This article will give an overview of the types of different man-made mineral fibres and the associated occupational health and safety issues. The different kinds of fibres are defined by specific geometric parameters (length, diameter and ratio between them, the so-called aspect ratio) and their biopersistence. These parameters also define their hazard potential and potency, especially with regard to carcinogenicity. Some examples of fibres, including their risk potential (hazard, exposure) and use pattern will be described focusing on possibilities and successful stories of substitution. The reader will learn what man-made mineral fibres are, which factors determine their risks to human health and information of the putative and established substitutions of carcinogenic fibres. For more details on the group of fibres known as man-made vitreous fibres (MMVF) the WHO publication on this topic provides extensive information[1].
Man-made mineral fibres (MMMF)
Man-made mineral fibres are produced from natural and synthetic raw minerals. The most important product groups are mineral wools, high temperature glass wools (alkaline earth silicate fibres – AES), refractory ceramic fibres (RCF) and (poly-)crystalline fibres (PCW – polycrystalline wools). The main field of application is thermal insulation. Mineral wools, AES and RCF belong to a sub-group called man-made vitreous fibres (MMVF), which are also used for filtration, soundproofing and some other minor purposes not discussed in this article. The term vitreous is mainly used to distinguish the polymorph (glass-like) fibres from the crystalline fibres. These woollen materials consist of fibres with random orientation and a broad range of fibre diameters. In contrast to this, synthetic glass filaments, which are used for fire-protecting textiles, consist of drawn fibres of a similar profile (they are aligned). PCWs are crystalline and therefore not vitreous. For all MMMF, the fibre structure provides mechanical properties like flexibility, which removes the need for expansion joints and gives a high resistance against damage through e.g. vibrations and a high thermal shock resistance. The fibrous structure on the other hand may lead to specific human health hazards; the carcinogenic properties of the well known fibrous mineral asbestos (which is actually a natural and not a man-made fibre) are the warning example.
The fibre principle - Carcinogenic potential and potency
MMMF may pose a risk to humanhealth, if respirable fibres are released during production and handling of insulation products. Fibres are long and slender particles. Length, diameter and the aspect ratio between the two are the physical parameters used to characterise fibres. Typically the term fibre is used if the length to diameter ratio is 3:1 or greater. From a toxicological viewpoint the biosolubility – the time for fibres to disintegrate in biological media– is of significant importance [1][3].
The specific and unique mode of toxic action of respirable biopersistent fibres is described as the fibre paradigm or the 3D-principle. The 3D’s are Dose, Dimension and Durability which determine the unique chronic toxicity of fibres leading to lung cancer and mesothelioma. This principle was formulated by Pott[4] and Stanton[5] and is the scientific basis for the regulation of fibre toxicity.
The most commonly used definition to describe fibres critical to human health was established by the World Health Organisation (WHO) in 1997. It defines fibres that have an aspect ratio of 3:1 or greater, a diameter below 3 µm and a length greater then 5 µm [6].
The cut-off value of 3 µm was set due to the fact that such fibres can reach the alveolar region of the human lung – such fibres are respirable. The length of these respirable fibres has a direct effect on the carcinogenic potency – the longer the more potent they are. With respect to diameter of respirable fibres, the impact on carcinogenic potency is less clear. The biopersistency – or biosolubility as its reciprocal if the fibre is solvable – also has got a direct effect on the carcinogenic potency, the longer the fibre remains in the lung the more potent it is. The oxidative stress created by macrophages not being able to phagocytise and disintegrate fibres leads to chronic inflammations and then possibly to tumour development on the long run [7][8].
The chemical composition of the fibrous material determines the biopersistency and therefore provides an important key to design safer materials for thermal insulation.
Still, the carcinogenic properties are not directly based on chemical composition, but on geometric properties (fibre structure) combined with biopersistency (which is based on chemical composition). It should be kept in mind that the chemical composition is not the crucial parameter leading to human health hazard, but the specific physical form. In other words, if fibres are respirable and sufficiently biopersistent, they are carcinogenic independent of their chemical identity or composition.
