Mortality and cancer experience of Quebec aluminum reduction plant workers. Part 2: mortality of three cohorts hired on or before january 1, 1951

Workers in Australian prebake aluminium smelters: update on risk of mortality and cancer incidence in the Healthwise cohort

OBJECTIVES

To investigate mortality and the rates of incident cancer among a cohort of aluminium industry workers.

METHODS

Among 4507 male employees who worked in either of two Australian prebake smelters for at least 3 months, data linkage was undertaken with the Australian National Death Index and Australian Cancer Database. Standardised Mortality Ratios (SMRs) and Standardised Incidence Rates (SIRs) were estimated for the whole cohort and for: production; maintenance and office workers. SMRs and SIRs were calculated by time since first employment.

RESULTS

Among production workers, there was an excess risk of mortality from mesothelioma (SMR 2.8, 95% CI 1.3 to 5.2), lung (SMR 1.4, 95% CI 1.0 to 1.8), prostate (SMR 1.9, 95% CI 1.3 to 2.7) and liver cancer (SMR 2.0, 95% CI 1.1 to 3.4) and the SIR was also increased for overall respiratory cancers, specifically lung cancers. An excess risk of death from stomach cancer (SMR 2.9, 95% CI 1.2 to 6.1) and Alzheimer's disease (SMR 3.4, 95% CI 1.1 to 7.9) was seen among maintenance workers. The overall risk of death was similar to that of the Australian general population, as was mortality from cancers overall and non-malignant respiratory disease.

CONCLUSIONS

No excess risk of death from bladder cancer or non-malignant respiratory disease was found. Excess lung cancer mortality and incidence may be explained by smoking and excess mortality from mesothelioma may be explained by asbestos exposure. An excess risk of mortality from liver and prostate cancer has been shown in production workers and requires further investigation.

Risk of Lung Cancer and Occupational Exposure to Polycyclic Aromatic Hydrocarbons Among Workers Cohorts - Worldwide, 1969-2022

What is already known about this topic?

Lung cancer has a high mortality, resulting in a severe disease burden. Polycyclic aromatic hydrocarbons (PAHs) are definitive carcinogen to human, and occupational exposure to PAHs is associated with lung cancer.

What is added by this report?

We analyzed the cancer cases from cohort studies on various PAHs exposed workers in China and other countries, calculated the quantitative risk of lung cancer based on meta-analyses, and confirmed the increased risk from lung cancer in selected PAHs exposed occupations.

What are the implications for public health practices?

There is a clear need to prevent lung cancer on a wide range of PAHs-related occupations in China and around the world. It is crucial to establish guidelines for improving the monitoring on exposure and health promotion in related working environments.

Coal tar pitch extract could induce chromosomal instability of human bronchial epithelial cells mediated by spindle checkpoint-related proteins

Coal tar pitch (CTP) is a byproduct of coal tar distillation. The workers working with coal tar or in aluminum smelters, potrooms and carbon plants have the opportunities of exposing to coal tar pitch volatiles. Coal tar pitches from which polycyclic aromatic hydrocarbons (PAHs) originate have been shown to exhibit lung carcinogenicity in humans. Chromosomal instability (CIN) is a mechanism in carcinogenesis, however, whether CIN is involved in coal tar pitch-induced lung cancer remains elusive. In this present study, human bronchial epithelial cells (BEAS-2B) were first exposed to coal tar pitch extracts (CTPE) to induce a malignant transformation model. Then, the occurrence of severe chromosomal changes detected using G band, R band and multiplex fluorescence in situ hybridization (M-FISH) staining were examined. It was shown that more clones of transformed BEAS-2B cells at passage 30 following stimulation with CTPE were formed in the soft agar compared with the vehicle control. Moreover, the expression of the spindle checkpoint-related proteins, mitotic arrest defective 2 (Mad2), budding uninhibited in benzimidazole 1 (Bub1), and anaphase-promoting complex (APC), indicators of abnormal chromosomes and carcinogenesis, reduced in CTPE-treated BEAS-2B cells at Passage 30 compared with the vehicle control using real-time PCR and immunohistochemistry. In summary, exposure of BEAS-2B cells to CTPE may induce chromosomal instability through spindle checkpoint-related proteins.

Annual decline in forced expiratory volume is steeper in aluminum potroom workers than in workers without exposure to potroom fumes

Background

Aluminum potroom exposure is associated with increased mortality of COPD but the association between potroom exposure and annual decline in lung function is unknown. We have measured lung volumes annually using spirometry from 1986 to 1996. The objective was to compare annual decline in forced expiratory volume in 1 s (dFEV1) and forced vital capacity (dFVC).

