Cancer mortality in chrysotile miners and millers, Russian Federation: main results (Asbest Chrysotile Cohort-Study).

BACKGROUND: We investigated mortality in workers of the world's largest chrysotile mine and enrichment factories located in the town of Asbest, Russian Federation. METHODS: This historical cohort study included all workers employed for at least 1 year between 1975 and 2010 and follow-up until the end of 2015. Cumulative exposure to dust was estimated based on workers' complete occupational history linked to dust measurements systematically collected from the 1950s. Exposure to chrysotile fibers was estimated using dust-to-fiber conversion factors. Relative risks (RRs) and 95% confidence intervals (CIs) were estimated as mortality rate ratios in Poisson regression models. RESULTS: A total of 30 445 (32% women) workers accumulated 721 312 person-years at risk and 11 110 (36%) died. Of the workers, 54% had more than 30 years since their first exposure. We found an exposure-response between cumulative dust and lung cancer mortality in men. No clear association with dust exposure but a modest increase in the highest category of fiber exposure was seen for lung cancer in women. Mesothelioma mortality was increased (RR = 7.64, 95% CI = 1.18 to 49.5, to at least 80 fibers per cm3 years and RR = 4.56, 95% CI = 0.94 to 22.1, to at least 150 mg/m3 years [dust]), based on 13 deaths. For colorectal and stomach cancer, there were inconsistent associations. No associations were seen for laryngeal or ovarian cancer. CONCLUSION: In this large-scale epidemiological study in the world's largest active asbestos mine, we confirmed an increased risk of mesothelioma with high fiber exposure and an increasing mortality for lung cancer in men with increasing dust exposure. Less clear-cut increased lung cancer mortality was seen in the women. Continued mortality follow-up is warranted.

Accidentes de trabajo mortales y enfermedades profesionales en la minería (Régimen General). Perú: 2010-2019 / Fatal work accidents and professional diseases in mining (General Regime). Peru: 2010-2019

Se analiza el comportamiento de los accidentes de trabajo mortales (ATM) y de las enfermedades profesionales (EP), en relación con las empresas del régimen general en la minería peruana, durante los años 2010 al 2019. Se realizó un estudio transversal de la base de datos del Ministerio de Energía y Minas. El estudio incluyó las notificaciones de accidentes de trabajo mortales y de las enfermedades profesionales reportadas en esa década por las empresas mineras del régimen general; del 2010 al 2019 para los ATM, y entre 2011- 2019 para las EP, a nivel nacional. Resultados: De 422 ATM notificados entre 2010-2019 se determinan cuatro rangos, considerando 126 empresas. El rango D (dos empresas) son el 2% pero las que presentan la mayor siniestralidad laboral. La empresa D1 acredita 29 ATM y la empresa D2 tiene19 ATM, ambas asumen el 11.34% del total de los ATM en la década analizada. El rango A, son 95 empresas, conforman el 75% del total y presentan entre 1 a 3 ATM para el mismo periodo. El 61% de trabajadores víctimas de ATM son de contratistas y conexas; mientras que el 39% son ATM de las empresas principales. Entre 2011-2019 se notificaron 40,001 EP en las empresas mineras, trabajadores con menos de un año registran EP y mayores de 55 años tienen una curva pronunciada de EP. El 1% son trabajadoras mineras y el 99% son trabajadores. Se necesita mayor investigación sobre las EP en el sector minero(AU)

