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Workplace Exposure to Asbestos:
Review and Recommendation
EXPOSURE TO
ASBESTIFORM MINERALS
OTHER THAN
COMMERCIALLY MINED ASBESTOS
Memorandum on Asbestos Update and Recommended
Occupational Standard
I. Asbestos Nomenclature/Definitions
II. Asbestos Sampling and Analysis
III. Biologic Effects of Exposure to
Asbestos in Animals
IV. Biologic Effects of Exposure to
Asbestos in Humans
V. Smoking and Asbestos
VI. Exposure to Asbestiform Minerals
other than Commerically Mined Asbestos
VII. Non-Occupational Exposure to Commerical
Sources of Asbestos
VIII. Dose-Response Relationships
References
Gillam et al. (1976) reported a threefold excess risk of mortality from
respiratory cancer and a twofold excess of non malignant respiratory disease
(excluding influenza and pneumonia) among miners exposed to amphibole
fibers in the cummingtonite-grunerite ore series at concentrations less
than 2.0 fibers/cm 3 . A large majority of the airborne fibers
was shorter than 5 mcm in length. McDonald et al. (1978), in a subsequent
study of the same mine, examined the mortality experience of persons with
at least 21 years of employment at the mine and mill. This study showed
significant excesses of pneumoconiosis (mainly silicosis), tuberculosis,
and heart disease. No overall excess of malignant diseases was found.
However, when the population was broken down by estimated exposure, respiratory
cancer was in excess in the highest exposure group. The findings of McDonald
et al. do not negate those reported by Gillam et al., but, rather, tend
to strengthen them in that McDonald et al. used a rigid survival criteria
(inclusion only of those employed 21 or more years), and further diluted
the underground exposed effect by including persons never exposed underground.
Commercial talc deposits are sometimes found to contain serpentines
(chrysotile, antigorite, and lizardite) and fibrous and non-fibrous amphiboles.
One important deposit studied has been mined in the Gouveneur Talc District
of upper New York State. Talcs in this area contained less than 1-2% silica,
but have been shown to contain tremolite and anthophyllite, resulting
in elevated miner and miller exposures to these fibers (Dement and Zumwalde,
1979).
Kleinfeld et al. (1967, 1974) demonstrated elevated proportionate mortality
due to lung cancer and respiratory disease among talc miners and millers
in New York State. Brown et al. (1979) conducted a retrospective cohort
mortality study among workers of one company in this area. The study cohort
consisted of all white males initially employed sometime between January
1, 1947 and December 31, 1959, with followup through June 30, 1975. Expected
cause-specific deaths were calculated using age, calendar time, and cause-specific
mortality rates of the U.S. Among this cohort, 10 respiratory cancers
were observed, whereas only 3.5 were expected. Excess mortality was also
observed for nonmalignant respiratory diseases. One case of mesothelioma
was observed; however, this worker was known to have had prior employment
with unknown exposures in the construction industry.
Gamble et al. (1979) studied respiratory disease morbidity among
a cohort employed at the same mine and mill studied by Brown et al. (1979).
A total of 121 currently employed workers were given a respiratory questionnaire,
PA and lateral chest films, and spirometry tests. Talc workers with greater
than 15 years employment were found to have an increased prevalence of
pleural abnormalities compared to coal miners, potash miners, and chrysotile
asbestos workers. FEV1 and FVC reductions demonstrated significant association
with particulate and fiber exposure.
Mesothelioma of the pleura and peritoneum have been detected in
two villages in Turkey: Tuzkoy and Karain (Artvinli and Baris, 1979 and
Baris et al., 1978). Mineralogical analysis of samples from ore and water
has revealed the asbestiform mineral zeolite but no asbestos. These fibers
were usually 1-2 mcm in diameter and 30-40 mcm in length. Annual rates
of malignant pleural mesothelioma in Tuzkoy were found to be 22 cases
per 10,000 people, and 182 cases per 10,000 in Karain, while studies in
Pennsylvania (Lieben and Pistawka, 1967), Finland (Nurminen, 1975), and
England, Wales, and Scotland (Greenberg and Davies, 1974) reported annual
incidences of 1 to 2.3 cases per 1,000,000 persons.
Memorandum on Asbestos Update and Recommended
Occupational Standard
I. Asbestos Nomenclature/Definitions
II. Asbestos Sampling and Analysis
III. Biologic Effects of Exposure to
Asbestos in Animals
IV. Biologic Effects of Exposure to
Asbestos in Humans
V. Smoking and Asbestos
VI. Exposure to Asbestiform Minerals
other than Commerically Mined Asbestos
VII. Non-Occupational Exposure to Commerical
Sources of Asbestos
VIII. Dose-Response Relationships
References
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