Methods

The number of aluminum potroom workers was 4,546 (81% males) and the number of workers in the reference group was 651 (76% males). The number of spirometries in the index group and the references were 24,060 and 2,243, respectively.

Results

After adjustment for confounders, the difference in dFEV1 and dFVC between the index and reference groups were 13.5 (P < 0.001) and −8.0 (P = 0.060) ml/year.

Conclusion

Aluminum potroom operators have increased annual decline in FEV1 relative to a comparable group with non‐exposure to potroom fumes and gases. Am. J. Ind. Med. 59:322–329, 2016. © 2016 The Authors. American Journal of Industrial Medicine Published by Wiley Periodicals, Inc.

Bladder cancer screening in aluminum smelter workers

Objective:

To present results of a bladder cancer screening program conducted in 18 aluminum smelters in the United States from January 2000 to December 2010.

Methods:

Data were collected on a cohort of workers with a history of working in coal tar pitch volatile exposed areas including urine analysis for conventional cytology and ImmunoCyt/uCyt+ assay.

Results:

ImmunoCyt/uCyt+ and cytology in combination showed a sensitivity of 62.30%, a specificity of 92.60%, a negative predictive value of 99.90%, and a positive predictive value of 2.96%. Fourteen cases of bladder cancer were detected, and the standardized incidence ratio of bladder cancer was 1.18 (95% confidence interval, 0.65 to 1.99). Individuals who tested positive on either test who were later determined to be cancer free had undergone expensive and invasive tests.

Conclusions:

Evidence to support continued surveillance of this cohort has not been demonstrated.

Construction of a Job Exposure Matrix to Dust, Fluoride, and Polycyclic Aromatic Hydrocarbons in the Norwegian Aluminum Industry using Prediction Models

BACKGROUND

The Norwegian aluminum industry developed and implemented a protocol for prospective monitoring of employees' exposure using personal samplers. We analyzed these data to develop prediction lines to construct a job exposure matrix (JEM) for the period 1986-1995.

METHODS

The protocol for personal monitoring of exposure was implemented in all seven Norwegian aluminum plants in 1986 and continued until 1995. Personal samplers were used to collect total dust, fluorides, and total polycyclic aromatic hydrocarbons (PAH). In addition, exposure could be categorized according to process, i.e. prebake, Søderberg, and 'other'. We constructed four-dimensional JEMs characterized by: Plant, Job descriptor, Process, and Year. Totally 8074, 6734, and 3524 measurements were available for dust, fluorides, and PAH, respectively. The data were analyzed using linear mixed models with two-way interactions. The models were assessed using the Akaike criterion (AIC) and unadjusted R (2). The significance level was set to 10% (two-sided) for retaining variables in the model.

RESULTS

In 1986, the geometric mean (95% confidence interval in parentheses) for total dust, total fluorides, and PAH were 3.18 (0.46-22.2) mg m(-3), 0.58 (0.085-4.00) mg m(-3), and 33.9 (2.3-504) µg m(-3), respectively. During 10 years of follow-up, the exposure to total dust, fluorides, and PAH decreased by 9.2, 11.7, and 14.9% per year, respectively. Each model encompassed from 49 to 72 significant components of the interaction terms. The interaction components were at least as important as the main effects, and 65 to 91% of the significant components of the interaction terms were time-dependent.

CONCLUSION

Our prediction models indicated that exposures were highly time-dependent. We expect that the time-dependent changes in exposure are of major importance for longitudinal studies of health effects in the aluminum industry.

Respiratory disorders in aluminum smelter workers

Objectives:

Summarizing the knowledge status, including the morphology, possible etiological factors, and clinical expression of aluminum potroom asthma and chronic obstructive pulmonary disease related to aluminum potroom exposure.

Methods:

A review of the literature from the last two decades as it appears in PubMed.

Results:

There is substantial evidence for the existence of potroom asthma, although the incidence seems to decline over the last 10 years. Increased mortality from chronic obstructive pulmonary disease and longitudinal decline in forced expiratory volume in the first second of expiration has been shown in aluminum potroom workers. Morphological manifestations in bronchial biopsies and the inflammatory markers NO and eosinophils in airway tissue and blood are consistent with asthma in general. The causative agent(s) is (are) not known.

Conclusions:

Reduction of exposure and cessation of smoking seem to be the major preventive measures to avoid respiratory disorders in the aluminum industry.