To analyse the behavior of fatal work accidents (ATMs for its acronym in Spanish) and occupational diseases (EPs), in companies under the general regime of the mining sector in Peru during the years 2010 to 2019. A cross-sectional study was carried out using the database from the Ministry of Energy and Mines (MINEM). The study included notifications at the national level of ATMs (2010-2019) and EPs (2011 to 2019) reported by the mining companies under the general regime. Results: Of 422 ATMs reported by 126 companies between 2010-2019, four range categories were determined. Rank D grouped two companies (representing only 2%) that had the highest occupational accident rate. Company D1 reported 29 ATMs and company D2 reported 19 ATMs, together accounting for 11.34% of the total number of ATMs during the study period. Rank A consisted of 95 companies (representing 75%) and reporting between 1 to 3 ATMs for the same period. Contractor and outsourcing companies reported 61% of workers victims of ATMs, while main companies reported 39% of ATMs. Between 2011-2019, 40,001 EPs were reported in mining companies, workers under one year reported EPs, and workers over 55 years of age had a steep EP curve. Female workers represent 1% of mining workers and 99% are male workers. More research is needed on EPs in the mining sector(AU)

Effects of chronic intermittent hypobaric hypoxia on prostate-specific antigen (PSA) in Chilean miners.

OBJECTIVE: The aim was to determine the effects of chronic intermittent hypobaric hypoxia (CIHH) on prostate-specific antigen (PSA) levels in Chilean miners who work at different altitudes. METHODS: A cross-sectional study was conducted between April and July 2019. Miners from five mines (N=338) at different altitudes were evaluated. We recorded sociodemographic, working and altitude information. Haemoglobin oxygen saturation (SaO2) and haemoglobin (Hb) were measured in situ, while PSA and testosterone were analysed at a low level. Linear mixed-effect models were used to evaluate the association between PSA level and two CIHH exposures: composite CIHH (with four descriptors) and ChileStd-CIHH (CIHH Chilean standard; based on the Chilean technical guide for occupational exposure to CIHH). All models were adjusted by age, body mass index and day of the work the samples were taken. RESULTS: Highest and lowest PSA levels were found in mines ≥3000 m above sea level (mine 3: median=0.75, IQR=-0.45; mine 4: median=0.46, IQR=-0.35). In the multilevel models, the wider altitude difference between mining operation and camp showed lower PSA levels (model D: ßPSA=-0.93 ng/mL, ßlogPSA=-0.07, p<0001), adjusted for other CIHH descriptors, SaO2, Hb and testosterone. The descriptors of composite CIHH explained better PSA variations than ChileStd-CIHH (model D: marginal R2=0.090 vs model A: marginal R2=0.016). CONCLUSIONS: Occupational health regulations and high altitude medicine should consider these results as initial evidence on the inclusion of new descriptors for CIHH and the possible effect of this exposure on PSA levels in this male-dominated occupational sector.

Case finding of tuberculosis among mining communities in Ghana.

BACKGROUND: Data on active TB case finding activities among artisanal gold mining communities (AMC) is limited. The study assessed the yield of TB cases from the TB screening activities among AMC in Ghana, the factors associated with TB in these communities and the correlation between the screening methods and a diagnosis of TB. METHODS: We conducted secondary data analyses of NTP program data collected from TB case finding activities using symptom screening and mobile X-ray implemented in hard to reach AMC. Yield of TB cases, number needed to screen (NNS) and the number needed to test (NNT) to detect a TB case were assessed and logistic regression were conducted to assess factors associated with TB. The performance of screening methods chest X-ray and symptoms in the detection of TB cases was also evaluated. RESULTS: In total 10,441 people from 78 communities in 24 districts were screened, 55% were female and 60% (6,296) were in the aged 25 to 54 years. Ninety-five TB cases were identified, 910 TB cases per 100,000 population screened; 5.6% of the TB cases were rifampicin resistant. Being male (aOR 5.96, 95% CI 3.25-10.92, P < 0.001), a miner (aOR 2.70, 95% CI 1.47-4.96, P = 0.001) and age group 35 to 54 years (aOR 2.27, 95% CI 1.35-3.84, P = 0.002) were risk factors for TB. NNS and NNT were 110 and 24 respectively.; Cough of any duration had the strongest association with X-ray suggestive of TB with a correlation coefficient of 0.48. Cough was most sensitive for a diagnosis of TB; sensitivity of 86.3% (95% CI 79.4-93.2) followed by X-ray, sensitivity 81.1% (95% CI 71.7-88.4). The specificities of the symptoms and X-rays ranged from 80.2% (cough) to 97.3% (sputum). CONCLUSION: The high risk of TB in the artisanal mining communities and in miners in this study reinforces the need to target these populations with outreach programs particularly in hard to reach areas. The diagnostic value of cough highlights the usefulness of symptom screening in this population that may be harnessed even in the absence of X-ray to identify those suspected to have TB for further evaluation.

