<b>Bijsluiter</b>. De hyperlink naar het originele document werkt niet meer. Daarom laat Woogle de tekst zien die in dat document stond. Deze tekst kan vreemde foutieve woorden of zinnen bevatten en de opmaak kan verdwenen of veranderd zijn. Dit komt door het zwartlakken van vertrouwelijke informatie of doordat de tekst niet digitaal beschikbaar was en dus ingescand en vervolgens via OCR weer ingelezen is. Voor het originele document, neem contact op met de Woo-contactpersoon van het bestuursorgaan.<br><br>====================================================================== Pagina 1 ======================================================================

<pre>Slate dust
Health-based Reassessment of Administrative Occupational Exposure Limits
Committee on Updating of Occupational Exposure Limits,
a committee of the Health Council of the Netherlands
No. 2000/15OSH/089, The Hague, 22 October 2003
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<pre>Preferred citation:
Health Council of the Netherlands: Committee on Updating of Occupational
Exposure Limits. Slate dust; Health-based Reassessment of Administrative
Occupational Exposure Limits. The Hague: Health Council of the Netherlands,
2003; 2000/15OSH/089.
all rights reserved
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<pre>1     Introduction
      The present document contains the assessment of the health hazard of slate dust
      by the Committee on Updating of Occupational Exposure Limits, a committee of
      the Health Council of the Netherlands. The first draft of this document was
      prepared by AAE Wibowo, Ph.D. (Coronel Institute, Academic Medical Centre,
      University of Amsterdam, Amsterdam, the Netherlands).
          In June 1999, literature was searched in the databases Medline, Embase, and
      Chemical Abstracts starting from 1966, 1988, and 1970, respectively, and using
      the following key word: slate. HSELINE, CISDOC, MHIDAS, and NIOSHTIC
      (covering the period 1985/87 up to 1998), databases available from CD-ROM,
      were consulted as well. The final search was carried out in Medline and Toxline
      in October 2002.
          In April 2003, the President of the Health Council released a draft of the
      document for public review. The committee received no comments.
2     Identity
      Slate is a very fine-grained, splittable rock. It has a leaden-greyish, reddish or
      greenish colour. It has a high calcium carbonate content; it also contains silicates
      (mica, chlorite, hydrosilicates), iron oxides, and amorphous and crystalline silica.
      The crystalline silica (quartz) content of slate dust ranged from less than 10% to
      more than 50%. Slade dust is a mixture of minerals, the composition of which
      depends on the geological characteristics of the geographic location where the
      slate stones are quarried. For example, in North-Wales (United Kingdom)
      quarries, respirable slate dust contains between 13% and 32% of quartz.
      Microscopic examination showed fine crystalline structures made of calcites,
      mica and particles of quartz of 2 to 30 µm in size (Don83). Higher quartz content
      (>50%) was reported in respirable slate dust retained from India (Sai85a,
      Sai85b). However, Fulekar and Khan (Ful95) reported that the quartz content in
      airborne total dust generated by different manufacturing units in the production
      of slate pencil in India varied from 6.7 to 29.1% (mean 15.3%). The typical
      chemical composition of slate dust collected from areas of Mandsaur in India
      was reported as follows: Si 45.8%, Mn 15%, Fe 3.4%, Mg 3.2%, K 0.7%, Ti
      0.65%, Ba 950 ppm, Zr 190 ppm, Rb 160 ppm, Ce 105 ppm, Sr 70 ppm, La 40
      ppm and Mb 10 ppm (Kha89). Craighead et al. described slate as a metamorphic
      rock made up of several minerals. The mineral composition of slate, retained
      from Vermont and New York, USA, was: muscovite (white mica) 38-40%,
089-3 Slate dust
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<pre>      quartz 31-45%, chlorite 6-18%, haematite 3-6%, carbonate 1-5%, and magnetite
      1-2% (Cra92). Because of its variable mineral composition, no CAS number has
      been given for slate dust.
3     Physical and chemical properties
      Of the major components, quartz (CAS No: 14808-60-7) is a colourless,
      odourless, non-combustible solid with a molecular weight of 60 and boiling and
      melting points of 2230 and 1610oC, respectively. Muscovite (CAS No: 12001-
      26-2) is an odourless, non-flammable, non-fibrous, water-insoluble silicate from
      the mica group of chemicals with a molecular weight of 797 and no known
      additional physical chemical data.