For vitreous fibres, which have a similar density compared to asbestos, the WHO fibres can be regarded as the fraction of respirable fibres, able to enter the alveolar region of the human lung. The WHO fibre definition has got an important regulatory role in occupational safety and health (e.g. survey of exposure limits) as it is the basis for the quantification of critical fibres at workplaces.
For the legislation on worker protection [9] and chemical safety (CLP)[2](REACH)[11], the ability of a MMMF product to release WHO fibres has to be considered. The EU classification criteria for mineral wool and refractory ceramic fibres are limited to fibres with a length weighted geometric mean diameter less than two standard geometric errors smaller than 6 µm. This has to be proven by the manufacturer or importer on the basis of a corresponding method for determining the geometric parameters.
Research in fibre toxicology has shown that the knowledge of the biological half-life of WHO fibres in the human lung is a good parameter for the carcinogenic potency of a fibre. A significant hazard can be assumed if specific animal experiments show a long half-life (is biopersistent) or, respectively, a low biosolubility. In relation to biopersistence, the EU Scientific Committee on Occupational Exposure Limits (SCOEL) states that all inorganic fibres with critical dimensions are suspected of having a carcinogenic potential and therefore are classified a priori as category 3 carcinogens (cause concern for man owing to possible carcinogenic effects shown from animal studies). This classification need not apply it can be shown that the fibre fulfils one of a number of conditions including:
a short-term biopersistence test by inhalation showing that the fibres longer than 20 µm have a weighted half-life of less than 10 days;
a short-term biopersistence test by intratracheal instillation showing that the fibres longer than 20 µm have a weighted half-life of less than 40 days[12].
In Germany, a half-life of more than 40 days has been chosen by the Hazardous Substances Committee as a borderline for applying additional controls at the workplace. For vitreous mineral wools a carcinogenicity index was derived from their chemical composition, which serves as a starting point for the production of safe, biosoluble products for thermal insulation.
In summary, if a fibre product contains or may release fibres or fibre dust [3] containing WHO fibres, a carcinogenic risk may exist. The potency of the carcinogenic potential is based on the biopersistence of the fibres – the longer the half-life the higher the risk. The potency ranges from not existing (high biosolubility) up to higher than asbestos-like.
Another problem arising from the fibre structure is physical effect on the upper layer of the skin. Continuous work with fibres (without protection) can cause small skin lesions. These lesions might increase the amount of dermal absorption of other chemicals handled at the same time or may boost their irritating or sensitizing effects. The former classification for some fibres included a classification as irritant, but it was removed due to the effect being based on physical and not chemical properties. The decision was taken in the technical committee on classification and labelling at the meeting in March 2006. Therefore fibres are not irritants themselves and the term ‘itching’ is used to describe the risk of physical lesions/uncomfortable feelings during work with the fibre.
Types of MMMF (Mineral Wools, AES, RCF, PCW)
Mineral wools
Mineral wools, first synthesised in the mid 19th century, are vitreous fibres made from natural or synthetic minerals. They are typically composed of alkalines, earth alkalines and silicates. The term mineral wool describes a wide margin of different fibres which are used for insulation purposes at temperature ranges up to 600 °C. They are mainly used for the insulation of buildings. Mineral wools are listed in the Annex VI of CLP under the Index No. 650-016-00-2 ‘[Man-made vitreous (silicate) fibres with random orientation with alkaline oxide and alkali earth oxide (Na2O+K2O+CaO+MgO+BaO) content greater than 18 % by weight]’ and are legally classified as Carc. 2; H351 – suspected of causing cancer. Additionally, in Germany the fibrous dust from mineral wools is regarded as carcinogenic. They must be handled at workplaces under the provision of the EU Carcinogens Directive 2004/37/EC [14]. The EU classification [15] offers drop-out conditions for fibres with a low carcinogenic potency. This means that fibres fulfilling the definition of the Annex VI [16] entry of CLP may still not be classified as carcinogenic, if specific conditions (e.g. nota Q in CLP) are being met. One of the conditions in nota Q is e.g. a proven biopersistence under a specific value (specific studies and study-dependent biopersistence values are included in the nota Q). In the 1980s the first biosoluble glass wool was designed for toxicological research. Since 2000 most commercial glass and stone wools in the EU are identified as low-risk e.g. by the RAL-certificate, a quality label placed on products given by the Gütegemeinschaft Mineralwolle - GGM, an association of mineral wool manufacturers [17].