Occupational skin disease in mining: an Australian case series.

The mining industry has one of the highest rates of occupational disease across all industries. However, occupational skin disease (OSD) is not commonly reported in this industry, although has been estimated to affect up to 51 people per 100,000 workers, with contact dermatitis accounting for the majority of cases. It often has a poor prognosis and leads to days lost from work. There have been relatively few reports regarding the specific forms of OSD encountered by miners worldwide. We report our experience of miners attending our Occupational Dermatology Clinic and our investigations at two Australian mines. We compare our findings with other reports of OSD in the mining population. The most commonly observed skin condition was irritant contact dermatitis, but miliaria and allergic contact dermatitis were also observed. It is not surprising that most cases of OSD appear to be related to harsh working conditions and exposures to multiple skin irritants, however, specific exposures causing ACD should not be forgotten. Our findings are consistent with previous studies of OSD in miners.

Health conditions in retired manual labor miners and oil and gas extraction workers: National Health Interview Survey, 2007-2017.

BACKGROUND: Within the mining industrial sector, workers in the mining and oil and gas extraction (OGE) industries have demonstrated disparities in chronic health status compared with the general working population. However, we know much less about miner and OGE worker health once retired. This study separately compares chronic illnesses in retired miners and OGE workers with all other retirees. METHODS: National Health Interview Survey (NHIS) public data were analyzed for the years 2007-2017 to estimate weighted unadjusted and adjusted prevalence of selected health conditions (cancer, cardiovascular disease, high cholesterol, diabetes, hypertension, respiratory conditions, health status, and hearing loss) in retirees. Three retired worker groups (miners, OGE, and other retirees) were defined using the respondents' longest-held industry and occupation. RESULTS: Higher prevalence of a number of adverse health conditions was noted in miners and OGE workers when compared with all other retirees. A significantly higher adjusted prevalence of hypertension, hearing loss, functionally limiting lung problems, and fair or poor health was seen in miners over other retirees. Retired OGE workers demonstrated a significantly higher adjusted prevalence of both hearing loss and poor health status. CONCLUSIONS: Miners and OGE workers have higher morbidity during their working years, and this study demonstrates that poorer health appears to continue into retirement. These results suggest the need to expand occupational health and safety programs in the mining sector to improve the health of workers into retirement. Future studies that include more robust information on workplace exposures are needed to evaluate the long-term health of retired workers.

Prevalence and epidemiological characteristics of human immunodeficiency virus-1 infection in an iron mining area with intense migratory flow in Pará State, Brazilian amazon, 2005-2014.

Acquired immunodeficiency syndrome (AIDS) caused by human immunodeficiency virus (HIV) is a major global public health problem. The aim of this study is to determine the prevalence of HIV-1 infection in four municipalities of Pará State (Marabá, Parauapebas, Curionópolis, and Canaã dos Carajás), in northern, Brazil. The municipalities are located in the Carajás Complex iron mining area. The employment opportunities result in extensive migratory flow of people. A total of 4771 serum samples were obtained from 2005 to 2014 and were sent to Evandro Chagas Institute, Belém-Pará, where they were tested by enzyme-linked immunosorbent assay, with reactive samples confirmed by Western blot analysis. The samples were from individuals from 23 Brazilian states and the Federal District, mainly Maranhão (39.53%) and other municipalities of Pará (34.25%). The total positivity rate was 0.48% (23/4771). The rate was 0.47% (14/2975) in males and 0.50% (9/1796) in females. Of these, 0.33% (14/4275) were from asymptomatic individuals whose serum were collected during the serological survey, 1.81% (9/497) were from cases featuring clinical symptoms including fever/diarrhea/jaundice, which were included in febrile, diarrheal, and icteric syndromes analyzed during the study. The findings indicated the presence of HIV-1 infection in the general population studied. The majority of cases (60.9%, 14 of 23 positive cases) were asymptomatic.

