End stage renal disease among ceramic workers exposed to silica

Occupational particle exposure and chronic kidney disease: a cohort study in Swedish construction workers

OBJECTIVES

Increasing epidemiological and experimental evidence suggests that particle exposure is an environmental risk factor for chronic kidney disease (CKD). However, only a few case-control studies have investigated this association in an occupational setting. Hence, our objective was to investigate associations between particle exposure and CKD in a large cohort of Swedish construction workers.

METHODS

We performed a retrospective cohort study in the Swedish Construction Workers' Cohort, recruited 1971-1993 (n=286 089). A job-exposure matrix was used to identify workers exposed to nine different particulate exposures, which were combined into three main categories (inorganic dust and fumes, wood dust and fibres). Incident CKD and start of renal replacement therapy (RRT) were obtained from validated national registries until 2021 and analysed using adjusted Cox proportional hazards models.

RESULTS

Exposure to inorganic dust and fumes was associated with an increased risk of CKD and RRT during working age (adjusted HR for CKD at age <65 years 1.15, 95% CI 1.05 to 1.26). The elevated risk did not persist after retirement age. Exposure to cement dust, concrete dust and diesel exhaust was associated with CKD. Elevated HRs were also found for quartz dust and welding fumes.

CONCLUSIONS

Workers exposed to inorganic particles seem to be at elevated risk of CKD and RRT. Our results are in line with previous evidence of renal effects of ambient air pollution and warrant further efforts to reduce occupational and ambient particle exposure.

Third mortality follow-up of the Mallinckrodt uranium processing workers, 1942-2019

INTRODUCTION

Mallinckrodt Chemical Works was a uranium processing facility during the Manhattan Project from 1942 to 1966. Thousands of workers were exposed to low-dose-rates of ionizing radiation from external and internal sources. This third follow-up of 2514 White male employees updates cancer and noncancer mortality potentially associated with radiation and silica dust.

MATERIALS AND METHODS

Individual, annualized organ doses were estimated from film badge records (n monitored = 2514), occupational chest x-rays (n = 2514), uranium urinalysis (n = 1868), radium intake through radon breath measurements (n = 487), and radon ambient measurements (n = 1356). Silica dust exposure from pitchblende processing was estimated (n = 1317). Vital status and cause of death determination through 2019 relied upon the National Death Index and Social Security Administration Epidemiological Vital Status Service. The analysis included standardized mortality ratios (SMRs), Cox proportional hazards, and Poisson regression models.

RESULTS

Vital status was confirmed for 99.4% of workers (84.0% deceased). For a dose weighting factor of 1 for intakes of uranium, radium, and radon decay products, the mean and median lung doses were 65.6 and 29.9 mGy, respectively. SMRs indicated a difference in health outcomes between salaried and hourly workers, and more brain cancer deaths than expected [SMR: 1.79; 95% confidence interval (CI): 1.14, 2.70]. No association was seen between radiation and lung cancer [hazard ratio (HR) at 100 mGy: 0.93; 95%CI: 0.78, 1.11]. The relationship between radiation and kidney cancer observed in the previous follow-up was maintained (HR at 100 mGy: 2.07; 95%CI: 1.12, 3.79). Cardiovascular disease (CVD) also increased significantly with heart dose (HR at 100 mGy: 1.11; 95%CI: 1.02, 1.21). Exposures to dust ≥23.6 mg/m3-year were associated with nonmalignant kidney disease (NMKD) (HR: 3.02; 95%CI: 1.12, 8.16) and kidney cancer combined with NMKD (HR: 2.46; 95%CI: 1.04, 5.81), though without evidence of a dose-response per 100 mg/m3-year.

CONCLUSIONS

This third follow-up of Mallinckrodt uranium processors reinforced the results of the previous studies. There was an excess of brain cancers compared with the US population, although no radiation dose-response was detected. The association between radiation and kidney cancer remained, though potentially due to few cases at higher doses. The association between levels of silica dust ≥23.6 mg/m3-year and NMKD also remained. No association was observed between radiation and lung cancer. A positive dose-response was observed between radiation and CVD; however, this association may be confounded by smoking, which was unmeasured. Future work will pool these data with other uranium processing worker cohorts within the Million Person Study.