Changes in telomere length and telomerase activity in human bronchial epithelial cells induced by coal tar pitch extract

Coal tar pitch is a confirmed human carcinogen and is composed mainly of polycyclic aromatic hydrocarbons.

Relevance of urinary 3-hydroxybenzo(a)pyrene and 1-hydroxypyrene to assess exposure to carcinogenic polycyclic aromatic hydrocarbon mixtures in metallurgy workers

OBJECTIVES

In metallurgy, workers are exposed to mixtures of polycyclic aromatic hydrocarbons (PAHs) in which some compounds are carcinogenic. Biomonitoring of PAH exposure has been performed by measuring urinary 1-hydroxypyrene (1-OHP), a metabolite of pyrene which is not carcinogenic. This study investigated the use of 3-hydroxybenzo(a)pyrene (3-OHBaP), a metabolite of benzo(a)pyrene (BaP) which is the main carcinogenic component in PAHs, to improve carcinogen exposure assessment.

METHODS

We included 129 metallurgy workers routinely exposed to PAHs during working hours. Urinary samples were collected at three sampling times at the beginning and at the end of the working week for 1-OHP and 3-OHBaP analyses.

RESULTS

Workers in anode production showed greater exposure to both biomarkers than those in cathode or silicon production, with respectively, 71, 40, and 30% of 3-OHBaP concentrations exceeding the value of 0.4 nmol mol(-1) creatinine. No difference was observed between the 3-OHBaP levels found at the end of the penultimate workday shift and those at the beginning of the last workday shift. Within these plants, the 1-OHP/3-OHBaP ratios varied greatly according to the workers' activity and emission sources. Using linear regression between these two metabolites, the 1-OHP level corresponding to the guidance value for 3-OHBaP ranged from 0.7 to 2.4 µmol mol(-1) creatinine, depending on the industrial sector.

CONCLUSIONS

This study emphasizes the interest of monitoring urinary 3-OHBaP at the end of the last workday shift when working week exposure is relatively steady, and the irrelevance of a single guideline value for 1-OHP when assessing occupational health risk.

Community health risk assessment of primary aluminum smelter emissions

OBJECTIVE

Primary aluminum production is an industrial process with high potential health risk for workers. We consider in this article how to assess community health risks associated with primary aluminum smelter emissions.

METHODS

We reviewed the literature on health effects, community exposure data, and dose-response relationships of the principal hazardous agents emitted.

RESULTS

On the basis of representative measured community exposure levels, we were able to make rough estimates on health risks associated with specific agents and categorize these as none, low, medium, or high.

CONCLUSIONS

It is possible to undertake a rough-estimate community Health Risk Assessment for individual smelters on the basis of information available in the epidemiological literature and local community exposure data.

Cancer risks in aluminum reduction plant workers: a review

OBJECTIVE AND METHODS

This review examines epidemiological evidence relating to cancers in the primary aluminum industry where most of what is known relates to Söderberg operations or to mixed Söderberg/prebake operations.

RESULTS AND CONCLUSIONS

Increased lung and bladder cancer risks have been reported in Söderberg workers from several countries, but not in all. After adjustment for smoking, these cancer risks still increase with cumulative exposure to benzo(a)pyrene, used as an index of coal tar pitch volatiles exposure. Limited evidence has been gathered in several cohorts for an increased risk of tumors at other sites, including stomach, pancreas, rectum/rectosigmoid junction, larynx, buccal cavity/pharynx, kidney, brain/nervous system, prostate, and lymphatic/hematopoietic tissues (in particular non-Hodgkin lymphoma, Hodgkin disease, and leukemia). Nevertheless, for most of these tumor sites, the relationship with specific exposures has not been demonstrated clearly and further follow-up of workers is warranted.

Validation of RiskCheck Bladder Cancer ©, version 5.0 for risk-adapted screening of bladder cancer

INTRODUCTION

The aim of the study was to assess the strength of the online tool RiskCheck Bladder Cancer©, version 5.0 (RCBC) for early detection of bladder cancer (BC).

MATERIALS AND METHODS

RCBC was evaluated retrospectively based on the data of 241 patients, of which 141 were suffering from BC. Statistical analysis was performed by descriptive statistics, nonparametric group comparison, classification tree analysis and ROC analysis.

RESULTS

ROC analysis of the risk classification showed a sensitivity of 71.6%, a specificity of 56.5%, a positive predictive value of 67.8%, a negative predictive value of 52% and an accuracy of 63.5%. BC risk factors ranked by importance are time of smoking (p < 0.0001), gender (within the nonsmoking group: p < 0.009), occupational toxin exposure (within the group <35 years of smoking: p < 0.048) and amount of consumed cigarettes resulting in a 95% association with BC (within the group >35 years of smoking: p < 0.0001).