American cutaneous leishmaniasis in French Guiana: an epidemiological update and study of environmental risk factors.

BACKGROUND: American cutaneous leishmaniasis (ACL) is endemic in French Guiana. Its epidemiology is evolving, notably because of immigration, anthropization of natural areas, and new microbiological methods. Our first objective was to update epidemiological data. Our second objective was to look for risk factors of ACL. METHODS: This multicentric study was conducted from October 2017 to June 2018 in French Guiana. Patients with suspicion of mucocutaneous leishmaniasis were included in case of positive smear, culture, or PCR-RFLP on skin biopsy. RESULTS: One hundred and twenty-three patients met the inclusion criteria. Among those patients, 59.3% were Brazilian, mostly gold miners. Most of them (58%) were between 16 and 40 years old, and 69% were male. A large proportion of patients lived in traditional wooden houses (51%). Patients living in coastal towns were usually infected during trips to the primary forest (60%) and had a shorter time to diagnosis than workers of the hinterland. Among environmental risk factors, the presence of a water spring (40%) and dogs around houses (40%) were frequently reported. Leishmania guyanensis represented 80% of cases, followed by Leishmania braziliensis (6%), Leishmania naiffi (2%), and Leishmania amazonensis (1%). CONCLUSIONS: Gold mining and trips to the primary forest represent high-risk situations for ACL in French Guiana, where the population of infected patients is dominated by Brazilian immigrants. Possible environmental risk factors such as the presence of dogs, water sources, and traditional wooden houses require further investigation.

A 37-year Update on Mortality Patterns in an Expanded Cohort of Vermont Talc Miners and Millers.

OBJECTIVES: The aim of this study was to update a cohort of Vermont talc workers to include 37 additional years of follow-up time. METHODS: Standardized mortality ratios (SMR) and 95% confidence intervals (CIs) were calculated for 70+ causes of death. US population mortality rates were used as reference. RESULTS: All-cause mortality was 30% higher than the US population (SMR 133.4, 95% CI, 119.7 to 148.3). Significant elevations occurred in nonmalignant respiratory disease (NMRD) (SMR 273.0, 95% CI, 210.2 to 348.6) and other nonmalignant respiratory disease (ONMRD) (SMR 413.1, 95% CI, 287.7 to 574.5). ONMRD was elevated across all length of employment categories and a test for linear trend was significant (P = 0.007). CONCLUSIONS: This study provides further evidence that excess deaths among Vermont talc workers are due largely to excess mortality from NMRD; there is no evidence of increased risk of respiratory cancer.

Prevalence of hearing loss among noise-exposed workers within the Mining and Oil and Gas Extraction sectors, 2006-2015.

BACKGROUND: The purpose of this study was to estimate the prevalence of hearing loss (HL) among noise-exposed US workers within the Mining, and Oil and Gas Extraction (OGE) sectors. METHODS: Audiograms of 1.9 million workers across all industries (including 9389 in Mining and 1076 in OGE) from 2006 to 2015 were examined. Prevalence and adjusted risk as compared to a reference industry (Couriers and Messengers) were estimated for all industries combined and the Mining and OGE sectors and subsectors. RESULTS: The prevalences of HL in Mining and OGE were 24% and 14%, respectively, compared with 16% for all industries combined. Many Mining and one OGE subsector exceeded these prevalences and most had an adjusted risk (prevalence ratio) significantly greater than the reference industry. Some subsectors, particularly in OGE, could not be examined due to low sample size. The prevalences in Construction Sand and Gravel Mining and Natural Gas Liquid Extraction were 36% and 28%, respectively. Workers within Support Activities for Coal Mining had double the risk of HL than workers in the reference industry. CONCLUSIONS: The many subsectors identified with high prevalences and/or worker risks for HL well above risks in the reference industry need critical attention to conserve worker hearing and maintain worker quality of life. Administrative and engineering controls can reduce worker hazardous noise exposures. Noise and ototoxic chemical exposure information is needed for many subsectors, as is audiometric testing results for OGE workers. Additional research is also needed to further characterize exposures and improve hearing conservation measures.