4     Uses
      Slate slabs are used for roofing, stair treads, door, window and porch casements,
      flooring, fireplaces, billiard tables, electricity switch panels, school blackboard,
      pencils, etc. Powdered slate has been used as a filler or pigment in rust-proofing
      or insulating paints, in mastics, and in paints and bituminous products for road
      surfacing.
5     Biotransformation and kinetics
      In vitro experimental studies showed that about 3.8% of the silica in slate dust
      binds with proteins in rat plasma, and 2.4% with purified bovine serum albumin
      within 96 hours. Binding of silica to protein occurs most rapidly in the first 24
      hours, and reaches a plateau after 48-72 hours. It was hypothesised that when
      slate dust particles come into contact with blood, a proportion of the silica is
      dissolved, and in turn combines with blood protein and possibly with other
      biomacromolecules. The results indicate that in mammalian blood, natural silica
      may exist in protein-bound form and that exposure to silica dust could enhance
      the level. In rat lung, silica-binding protein was found to be a glycoprotein
      (Sin84). The authors commented that besides a normal physiological role,
      silica-binding protein could function as a biochemical mechanism for dust
      clearance in subjects exposed to slate dust, apart from clearance through
      lymphatics and coughing (Sin84).
089-4 Health-based Reassessment of Administrative Occupational Exposure Limits
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<pre>6     Effects and mechanism of action
      Human data
      In slate workers, a disease called ‘slate-worker’s pneumoconiosis’ has attracted
      attention since early 19th century. This disease is primarily respiratory in nature
      and has a relatively slow progression. Silicotic lesions become apparent after
      about 15 years of exposure, and nodular forms are seen only after a period of
      exposure exceeding 20 years (Don83).
          A study was conducted on the lungs of 12 slate workers who developed
      pneumoconiosis while employed in the quarries of Vermont (US) and adjacent
      areas of New York. Perivascular and peribronchial lesions, accompanied by
      interstitial fibrosis and macules, were scattered diffusely in the lungs. The lesions
      were associated with a variable number of silicotic nodules. Scanning electron
      microscopy combined with energy-dispersive X-ray spectrometry, demonstrated
      aluminium- and silica-containing particles with variable cationic constituents,
      and silica alone in a pattern typical of free crystalline quartz. By X-ray
      diffraction analysis, the majority of mineral particulates were free crystalline
      quartz and muscovite. The author concluded that slate workers are exposed to
      respirable airborne dust that has the capacity to induce a pneumoconiosis that
      differs from classic silicosis in that slate workers reveal a diffuse interstitial
      pulmonary disease differing from the nodular lesions characteristic of silicosis
      (Cra92).
          Three studies have been reported on the effects of slate-dust exposure on the
      lungs of slate quarry workers in North Wales, United Kingdom. In the first study,
      a health survey was conducted on 2432 male workers. The objective of the study
      was to ascertain the prevalence of pneumoconiosis purely by examination of
      chest X-ray film of these workers, as read by 3 independent clinicians. The level
      of exposure to slate dust of these workers was not reported. The results showed
      that 69% of the workers had normal radiographs, 30% were diagnosed with
      pneumoconiosis from grade 1 to grade 3, and 0.6% of the workers had a
      progressive massive fibrosis. It was also found that 27 out of 219 workers who
      were referred to the chest clinic for further assessment were also suffering from
      pulmonary tuberculosis (Jar57). The second study was a cross-sectional study,
      conducted in 1975 on 725 workers and ex-workers who had been occupationally
      exposed to slate dust, but not to any other industrial dust. Another group of 530
      men from the same area had never been exposed to any industrial dust, and
      served as a control group. The fraction of respirable quartz in respirable slate
089-5 Slate dust
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<pre>      dust was between 13% and 32%. Evidence of pneumoconiosis was found in
      one-third of the slate workers. The prevalence of respiratory symptoms was high,
      and there was evidence of an effect of both simple and complicated
      pneumoconiosis on lung function, additional to that of age. No exposure data
      were reported (Glo80). In a follow-up study, the mortality during a 6-year period
      (1975 till 1981) was investigated in the above 2 groups of workers. At date of
      interview in 1975, the workers’ age, smoking habits, radiological score derived
      from the radiological classification of pneumoconiosis, anthropometric data,
      forced vital capacity (FVC), and 1-second forced vital capacity (FEV1) were
      collected. The complete data set was available for 89% of the slate workers and
      for 87% of the controls. In slate workers, 129 out of 725 (17.8%) died during the
      survey, compared with 73 out of 530 (13.8%) of the controls. Eight slate workers
      died from pneumoconiosis. In non-smokers, there was no significant excess
      mortality associated with exposure to slate dust, but in smokers, there was a 26%
      excess. In slate workers, the risk for smokers was on average 76% greater than
      for non-smokers, and increased with severity of pneumoconiosis. In the control
      group, the risk was 50% greater for smokers than non-smokers. In slate workers,
      the risk of death of the ex-smokers, but not of the smokers or non-smokers, was
      higher in those with a lower FVC and FEV1. Exposure data to slate dust were not
      reported (Old86).