However, a significant amount of biopersistent wool is still in place, leading to the need for additional precautions to ensure the safety and health of workers in the building trade [4] and for the users of buildings and plants. For biosoluble products, only the problem of itching remains in regard to occupational safety and health. This can be avoided easily by applying the usual standards of good occupational hygiene [5] for the handling of chemicals in the workplaces.
AES-fibres
AES-fibres are mainly calcium and magnesium vitreous silicate wools, optionally containing zirconia, titania, alumina and traces of other oxides. The AES fibres are also covered by the generic entrance ‘[Man-made vitreous (silicate) fibres with random orientation with alkaline oxide and alkali earth oxide (Na2O+K2O+CaO+MgO+BaO) content greater than 18% by weight]’ in the Annex VI of CLP under the Index No. 650-016-00-2. The same drop-out criteria as for mineral wools also exist for AES-fibres. AES-fibres consist of fibres with diameters less than 10 µm. The length weighted geometric mean diameter is about 2.5µm, and the fibre length ranges from millimetres to centimetres. Based on their geometric properties and their ability for breaking, released fibres are respirable and fall under the scope of the WHO fibre definition. The AES fibres are mostly used for insulation at high temperatures ranging from 800°C to 1250°C. In the last decade, a lot of efforts have been put into designing biosoluble AES-fibres, but there is a conflict in making fibres resistant against high temperatures and chemical influences on the one hand and biosoluble on the other hand.
In Germany, the ban on marketing and use of biopersistent mineral wools exempts AES-fibres for application temperatures up to 1000°C, if they have a half-life of less than 65 days, and for application temperatures up to 1200°C, if the half-life is less than 100 days. While these AES-wools may still be placed on the market, they are classified as Carc. 2; H351 – suspected of causing cancer - and work-place prevention measures[20][21] have to be taken accordingly.
RCF
RFC are vitreous zirconium or aluminium silicate wools with a significant lower (earth) alkaline content than the AES fibres. RCF are listed in the Annex VI of CLP under the Index No. 650-017-00-8 as ‘Refractory Ceramic Fibres, Special Purpose Fibres, with the exception of those specified elsewhere in this Annex; (Man-made vitreous (silicate) fibres with random orientation with alkaline oxide and alkali earth oxide (Na2O+K2O+CaO+ MgO+BaO) content less or equal to 18% by weight)’ and are legally classified as Carc. 1B; H350i– may cause cancer by inhalation.
The RCF have additionally been identified as Substances of Very High Concern under the REACH-regulation[6][7].
RCF have a nominal fibre diameter between 3 to 4 µm, ranges are mainly between 0.2 and 8 µm. Typically 10 - 40% of the fibres are less then 3 µm in diameter. Based on their geometric properties and their ability for breaking, RCF products usually have a high potential for release of WHO fibres. RCF are used for insulation purposes at temperature ranges from 1200 °C to about 1500 °C. In animal studies RCF have shown a half-life of about 200 days.
In addition to high temperature resistance, RCF are also more resistant against chemicals than AES-wools. So even at temperature ranges where AES-wools with a low half-life could be used, for some chemical furnaces RCF still need to be used due to their resistance to chemicals.
PCWs
PWCs are polycrystalline aluminium silicate fibres with a higher percentage of alumina compared to RCF. PCWs usually have an average fibre diameter of 3 to 6 µm. This leads to a significantly lower potential for release of WHO fibres in the products’ life cycle and therefore no, or only a small amount of respirable fibres are expected to be released. There is a lack of toxicological information on their carcinogenic potency, but due to their chemical composition and crystalline structure, a biopersistence similar to RCF can be assumed. The high alumina content enables the fibres to be used up to 1600 °C and strengthens their chemical resistance in industrial applications. At the moment, PCWs are not classified as carcinogens and there are currently no data indicating that they are unsafe. PCWs might therefore be an – expensive - alternative for some cases where RCF are being used. PCWs are not vitreous but crystalline fibres. They are part of the MMMF but not of the MMVF group.