Risk of Chronic Kidney Disease in Pneumoconiosis: Results from a Retrospective Cohort Study (2008-2019)

Background: Pneumoconiosis has considerable comorbidities, most notably pulmonary and cardiovascular diseases. However, the relationship between pneumoconiosis and chronic kidney disease (CKD) is largely unknown. The present study aimed to use a retrospective cohort study design to further clarify the association between pneumoconiosis and subsequent CKD risk. Methods: This is a nationwide, population-based, retrospective cohort study that used data from Taiwan’s National Health Insurance Database. Between 2008 and 2018, 17,952 newly diagnosed patients were included in the pneumoconiosis cohort, while 71,808 individuals without pneumoconiosis were included in the comparison cohort, with a propensity score matching for age, gender, and date of pneumoconiosis diagnosis. The development of CKD was monitored until the end of 2019. The risk was assessed using Cox proportional hazard regression models. Results: After controlling for age, gender, and comorbidity, the overall incidence of CKD was 1.69-fold higher in the pneumoconiosis cohort than in the comparison cohort (19.71 vs. 11.76 per 1000 person-years, respectively, p < 0.001), with an adjusted hazard ratio of 1.83 (95% confidence interval: 1.73−1.93). Stratified analyses by age group, gender, and presence of comorbidity revealed that the adjusted hazard ratios of CKD associated with pneumoconiosis remained significant (8/9). Furthermore, pneumoconiosis and tri-high (hypertension, hyperglycemia, and hyperlipidemia) interact positively with CKD development (p < 0.001). Conclusion: Patients with pneumoconiosis had a significantly higher risk of developing CKD than those without. Pneumoconiosis combined with hypertension, hyperglycemia, or hyperlipidemia would increase the risk even further. More studies are required to understand the possible pathophysiological mechanisms.

Asymptomatic Renal Function Abnormalities in Patients having Silicosis

BACKGROUND

A number of occupational exposures are associated with various types of renal dysfunction. Several studies for many years have drawn attention to renal dysfunction and nephrotoxicity among workers exposed to silica. This study was conducted to evaluate renal dysfunction, if any, among Indian patients having silicosis and its correlation with the duration of exposure to silica dust.

MATERIALS AND METHODS

This study includes 52 eligible patients with a history of silica dust exposure and silicosis confirm on radiological examination by the pneumoconiosis board. Investigations like serum creatinine, urinary albumin creatinine ratio, etc. were done. The "modification of diet in renal disease" (MDRD) formula was used to calculate the glomerular filtration rate (GFR).

RESULTS

This study showed 53.84% of patients (n = 28) having albuminuria and a mean "urinary albumin to creatinine ratio" (UACR) of 101.88 ± 128.99 mg/gm. Isolated macroalbuminuria was detected in 11.5% of patients (n = 6) while 42.3% of patients (n = 22) presented with microalbuminuria. The mean GFR was 81.94 ± 22.09 mL/min/1.73 m2 among study patients of which four (7.7%) patients had GFR value &lt;60 mL/min/1.73 m2 . We could also identify a significant association between the duration of exposure to silica dust and UACR and GFR (p &lt; 0.01).

CONCLUSION

Albuminuria and reduced estimated GFR in patients with silica dust exposure is not uncommon and reflect early underlying renal dysfunctions. Our study suggests a simple and cost-effective screening strategy for early detection of renal dysfunction among silicosis patients that may be considered as a tool to prevent further renal damage in such patients.

Mortality among mine and mill workers exposed to respirable crystalline silica

BACKGROUND

Millions of workers are potentially exposed to respirable crystalline silica (RCS) which has been associated with several diseases. We updated the mortality experience of a cohort of 2,650 mine and mill workers at four manufacturing facilities to assess cause-specific mortality risks associated with estimated cumulative RCS exposure.

METHODS

Study eligibility was defined as any employee who had ≥1 year of service by 2000, with work history experience available from 1945 through 2004. Vital status and cause of death were ascertained from 1945 through 2015. RCS exposure was estimated across plant-, department-, job-, and time-dependent categories using historic industrial hygiene sampling data and professional judgment. Associations between cumulative RCS (mg/m3-years) and cause-specific mortality were examined using Cox proportional hazard regression models.

