Environmental asbestos exposure from nephrite jade mining and lung cancer.

BACKGROUND: Nephrite is an asbestos mineral composed of tremolite and actinolite. Fengtian is a community where nephrite was mined between 1970 and 1980 and asbestos was mined between 1960 and 1985. The lung cancer risk to the surrounding community is unknown. AIMS: To analyse the trend of lung cancer caused by environmental contamination from nephrite mining. METHODS: We conducted a field survey of nephrite mines and tracked new cases of lung cancer from 1980 to 2019. We calculated the age-standardized incidence rates (ASIRs) and applied join-point regression to examine the lung cancer trend. We assessed the age effect, period effect, and birth cohort effect on lung cancer risk. RESULTS: The nephrite mines were contaminated with chrysotile and tremolite/actinolite asbestos. A total of 278 new cases of lung cancer were reported during the study period. There was an apparent age effect and a slight period effect for lung cancer. After adjustment for the age and period effects, the birth cohort born between 1970 and 1980 during the period of nephrite mass production had the highest relative risk compared with other birth cohorts. The ASIR of lung cancer increased significantly from 1980 to 2010 (the annual percentage change = 6.8 %, 95 % CI: 4.0-9.7 %, P < 0.01) and then decreased 30 years after the cessation of nephrite jade mining. CONCLUSION: Nephrite mining increases the risk of lung cancer in nearby communities.

A review of the mesotheliogenic potency of cleavage fragments found in talc.

It has long been recognized that amphibole minerals, such as cleavage fragments of tremolite and anthophyllite, may exist in some talc deposits. We reviewed the current state of the science regarding the factors influencing mesotheliogenic potency of cleavage fragments, with emphasis on those that may co-occur in talc deposits, including dimensional and structural characteristics, animal toxicology, and the most well-studied cohort exposed to talc-associated cleavage fragments. Based on our review, multiple lines of scientific evidence demonstrate that inhaled cleavage fragments associated with talc do not pose a mesothelioma hazard.

Dimensions of elongate mineral particles and cancer: A review.

CONTEXT: Based on a decade-long exploration, dimensions of elongate mineral particles are implicated as a pivotal component of their carcinogenic potency. This paper summarizes current understanding of the discovered relationships and their importance to the protection of public health. OBJECTIVES: To demonstrate the relationships between cancer risk and dimensions (length, width, and other derivative characteristics) of mineral fibers by comparing the results and conclusions of previously published studies with newly published information. METHODS: A database including 59 datasets comprising 341,949 records were utilized to characterize dimensions of elongate particles. The descriptive statistics, correlation and regression analysis, combined with Monte Carlo simulation, were used to select dimensional characteristics most relevant for mesothelioma and lung cancer risk prediction. RESULTS: The highest correlation between mesothelioma potency factor and weight fraction of size categories is achieved for fibers with lengths >5.6 µm and widths ≤0.26 µm (R = 0.94, P < 0.02); no statistically significant potency was found for lengths <5 µm. These results are consistent with early published estimations, though are derived from a different approach. For combinations of amphiboles and chrysotile (with a consideration of a correction factor between mineral classes), the potency factors correlated most highly with a fraction of fibers longer than 5 µm and thinner than 0.2 µm for mesothelioma, and longer than 5 µm and thinner than 0.3 µm for lung cancer. Because the proportion of long, thin particles in asbestiform vs. non-asbestiform dusts is higher, the cancer potencies of the former are predicted at a significantly higher level. The analysis of particle dimensionality in human lung burden demonstrates positive selection for thinner fibers (especially for amosite and crocidolite) and prevailing fraction of asbestiform habit. CONCLUSION: Dimensions of mineral fibers can be confirmed as one of the main drivers of their carcinogenicity. The width of fibers emerges as a primary potency predictor, and fibers of all widths with lengths shorter than 5 µm seem to be non-impactful for cancer risk. The mineral dust with a fibrous component is primarily carcinogenic if it contains amphibole fibers longer than 5 µm and thinner than 0.25 µm.

Cancer mortality in a population exposed to nephrite processing.