Whiskers
Whiskers are crystalline materials from silicon carbide, silicon nitride and other advanced materials (e.g. silicon carbide fibre). They are mostly used for reinforcement of plastics and metals. Fibre diameters range between 0.1 and 2 µm in diameter. Whiskers can be released as WHO fibres. Due to their high biopersistence the German MAK Kommission [25] (a German Commission for the evaluation of health hazards of chemical agents in the workplace) has assigned several types of whiskers as carcinogens [8]. As for PCWs, whiskers are crystalline and not part of the MMVF group.
Continuous glass filaments
Continuous glass filaments are mostly used in textiles for fire protection and for reinforcement of materials. The fibres are aligned and have a small range of similar diameters of about 8 µm. Therefore continuous glass filaments have only very small potency for release of WHO fibres. The continuous glass filaments have the same chemical composition as mineral wools, but the aligned form and high diameter renders them safe to use [30] – a good example for the domination of the geometric properties over the chemical composition at fibre toxicity.
Use pattern and exposure
MMMF, as stated by the name, are man made and do not occur in nature. In 2010 over 4 million tons of MMMF were produced in the EU. 50,000 tonnes were high-temperature insulation wools, of that 25,000 tonnes AES-wools, 24,000 tonnes RCF and around 1,500 tonnes PCW.
The most important use pattern of MMMF is thermal insulation. Mineral wools are widely used in the building trade. But they also have a broad field of application in technical insulation. AES and RCF are commonly used for high temperature insulation of industrial furnaces. The specific type of fibre and product depends on the application temperature and the chemical properties of emissions from the kiln run in the furnace. Depending on the furnace atmosphere RCF may be more resistant than AES wools. Therefore AES wools cannot generally replace the more biopersistent RCF in furnace insulation. In the last decade great efforts have been made to broaden the application range of AES wools, which pose a lower risk for workers health during the installation and removal of high-temperature insulation.
MMMF are also used for filtration purposes, as soundproofing-material, in vehicles (e.g. in brakes and old catalytic converters) and for other purposes. This article concentrates on their use for thermal insulation. Fibres for thermal insulation are mainly used as mats, blankets or pre-cut building blocks. Such blocks are filed and grinded to the specific form needed, e.g. to seamlessly cover the inside of an industrial furnace.
Exposure to released WHO fibres occurs during cutting, grinding and fitting of the fibrous materials. Also of significant importance for occupational safety and health is the removal of insulation products "after-service". Very high concentrations of WHO fibres are released during such working procedures. Thermal influences on fibres and binders make the products brittle and also change the morphology of the fibres. Additionally, there is exposure to silica dust if RCF and AES wools are removed from furnaces.
Examples of man-made mineral fibres and safe alternatives
From biopersistent to biosoluble mineral wools
Mineral wool was developed in 1840 and has been commercially produced since 1870. More than a century later in the 1970s, the fibre principle by Pott[25] and Stanton[26] provided a scientifically sound hypothesis for the carcinogenic properties of asbestos. The fibre principle has drawn the attention of toxicologists to other types of biopersistent fibres, e.g. mineral wools. Results from intraperitonial animal studies demonstrate that fibres released from commercial mineral wools pose a significant carcinogenic potential [27][28]. Based on these study results, the first experimental biosoluble glass wool was developed in the 1980s. But it was more than ten years before a major producer launched a commercial mineral wool based on the criteria for biosoluble fibres. Such criteria for biosoluble fibres were for example laid down by the German Hazardous Substances Committee in a Technical Rule on Hazardous Substances (TRGS 905) in 1994. The consumer can identify the safe products by an RAL quality label [29]. Today it can be assumed that in the EU biosoluble products have mostly replaced unsafe mineral wools in the building trade [30][1], while the older built-in biopersistent mineral wools still pose a risk for occupational safety and health.
