2014/05/01 by James C. Wesdock, Ian M. F. Arnold · 1 citation
Agricultural and Biological Sciences · Medicine · Health Professions · #Aluminum toxicity and tolerance in plants and animals #Occupational and environmental lung diseases #Noise Effects and Management
paper · doi:10.1097/jom.0000000000000071
openalex publication_date 2014/05/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/30
Aluminum, the most abundant metal in the earth's crust (making up approximately 8%), has a multitude of uses ranging from aerospace to construction through manufacturing to food and pharmaceutical applications. The production of primary aluminum begins with the mining of raw ore and is followed by the extraction of aluminum metal through a series of long established and vertically integrated industrial processes. In this issue of the Journal, these processes and their technologies—both contemporary and innovative—are fully described. The basic chemical process produces, for every 4 to 6 kg of bauxite, approximately 2 kg of alumina and 1 kg of aluminum. Other raw materials include carbon, aluminum fluoride, cryolite, and electrical energy. The chemical, physical, biological, psychosocial, and ergonomic hazards related to primary aluminum production are also characterized, in the context of both occupational and community health. Epidemiological analyses detailing known health risks are comprehensively summarized. Emerging issues of interest and study, such as environmental and community health in relation to aluminum production facilities, are also discussed. Public and consumer health considerations, focused on hypotheses about aluminum and neurocognitive impacts, are systematically reviewed and assessed. BAUXITE MINING PROCESS AND ASSOCIATED OCCUPATIONAL HEALTH HAZARDS AND RISKS Although a very small percentage (less than 1% globally) of aluminum is derived from ores such as nepheline and from alternative sources, such as fly ash from coal-fired power stations, bauxite mining represents, by far, the most common initial upstream step in the eventual production of aluminum metal. A brief historical perspective, process overview, and sustainable bauxite mining report are available via the International Aluminium Institute's (IAI's) Aluminium for Future Generations project.1 Bauxite ore, named for the town of Les Baux, France, is one of the earliest sources of bauxite and contains alumina (Al2O3), the immediate precursor of aluminum (Al) in the production cascade. The overwhelming majority of known global bauxite reserves are found in the geographic band bounded by the Tropics of Cancer and Capricorn. Key deposits are found in West Africa, South America and the Caribbean, South and Southeast Asia, and Australia. Most bauxite is very near the surface and thus easily mined relative to other ores. Nevertheless, a number of physical, chemical, biological, ergonomic, and psychosocial hazards exist throughout the mining process, as described in the article by Donoghue et al.2 Physical hazards include noise, heat and humidity, ergonomics including vibration, naturally occurring radioactive material, and ultraviolet radiation. The potential for traumatic injury is a reality that compels operating locations to assure the proximate availability of skilled emergency medical response capability. Noise from sources such as earth-moving equipment, blasting, drilling, and crushing is ever present. Consequently, noise-induced hearing loss is a significant risk to be managed, and robust hearing conservation programs are essential. The climate of tropical mining locations, with its inherent high ambient heat and humidity, can lead to heat-related illnesses; thus, appropriate employee awareness and control strategies are necessary. Operators of heavy equipment and machinery are subject to whole-body vibration, which can contribute to or exacerbate spinal disorders. Naturally occurring radioactive material is present in bauxite at very low levels and transfers to the solid residue stream during refining, being absent in the alumina end product. This latter hazard must be considered and monitored; however, occupational monitoring data from the bauxite mining and alumina refining sector indicate personal dose levels less than applicable public exposure limits; thus, it is unlikely to be of significant human health concern.3 Ultraviolet radiation exposure, logically more pronounced, given the concentration of bauxite mining activity in tropical zones, can contribute to the occurrence of both squamous and basal cell carcinoma; however, it is reassuring to note that prolonged occupational outdoor work does not seem to confer an increased risk for melanoma, as noted by Donoghue et al.2 Generally accepted control measures include enclosed mobile equipment cabs, creative scheduling to avoid midday sun exposure, and proper protective clothing and sunscreen. Chemical hazards are few, because bauxite per se is generally considered to be biologically inert. In the occupational hygiene context, it is best categorized as a nuisance dust, or particle not otherwise specified. Although Donoghue et al2 point out that there