CONCLUSIONS

The high predictive power of RCBC for the identification of asymptomatic patients living under risk could be demonstrated.

Oral benzo[a]pyrene: understanding pharmacokinetics, detoxication, and consequences--Cyp1 knockout mouse lines as a paradigm

Benzo[a]pyrene (BaP) is a prototypical polycyclic aromatic hydrocarbon (PAH); this ubiquitous environmental carcinogenic agent is found in tobacco smoke, charcoal-grilled foods, and PAH-contaminated surfaces of roofs, playgrounds, and highways. Cytochrome P450 1 wild-type, Cyp1a2(-/-), Cyp1b1(-/-), or Cyp1a2/1b1(-/-) knockouts, and mice with Cyp1a1 expression deleted in hepatocytes can ingest large oral BaP doses (125 mg/kg/d) without apparent toxicity. Cyp1a1(-/-) and Cyp1a1/1a2(-/-) knockouts and mice with Cyp1a1 expression deleted in gastrointestinal (GI) tract epithelial cells develop immunotoxicity and die within 32 days, indicating that GI tract inducible CYP1A1 is absolutely required for detoxication of oral BaP. Cyp1a1/1b1(-/-) and Cyp1a1/1a2/1b1(-/-) mice are rescued from immunosuppression and early death due to absent metabolic activation of BaP by CYP1B1 in immune cells. Ten-fold lower oral BaP doses result in adenocarcinoma of the proximal small intestine (PSI) in Cyp1a1(-/-) mice; Cyp1a1/1b1(-/-) double-knockout mice show no PSI cancer but develop squamous cell carcinoma of the preputial gland duct (PGD). BaP-metabolizing CYP1B1 in the PSI and CYP3A59 in the PGD are the most likely candidates to participate in tumor initiation in the epithelial cells of these two tissues; oncogenes and tumor-suppressor genes upregulated and downregulated during tumorigenesis are completely different between these tissues. This "oral BaP Cyp1" mouse paradigm represents a powerful teaching tool, showing that gene-environment interactions depend on route-of-administration: the same oral, but not intraperitoneal, BaP exposure leads to dramatic differences in target-organ toxicity and tumor type as a function of dose and Cyp1 genotype.

Lung cancer risk and pollution in an industrial region of Northern Spain: a hospital-based case-control study

Background

Asturias, an Autonomous Region in Northern Spain with a large industrial area, registers high lung cancer incidence and mortality. While this excess risk of lung cancer might be partially attributable to smoking habit and occupational exposure, the role of industrial and urban pollution also needs to be assessed. The objective was to ascertain the possible effect of air pollution, both urban and industrial, on lung cancer risk in Asturias.

Methods

This was a hospital-based case-control study covering 626 lung cancer patients and 626 controls recruited in Asturias and matched by ethnicity, hospital, age, and sex. Distances from the respective participants' residential locations to industrial facilities and city centers were computed. Using logistic regression, odds ratios (ORs) and 95% confidence intervals (95%CIs) for categories of distance to urban and industrial pollution sources were calculated, with adjustment for sex, age, hospital area, tobacco consumption, family history of cancer, and occupation.

Results

Whereas individuals living near industries displayed an excess risk of lung cancer (OR = 1.49; 95%CI = 0.93-2.39), which attained statistical significance for small cell carcinomas (OR = 2.23; 95%CI = 1.01-4.92), residents in urban areas showed a statistically significant increased risk for adenocarcinoma (OR = 1.92; 95%CI = 1.09-3.38). In the Gijon health area, residents in the urban area registered a statistically significant increased risk of lung cancer (OR = 2.17; 95%CI = 1.25-3.76), whereas in the Aviles health area, no differences in risk were found by area of exposure.

Conclusions

This study provides further evidence that air pollution is a moderate risk factor for lung cancer.