          A medical survey was undertaken on 151 workers (144 males, 7 females)
      engaged in the production of slate pencils in Mandsaur, India, to investigate the
      prevalence of silicosis. The age of 124 workers was below 30 years. The silica
      content of the dust was 69% (type of silica not reported). Exposure levels were
      not reported. Cough, dyspnoea, and pain in the chest were the most important
      respiratory symptoms. Symptoms were correlated with length of employment in
      slate-pencil production. All workers experienced cough and dyspnoea after
      15 years of employment. Chest X-ray films were taken of 145 workers. In 82
      radiographs (57%), there was evidence of silicosis. The incidence and severity of
      pneumoconiosis as judged by chest X-ray films were found to be directly
      proportional to the duration of employment (Jai77).
          In a health survey of 593 slate-pencil workers in Mandsaur, India, the
      workers were divided into 3 groups. Group 1 comprised 405 males (‘cutters’),
      who were engaged in cutting of slate pencils, and who were directly exposed to
      the dust; group 2 comprised 117 males (‘non-cutters’), who were engaged in
      separating, counting, and packing of the pencils, and who worked about 1.5-3
      meters from the cutters; group 3 consisted of 71 females (‘non-cutters’), who
      frequently took the work to their homes to carry out separating, counting, and
      packing of the pencils. Air concentrations of dust were measured in 6 factories.
089-6 Health-based Reassessment of Administrative Occupational Exposure Limits
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<pre>      Dust samples were collected from the breathing zone of the cutters and from the
      different workplaces of the factories (sampling times not given). The mean dust
      exposure level of the cutters was 46 mg/m3 for total dust (range: 11-177 mg/m3)
      and 10.4 mg/m3 for respirable dust (range: 4.3 - 18.4 mg/m3). The mean total
      mg/m3 for total dust (range: 7.4-97 mg/m3) and 5.5 mg/m3 for respirable dust
      (range 3.7 - 8.8 mg/m3). The mean free silica (quartz) content of the dust was
      56%. The mean duration of employment for cutters, male non-cutters, and
      female non-cutters was 7.3, 7.6, and 14.7 years, respectively. There was a higher
      proportion of smokers among the cutters (85%) than the non-cutters (males:
      60%, females: 0%). Chest radiographic films of 324 workers (54.6%) showed
      silicosis. Of these, 17.7% had progressive massive fibrosis (PMF). In the group
      of cutters, prevalences of silicosis and PMF were 60% and 22%, respectively. In
      the group of male non-cutters, 41% had silicosis and 11% PMF, and in the group
      of female non-cutters, 47% had silicosis and 7% PMF. The prevalence of
      silicosis and PMF was related with the duration of employment in all 3 groups.