Heavy Metals in California Women Living in a Gold Mining-Impacted Community.

Gold mining activities occurred throughout the foothills of the Sierra Nevada Mountains in California, leaving behind persistent toxic contaminants in the soil, dust, and water that include arsenic and cadmium. Despite a high level of concern among local residents about potential exposure and high breast cancer rates, no biomonitoring data has been collected to evaluate the levels of heavy metals. We conducted a study to characterize the urinary levels of heavy metals among women in this region by working with the community in Nevada County. Sixty women provided urine samples and completed a questionnaire. We examined levels of arsenic, cadmium, and other metals in relation to the length of residency in the area, age, dietary factors, recreational activities, and smoking. We compared urinary metal levels in participants to levels in the United States National Health and Nutrition Examination Survey (NHANES). Overall, study participants had higher urinary levels of arsenic than women in the national sample. Cadmium levels were similar to the national average, although they were elevated in women ≥35 years who had lived in the region for 10 years or more. Arsenic levels were higher among women who smoked, ate fish, ate home-grown produce, and who reported frequent hiking or trail running, although these differences were not statistically significant. This study established a successful community-research partnership, which facilitated community dialogue about possible human health consequences of living in a mining-impacted area.

North-south gradient of mesothelioma and asbestos consumption-production in the United States-Progresses since the 1st asbestos partial ban in 1973.

BACKGROUND: Temporal trends and broad geographical distributions of asbestos use and the incidence of malignant mesothelioma (MM) in the US still need to be studied. METHODS: Data on asbestos consumption and production between 1900 and 2015 and MM mortality and incidence rates between 1975 and 2015 in the US were examined. Spatial distributions of MM mortality and incidence rates and their association with climate zone were analyzed. RESULTS: Decline of MM incidence and mortality rates in the US occurred about 20 years after the peak of asbestos consumption-production in 1973. There are apparent north-south (N-S) gradients in MM mortality and incidence rates in the US. CONCLUSION: Recent decline of MM incidence and mortality rates in the US may be associated with reduced US asbestos consumption. N-S MM gradients between 1999 and 2015 were likely related to larger asbestos requirements in building materials in the northern states.

The Diesel Exhaust in Miners Study provides no evidence for an increase in risk for lung cancer in miners exposed to diesel engine emissions.

The Diesel Exhaust in Miners Study is unquestionably the most suitable data material to date to examine a possible link between diesel engine emissions and lung cancer risk. But the results do not appear to be consistent in themselves. The crucial methodological problem in this study, however, has yet to be discovered, to which the lack of any description of age related information (year of birth, year of hire, year of first exposure, year of death) for the cohort as well as for the cases might have contributed. This information is important to understand the flaws in the analysis. It turns out that the year of birth is associated with the exposure, i.e. with the chance to be exposed over a certain period of time as well as with the chance to be an ever-smoker. A further important issue for the interpretation of the results is the validity of the data on smoking, which are mainly obtained from next of kin for decedents up to 50 years after death. Taking all these aspects into account, it can be concluded that only the SMR-analysis can be considered from all published results.

Adverse health effects of asbestos: solving mysteries regarding asbestos carcinogenicity based on follow-up survey of a Chinese factory.