RESULTS

In the exposure-response analysis defined on quartiles of cumulative RCS exposure, no increasing trend (ptrend = 0.37) in lung cancer mortality (n = 116 deaths) was observed (Hazard ratio (HR) = 1.00 (referent), 1.20, 1.85, 0.92). Mortality risk for non-malignant respiratory disease was increased across quartiles (HR = 1.00, 1.35, 1.89, 1.70; ptrend = 0.15), based on 83 deaths. Non-malignant renal disease mortality was increased across quartiles (HR = 1.00, 6.64, 3.79, 3.29; ptrend = 0.11), based on 26 deaths.

CONCLUSIONS

After nearly seven decades of follow-up, the exposure-response analyses showed no evidence of a positive trend for lung cancer, and limited evidence of a trend for non-malignant respiratory disease, and non-malignant renal disease mortality as a result of cumulative RCS exposure in this occupational cohort.

Multisystem Amyloidosis in a Coal Miner with Silicosis: Is Exposure to Silica Dust a Cause of Amyloid Deposition?

The over-secretion of monoclonal immunoglobulin light chains by clonal B cells followed by the aggregation and extracellular deposition of fibrillar deposits are responsible forthe clinical course AL amyloidosis. It is well documented that silica significantly increases the number of immunoglobulin-secreting cells. In the present paper, we report on a coal miner with silicosis and fast progressing primary amyloidosis with predominantly heart, kidney, and lung manifestations. Severeheart failure due to myocardial hypertrophy resulted in the patient’s death. We conclude that long-term environmental silica exposure and silica deposition may contribute to the development of monoclonal gammopathy and amyloidosis due to chronic stimulus and the dysregulation of the immune system.

Renal involvement in a silicosis patient - case report and literature review

A 43-year-old Chinese man with a silicosis history was admitted to our hospital due to bilateral lower extremity edema for 1 year, exacerbating with hematuria for 2 months. He started working as a coal miner 30 years ago, and was diagnosed as silicosis 3 months ago. Lab tests revealed hematuria 3+, proteinuria 3+, and a serum creatinine value 2.47 mg/dl on routine check. He was diagnosed with focal proliferative IgA nephropathy (IgAN) and acute tubulo-interstitial nephritis by renal biopsy. He was treated with corticosteroids and got a remission 4 months later. Immunohistochemical staining showed the deposition of macrophage receptor with collagenous structure (MARCO), nod-like receptor pyrin domain-containing-3 (NLRP3), Caspase-1, apoptosis-associated speck (ASC), interleukin (IL)-1β, and IL-18 in both glomerular and tubulo-interstitial areas. We proposed that the silicon exposure could be related to his kidney disease in the patient and NLRP3 mediated inflammation might be involved in its pathogenesis which needs further explorations.

Quantifying the Economic Impact of Hydraulic Fracturing Proppant Selection in Light of Occupational Exposure Risk and Functional Requirements

Selection of an effective and economic proppant material for hydraulic fracturing is an important design choice to optimize the production of oil and natural gas. Proppants are made of silica (quartz sand), alumina, resin-coated silica, ceramics, and others. These materials can be toxic to varying degrees and lead to health problems in the employees handling them primarily due to inhalation exposure. Proppants are selected based on grain size, shape, strength, and cost. Current use is dominated by crystalline silica-the proppant that also has the greatest hazard as an inhalation toxin. Existing research describes the effect of silica on human health, but little research has been done to determine the risk-reduction and social-cost-effectiveness associated with using alternative proppants in light of the health risks. This study quantifies the relative risks or benefits to human health by the use of these proppants through an economic analysis considering the health-related economic impact and its technical attributes. Results show that the use of each ton of silica proppant results in $123 of external costs from fatalities and nonfatal illness arising due to exposure to silica for a crew handing 60,000 tons of proppants. If these health-related externalities were incorporated into the cost, silica proppant could be economically replaced by less harmful, more expensive alternatives for hydraulic fracturing crews handling less than 60,000 tons of proppant each year.

Occupational exposures and chronic kidney disease: Possible associations with endotoxin and ultrafine particles

BACKGROUND

Chronic kidney disease (CKD) carries a high public health burden yet there is limited research on occupational factors, which are examined in this retrospective case-control study.