Chronic and acute effects of coal tar pitch exposure and cardiopulmonary mortality among aluminum smelter workers

Air pollution causes several adverse cardiovascular and respiratory effects. In occupational studies, where levels of particulate matter and polycyclic aromatic hydrocarbons (PAHs) are higher, the evidence is inconsistent. The effects of acute and chronic PAH exposure on cardiopulmonary mortality were examined within a Kitimat, Canada, aluminum smelter cohort (n = 7,026) linked to a national mortality database (1957-1999). No standardized mortality ratio was significantly elevated compared with the province's population. Smoking-adjusted internal comparisons were conducted using Cox regression for male subjects (n = 6,423). Ischemic heart disease (IHD) mortality (n = 281) was associated with cumulative benzo[a]pyrene (B(a)P) exposure (hazard ratio = 1.62, 95% confidence interval: 1.06, 2.46) in the highest category. A monotonic but nonsignificant trend was observed with chronic B(a)P exposure and acute myocardial infarction (n = 184). When follow-up was restricted to active employment, the hazard ratio for IHD was 2.39 (95% confidence interval: 0.95, 6.05) in the highest cumulative B(a)P category. The stronger associations observed during employment suggest that risk may not persist after exposure cessation. No associations with recent or current exposure were observed. IHD was associated with chronic (but not current) PAH exposure in a high-exposure occupational setting. Given the widespread workplace exposure to PAHs and heart disease's high prevalence, even modest associations produce a high burden.

Relationship between cardiopulmonary mortality and cancer risk and quantitative exposure to polycyclic aromatic hydrocarbons, fluorides, and dust in two prebake aluminum smelters

OBJECTIVES

We examined the risk of mortality and cancer incidence with quantitative exposure to benzene-soluble fraction (BSF), benzo(a)pyrene (BaP), fluoride, and inhalable dust in two Australian prebake smelters.

METHODS

A total of 4,316 male smelter workers were linked to mortality and cancer incidence registries and followed from 1983 through 2002 (mean follow-up: 15.9 years, maximum: 20 years). Internal comparisons using Poisson regression were undertaken based on quantitative exposure levels.

RESULTS

Smoking-adjusted, monotonic relationships were observed between respiratory cancer and cumulative inhalable dust exposure (trend p = 0.1), cumulative fluoride exposure (p = 0.1), and cumulative BaP exposure (p = 0.2). The exposure-response trends were stronger when examined across the exposed categories (BaP p = 0.1; inhalable dust p = 0.04). A monotonic, but not statistically significant trend was observed between cumulative BaP exposure and stomach cancer (n = 14). Bladder cancer was not associated with BaP or BSF exposure. No other cancer and no mortality outcomes were associated with these smelter exposures.

CONCLUSIONS

The carcinogenicity of Söderberg smelter exposures is well established; in these prebake smelters we observed an association between smelter exposures and respiratory cancer, but not bladder cancer. The exploratory finding for stomach cancer needs confirmation. These results are preliminary due to the young cohort and short follow-up time.

Mortality and cancer experience of Quebec aluminum reduction plant workers, part 4: cancer incidence

OBJECTIVE

To describe the cancer experience of Quebec aluminum smelter workers.

METHODS

Cancer incidence was compared with that of the Quebec general population and examined in relation to benzo[a]pyrene (B[a]P) and smoking exposure indices.

RESULTS

There was a statistically significant increased incidence of stomach (two cohorts), pancreatic (one cohort), laryngeal (one cohort), lung (three cohorts), and bladder (four cohorts) cancers. Unlike lung and bladder cancers, pancreatic and stomach cancer risks do not relate meaningfully to cumulative B[a]P exposure. Laryngeal and buccal cavity cancer standardized incidence ratios (SIRs) seem to increase with increasing B[a]P exposure. SIRs from lung cancer have greatly diminished whereas bladder cancer SIRs remain elevated in all but one cohort.

CONCLUSIONS

The cancer incidence results are consistent with those from mortality studies, but identify other cancers that deserve scrutiny in future follow-ups.

Mortality and cancer experience of Quebec aluminum reduction plant workers. Part 3: monitoring the mortality of workers first employed after January 1, 1950

OBJECTIVE

To monitor changes over time in mortality of workers first employed in Quebec aluminum smelters after January 1, 1950 (1951-one cohort).

METHODS

Mortality of cohorts by decade of hire was compared with Quebec and same plant experience before 1950 (1951).

RESULTS

Chronic obstructive pulmonary disease and respiratory cancer (one cohort each) mortality were statistically in excess. In the combined cohorts, standardized mortality ratios exceeded 110 for cancers of esophagus, rectum, and rectosigmoid junction, pancreas, larynx, lung, non-Hodgkin lymphoma, cerebrovascular disease, and asthma. These findings essentially mirrored the experience of pre-1950 workers. There was a significant downward trend in mortality from all causes, lung and bladder cancer.

CONCLUSIONS

Statistically significant improvements were found in mortality from all causes combined, from cancer and from cancer of the lung and bladder. Slightly increased mortality continues from certain other causes.