The present review summarizes the results of several follow-up studies assessing an asbestos product manufacturing plant in Chongqing, China, and discusses three controversial issues related to the carcinogenicity of asbestos. The first issue is the amphibole hypothesis, which asserts that the carcinogenicity of asbestos is limited to amphiboles, such as crocidolite, but not serpentines, such as chrysotile. However, considering the possible multiple component of asbestos carcinogenicity in the presence of tobacco smoke or other carcinogens, chrysotile cannot be regarded as non-carcinogenic. Additionally, in a practical sense, it is not possible to assume "pure" chrysotile due to its ubiquitous contamination with tremolite, which is a type of amphibole. Thus, as the International Agency for Research on Cancer (IARC) assessed, all forms of asbestos including chrysotile should be regarded carcinogenic to humans (Group 1). The second issue is the chrysotile/tremolite paradox, which is a phenomenon involving predominant levels of tremolite in the lung tissues of individuals who worked in locations with negligible levels of tremolite due to the exclusive use of chrysotile. Four possible mechanisms to explain this paradox have been proposed but this phenomenon does not support the claim that amphibole is inert. The final issue discussed is the textile mystery, i.e., the higher incidence of cancer in asbestos textile plants compared to asbestos mines where the same asbestos was produced and the exposure levels were comparable. This phenomenon was first reported in North America followed by UK and then in the present observations from China. Previously, levels of fiber exposure were calculated using a universal converting coefficient to estimate the mass concentration versus fiber concentration. However, parallel measurements of fiber and mass concentrations in the workplace and exposed air indicated that there are wide variations in the fiber/mass ratio, which unjustifies the universal conversion. It is possible that contamination by airborne non-fibrous particles in mines with mass fiber conversion led to the overestimation of fiber concentrations and resulted in the textile mystery. Although the use and manufacturing of asbestos has been banned in Japan, more than 10 million tons of asbestos had been imported and the majority remains in existing buildings. Thus, efforts to control asbestos exposure should be continued.

Estimating the Impact of Changes to Occupational Standards for Silica Exposure on Lung Cancer Mortality.

BACKGROUND: Respiratory exposure to silica is associated with the risk of death owing to malignant and nonmalignant disease. 2.3 million US workers are exposed to silica. Occupational exposure limits for silica are derived from a number of lines of evidence, including observational studies. Observational studies may be subject to healthy worker survivor bias, which could result in underestimates of silica's impact on worker mortality and, in turn, bias risk estimates for occupational exposure limits. METHODS: Using data on 65,999 workers pooled across multiple industries, we estimate the impacts of several hypothetical occupational exposure limits on silica exposure on lung cancer and all-cause mortality. We use the parametric g-formula, which can account for healthy worker survivor bias. RESULTS: Assuming we could eliminate occupational exposure, we estimate that there would be 20.7 fewer deaths per 1,000 workers in our pooled study by age 80 (95% confidence interval = 14.5, 26.8), including 3.91 fewer deaths owing to lung cancer (95% CI = 1.53, 6.30). Less restrictive interventions demonstrated smaller but still substantial risk reductions. CONCLUSIONS: Our results suggest that occupational exposure limits for silica can be further strengthened to reduce silica-associated mortality and illustrate how current risk analysis for occupational limits can be improved.

Community-Level Exposure to the Rural Mining Industry: The Potential Influence on Early Adolescent Alcohol and Tobacco Use.

