Refractory Ceramic Fibres
Full Profile
General Information
Refractory ceramic fibres (RCFs) belong to a class of fibres called man-made vitreous fibres (MMVFs), which are primarily valued for their insulating qualities.[1] Raw refractory ceramic fibres are white or gray fibrous materials supplied in bulk fibre, blanket form or contained in a solid product.[2]
RCFs are produced when raw materials (kaolin clay, Al2O3, SiO2 and sometimes ZrO2) are melted, then spun or blown into alumino-silicate fibres with average diameters between 1.2 to 3.5mm.[2,3] The fibres differ from natural mineral fibres like asbestos in that they have an amorphous structure (i.e. not crystalline) and they tend to be less durable.[3,4] At temperatures above 1000°C, RCFs can be transformed into crystalline silica (cristobalite).[2] Please refer to the CAREX Canada profiles for Silica (Crystalline) and Asbestos for more information about these substances.
Refractory ceramic fibres have been classified by IARC Group 2B, possibly carcinogenic to humans, based on an increased risk of lung cancer and mesothelioma in experimental animals.[1] Pleural plaques, common in asbestos-exposed workers, are also reported to be present in people working with RCFs.[1]
Additional adverse health effects from inhalation exposure include respiratory irritation, often resulting in sore throat, nasal congestion and cough.[4] Dermal exposure can result in contact dermatitis and itching.[6]
Refractory ceramic fibres have been ranked by CAREX Canada as Group A (immediate high priority) for occupational settings. Prioritization was based on the carcinogenicity and other toxic properties of the substance, the prevalence of exposure in Canada, and the feasibility of assessing exposure.
Regulations and Guidelines
Occupational Exposure Limits (OEL)
| Canadian Jurisdictions | OEL (f/cc) |
|---|---|
| Canada Labour Code | 0.2 [f] |
| BC, AB, MB, NB, NL, PE, NS |
0.2 [f] |
| SK | 0.2 [f,ds] |
| ON | 0.5 [f] |
| QC | 1 |
| YT, NT, NU | Not listed |
| Other Jurisdiction | OEL (f/cc) |
| ACGIH 2011 TLV | 0.2 [f] |
Canadian Environmental Guidelines
| Jurisdiction | Limit | Year |
|---|---|---|
| Residential Indoor Air Quality | Minimize exposure during renovations and installations. Materials and products to be examined for deterioration. |
1987[8] |
Canadian Agencies/Organizations
| Agency | Designation/Position | Year |
|---|---|---|
| CEPA | Schedule 1, paragraph ‘c’ (human health) | 1999[10] |
Main Uses
Because of their high thermal resistance, refractory ceramic fibres are used in high temperature applications such as furnace linings and doors, kilns, catalytic converters, brake pads and heat shields.[2]
Canadian Production and Trade
In 2004, there was one Canadian producer of RCFs.[2] The majority of RCFs used in Canadian industry were imported from the United States.[2] Several Canadian factories use bulk RCF for the manufacture of products to be sold in other industries.[2]
Occupational Exposures
Inhalation is the most important route of occupational exposure.[5]
The main occupations exposed include workers involved in the manufacture, processing or use of products containing RCFs.[5] Industries using RCF end products include steel, petrochemical, ceramic, automotive, and metal industries.[2] Other potentially exposed workers are involved in installing high-temperature installation materials, demolition work, and maintenance and repair.[6]
Removal of refractory ceramic fibre insulating material from industrial furnaces and walls has resulted in some of the highest concentrations measured in occupational settings.[6]
Environmental Exposures
RCF exposure to the general public is expected to be low. However, uncertainty about releases and environmental concentrations prompted CEPA to conclude in 1993 that RCFs may enter the environment in quantities or under conditions that may constitute a danger in Canada to human life or health.[3] Potential sources of environmental exposure include inhalation of fibres when materials containing RCFs are physically disturbed.[6]
Lack of data on RCF concentrations in Canadian air, water, sediment or soil prompted an agreement between the Canadian government and the RCF industry to monitor environmental exposures for a limited time period.[13] Data from the US indicates that environmental levels are low, and that occupational levels are declining with the implementation of a stewardship program.[13]
RCF releases are not reportable to the National Pollutant Release Inventory (NPRI).[15] No consumer products containing RCF were found in the US Household Products Database.[16]
Sources
- IARC monograph summary, Volume 81 (2002)
- Occupational health Clinics for Ontario Workers Inc (2004) Refractory Ceramic Fibres
- Priority Substances List assessment report (CEPA) for Mineral Fibres (Man-Made Vitreous Fibres) (1993)
- NIOSH (2006) Criteria for a Recommended Standard - Occupational Exposure to Refractory Ceramic Fibres
- NTP 12th Report on Carcinogens for Ceramic Fibres (Respirable Size) (2011)
- ATSDR Toxicological Profile for Synthetic Vitreous Fibers (2004)
- Health Canada (2010) Guidelines for Canadian Drinking Water
- Exposure Guidelines for Residential Indoor Air Quality (1987)
- Health Canada’s Prioritization of the DSL
- CEPA List of Toxic Substances
- Health Canada (2011) Cosmetic Ingredient Hotlist
- Health Canada (2006) Food Additives Permitted for Use in Canada
- Environment Canada: Strategic options for the management of toxic substances: Refractory Ceramic Fibres
- Government of Canada (2010) Chemicals Management Plan – List of all Challenge Substances
- The National Pollutant Release Inventory
- Household Products Database (US)
Other Resources
- Hazardous Substances Data Bank (search term: Synthetic Vitreous Fibers)
- Environment Canada, CEPA Substance Detail, Refractory Ceramic Fibers
- INCHEM (1988) Environmental Health Criteria 77: Man Made Mineral Fibres