Aluminum Reduction Plant Research Articles

Aluminum: The Light Metal, Part II

Abstract The cost of electric power is the biggest expense involved in aluminum production. Proximity to economical power sources determined the location of major aluminum reduction plants. This article describes the development of the aluminum industry in the early part of the twentieth century.

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.

Strategic environmental assessment (SEA) as a means to include environmental knowledge in decision making in the case of an aluminium reduction plant in Greenland

The purpose and means of strategic environmental assessment (SEA) can vary depending on the case investigated and interests of actors involved. Based on the objective for the SEA of a proposed aluminium reduction plant (ARP) in Greenland, this paper evaluates the SEA's effectiveness in securing environmental knowledge in a decision-making process. It is concluded that the SEA secured inclusion of environmental knowledge in three out of four key decision arenas, which determined the direction and outcome of the process. The results from the SEA did not oppose the recommendations based on the economic assessments. As there was no conflict between economic and environmental recommendations, and hence no visible proof of SEA's influence on the outcome of the decision, it is discussed whether environmental knowledge, in this decision making process, equals influence. The investigation was carried out as a part of a PhD project and is meant as a contribution to the debate about how to investigate SEA effectiveness and to broaden the understanding of the use of SEA in Greenland.

Fluoride pollutants as causative agents for nitrotoxins generated in some legume plants

Leaflets of six collected legume species including Alhagi camelorum Fisch., Cercis siliquastrum L., Glycyrrhiza glabra L., Medicago sativa L., Robinia peseudoacacia L., and Sophora alopecuroides L. from an aluminum reduction plant area in Iran were analyzed for presence of toxic aliphatic nitro compounds. In addition, studies were conducted to determine fluoride (Fl) levels in these plants. Controls were from 10 km distance of the factory. Results showed high Fl concentration in all polluted samples. Phytochemical changes in all polluted leaves, with the exception of C. siliquastrum and G. glabra, were observed with presence of nitrotoxins.

Determination of fluoride and its effects on flavonoids in some legumes

The effects of fluoride (Fl) emission, from an aluminum (Al) reduction plant in Iran, on the concentration of Fl in six legume species were studied. In addition, the influence of Fl on leaf flavonoids was investigated. Determination of Fl in collected plants (Alhagi camelorum Fisch., Cercis siliquastrum L., Glycyrrhiza glabra L. Medicago sativa L., Robinia peseudoacacia L., and Sophora alopecuroides L.) from the factory area was performed using a Fl ion-selective electrode. Identification of flavonoids in the samples was obtained by two-dimensional paper chromatography (2-D PC) and thin layer chromatography (TLC). Controls were obtained from plants located 10 km distance from the factory. Results showed high Fl concentration in all polluted samples. Phytochemical changes in polluted leaves were observed with appearance or disappearance of some flavonoids.

UP.87: Bladder Cancer and the Aluminum Industry: A Review of the Current Literature

An increased risk of bladder cancer among workers in the aluminum processing industry has been documented in several epidemiologic studies. We review the current literature on the etiology and risk of bladder cancer among aluminum reduction plant workers.

Mortality and Cancer Experience of Quebec Aluminum Reduction Plant Workers, Part 4: Cancer Incidence

To describe the cancer experience of Quebec aluminum smelter workers. 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. 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. 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

To monitor changes over time in mortality of workers first employed in Quebec aluminum smelters after January 1, 1950 (1951-one cohort). Mortality of cohorts by decade of hire was compared with Quebec and same plant experience before 1950 (1951). 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. 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.

Mortality and Cancer Experience of Quebec Aluminum Reduction Plant Workers, Part 2: Mortality of Three Cohorts Hired on or Before January 1, 1951

To describe the mortality of Quebec aluminum smelter workers employed before 1951. The mortality of 5,977 men hired at three plants on or before January 1, 1951 was compared with that of Quebec men. Relationships to benzo[a]pyrene, benzene-soluble material, and smoking were examined. Statistically significant causes of death were lung cancer (three plants); bladder cancer; chronic obstructive lung disease (two plants each); cancers of the stomach, digestive system unspecified, rectum and rectosigmoid, pancreas, and larynx; Alzheimer's disease (one plant); and cerebrovascular disease (one plant). Not significant increases were also observed. Mortality from cancer of the lung and bladder and chronic obstructive pulmonary disease are related to exposure in Söderberg smelters. The cause of increased stomach cancer mortality is unclear. Excess mortality from some other diseases may be explained by factors other than coal tar pitch volatiles exposure.