PURPOSE: Rural youth have higher rates of alcohol and tobacco use compared to their urban counterparts. However, the economic dependence of rural communities may differentially influence risk behaviors. While research has shown that adults working in mining have elevated rates of alcohol and tobacco use, the influence of living in a mining community on early adolescent substance use is unknown. METHODS: Using data from a representative sample of 4,535 middle school students in a state with heavy reliance on mining, we conducted weighted logistic regression to investigate whether community-level mining economic dependence influences rural-urban differences in adolescent alcohol and tobacco use. All models adjusted for sociodemographics, military family involvement, parental monitoring, and length of residence. FINDINGS: Over one quarter of the sampled students lived in rural counties and approximately half of these counties met the USDA mining economic typology. After stratifying rural counties by mining and nonmining economic dependence, students in rural mining counties had significantly higher odds of all measures of alcohol use (AORs ranged from 1.83 to 3.99) and tobacco use (AORs ranged from 1.61 to 5.05) compared to students in urban counties. Only use of smokeless tobacco was higher among students in rural nonmining counties. CONCLUSIONS: Our findings demonstrate rural-urban disparities in adolescent substance use that are particularly pronounced among youth living in counties with economic dependence on mining. Future research on this subject should include a wider range of community-level factors that may have specific relevance in rural settings to inform the development of population-level interventions.

ADA Title I allegations and the Mining, Quarrying, and Oil/Gas Extraction industry.

BACKGROUND: The majority of research about employment discrimination in the U.S. Mining, Quarrying, and Oil/Gas (MQOGE) industries has concentrated on gender and race, while little attention has focused on disability. OBJECTIVE: To explore allegations of Americans with Disabilities Act (ADA) Title I discrimination made to the Equal Employment Opportunity Commission (EEOC) by individuals with disabilities against MQOGE employers. METHODS: Key data available to this study included demographic characteristics of charging parties, size of employers, types of allegations, and case outcomes. Using descriptive analysis, allegation profiles were developed for MQOGE's three main sectors (i.e., Oil/Gas Extraction, Mining except Oil/Gas, and Support Activities). These three profiles where then comparatively analyzed. Lastly, regression analysis explored whether some of the available data could partially predict MQOGE case outcomes. RESULTS: The predominant characteristics of MQOGE allegations were found to be quite similar to the allegation profile of U.S. private-sector industry as a whole, and fairly representative of MQOGE's workforce demographics. Significant differences between MQOGE's three main sector profiles were noted on some important characteristics. Lastly, it was found that MQOGE case outcomes could be partially predicted via some of the available variables. CONCLUSIONS: The study's limitations were presented and recommendations were offered for further research.

Total and Cause-Specific Mortality Risk Associated With Low-Level Exposure to Crystalline Silica: A 44-Year Cohort Study From China.

The association between low-level crystalline silica (silica) exposure and mortality risk is not well understood. We investigated a cohort of 44,807 Chinese workers who had worked in metal mines or pottery factories for at least 1 year from January 1, 1960, to December 31, 1974, and were followed through 2003. Low-level silica exposure was defined as having a lifetime highest annual mean silica exposure at or under a permissible exposure limit (PEL). We considered 3 widely used PELs, including 0.05 mg/m3, 0.10 mg/m3, and 0.35 mg/m3. Cumulative silica exposure was estimated by linking a job exposure matrix with each participant's work history. For the 0.10-mg/m3 exposure level, Cox proportional hazards models showed significantly increased risk of mortality from all diseases (for each 1-ln mg/m3-years increase in logged cumulative silica exposure, hazard ratio (HR) = 1.05, 95% confidence interval (CI): 1.03, 1.07), malignant neoplasms (HR = 1.06, 95% CI: 1.03, 1.09), lung cancer (HR = 1.08, 95% CI: 1.02, 1.14), ischemic heart disease (HR = 1.09, 95% CI: 1.02, 1.16), pulmonary heart disease (HR = 1.08, 95% CI: 1.00, 1.16), and respiratory disease (HR = 1.20, 95% CI: 1.14, 1.26). The 0.05-mg/m3 and 0.35-mg/m3 exposure levels yielded similar associations. Long-term exposure to low levels (PELs ≤0.05 mg/m3, ≤0.10 mg/m3, or ≤0.35 mg/m3) of silica is associated with increased total and certain cause-specific mortality risk. Control of ambient silica levels and use of personal protective equipment should be emphasized in practice.