From RCF to high-temperature mineral wools
RCF are used for high temperature insulation. One of the main uses of RCF is the insulation of industrial furnaces. RCF have a high thermal resistance. They are lightweight and can be repaired easily. On the down side, RCF release carcinogenic WHO fibres. This does not pose a significant health risk during the use of the furnace, but it becomes a serious problem during installation, repair and removal of the products. Cutting, removal and other mechanical impacts on the materials significantly increase the exposure of workers to WHO fibres [2][3][34]. Therefore governmental research institutions in France and in Germany have conducted investigations into the identification of alternatives for RCF with a lower or even negligible carcinogenic potency [4][5][6]. A promising alternative in the high temperature range above 600°C are AES fibres. Due to the high content of earth alkalines their biosolubility is higher than RCF, but only some products for the lower end of the application temperature range could pass the limit of a half life below 40 days to be regarded as safe. Therefore, it has to be assumed that WHO fibres from most AES wools have a carcinogenic potency relevant for occupational safety and health. Nevertheless, the health risks for work involving AES-wools are lower compared to RCF. PCW are regarded as an alternative for RCF, because of their significantly lower potential for release of WHO fibres. However, they are much more expensive and the discussion regarding their carcinogenic potential is still ongoing.
Safe handling of MMMF in the workplace
The health hazards of MMMF have to be taken into account when working with these materials. Therefore, according to Directives 98/24/EC (chemical agents Directive)[38] and 2004/37/EC (carcinogen and mutagen Directive) [39], a risk assessment has to be conducted by the employer and adequate measures, following the hierarchy of control measures, have to be implemented. Substitution with safe alternatives (low release of WHO fibres, biosoluble materials) is the best way to ensure safe working conditions. This can be done by implement a different work process that involves no, or less hazardous substances, or by using a less hazardous substance. Still great care has to be taken if old biopersistent mineral wools are removed and RCF products are still used in high-temperature applications. ILO guidance is available regarding the safe use of synthetic vitreous fibre insulation wools such as glass wool, rock wool and slag wool[40].
Biopersistent mineral wools
In Germany, biopersistent mineral wools are banned for manufacture, placing on the market and use according to Annex IV No. 22 of the Hazardous Substance Ordinance since June 2000. Since all major producers changed to biosoluble fibres as a consequence of Germany’s ban, new mineral wools placed on the marked in the EU can generally be expected to be biosoluble. The German ban has not been harmonised in the EU.
For residual biopersistent mineral wools in building and technical insulation, a Technical Rule for Hazardous Substances (TRGS) from the German Hazardous Substances Committee provides practical support for employers in fulfilling their legal obligation regarding occupational safety and health. From this technical rule, which has become part of a recommendation by the International Labour Organisation (ILO) [3] for the safe use of mineral wools in 2001, mineral wools installed prior to 1996 are generally assumed to be biopersistent. Since a lot of private buildings and industrial plants still contain older insulation wools, a lot of workers in the building trade are still at risk from released biopersistent WHO fibres. Biopersistent mineral wools may also still be part of ships, vehicles and other products.
The most relevant risk to workers’ health comes from inhalation of WHO fibres. According to EU legislation on occupational safety and health [41][42][1] it is the responsibility of the employer that a risk assessment is performed by a person with adequate knowledge before starting work with biopersistent mineral wools and that workers’ exposure is prevented. For this purpose the following aspects have to be considered:
Measures for minimising exposure to WHO fibres at the source and their effectiveness,
Working conditions and processes including the work equipment and quantity of mineral wool,
Extent and duration of the exposure to WHO fibres,
Personal protective equipment to protect against inhalation of fibres,
Good personal hygiene for protection against mechanical irritation of the eyes and skin[44] (itching).
The German Technical Rule TRGS 521 “Demolition, reconstruction and maintenance work with biopersistent mineral wools" [2] has used broad expert knowledge on the aspects mentioned above to provide risk-related control strategies for typical processes and tasks with biopersistent mineral wools. These strategies can be applied as standardised working procedures without any duty for workplace measurements. TRGS 521 therefore provides a useful support in particular to small and medium sized enterprises in the building trade and technical insulation.