      All 29 cutters, who had been employed in the slate pencil industry for 16-20
      years, and all 6 non-cutters, who had been employed for more than 21 years, had
      developed silicosis (Sai85a). The same authors conducted a follow-up study, 16
      months after the initial survey. During this period, 23 out of the 593 workers
      (3.9%) had died. All those died were males, 20 were cutters and 3 were non-
      cutters, and they had been diagnosed as having PMF in the initial survey. Their
      mean age was 34.7 years (range 18-55 years), and they had been employed in the
      slate-dust industry for on average 12 years (range 3-20 years). In the follow-up
      study, 279 out of the 570 remaining workers participated. The cutters comprised
      204 men and the non-cutters 47 men and 28 women. The prevalences of silicosis
      at the initial examination were 59%, 40%, and 29%, and were increased after the
      16-months follow-up to 96%, 62%, and 43%, respectively. The prevalence was
      slightly higher among smokers as compared to non-smokers in the same group
      (Sai85b).
      Testing of silicate dusts for cytotoxicity has been done in in vitro model systems.
      In vitro haemolysis of human erythrocytes in isotonic conditions was used as a
      test system for the prediction of the relative cytotoxicity of different samples of
      slate dust from Mandsaur, India. The haemolytic index of slate dust, i.e., the dust
      concentration needed to induce 50% haemolysis of human erythrocytes, was
      relatively high (1.5 mg of dust per mL of human erythrocyte suspension in
      normal saline) and comparable to that of chrysotile asbestos, indicating
      potentially high cytotoxicity (Sin83a, Sin83b, Sin87).
089-7 Slate dust
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<pre>      Animal data
      Irritation and sensitisation
      The committee did not find data from eye- or skin-irritation, or on skin-
      sensitisation studies of slate dust
      Acute toxicity
      The committee did not find data from acute lethal toxicity studies of slate dust.
      Several studies have been conducted to study the biochemical changes in the
      lung of rats, treated with single intratracheal doses of slate dust.
          Female albino rats (n = 70) were given a single intratracheal dose of 50 mg of
      slate dust suspended in saline, and biochemical changes in the lung lavage and in
      the blood were monitored up to 90 days after treatment. A control group of 70
      rats was given only saline solution. A several-fold increase of free cell
      population (initially macrophages) was elicited by the dust. The effect was at its
      maximum after 4 days, and was 2-fold higher by the end of 90 days. An increase
      in acid phosphatase activity was seen over the whole observation period in the
      acellular fraction, but the activity gradually decreased in the cellular fraction.
      The phospholipid content varied both in cellular and acellular fractions,
      indicating altered turnover of membrane lipids and surfactants. At advanced
      periods of the study, sialic acid was found to be released into the acellular
      fraction, indicating membrane damage. These results indicate a cytotoxic action
      of slate dust in vivo (Kha83). In a subsequent study, rats were monitored for 150
      days after intratracheal treatment with 50 mg of slate dust. Biochemical changes
      in the lung included a turnover of collagen after 90 days, reaching substantially
      higher values at 150 days. A concurrent increase of hexosamine and sialic acid
      content was also observed. The phospholipid content in whole lung tissue, as
      well in the mitochondria, was generally higher in the dust-treated rats. The
      mitochondrial cytochrome c oxidase and glutamate dehydrogenase activities
      were increased, whereas monoamine oxidase was marginally affected, compared
      with control animals (Kha84). In another experiment, 6 female albino rats were
      treated intratracheally with 14C-acetate, 4 and 40 days after intratracheal
      installation of 50 mg of slate dust, to investigate the incorporation of
      radioactivity into lung lipids. The results indicated that slate dust caused an
      enhanced synthesis of pulmonary surfactant and other lung lipids and, therefore,
      had an effect on the metabolism of type II alveolar epithelial cells (Kha89).
089-8 Health-based Reassessment of Administrative Occupational Exposure Limits
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<pre>      The committee did not find data from repeated-dose toxicity, including
      carcinogenicty and reproduction toxicity, or mutagenicity and genotoxicity
      studies of slate dust.
7     Existing guidelines
      The current administrative occupational exposure limit (MAC) for slate dust in
      the Netherlands is 10 mg/m3, 8-hour TWA, as inhalable dust.
           The committee could not find occupational exposure limits for slate dust on
      lists of the European Commission (EC03), European countries such as Denmark
      (Arb02), Germany (DFG02, TRG00), Sweden (Swe00), and the UK (HSE02), or
      the USA (ACG03a, ACG03b).