METHODS

Newly diagnosed cases of CKD (n = 547) and controls (n = 508) from North Carolina provided detailed work histories in telephone interviews. Unconditional logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

There was heterogeneity in the association of CKD and agricultural work, with crop production associated with increased risk and work with livestock associated with decreased risk. Work with cutting/cooling/lubricating oils was associated with a reduced risk. CKD risk was increased for working in dusty conditions.

CONCLUSIONS

CKD risk was reduced in subjects with occupational exposures previously reported to involve endotoxin exposure. Further, exposure to dusty conditions was consistently associated with increased risk of glomerulonephritis across industry, suggesting that research on CKD and ultrafine particulates is needed.

Occupational silica exposure and chronic kidney disease

INTRODUCTION

Occupational exposure to silica may be associated with chronic kidney disease (CKD). Most studies have been conducted in occupational cohorts with high levels of exposure but small numbers of cases. We analyzed data from a population-based case-control study of occupational silica exposure and CKD.

METHODS

Cases were hospital patients with newly diagnosed CKD, and community controls were selected using random digit dialing and frequency matched by age, gender, race, and proximity to the hospital. Silica exposure estimates were assigned by industrial hygiene review of lifetime job history data and weighted for certainty and intensity. Conditional logistic regression was used to estimate the odds ratios (ORs) for CKD conditioned on demographic, lifestyle, and clinical variables.

RESULTS

The mean age of participants was 63 years (range 30-83 years); 59% were male and 55% were white. Any silica exposure (compared with none) was associated with a 40% increased risk of CKD [OR = 1.40, 95% confidence interval (CI): 1.04, 1.89] in a multivariable adjusted model. The mean cumulative duration of silica exposure was significantly higher in exposed cases than in exposed controls (33.4 vs. 24.8 years, respectively). Overall, compared with nonexposed participants, the ORs (95% CI) for those below and above the median duration of silica exposure were 1.20 (0.77, 1.86) and 1.76 (1.14, 2.71), respectively.

CONCLUSIONS

We found a positive relationship between occupational silica exposure and CKD. A dose-response trend of increasing CKD risk with increasing duration of silica exposure was observed and was particularly strong among nonwhites.

Mortality in the German porcelain industry 1985-2005: first results of an epidemiological cohort study

OBJECTIVES

To evaluate mortality due to lung cancer, silicosis, renal cancer, renal disease and other causes among German porcelain production workers potentially exposed to crystalline silica.

METHODS

Seventeen thousand six hundred forty-four medical surveillance participants (1985-1987) were followed through 2005 for mortality. Cause-specific Standardized Mortality Ratios (SMR) and 95% confidence intervals were estimated.

RESULTS

Women (SMR = 0.85; 95% CI = 0.78 to 0.93), but not men, demonstrated a healthy worker effect. Lung and renal cancers, and renal disease (non-malignant renal disease) were not associated with employment or exposure surrogates. Mortality was increased from silicosis (SMR = 7.20; 95% CI = 2.32 to 16.8) liver (SMR = 1.99; 95% CI = 1.29 to 2.93) and pancreatic (SMR = 1.71; 95% CI = 1.18 to 2.41) cancers among men, and diabetes among women (SMR = 1.74; 95% CI = 1.07 to 2.65). A sub-cohort of Bavarian workers generated similar but generally higher SMRs.

CONCLUSIONS

Silicosis mortality was increased in this, among the largest studies to date. However, associations previously observed between crystalline silica exposure and renal or lung cancers or non-malignant renal disease were not supported.