Mortality and Cancer Experience of Quebec Aluminum Reduction Plant Workers. Part I: The Reduction Plants and Coal Tar Pitch Volatile (CTPV) Exposure Assessment

This paper presents the exposure assessment and job-exposure matrix (JEM) used to estimate coal tar pitch volatile (CTPV) exposure for a study of mortality and cancer incidence in aluminum smelter workers in Quebec, Canada. Historical CTPV exposure was assessed by estimating benzene-soluble material (BSM) and benzo[a]pyrene (B[a]P) levels for combinations of job and time period. Estimates were derived by using several procedures including averaging measurement data, a deterministic mathematical model using process-related correction factors, and expert-based extrapolation. The JEM comprised 28,910 jobs, covering 7 facilities from 1916 to 1999. Estimated exposures ranged from 0.01 microg/m(3) to 68.08 microg/m(3) (B[a]P) and 0.01 mg/m(3) to 3.64 mg/m(3) (BSM) and were lowest before 1940 and after 1980. This methodology constitutes an improvement compared with methods used for previous studies of the Quebec cohort.

Cancer risk in aluminum reduction plant workers (Canada)

A 14-year update to a previously published historical cohort study of aluminum reduction plant workers was conducted [1]. All men with three or more years at an aluminum reduction plant in British Columbia (BC), Canada between the years 1954 and 1997 were included; a total of 6,423 workers. A total of 662 men were diagnosed with cancer, representing a 400% increase from the original study. Standardized mortality and incidence ratios were used to compare the cancer mortality and incidence of the cohort to that of the BC population. Poisson regression was used to examine risk by cumulative exposure to coal tar pitch volatiles (CTPV) measured as benzene soluble materials (BSM) and benzo(a)pyrene (BaP). The risk for bladder cancer was related to cumulative exposure to CTPV measured as BSM and BaP (p trends <0.001), and the risk for stomach cancer was related to exposure measured by BaP (p trend BaP <0.05). The risks for lung cancer (p trend <0.001), non-Hodgkin lymphoma (p trend <0.001), and kidney cancer (p trend <0.01) also increased with increasing exposure, although the overall rates were similar to that of the general population. Analysis of the joint effect of smoking and CTPV exposure on cancer showed the observed dose-response relationships to be independent of smoking.

A Review of the Formation, Environmental Fate, and Forensic Methods for PAHs from Aluminum Smelting Processes

This article provides a description of the processes used in modern aluminum reduction plants and explores the sources of polycyclic aromatic hydrocarbons (PAHs) at pertinent steps in the industrial process. Chemical and physical characteristics of raw and processed source materials are described, and the effects of process modifications and alternative processes on generation of PAHs are explored. For example, the self-bake Söderberg method is contrasted with the prebake method of anode formation by describing the quantities of PAHs generated and characteristics of PAHs associated with each process. Available datasets for aluminum smelters are predominantly limited to analyses of selected parent PAHs (unsubstituted). Thus, many preferred forensic methods for characterizing PAHs cannot be applied to much of the existing data. However, typical parent PAH distributions and isomer ratios are explored using up to 17 selected unsubstituted PAHs in emissions from aluminum reduction plants and environmental media affected by emissions. In addition, summaries are presented of selected environmental studies conducted in areas influenced by aluminum reduction and non-aluminum reduction sources of PAHs. Forensic tools for identifying influences from aluminum smelters in environmental samples reflecting mixed sources are also discussed.

An Application of Parametric and Nonparametric Models to the Assessment of Fluoride Levels in Vegetation Exposed to Stack Emissions of an Aluminum Reduction Plant in Greece

Various statistical models were developed for assessing airborne fluoride (F) levels in natural vegetation near an aluminum reduction plant using as predictor variables the distance from the emission source, the predominating wind, and characteristic topography-geomorphology parameters. Results revealed that F concentrations in vegetation showed a predictable response to both wind conditions and landscape features. The linear model was found to give good estimations, taking advantage of the relatively strong linear correlation between concentration and distance. A nonlinear relationship between the F concentration in vegetation and the other variables was also found, while interactions between the variables were found to be non-first-order. The nonlinear relationship hypothesis was supported by the improved results of various nonlinear models that also indicated the importance of the area’s topography-geomorphology and meteorology in model predictions. The application of an artificial neural network (ANN) model showed the closest agreement between predicted and observed values with a correlation coefficient of 0.92. The improved reliability of the ANN and a regression tree model (RTM) also were indicated by the normal distribution of their residuals. The RTM and the ANN were further investigated and found to be capable of identifying the importance of the variables in vegetation exposure to air emissions.

