Long fibre asbestos in a chrysotile textile worker

Anthophyllite asbestos: state of the science review

Anthophyllite is an amphibole form of asbestos historically used in only a limited number of products. No published resource currently exists that offers a complete overview of anthophyllite toxicity or of its effects on exposed human populations. We performed a review focusing on how anthophyllite toxicity was understood over time by conducting a comprehensive search of publicly available documents that discussed the use, mining, properties, toxicity, exposure and potential health effects of anthophyllite. Over 200 documents were identified; 114 contained relevant and useful information which we present chronologically in this assessment. Our analysis confirms that anthophyllite toxicity has not been well studied compared to other asbestos types. We found that toxicology studies in animals from the 1970s onward have indicated that, at sufficient doses, anthophyllite can cause asbestosis, lung cancer and mesothelioma. Studies of Finnish anthophyllite miners, conducted in the 1970s, found an increased incidence of asbestosis and lung cancer, but not mesothelioma. Not until the mid-1990s was an epidemiological link with mesothelioma in humans observed. Its presence in talc has been of recent significance in relation to potential asbestos exposure through the use of talc-containing products. Characterizing the health risks of anthophyllite is difficult, and distinguishing between its asbestiform and non-asbestiform mineral form is essential from both a toxicological and regulatory perspective. Anthophyllite toxicity has generally been assumed to be similar to other amphiboles from a regulatory standpoint, but some notable exceptions exist. In order to reach a more clear understanding of anthophyllite toxicity, significant additional study is needed. Copyright © 2016 John Wiley & Sons, Ltd.

Follow-up study of chrysotile asbestos textile workers: cohort mortality and case-control analyses

Previous studies of mortality among white males employed in a Charleston, South Carolina asbestos textile plant using chrysotile demonstrated significant excess mortality due to asbestos-related disease and a steep exposure-response relationship for lung cancer. This cohort was further studied by adding 15 years of follow-up and including mortality among white female and black male workers. Nested case-control analyses were undertaken to further explore possible differences in lung cancer risk by textile operation as well as possible confounding by mineral oil exposures. Preliminary data for white males have been previously published. White males experienced statistically significant excess mortality due to lung cancer (standardized mortality ratio [SMR] = 2.30; confidence interval [CI] = 1.88-2.79), all causes (SMR = 1.48; CI = 1.38-158), all cancers (SMR = 1.50; CI = 1.29-1.72), diabetes mellitus (SMR = 2.05; CI = 1.18-3.33), heart disease (SMR = 1.41; CI = 1.26-1.58), cerebrovascular disease (SMR = 1.50; CI = 1.08-2.02), pneumoconiosis and other respiratory diseases (SMR = 4.10; CI = 3.10-5.31), and accidents (SMR = 1.49; CI = 1.15-1.91). Among white females, statistically significant excesses occurred for lung cancer (SMR = 2.75; CI = 2.06-3.61), all causes (SMR = 1.21; CI = 1.11-1.32), pneumoconiosis and other respiratory diseases (SMR = 2.40; CI = 1.53-3.60), and other respiratory cancers (SMR = 14.98; CI = 4.08-38.7). Among the total cohort of black males, the only statistically significant excess observed was for pneumoconiosis (SMR = 2.19; CI = 1.23-3.62). Based on historical exposure measurements at the plant, there was a positive exposure-response relationship for both lung cancer and pneumoconiosis. Data for the entire cohort demonstrate an increase in the lung cancer relative risk of 2-3% for each fiber/cc-year of cumulative chrysotile exposure. This relationship was more consistent for the white male workers. The excess risk for lung cancer among white males and females appeared to occur at cumulative exposures lower than those for black males. Possible reasons for the lesser lung cancer risk among black males include less smoking and differences in airborne fiber characteristics experienced by black males as a result of plant job placement patterns. The case-control analysis found employment in preparation and carding operations (where most of the black males worked) to be associated with a slightly reduced lung cancer risk, although not statistically significant, whereas spinning and twisting employment was associated with a statistically significant increased lung cancer risk compared to other plant operations.(ABSTRACT TRUNCATED AT 400 WORDS)

Fiber size and number in workers exposed to processed chrysotile asbestos, chrysotile miners, and the general population

We analyzed chrysotile and chrysotile-associated amphibole (largely tremolite) asbestos fibers in 21 workers exposed to various types of processed (milled) chrysotile ore, 20 long-term chrysotile miners, and 20 members of the general population (controls). Significantly greater amounts of both chrysotile and tremolite were found in processed-ore workers and miners than in controls. On average, the mean fiber lengths and aspect ratios for the mining and processed-ore-exposed workers were similar and were significantly greater than the values seen in the controls; within the processed-ore group, there was a marked variation in these parameters, and some workers appeared to be exposed to fairly long, thin fibers. It was found empirically that the fiber size data, and to a lesser extent the concentration data, could be used to classify workers accurately into those with processed-ore exposure and controls. We conclude that fiber sizes in the lungs of processed-ore-exposed workers are similar to those of chrysotile miners and are considerably longer than those found in the general population; some processed-ore workers have longer fibers which might be responsible for higher disease incidences in certain working groups; tremolite accompanies chrysotile in a variable proportion of workers exposed to processed chrysotile products and might be important in the genesis of mesothelioma in such workers; and mineralogic analysis will usually detect exposure even when chrysotile has largely disappeared from lung tissue.