State-of-the-science review of the occupational health hazards of crystalline silica in abrasive blasting operations and related requirements for respiratory protection

Excessive exposures to airborne crystalline silica have been known for over 100 years to pose a serious health hazard. Work practices and regulatory standards advanced as the knowledge of the hazards of crystalline silica evolved. This article presents a comprehensive historical examination of the literature on exposure, health effects, and personal protective equipment related to silica and abrasive blasting operations over the last century. In the early 1900s, increased death rates and prevalence of pulmonary disease were observed in industries that involved dusty operations. Studies of these occupational cohorts served as the basis for the first occupational exposure limits in the 1930s. Early exposure studies in foundries revealed that abrasive blasting operations were particularly hazardous and provided the basis for many of the engineering control and respiratory protection requirements that are still in place today. Studies involving abrasive blasters over the years revealed that engineering controls were often not completely effective at reducing airborne silica concentrations to a safe level; consequently, respiratory protection has always been an important component of protecting workers. During the last 15-20 yr, quantitative exposure-response modeling, experimental animal studies, and in vitro methods were used to better understand the relationship between exposure to silica and disease in the workplace. In light of Occupational Safety and Health Administration efforts to reexamine the protectiveness of the current permissible exposure limit (PEL) for crystalline silica and its focus on protecting workers who are known to still be exposed to silica in the workplace (including abrasive blasters), this state-of-the-science review of one of the most hazardous operations involving crystalline silica should provide useful background to employers, researchers, and regulators interested in the historical evolution of the recognized occupational health hazards of crystalline silica and abrasive blasting operations and the related requirements for respiratory protection.

One agent, many diseases: exposure-response data and comparative risks of different outcomes following silica exposure

BACKGROUND

Evidence in recent years indicates that silica causes lung cancer, and probably renal disease, in addition to its well-known relationship to silicosis. There is also suggestive evidence that silica can cause arthritis and other auto-immune diseases. Silica has, therefore, joined a handful of other toxic exposures such as tobacco smoke, dioxin, and asbestos which cause multiple serious diseases.

METHODS

The available exposure-response data for silica and silicosis, lung cancer, and renal disease are reviewed. We compare the corresponding excess risks (or absolute risks in the case of silicosis) of death or disease incidence by age 75 for these three diseases, subsequent to a lifetime (45 years) of exposure to silica at current US standard (0.1 mg/m(3) respirable crystalline silica).

RESULTS

The absolute risk of silicosis, as defined by small opacities greater than or equal to ILO classification 1/1 on an X-ray, ranges from 47% to 77% in three cohort studies with adequate follow-up after employment. The absolute risk of death from silicosis is estimated at 1.9% (0.8%-2.9%), based on a pooled analysis of six cohort studies. The excess risk of lung cancer death, assuming US male background rates, is 1.7% (0.2%-3.6%), based on a pooled analysis of ten cohort studies. The excess risk of end-stage renal disease (assuming male background rates) is 5.1% (2.2%-7.3%), based on a single cohort. The excess risk of death from renal disease is estimated to be 1.8% (0.8%-9.7%), based on a pooled analysis of three cohorts.

CONCLUSIONS

Keeping in mind that the usual OSHA acceptable excess risk of serious disease or death for workers is 0.1%, it is clear that the current standard is far from sufficiently protective of workers' health. Perhaps surprisingly, kidney disease emerges as perhaps a higher risk than either mortality from silicosis or lung cancer, although the data are based on fewer studies.

Occupational silica exposure and risk of various diseases: an analysis using death certificates from 27 states of the United States

BACKGROUND

Although crystalline silica exposure is associated with silicosis, lung cancer, pulmonary tuberculosis, and chronic obstructive pulmonary disease (COPD), there is less support for an association with autoimmune disease, and renal disease.

METHODS

Using data from the US National Occupational Mortality Surveillance (NOMS) system, a matched case-control design was employed to examine each of several diseases (including silicosis, lung cancer, stomach cancer, oesophageal cancer, COPD, pulmonary tuberculosis, sarcoidosis, systemic lupus erythematosus, systemic sclerosis, rheumatoid arthritis, and various types of renal disease). Cases were subjects whose death certificate mentioned the disease of interest. A separate control group for each of the diseases of interest was selected from among subjects whose death certificate did not mention the disease of interest or any of several diseases reported to be associated with crystalline silica exposure. Subjects were assigned into a qualitative crystalline silica exposure category based on the industry/occupation pairing found on their death certificate. We also investigated whether silicotics had a higher risk of disease compared to those without silicosis.