Lung and bladder cancer among workers in a Norwegian aluminium reduction plant

OBJECTIVETo investigate the relation between exposure to polycyclic aromatic hydrocarbons (PAHs) and the incidence of lung and bladder cancer among aluminium production workers.METHODSThe cohort comprised 1790 men employed for more...

A mortality study among workers in a French aluminium reduction plant.

A mortality study on the association between lung cancer and occupational exposure to polycyclic aromatic hydrocarbons (PAHs) was carried out in a French aluminium reduction plant. This study updated a previous mortality study. The historical cohort included every male worker who had been employed in the plant for at least 1 year between 1950 and 1994. Workers were followed-up for mortality from 1968 to 1994. Causes of death were obtained from death certificates. Standardised mortality ratios (SMRs) and 95% confidence intervals (CI) were computed using regional mortality rates as external reference to compare observed and expected numbers of deaths, adjusted for gender, age and calendar time. The cohort comprised 2,133 men, of whom 335 died during the follow-up period. The observed mortality was lower than expected for all causes of death (SMR = 0.81, CI 0.72-0.90) and for lung cancer (observed = 19, SMR = 0.63, CI 0.38 0.98). No lung cancer excess was observed in workshops where PAH exposure was likely to have occurred, and no trend was observed according to duration of exposure and time since first exposure. This low lung cancer mortality could be partly explained by a marked healthy worker effect and a possible negative confounding by smoking. An excess was observed for bladder cancer (observed = 7, SMR = 1.77, CI 0.713.64) in the whole cohort, that was higher among workers employed in workshops where PAH exposure was likely to have occurred (observed = 6, SMR = 2.15, CI 0.79-4.68). In addition, an SMR higher than unity was observed for "psychoses and neuro-degenerative diseases" (observed = 6, SMR = 2.39, CI 0.88-5.21), that could not be related to occupational aluminium exposure. No lung cancer risk was detected. Non-significant excesses were observed for bladder cancer and for psychoses and neuro-degenerative diseases.

Coupled LC-GC-NPD for Determination of Carbazole-Type PANH and Its Application to Personal Exposure Measurement

A coupled LC-GC method for the analysis of carbazole-type PANH has been developed and evaluated. Group separation and isolation of carbazoles from interfering acridines in a complex sample matrix was accomplished by using a back-flush technique and an in situ end-capped dimethylaminopropyl silica column in the HPLC part of the system. On-line injection of the carbazole fraction into the GC column was performed with a loop-type interface utilizing concurrent solvent evaporation technique. An LOD of 1–3 pg of individual carbazole compounds was achieved by nitrogen selective detection using an NPD. The method is shown to be robust and is demonstrated by application to personal exposure measurement in an aluminum reduction plant.

Cancer incidence and cause specific mortality among workers in two Norwegian aluminum reduction plants.

Concern about the health hazards in the aluminum industry has initiated this study where we have investigated associations between exposure to polycyclic aromatic hydrocarbons (PAH) and fluorides, and cancer incidence and cause specific mortality among workers in two Norwegian aluminum plants in operation since 1954 and 1957, respectively. The study was designed as a historical cohort study and comprised 5627 identified men employed for more than six months. Cancer incidence was investigated from start of employment to 1995, and cause specific mortality was investigated from 1962 to 1995. The observed cases of cancers and observed deaths were compared with expected numbers calculated from national rates. Internal comparisons were made using Poisson regression with age and smoking included in the models. Historical exposure to PAH and fluoride had been estimated previously by use of statistical modeling on industrial hygiene measurements and process parameters. A job exposure matrix was used to investigate possible associations between cumulative exposures, and cancer incidence and cause specific mortality. Smoking habits were identified for 92% of the cohort members. The study showed a significant excess risk for urinary bladder cancer among workers exposed to PAH, but no clear dose-response relationship. When using a 30-year lag period, a significant excess of bladder cancer in the highest exposure category (> 2000 microg/m(3);year PAH) was shown (SIR 4.08). The data also suggested an association between exposure to PAH and pancreatic cancer, but no association with lung cancer was seen. The mortality analysis indicated an association between exposure to pot-room emissions (fluorides) and mortality from chronic bronchitis, emphysema and asthma, but no associations with cardiovascular diseases. The study findings are compatible with an excess risk for bladder cancer for aluminum plant workers exposed to PAH. The increased risk for cancer of the pancreas indicated, should be further evaluated in larger exposed populations.

