Asbestos
South Africa has deposits of three types of asbestos of value and in certain regions these
ore bodies can be exploited commercially. It is important to note that at certain times
the amount of the three types of asbestos produced has been comparable, and so have
the workforces. By far the most mined asbestos fibre in the world (accounting for 95%)
is the white, chrysotile, found in serpentine rock, the ore of which can be mined in the
Eastern Transvaal and Swaziland. Amosite (accounting for 1% of the world market)
occurs in the Northern Transvaal, is greyish-brown in colour, is an amphibole and is
found in banded ironstone. Crocidolite, or blue asbestos (accounting for 2% of the worlds
market), at one stage was colour graded, the lavender-blue being the most valuable. It is
also an amphibole occurring in banded ironstone. It is found in the north-west Cape
(Griqualand West). It is also found in the Northern Transvaal, where in some situations,
amosite and crocidolite occur in the same seam. Exploitation of the Transvaal deposits
of crocidolite peaked during the Second World War and then declined.
The mining of crocidolite in Griqualand West (north-west Cape) was begun south of
Prieska, the southern most town in these asbestos fields, in 1893. In that year 100 tons of
crude ore was produced. The early method of mining was open-cast quarrying. In the
Cape, the black workers (unlike elsewhere in South Africa) carried out the blasting. They
also did the quarrying, whilst their women cobbed the fibre, and their children recovered
any asbestos fibres that had been discarded. Cobbing, or knapping as it was originally
called, consists in separating the rock from the fibre by striking the fragments with a
square faced hammer. The women then sorted the fibre into different lengths. The work
was supervised by the whites. The fibre was bought by companies on the tribute system.
Gradually, as the overseas market for crocidolite increased, underground mining
started at the richer strikes, so that by 1918 there were mines in the south near Prieska
and 150 miles to the north at Kuruman. In 1930 Hall listed 104 sites in the asbestos mountains,
but there were only 12 actual mines. Most of these mines were worked by black
workers, but white farmers were working outcrops, especially during times of drought
There was a greatly increased demand for crocidolite immediately before and
during the First World War, with mills being built in the towns of Prieska and Kuruman.
Following a lull, the industry revived in the late 1930s, increasing further during the
Second World War. Then came another major increase between 1950 and 1960, production
rising from 40 000 tons to 100 000 tons. By this time, the mills were modernised
and mining occurred on a large scale with underground shafts. Only in Prieska did the
tribute system continue and there was an active mill in the town. In other areas the
mill was attached to the mine.
By 1962 as the mills became larger the amount of dust increased, as did the size
of the tailings dumps, which released more dust during dry and windy conditions.
Furthermore, the demand from the manufacturing industry for fine crocidolite fibre
increased the amount of dust. The large tailings dumps contained about 20% fibre in
the vicinity of active and previous sites of mills.
Mesotheliomas
During the Second World War, a Royal Air Force hospital was built in Kimberly, which
is in the northern part of the Cape Province. After the war, this hospital was presented
to the South African government, which decided it should be used for the treatment of
tuberculosis. Dr C. A. Sleggs was appointed as Superintendent. The area covered by
the hospital stretched from the Orange Free State in the east, to what is now Namibia
in the west. Before 1950, tuberculosis was endemic in the whole of this area. In the
next few years, with the advent of specific anti-tuberculous treatment, Sleggs noticed
that there was a difference in the response to treatment of those with tuberculous
pleurisy. Patients from the eastern part of the area showed a good response, whilst
there was a poor response from some of the cases from the west. Twelve of these latter
were seen by thoracic surgeons in Capetown, Pretoria or Johannesburg. In all cases a
diagnosis of metastatic carcinoma from an unknown primary site was made. By February
1956, there were a further 6 cases in this (west-end) hospital.
In February 1956 in Johannesburg, a black male patient came to necropsy examination.
He was thought to have had tuberculous pleurisy and had been treated
in the main mine hospital in Johannesburg but did not respond to treatment. Aspiration
of his pleural cavity had failed, as the fluid was thick and sticky. A diagnosis of
empyema was made and subsequently given as the cause of death. However, at postmortem
examination the findings were different with the presence of a huge gelatinous
tumour filling the right thoracic cavity, completely surrounding and compressing
the right lung, infiltrating the pericardium and displacing the mediastinum.
Mesothelioma was a rare tumour. At this time most pathologists agreed with R. A.
Willis5 that these tumours did not exist and that any tumour found in the pleural
cavity was a metastasis from a primary site elsewhere.6 Wagner carried out the postmortem,
and he consulted the professor of pathology at Witwatersrand University
(B. J. P. Becker). Becker suggested that a detailed examination should be made to
eliminate any other primary tumour. None was found and the diagnosis of asbestos
bodies were observed in the lung tissue, but no evidence of asbestosis.
