THE SCHUNDLER COMPANY
FOR POSSIBLE ASBESTIFORM FIBRE AND QUARTZ CONTENT
BASED ON VERMICULITE FROM PALABORA, SOUTH AFRICA---DECEMBER 2003
by
IOM CONSULTING
IOM CONSULTING
PROJECT NO: 609-00324(610)
Palabora Europe Limited is the European distributors of vermiculite produced by the Palabora Mining Company from open cast mines at Phalaborwa, Transvaal, South Africa.
In order to address concern on Health and Safety issues in the world-wide market for vermiculite, Palabora Europe have previously commissioned LOM Consulting to undertake a detailed analysis of vermiculite from the main PP & V ore body at Phalaborwa and one grade from the adjacent VODT deposit. This original study produced favourable results and has been followed up by routine screening of stocks.
The main aims were to collect representative samples from each grade of vermiculite as available in the European market, split them and analyse them at the IOM Consulting’s Edinburgh headquarters for asbestiform mineral and crystalline silica.
Mr Steve Klek of IOM Consulting and Mr Mike Darling of Palabora Europe Limited visited the Palabora Europe Ltd vermiculite bulk store at North Killingholme Humberside, on 2nd December 2003. At the North illingholme site, there are normally six different grades of vermiculite stored inside large silos of approximately 27 metres diameter and 9 metres high (micron PP & V, superfine PP & V, fine PP & V, medium PP & V, large PP & V and superfine VODT). At the time of this exercise
there were only five types in stock, there being no Superfine VODT.
Samples were collected from each grade as representatively as possible, by clearing
away loose dust from the top of the material and digging into the stock as far as
possible, avoiding any material falling in and re-mixing. A number of sub samples per
site were extracted and mixed from each stockpile. Each sample was split on site with
one sample being retained by Palabora Europe and the rest by IOM Consulting.
3.1 Asbestos
The main objective was to identify any hazardous asbestos fibres present in the
vermiculite. This was achieved as follows:
A portion of each sample was examined for the presence of fibrous asbestos minerals
at X8 - X40 magnification, using stereo-binocular microscopy. Any fibres detected,
were mounted in appropriate refractive liquid and identified at 125X magnification
using Polarised Light Microscopy (PLM) and dispersion staining microscopy.
This part of this analysis was carried out under IOM’s external quality accreditation,
awarded by the United Kingdom Accreditation Service (UKAS).
3.2 Crystalline silica
A portion of each sample was ground up and analysed using X-ray diffraction
techniques using modified versions of MDHS 51/2 (HSE 1988) and MDHS 76 (HSE
1994). Additional preparation of the Superfine PP&V sample was done to achieve a
lower detection limit. Detailed method description is shown in the certificate of
analysis in Appendix 1.
4.1 Polarised Light Microscopy examinations did not detect any amphibole or chrysotile
asbestos fibres present in any of the samples of vermiculite. As there were no
amphibole or chrysotile asbestos fibres detected in any of the samples of vermiculite
collected, quantitative analysis of the vermiculite materials was not undertaken.
4.2. X-ray diffractometry did not detect any crystalline silica in any of the samples of
vermiculite.
4.3 A summary of results is given in Table 1. Certificates of Analysis are attached
( Appendix 1 and complete IOM report (.pdf format).
Table 1. Summary of Results
5.1 The vermiculite materials tested comply with the proposed 0.1% European packaging
and labelling of carcinogen requirements (HSE, 1994b) and the 0.1% trigger value for
asbestos required for labelling of hazardous materials in the US.
The levels are also lower than the 0.001% for asbestos in loose aggregates proposed by
Addison et al (1988) based on work at the IOM using asbestos and soil mixtures.
Therefore, it is concluded that these materials or products containing them should not
present a significant asbestos-related health hazard when used in controlled
occupational environment.
5.2. Similarly with there being no crystalline silica detected in the samples and in
consideration of the detection limits of the analysis, there should not be any health
hazard, specifically related to crystalline silica, when the materials are used in a
controlled environment.
Considering an airborne total inhalable dust concentration of 10 mg/m³, based on the
higher limit of detection quoted in the certificate of analysis of <0.3%, the
concentration of crystalline silica would be <0.03 mg/m³; based on the lower limit of
detection achieved for the Superfine PP&V sample, the airborne crystalline silica
concentration would be 0.003 mg/m³. This is in comparison with the current
Maximum Exposure Limit of 0.3 mg/m³ (8 hour TWA) given in HSE document
EH40/2002.
REFERENCES:
The Schundler Company Back to Technical Information on Vermiculite, or
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Scotland
December 30, 2003
Analytical Science
Sampling and Analysis of Crude Vermiculite Samples
For Possible Asbestiform Fibre and Quartz Content
IOM Sample No. Description Asbestos Chystalline silia
R763 Medium (PP & V) None Detected None Detected *
R764 Micron (PP & V) None Detected None Detected*
R765 Fine (PP & V) None Detected None Detected*
R766 Large (PP & V) None Detected None Detected*
R767 Superfine (PP & V) None Detected None Detected*
*
The detection limit for quartz and cristobalite by this method is around 0.3%. This
figure is based upon three times the standard deviation of the measurement of a blank
sample run on a quantification programme. Previously, the detection limit was based
upon the lowest amount, which could be detected on a qualitative programme, which
was 0.1%. Although this has not changed, we are now required by the United Kingdom
Accreditation Service (UKAS) to base our detection limit on the quantitative rather than
the qualitative part of the analysis.
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