Accumulation of polycyclic aromatic hydrocarbons in semipermeable membrane devices and caged mussels (Mytilus edulis L.) in relation to water column phase distribution

AbstractSemipermeable membrane devices (SPMDs) and blue mussels (Mytilus edulis L.) were deployed at a site contaminated by discharges of polycyclic aromatic hydrocarbons (PAHs) from an aluminium reduction plant, and at a reference site. The accumulation of PAHs in SPMDs versus mussels, along with the ability of the two matrices to predict contaminant concentrations in the ambient environment, were evaluated through concurrent measurements of particulate, dissolved, and colloidal PAHs in the water column. Analysis of the results showed that blue mussels were more efficient at sequestering PAHs than were SPMDs. The PAH profile (i.e., the relative abundance of individual PAHs) in the two matrices were similar, but differed significantly from the profile in the dissolved phase. Further, back‐calculation of the ambient dissolved concentrations from SPMDs indicated systematic overtrapping with increasing hydrophobicity. Calculation of in situ bioconcentration factors (BCFs) for the blue mussels at the smelter site indicated that uptake via particles (&gt;0.7 μm) or from colloids dominated over direct uptake from the dissolved phase, as opposed to the reference site. The in situ BCFs differed markedly from literature values, which implies that the use of mussels to predict ambient concentrations would require that site‐specific BCFs be applied.

Accumulation and effects of aluminum smelter-generated polycyclic aromatic hydrocarbons on soft-bottom invertebrates and fish.

An integrated study involving measurements of polycyclic aromatic hydrocarbon (PAH) levels in bottom sediments, assessments of resident soft-bottom communities, the accumulation of PAHs in soft-bottom invertebrates, and biomarker responses in invertebrates and fish was conducted to assess the impact of an aluminum reduction plant in a Norwegian fjord. The fjord sediments were heavily contaminated by PAHs in the inner reaches near the aluminum smelter, where concentrations were well above levels elsewhere reported to induce biological effects. Nevertheless, the PAH contamination in the fjord did not seem to have severe effects on the benthic biota. This conclusion can be drawn from the soft-bottom communities as well as from biomarker analyses. Presumably, contaminant speciation is important for explaining the restricted biological effects. The results support the assumption that PAHs associated with soot-like structures have limited bioavailability. They also point to the need to link various single-species approaches to measurements of effects on higher levels of organization and with an understanding of the speciation of the chemical contaminant.

Influence of genetic polymorphisms of biotransformation enzymes on gene mutations, strand breaks of deoxyribonucleic acid, and micronuclei in mononuclear blood cells and urinary 8-hydroxydeoxyguanosine in potroom workers exposed to polyaromatic hydrocarbo

Airborne exposure to polycyclic aromatic hydrocarbons (PAH) in the potroom of an aluminum reduction plant was studied in relation to genotoxic or mutagenic effects, and the possibility of host genotypes of different metabolizing enzymes modifying associations between PAH exposure and genotoxic or mutagenic response was assessed. Ninety-eight male potroom workers and 55 male unexposed blue-collar workers constituted the study population. Micronuclei in CD4+ and CD8+ lymphocytes, DNA (deoxyribonucleic acid) single-strand breaks, hypoxanthine guanine phosphoribosyl transferase (HPRT) mutation frequency, and genotype for cytochrome P-4501A1, glutathione transferases M1, T1 and P1, and microsomal epoxide hydrolase were analyzed using peripheral mononuclear cells. Urine samples were collected for the analysis of 8-hydroxydeoxyguanosine. Micronuclei in peripheral CD4+ and CD8+ lymphocytes, DNA single-strand breaks, HPRT mutation frequency, and 8-hydroxydeoxyguanosine in urine did not differ between the potroom workers and the unexposed referents. With the exception of an observed exposure-response relationship for potroom workers with Tyr/Tyr genotype for microsomal epoxide hydrolase, between airborne PAH and CD8+ micronuclei, no correlations were found between any of the genotoxicity biomarkers and any of the exposure measures (airborne particulate PAH, airborne gas phase PAH, length of employment in the potroom, 1-hydroxypyrene in urine, or PAH-DNA adducts in peripheral lymphocytes), also when genotypes for biotransforamtion enzymes were considered. The results indicate that the employed biomarkers of mutagenic or genotoxic effects are not appropriate for surveillance studies of potroom workers exposed to current airborne levels of PAH. The significance of the correlation between airborne PAH and CD8+ micronuclei in Tyr/Tyr genotype subjects should be evaluated.