Refractory ceramic fibres
In the EU RCF are classified as Carc. 1B; H350i – may cause cancer by inhalation. For production and handling in the workplaces the provisions of the Carcinogens Directive [46] and their transposition into regulations of EU member states have to be observed. Some member states have set an OEL for fibres from RCF. For example, in Germany a level of 10.000 F/m³ currently serves as a threshold for specific measures to protect workers health, but this should be lowered to 1.000 F/m³ by 2018. Fibre concentrations exceeding 100.000 F/m³ are regarded as non-acceptable risks for workers by the social partners in the German Hazardous Substances Committee [3]. These are the same limits as for working with asbestos. With regard to the legal classification of RCF as carcinogens and a high biopersistence strictly controlled conditions are necessary, if the substance cannot be replaced by a less hazardous substance or process. As for biopersistent mineral wools a technical rule (TRGS 558 [4]) provides standardised working practices for “Activities involving high-temperature wool", based on the demands of the EC Carcinogens Directive [49].
When working with RCF, the STOP_principle has to be applied like for all other hazardous chemical agents. As a first step, Substitution by products or processes with a lower risk has to be evaluated. If this is not possible, Technical measures at source have to be implemented to reduce exposure as far as possible. If health risks remain, Organisational measures, e.g. reducing duration of exposure by sharing the work, must be taken. As the last resort, Personal protective equipment (PPE) should be used where exposure cannot be prevented by the measures previously mentioned. Respirators have to be selected against the need for reduction of WHO fibre concentrations, taking into account OEL or other exposure limits. For example, taking into account the German exposure level of 10.000 F/m³ the common dust protection devices FFP2 und FFP3 can only be used up to workplace concentrations of 100.000 F/m³ resp. 300.000 F/m³. For tasks with higher fibre concentrations other types of respiratory protection are necessary, such as those commonly used for asbestos removal works. Table 1, taken from Annex I of TRGS 558, gives a summary of measurement results for different tasks with RCF and other high temperature fibres.
Table 2 gives a summary of the number and exposure of workers who handle high-temperature mineral fibres in Germany and the EU in 1999. It can be assumed that all persons working with high-temperature fibres worked with RCF.
Table 1: Activity-related measures for the reduction of fibre dust exposure.
Source: TRGS 558 Annex 1 [5].Table 2: No. of workers exposed to high-temperature mineral fibres.
Source: Recognition and Control of Exposure to Refractory Ceramic Fibres (RCF) 1999, S. 10 [51].
Insulation products from biosoluble fibres
The work with biosoluble fibres is regarded as not relevant for a risk from a carcinogenic potential. To avoid itching, which is mainly related to the fibre diameter and stiffness, some basic occupational safety measures and exposure limits are recommended [52][6]:
Application of low emission techniques and ventilated devices for cutting
Some care should be given to fibres mixed with e.g. epoxy resins or other binders which might lead to dermal problems. In these cases the lesions due to the fibres can increase the dermal problems arising through the other chemical due to a higher internal exposure to the other chemical. The workplace risk assessment and the subsequent choice and implementation of control measures should therefore take possible combined exposures and risks into consideration.
[2] Oberdörster, G.,‘Determinants of the pathogenicity of man-made vitreous fibers (MMVF)’, International Archives of Occupational and Enviromental Health, Vol.73, No 1 Supplement, July 2000, pp. 60-68.
[3] Moolgavkar S.H., Brown R.C., Turim J., ‘Biopersistence, fiber length, and cancer risk assessment for inhaled fibers.’Inhalation Toxicology. Vol.13, No 9, Sep., 2001, pp. 755-772.
[4] Pott,F., Friedrichs K. H. ‘Tumoren der Ratte nach i.p.-Injektion faserförmiger Stäube’ (German), Naturwissenschaften, Vol. 59, No 7, 1972, pp. 318.