RESULTS

Those postulated to have had detectable crystalline silica exposure had a significantly increased risk for silicosis, COPD, pulmonary tuberculosis, and rheumatoid arthritis. In addition, a significant trend of increasing risk with increasing silica exposure was observed for these same conditions and for lung cancer. Those postulated to have had the greatest crystalline silica exposure had a significantly increased risk for silicosis, lung cancer, COPD, and pulmonary tuberculosis only. Finally, those with silicosis had a significantly increased risk for COPD, pulmonary tuberculosis, and rheumatoid arthritis.

CONCLUSIONS

This study corroborates the association between crystalline silica exposure and silicosis, lung cancer, COPD, and pulmonary tuberculosis. In addition, support is provided for an association between crystalline silica exposure and rheumatoid arthritis.

Occupational exposure to crystalline silica and risk of systemic lupus erythematosus: a population-based, case-control study in the southeastern United States

OBJECTIVE

Crystalline silica may act as an immune adjuvant to increase inflammation and antibody production, and findings of occupational cohort studies suggest that silica exposure may be a risk factor for systemic lupus erythematosus (SLE). We undertook this population-based study to examine the association between occupational silica exposure and SLE in the southeastern US.

METHODS

SLE patients (n = 265; diagnosed between January 1, 1995 and July 31, 1999) were recruited from 4 university rheumatology practices and 30 community-based rheumatologists in 60 contiguous counties. Controls (n = 355), frequency-matched to patients by age, sex, and state of residence, were randomly selected from driver's license registries. The mean age of the patients at diagnosis was 39 years; 91% were women and 60% were African American. Detailed occupational and farming histories were collected by in-person interviews. Silica exposure was determined through blinded assessment of job histories by 3 industrial hygienists, and potential medium- or high-level exposures were confirmed through followup telephone interviews. Odds ratios (ORs) and 95% confidence intervals (95% CIs) were estimated by logistic regression.

RESULTS

More patients (19%) than controls (8%) had a history of medium- or high-level silica exposure from farming or trades. We observed an association between silica and SLE (medium exposure OR 2.1 [95% CI 1.1-4.0], high exposure OR 4.6 [95% CI 1.4-15.4]) that was seen in separate analyses by sex, race, and at different levels of education.

CONCLUSION

These results suggest that crystalline silica exposure may promote the development of SLE in some individuals. Additional research is recommended in other populations, using study designs that minimize potential selection bias and maximize the quality of exposure assessment.

Kidney disease and arthritis in a cohort study of workers exposed to silica

Silica exposure has been associated with kidney disease and rheumatoid arthritis; an autoimmune mechanism has been proposed. Approximately 2 million people are occupationally exposed to silica in the United States, 100,000 at more than twice the National Institute for Occupational Safety and Health recommended exposure limit of 0.05 mg/m(3). We examined renal disease morbidity and mortality, as well as arthritis mortality, in a cohort of 4,626 silica-exposed workers in the industrial sand industry (an industry previously unstudied). We compared the cohort with the U.S. population and also conducted internal exposure-response analyses using a job-exposure matrix based on more than 4,000 industrial hygiene samples. We found excess mortality from acute renal disease [standardized mortality ratio (SMR) = 2.61, 95% confidence intervals (95% CIs) = 1.49--4.24; 16 deaths], chronic renal disease (SMR = 1.61, 95% CI = 1.13--2.22; 36 deaths), and arthritis (SMR = 4.36, 95% CI = 2.76--6.54; 23 deaths) on the basis of multiple-cause mortality data, which considered any mention of disease on a death certificate. Linking the cohort with the U.S. registry of end-stage renal disease for the years 1977-1996, we found an excess of end-stage renal disease incidence (standardized incidence ratio = 1.97, 95% CI = 1.25--2.96; 23 cases), which was highest for glomerulonephritis (standardized incidence ratio = 3.85, 95% CI = 1.55--7.93; 7 cases). We found increasing end-stage renal disease incidence with increasing cumulative exposure; standardized rate ratios by quartile of cumulative exposure were 1.00, 3.09, 5.22, and 7.79. A positive exposure-response trend was also observed for rheumatoid arthritis on the basis of death certificate data. These data represent the largest number of kidney disease cases analyzed to date in a cohort with well-defined silica exposure and suggest a causal link between silica and kidney disease. Excess risk of end-stage renal disease due to a lifetime of occupational exposure at currently recommended limits is estimated to be 14%, above a background end-stage renal disease risk of 2%.