OBJECTIVES: Although asbestos has been recognised as a strong carcinogen, many asbestos minerals exist in concrete masses, and the health risks of these materials remain inconclusive. Nephrite jade is a concrete mass of amphibole that consists of asbestiform and non-asbestiform particles. The objective of the study was to explore the carcinogenetic effect of nephrite. METHODS: We examined cancer mortality between 1979 and 2011 in Fengtian, where nephrite was mass produced from 1970 to 1980, and calculated standardised mortality ratios (SMRs). RESULTS: We observed significantly elevated mortality risks for cancer of the hypopharynx (SMR 2.31; 95% CI 1.37 to 3.65), larynx (SMR 2.51; 95% CI 1.55 to 3.83), oesophagus (SMR 2.04; 95% CI 1.62 to 2.54) and stomach (SMR 1.38; 95% CI 1.17 to 1.63). This study analysed the lengths, widths, structures, chemical compositions, aerodynamic diameters and distributions of elongated mineral particles (EMPs) in airways. The majority of the EMPs (68%) were short (<5 µm) and thin (<0.5 µm), and possessed asbestiform structures. The median aerodynamic diameter of the EMPs was 1.2 µm. The total deposition proportion in airways was 51.3%. The major deposition sites were the head airway (37.5%), followed by the alveolar region (10.6%) and the tracheobronchial region (3.2%). CONCLUSIONS: The results have shown an association between EMPs and increased risk of respiratory and digestive cancers. Further research is needed that includes information on smoking habits and exposure to asbestos.

A review of mortality associated with elongate mineral particle (EMP) exposure in occupational epidemiology studies of gold, talc, and taconite mining.

BACKGROUND: Mining of gold, taconite, and talc may involve exposure to elongate mineral particles (EMP). The involved EMPs are typically non-asbestiform, include dimensions that regulatory definitions exclude, and have been less studied. METHODS: A review of the literature was undertaken for this exposure and occupational epidemiological studies that occur in gold, talc, and taconite mining. RESULTS: Quantitative EMP exposure information in these industries is incomplete. However, there are consistent findings of pneumoconiosis in each of these types of mining. A recent case-control study suggests a possible association between this exposure and mesothelioma. Lung cancer is inconsistently reported in these industries and is an unlikely outcome of non-asbestiform EMP exposure. There is evidence of cardiovascular mortality excess across all of these types of mining. CONCLUSIONS: Non-malignant respiratory disease and cardiovascular mortality have been consistently increased in these industries. Further investigation, including additional insights for the role of non-asbestiform EMP, is warranted. Am. J. Ind. Med. 59:1047-1060, 2016. © 2016 Wiley Periodicals, Inc.

Carving of non-asbestiform tremolite and the risk of lung cancer: a follow-up mortality study in a historical nephrite processing cohort.

OBJECTIVES: The health risks associated with exposure to non-asbestiform asbestos minerals, including nephrite, are unclear. In 1965 nephrite processing began in the town of Fengtian in Taiwan, and the majority of inhabitants were involved in the industry from 1970 until 1980. The objectives of this study were to examine lung cancer deaths and assess the carcinogenic effects of nephrite carving. METHODS: We studied mortality due to lung cancer (ICD-9 code 162 for cancers of the trachea, bronchus and lung) from 1979 to 2011. We calculated the standardised mortality ratio (SMR) for lung cancer using the age- and sex-specific cancer mortality rates in eastern Taiwan as the standard rates. Air samples, bulk samples and a surface sample were analysed. RESULTS: Nephrite is a non-asbestiform asbestos mineral composed of microcrystalline tremolite. During nephrite processing, in personal air samples the average concentration of elongated mineral particles with the morphological characteristics of asbestos fibres was 1.4 f/cm(3), with rough grinding generating the highest concentrations (4.7 f/cm(3)). Transmission electron microscopy (TEM) confirmed that the air samples contained intact asbestiform tremolite fibres. The ambient air samples and the wipe sample indicated paraoccupational contamination. The crude mortality rates for lung cancer were higher in Fengtian than in Taiwan for all age groups and both genders. The SMR for lung cancer was 1.28 (95% CI 1.12 to 1.45). CONCLUSIONS: Nephrite carving may increase the risk of lung cancer. Appropriate medical monitoring is warranted for workers who are exposed to similar materials.