[5] Stanton, M.F. Wrench, C. ‘Mechanisms of mesothelioma induction with asbestos and fibrous glass’, Journal of the National Cancer Institute, Vol. 48, No 3, 1972, pp. 797-821.
[6] IARC – International Agency for Research on Cancer, ‘Man-made Vitreous Fibres’ IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 81,2002, pp. 1-418. Available at: http://monographs.iarc.fr/ENG/Monographs/vol81/mono81.pdf
[8] IARC – International Agency for Research on Cancer, ‘Man-made Vitreous Fibres’ IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 81,2002, pp. 1-418. Available at: http://monographs.iarc.fr/ENG/Monographs/vol81/mono81.pdf
[9] Council Directive 98/24/EC on the protection of the health and safety of workers from the risks related to chemical agents at work (fourteenth individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC), OJ L 131, 5.5.1998, p. 11. Available at: [1]
[10] BAuA – Bundesanstalt für Arbeitsschutz und Arbeitsmedizin, ‘Gefahrstoffe - Künstliche Mineralfasern - aktuelle Arbeitsschutzvorschriften und Handlungshilfen (Teil 2)’ (German) Amtliche Mitteilungen der BAuA, 1/2000 (German). Available at: http://www.sidiblume.de/info-rom/gefstoff/bma/baua199904.htm
[12] European Commission (2012) Recommendation from the Scientific Committee on Occupational Exposure Limits for man made-mineral fibres (MMMF) with no indication for carcinogenicity and not specified elsewhere. SCOEL/SUM/88 March 2012. Available at: http://ec.europa.eu/social/BlobServlet?docId=7722&langId=en
[20] Council Directive 98/24/EC on the protection of the health and safety of workers from the risks related to chemical agents at work (fourteenth individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC), OJ L 131, 5.5.1998, p. 11. Available at: [1]
[25] Pott,F., Friedrichs K. H. ‘Tumoren der Ratte nach i.p.-Injektion faserförmiger Stäube’ (German), Naturwissenschaften, Vol. 59, No 7, 1972, pp. 318.
[26] Stanton, M.F. Wrench, C. ‘Mechanisms of mesothelioma induction with asbestos and fibrous glass’, Journal of the National Cancer Institute, Vol. 48, No 3, 1972, pp. 797-821.
[27] Pott,F., Friedrichs K. H. ‘Tumoren der Ratte nach i.p.-Injektion faserförmiger Stäube’ (German), Naturwissenschaften, Vol. 59, No 7, 1972, pp. 318.
[28] Stanton, M.F. Wrench, C. ‘Mechanisms of mesothelioma induction with asbestos and fibrous glass’, Journal of the National Cancer Institute, Vol. 48, No 3, 1972, pp. 797-821.
[31] BAuA – Bundesanstalt für Arbeitsschutz und Arbeitsmedizin ‘Verzeichnis krebserzeugender, erbgutverändernder oder fortpflanzungsgefährdender Stoffe (TRGS 905)’ (German). Technische Regel für Gefahrstoffe (TRGS). 2008. pp. 1-22. Available at: http://www.baua.de/de/Themen-von-A-Z/Gefahrstoffe/TRGS/TRGS-905.html
[38] Council Directive 98/24/EC on the protection of the health and safety of workers from the risks related to chemical agents at work (fourteenth individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC), OJ L 131, 5.5.1998, p. 11. Available at: [1]
[41] Council Directive 98/24/EC on the protection of the health and safety of workers from the risks related to chemical agents at work (fourteenth individual Directive within the meaning of Article 16(1) of Directive 89/391/EEC), OJ L 131, 5.5.1998, p. 11. Available at: [1]
[51] European Ceramic Fibres Industry Association,‘Recognition and Control of Exposure to Refractory Ceramic Fibres (RCF)’, 1999.
[52] EC – European Comission,‘Recommendation from the Scientific Committee on Occupational Exposure - Limits for man made-mineral fibres (MMMF) with no indication for carcinogenicity and not specified elsewhere’, SCOEL Recommendation, SUM 88, 2012, pp. 1-17. Available at: [ec.europa.eu/social/BlobServlet?docId=7722&langId=en]
