Review of refractory ceramic fiber (RCF) toxicity, epidemiology and occupational exposure

Abstract

This literature review on refractory ceramic fibers (RCF) summarizes relevant information on manufacturing, processing, applications, occupational exposure, toxicology and epidemiology studies. Rodent toxicology studies conducted in the 1980s showed that RCF caused fibrosis, lung cancer and mesothelioma. Interpretation of these studies was difficult for various reasons (e.g. overload in chronic inhalation bioassays), but spurred the development of a comprehensive product stewardship program under EPA and later OSHA oversight. Epidemiology studies (both morbidity and mortality) were undertaken to learn more about possible health effects resulting from occupational exposure. No chronic animal bioassay studies on RCF have been conducted since the 1980s. The results of the ongoing epidemiology studies confirm that occupational exposure to RCF is associated with the development of pleural plaques and minor decrements in lung function, but no interstitial fibrosis or incremental lung cancer. Evidence supporting a finding that urinary tumors are associated with RCF exposure remains, but is weaker. One reported, but unconfirmed, mesothelioma was found in an individual with prior occupational asbestos exposure. An elevated SMR for leukemia was found, but was absent in the highly exposed group and has not been observed in studies of other mineral fibers. The industry will continue the product stewardship program including the mortality study.

Non-Malignant Respiratory Illnesses in Association with Occupational Exposure to Asbestos and Other Insulating Materials: Findings from the Alberta Insulator Cohort

“…However, apart from the only available safety data sheet from the National Institute of Occupational Safety and Health (NIOSH) [ 19 ], information on health-related issues due to occupational exposure to aerogels is not available. Among other MMVFs, mineral fibers and refractory ceramic fibers have been identified as potential respiratory hazards, and their inhalation may lead to pulmonary carcinoma [ 20 ], adverse pleural conditions [ 21 , 22 ], and to some extent, interstitial changes in the lungs [ 23 ]. However, whether these MMVFs are associated with any chronic respiratory illnesses has not been systematically investigated.…”

Rounded Atelectasis After Exposure to Refectory Ceramic Fibres - A Case Report

“…and silicon oxide (SiO 2 ) in approximately proportion or in combination with minor amounts of other inorganic oxides (1). Therefore the RCF were named also as aluminium silicate bres.…”

“…RCF were produced from melting and blowing or spinning process. As manufactured, RCF are in the form of bulk bres (1). The diameter of the bres depends on process parameters.…”

“…Respirable bres with the greatest toxicological potential are WHO bres with a length > 5 µm, a diameter ≤ 3 µm and the length to diameter ratio of at least 3:1. These bres impede clearance by alveolar macrophages (1). Lockey et al (2) showed that RCF can persist in human lung tissue for more than 20 years after exposure.…”

Improvement in heat resistivity of alkaline earth silicate fiber boards by Al4SiC4 coating

“…In recent years, the use of refractory ceramic fiber (RCF) products has increased due to their lightweight, high‐thermal resistivity and high‐thermal insulating properties. However, the International Agency for Research on Cancer has designated RCF as cancer risk category 2 . The Japanese Ministry of Health, Labor and Welfare also designated RCF as a cancer risk material in November 2015.…”