The Working Group noted that the greater particulate fraction of RCF 1 could have influenced the development of inflammation and subsequent carcinogenic response in the chronic inhalation studies of RCF 1.

…”

Section: Introductionmentioning

confidence: 99%

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Perspectives on refractory ceramic fiber (RCF) carcinogenicity: comparisons with other fibers

Greim

Utell

Maxim³

et al. 2014

Inhalation Toxicology

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In 2011, SCOEL classified RCF as a secondary genotoxic carcinogen and supported a practical threshold. Inflammation was considered the predominant manifestation of RCF toxicity. Intrapleural and intraperitoneal implantation induced mesotheliomas and sarcomas in laboratory animals. Chronic nose-only inhalation bioassays indicated that RCF exposure in rats increased the incidence of lung cancer and similar exposures resulted in mesothelioma in hamsters, but these studies may have been compromised by overload. Epidemiological studies in the US and Europe showed an association between exposure and prevalence of respiratory symptoms and pleural plaques, but no interstitial fibrosis, mesotheliomas, or increased numbers of lung tumors were observed. As the latency of asbestos induced mesotheliomas can be up to 50 years, the relationship between RCF exposure and respiratory malignances has not been fully determined. Nonetheless, it is possible to offer useful perspectives. RCF and rock wool have similar airborne fiber dimensions and biopersistence. Therefore, it is likely that these fibers have similar toxicology. Traditional rock wool has been the subject of numerous cohort and case control studies. For rock wool, IARC (2002) concluded that the epidemiological studies did not provide evidence of carcinogenicity. Based on analogies with rock wool (read across), it is reasonable to believe that increases in lung cancer or any mesotheliomas are unlikely to be found in the RCF-exposed cohort. RCF producers have developed a product stewardship program to measure and control fiber concentrations and to further understand the health status of their workers.

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“…However (Brown et al., 2005) the RCF study may have been compromised by overload resulting from use of a test substance that was not representative of that found in the workplace.…”

Section: Animal Studiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Perspectives on refractory ceramic fiber (RCF) carcinogenicity: comparisons with other fibers

Greim

Utell

Maxim³

et al. 2014

Inhalation Toxicology

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Refractory Ceramic Fiber (Alumino Silicate Wool)

Harrison¹

2023

Patty's Toxicology

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Refractory ceramic fiber (RCF) belongs to the group of fibrous materials known as man‐made vitreous fibers (MMVF) or synthetic vitreous fibers (SVF). It is produced from molten mineral raw material, predominantly silica, and alumina. RCFs may be sold in the form of loose wool, blankets, boards, or vacuum‐formed shapes. Products made from RCF are generally used at application temperatures above 900°C in industrial equipment such as furnaces and kilns. Individual fibers may be released into the air during manufacture, handling, use, decommissioning, and disposal. As with other fibrous materials, inhalation and consequent effects on the lungs are considered to be the most important health concerns, and sampling airborne fiber concentration is therefore the focus of exposure assessment. RCF is classified as possibly (or presumed to be) carcinogenic to humans and is subject to various national workplace exposure limits or guidelines. Also, like other SVFs, RCF can cause acute mechanical irritation to the skin and eyes. Epidemiological studies have demonstrated no increases in all‐cause mortality or mortality from lung cancer or all cancers combined in RCF‐exposed workers; overall, it is concluded that occupational exposure to RCF is associated with the development of pleural plaques and minor decrements in lung function but not interstitial fibrosis or increased lung cancer.

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Rock Wool and Refractory Ceramic Fibers

Rice¹

2012

Patty's Toxicology

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Man‐made vitreous fibers (MMVFs) is a generic descriptor for a group of fibrous materials made from melting inorganic substances such as sand, clay, glass, or slag. Synthetic vitreous fibers (SVFs) or man‐made synthetic vitreous fibers (MSVFs) may also be used to describe these groups of materials. These terms have generally replaced earlier use of man‐made mineral fibers (MMMFs). MMVF are further classified by the raw material used in production; major categories include glass fibers (glass wool or continuous filament), mineral wool (rock or slag), and refractory ceramic fibers. The latter two types are covered in this chapter. Within each category, a variety of commercial products have been produced and may be identified by manufacturer and product name and number. Each has a slightly different formulation and characteristics; therefore, it is important wherever possible to identify the particular product number. Dimension, durability, and dose delivered to the target organ are critical factors in the toxicity of MMVF. MMVF are characterized by length ( L ) and diameter ( D ). The arithmetic mean or median of the observed distribution of lengths and diameters may be given as the count mean or median diameter (CMD) or length (CML). If the observed values are transformed by taking the natural logarithm of the measured parameters, the geometric mean (GM) of each dimension may be given with a geometric standard deviation (GSD). The size determinations may be made by either scanning (SEM) or transmission electron microscopy (TEM). TEM has the lower limits of detection by which investigators can characterize fibers with diameters in the nanometer range. Dose by some routes of administration may be further described by the mass of material, for example, in implantation or single bolus injection studies. For inhalation studies, GM and GSD length and diameter are usually listed for the exposure aerosol, and often the number of fibers within specific size ranges is listed. Following inhalation, fibers may be deposited on surfaces within the respiratory tract or exhaled. For the fibers that are deposited, the site of deposition (dose) depends upon the characteristics of the fiber and results from one of the five mechanisms: impaction, interception, sedimentation, electrostatic precipitation, or diffusion. The majority of the deposition of MMVF is probably governed by the first three mechanisms. Impaction and interception occur when the fiber is removed from the airstream by physically contacting the surface of the airway or a bifurcation. Sedimentation occurs in the lower airways, where the velocity of the fiber becomes low enough for it to settle on the airway surface. Electrostatic precipitation results when the fiber carries a charge opposite to that of the airway surface; for mineral wool fibers, no reports have been found on surface charge measurements. Deposition due to diffusion requires that the air molecules collide with the fiber, resulting in movement toward the surface. This mechanism could contribute to deposition of very thin fibers, for example, those with diameters substantially less than one‐half micrometers, but few of them are expected in the work environment. The clearance mechanism of the deposited fibers depends upon the characteristics of the fiber and the site of deposition. Fibers deposited in the tracheobronchial region are cleared with the mucous by the cilia and swallowed. This process is completed in a matter of days, during which little change in fiber dimensions would be anticipated. Fibers deposited lower in the respiratory tract are cleared more slowly. Here the fibers are cleared by translocation to another area of the lung or dissolve; translocation may be facilitated by partial dissolution of the fiber or breakage into particles of shorter length. When fibers recovered from the lung or other tissues are characterized by dimensions, a comparison with the parent material provides information on deposition and distribution.

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Survey of the Biological Effects of Refractory Ceramic Fibres: Overload and Its Possible Consequences

Cited by 20 publications

References 66 publications

Perspectives on refractory ceramic fiber (RCF) carcinogenicity: comparisons with other fibers

Perspectives on refractory ceramic fiber (RCF) carcinogenicity: comparisons with other fibers

Refractory Ceramic Fiber (Alumino Silicate Wool)

Rock Wool and Refractory Ceramic Fibers

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