8     Assessment of health hazard
      The major route of occupational exposure to slate dust is by inhalation of the
      respirable particles. There are numerous human data that show that the lung is
      the target organ after long-term exposure and that pneumoconiosis is the critical
      effect. The induction of ‘slate worker’s pneumoconiosis’ is known since the 19th
      century. Recent epidemiological data show that the prevalence of
      pneumoconiosis due to slate dust in workers is dependent on the exposure level,
      the duration of exposure, as well as on smoking habits.
           Health hazard assessment of exposure to slate dust is hampered by the
      complexity of the material. Slate dust is a mixture of minerals. The composition
      of the minerals is dependent on the geologic characteristics of the area where the
      slate stones are quarried. The principal deposits are in France, Belgium, the
      United Kingdom, the United States, and Italy (Don83).
           From the induction of pneumoconiosis observed in humans, the committee
      concludes that quartz appears to be responsible for the lung effects of slate dust.
      The quartz content of slate dust ranges from less than 10% to more than 50% by
      weight. Other components should not be underestimated though, especially when
      quartz content is low. For example, manganese can make up to 15% of the slate
      dust and muscovite up to 40% (Cra92, Kha89).
           In the Netherlands, the current statutory occupational exposure limit for
      crystalline silicon dioxide (or ‘free silica’), which covers quartz, cristobalite, and
      tridymite is 0.075 mg/m3, 8-hour TWA, for respirable particles (SZW02). This
      limit is in agreement with the health-based occupational exposure limit
      recommended by the Dutch Expert Committee on Occupational Standards
      (DECOS), a committee of the Health Council of the Netherlands (DEC92).
089-9 Slate dust
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<pre>       Moreover, the Dutch Ministery of Social Affairs and Employment of the
       Netherlands classified quartz dust as carcinogenic (SZW02). Recently, DECOS
       concluded that crystalline silica inhaled in the form of quartz or cristobalite from
       occupational sources is carcinogenic to humans (DEC98). In its evaluation, this
       committee of the Health Council concluded that the tumours are induced by
       quartz by a non-genotoxic mechanism, i.e., caused by long-term irritation of the
       target tissue. This means that there is a threshold level justifying
       recommendation of a health-based occupational exposure limit.
            The current statutory occupational exposure limit (MAC) for manganese in
       the Netherlands is 1 mg/m3, 8-hour TWA (SZW02).
       Because of the varying composition of slate dust, the committee considers that
       recommendation of a health-based occupational exposure limit for slate dust is
       not justified. To protect workers from work-related diseases caused by exposure
       to slate dust, the committee advises the authorities to uphold the existing
       occupational exposure limits of individual components in the dust of which
       quartz appears to be the major one.
       References
ACG03a American Conference of Governmental Industrial Hygienists (ACGIH). Guide to occupational
       exposure values - 2003. Cincinnati OH, USA: ACGIH®, Inc, 2003.
ACG03b American Conference of Governmental Industrial Hygienists (ACGIH). 2003 TLVs® and BEIs®
       based on the documentation of the Threshold Limit Values for chemical substances and physical
       agents & Biological Exposure Indices. Cincinnati OH, USA: ACGIH®, Inc, 2003.
Arb02  Arbejdstilsynet. Grænseværdier for stoffer og materialer. Copenhagen, Denmark: Arbejdstilsynet,
       2002; At-vejledning C.0.1.
Cra92  Craighead JE, Emerson RJ, Stanley DE. Slate worker's pneumoconiosis. Human Pathol 1992; 23:
       1098-1105.
DEC92  Dutch Expert Committee on Occupational Standards (DECOS). Health-based recommended
       occupational exposure limits for crystalline forms of silicon dioxide (free silica). The Hague, the
       Netherlands: Ministry of Social Affairs and Employment, 1992; rep no RA 5/92.
DFG02  Deutsche Forschungsgemeinschaft (DFG): Commission for the Investigation of Health Hazards of
       Chemical Compounds in the Work Area. List of MAK and BAT values 2002. Maximum
       concentrations and biological tolerance values at the workplace. Weinheim, FRG: Wiley-VCH, 2002;
       rep no 38.
Don83  Donofrio V. Slate. In: Parmeggiani L, ed. Encyclopaedia of occupational health and safety. 1983 ed.