This case was presented to the local thoracic society group by Olaf Martiny7 and
Chris Wagner about 2 months later. In the meantime, Dr Sleggs was still perturbed
over his cases, and consulted L. Fatti, senior thoracic surgeon, and his partner, P.
Marchand, both of whom visited Kimberly. The marked similarity of clinical and radiological
findings of Dr Sleggs’ cases and the case that Wagner and Martiny had
presented was noted by both these surgeons. Dr Sleggs sent 2 needle biopsies from his
other cases, but the material was insufficient for a definite diagnosis. Marchand carried
out open biopsies on the cases in the West-End hospital. By the end of 1956 pathology
had been seen from 10 large pleural biopsies and 2 post-mortem examinations.
Obviously, a definite diagnosis could only be given after death, followed by a full
post-mortem examination. All material was shown to Professor P. Steiner from Chicago,
who had seen a number of mesotheliomas previously, and he agreed with the
diagnosis that had been made. He asked why there were so many of these rare tumours.
An association with asbestos was considered at an early stage, partly because
asbestos bodies had been found in the first case and the range of the asbestos mountains
was 90 miles west of Kimberly. Other possible aetiologies were suggested. Was there a
virus implicated, the situation being similar to that in East Africa, with the Epstein-Barr
virus? Could radioactivity play a part as monazite, the ore of thorium was known to
occur in the region? Was there a local genetic disposition, associated with tuberculosis?
Of the first 16 cases collected only 4 had worked in the asbestos industry. The
biopsies from these cases were mainly from the parietal pleura, but from 3 there were
fragments of lung tissue that contained a few asbestos bodies. The majority of these
16 people had lived in the Kuruman district.
Evidence against the implication that asbestos was responsible for the development
of these tumours was that only a quarter of the cases had admitted working with
asbestos. Secondly, since asbestos mining had been in progress for more than 50 years
in this region, it would be expected that the tumours could have been recognised at an
earlier date. Later it was discovered from the records that a pleural endothelioma was
first reported in 1917 and that several other tumours had been notified but always
considered to be from a primary site elsewhere. Thirdly, none of these tumours had
been observed where other types of asbestos were produced. Fourthly, Doll had shown
a dose response associated with other asbestos diseases, occurring in heavily exposed
(for more that 20 years) individuals. The majority of the mesothelioma cases denied
having worked with asbestos at all. Their occupations were diverse, including housewives,
domestic servants, cattle herders, farmers, a water-bailiff, an accountant and
later an international goal-keeper.
It was not until the middle of 1958 when Paul Marchand interviewed two brothers
that it was realised that a different question must be asked. One brother had a
mesothelioma, while the other had a suspicious x-ray. Marchand asked the latter
whether either of them had worked in the asbestos industry, to which he replied that
his father had owned a small asbestos mine and that they used to play on the dumps as
children. All the cases were then re-interviewed (or the relatives), mainly by Dr Sleggs.
From this information, it was clear that the majority had had exposure to blue asbestos.
They had lived in the vicinity of either the mills or the tailings dumps. Exposure
could be as little as 6 months even 40 years before. Some were exposed as infants and
others at school where the neighbouring dumps made excellent play slides. The first
patient diagnosed with mesothelioma whose occupation was given as a bath attendant
was found to have herded sheep in the Kuruman area when young.
Could these tumours have occurred in those countries where the Cape blue had
been exported? Preliminary enquiries in Europe during 1957–58 by Wagner elicited
evidence of one tumour in the Midlands, United Kingdom, and also one in Turin, Italy.
E. McCaughey reported 15 cases, which he had seen in Belfast, Northern Ireland, but
no association with asbestos was considered. (Webster in 1959 stated that he had seen
two further cases at the London Hospital, United Kingdom; personal communication).
In 1958 Dr Harold S. Stewart, Head of Cancer Research at the National Institutes
of Health, Washington, DC, and an authority on geographical distribution of cancer, was
keenly interested in these findings and he persuaded Dr A. J. Orenstein, Director of the
South African Pneumoconiosis Unit, that Wagner and Sleggs should present papers at
the International Pneumoconiosis Conference, to be held in Johannesburg in 1959. These
papers were ‘The pathological aspects of asbestosis in South Africa’ and ‘Clinical aspects
of asbestosis in the Northern Cape’. The main topics of this conference were the
diseases associated with the major industries of gold and coal mining. On the whole, no
one appeared strongly interested in the mesothelioma problem, except for Dr J. C. Gilson,
Director of the British Pneumoconiosis Unit.
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