       Geneva, Switzerland: International Labour Office, 1983: 2061-2 (Vol 2).
089-10 Health-based Reassessment of Administrative Occupational Exposure Limits
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<pre>EC03   European Commission: Directorate General of Employment and Social Affairs. Occupational
       exposure limits (OELs). http://europe.eu.int/comm/employment_social/h&s/areas/oels_en.htm.
Ful95  Fulekar MH, Alam Khan MM. Occupational exposure to dust in slate pencil manufacture. Ann
       Occup Hyg 1995; 39: 107-14.
Glo80  Glover JR, Bevan C, Cotes JE, et al. Effects of exposure to slate dust in North Wales. Br J Ind Med
       1980; 37: 152-62.
Hea98  Health Council of the Netherlands: Dutch Expert Committee on Occupational Standards (DECOS).
       Committee on the Evaluation of the Carcinogenicity of Chemical Substances. Quartz. Evaluation of
       the carcinogenicity and genotoxicity. The Hague, the Netherlands: Health Council of the
       Netherlands, 1998; rep no 1998/02 WGD.
HSE02  Health and Safety Executive (HSE). EH40/2002. Occupational exposure limits 2002. Sudbury
       (Suffolk), England: HSE Books, 2002.
Jai77  Jain SM, Sepaha GC, Khare KC, et al. Silicosis in slate pencil workers. Chest 1977; 71: 423-6.
Jar57  Jarman TF, Jones JG, Phillips JH, et al. Radiological surveys of working quarrymen and quarrying
       communities in Caernarvonshire. Br J Ind Med 1957; 14: 95-104.
Kha83  Khan MF, Jaffery FN, Ali S, et al. Biochemical studies on the toxicity of slate mine dust. Environ
       Health Perspect 1983, 51: 305-10.
Kha84  Khan MF, Ali S, Singh SV, et al. Pulmonary biochemical response to slate dust in rats. J Appl Toxicol
       1984; 4: 87-91.
Kha89  Khan MF, Ali S, Rahman Q. Bioreactivity of intratracheally administered slate dust in rats:
       incorporation of 14C-acetate into lung lipids. J Appl Toxicol 1989; 9: 305-11.
Old86  Oldham PD, Bevan C, Elwood PC, et al. Mortality of slate workers in North Wales. Br J Ind Med
       1986; 43: 550-5.
Sai85a Saiyed HN, Parikh DJ, Ghodasara NB, et al. Silicosis in slate pencil workers: I. An environmental
       and medical study. Am J Ind Med 1985; 8: 127-33.
Sai85b Saiyed HN, Chatterjee BB. Rapid progression of silicosis in slate pencil workers: II. A follow-up
       study. Am J Ind Med 1985; 8: 135-42.
Sin83a Singh SV, Das B, Rahman Q. Relationship between solubility and hemolytic effects of toxic dusts. J
       Appl Toxicol 1983; 3: 14-7.
Sin83b Singh SV, Viswanathan PN, Rahman Q. Interaction between erythrocyte plasma membrane and
       silicate dusts. Environ Health Perspect 1983; 51: 55-60.
Sin84  Singh SV, Das B, Khan MF, et al. The binding of silica to proteins from plasma and lungs of rat: in
       vitro. Chem Biol Interact 1984; 49: 155-64.
Sin87  Singh SV, Rahman Q. Interrelationship between hymolysis and lipid peroxidation of human
       erythrocytes induced by silicic acid and silicate dusts. J Appl Toxicol 1987; 7: 91-6.
Swe00  Swedish National Board of Occupational Safety and Health. Occupational exposure limit values and
       measures against air contaminants. Solna, Sweden: National Board of Occupational Safety and
       Health, 2000; Ordinance AFS 2000:3.
089-11 Slate dust
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<pre>SZW03  Ministerie van Sociale Zaken en Werkgelegenheid (SZW). Nationale MAC-lijst 2003. The Hague,
       the Netherlands: Sdu, Servicecentrum Uitgevers, 2003: 32.
TRG00  TRGS 900. Grenzwerte in der Luft am Arbeitsplatz; Technische Regeln für Gefahrstoffe. BArbBl
       2000; 2.
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