has been one reported case of mild pulmonary fibrosis in an individual exposed to bauxite crushing and transport over several decades more than 50 years ago, epidemiological studies of contemporary dust exposures in well-managed mining operations seem not to be associated with either clinically significant negative lung function impacts or pneumoconiosis. Trace quantities of beryllium and other metals are present in some bauxites; however, these have not been associated with adverse health impacts in those involved in the mining industry. Additional hazards include biological, ergonomic, fatigue, and psychosocial factors. Communicable diseases like malaria and dengue fever, in some areas, must be anticipated and addressed through appropriate mosquito and other vector control efforts, chemoprophylaxis, early diagnosis and treatment, employee education, and travel medicine consultation. Ergonomic hazards are minimized, because mining has matured to a highly mechanized state. Fatigue, however, is an increasingly relevant concern owing to extended shifts and overtime, and the implementation of fatigue risk management programs is growing within the industry. Recent concerns raised by the International Agency for Research on Cancer about shiftwork that involves circadian disruption are another area that deserves further consideration.4 Psychosocial factors—including alcohol and drug abuse—are compounded by isolation, social change, and the lack of health care and other usual social amenities in some mining settings and should also be considered and addressed. ALUMINA REFINING PROCESS AND ASSOCIATED OCCUPATIONAL HEALTH HAZARDS AND RISKS Alumina refining transforms bauxite ore to calcined alumina (Al2O3). This extraction method, known as the Bayer process, occurs through a progressive series of steps: crushing of the ore, digestion in a sodium hydroxide solution, clarification to remove solid waste materials, precipitation of solid hydrated alumina, and calcination to drive off water. A brief process overview and an alumina technology road map are available via the IAI's Aluminium for Future Generations project.5 Digestion requires large quantities of caustic soda, the signature chemical hazard linked to the refining process. Several other important physical, chemical, biological, ergonomic, and psychosocial hazards exist, which are also described in the article by Donoghue et al.2 Physical hazards include noise, heat and humidity, vibration, ergonomic, and ultraviolet radiation exposure. Minor traumatic injuries, particularly to hands and fingers, are not uncommon; however, the occurrence of major traumatic events is rare. The presence of adequately equipped on-site emergency response and medical personnel is therefore highly desirable. Noise is a ubiquitous hazard throughout aluminum refineries, and noise-induced hearing loss remains an unfortunate but still prevalent occupational illness for refinery workers. Aggressive hearing conservation programs are essential. Best-practice programs incorporate quantitative hearing protection fit-testing and emerging technologies that use personal noise dosimetry with real-time notification of daily exposure limit exceedance. Vibrating hand tools are frequently used within refineries, with hand–arm vibration syndrome occasionally manifesting in the workforce. Chemical hazards include alumina and bauxite dusts, caustic soda, and diesel exhaust fumes. Donoghue et al2 indicate that while Western Australia–based epidemiological studies hint at increased respiratory symptoms, such as wheeze and rhinitis, among production workers, no clinically significant lung function decrements have been observed. Cancer incidence and mortality studies are very limited. Published data from Western Australia indicate no increased risk for all-cause and all-combined cancer mortality compared with an external reference population, and no trends with employment duration. Analyses using an internal comparison population showed no excess cancer risk of any type with bauxite or alumina exposure. With strong alkalis (mostly NaOH) present throughout the refining process, chemical splashes and spills remain a concern. Serious burns of skin and eyes are possible. Traditional emergency showers and eye-wash stations using water are being augmented with more contemporary first aid agents, which are establishing evidence for safety and efficacy. Confined space entry hazards abound at refineries; thus, conventional health and safety practices to control for these risks are paramount. Diesel-powered mobile equipment—used, for example, inside refinery tanks for descaling—generates diesel particulates, exposure to which must be controlled. Welding-fume control through standard ventilation and respiratory protection is important. Residual asbestos may be present in older refineries and must be to The presence of in some can during the digestion with associated and are issues of potential concern both to and to alumina refineries to be in relative geographic to bauxite the environmental ambient concerns to heat and humidity, and ultraviolet as their control PROCESS AND ASSOCIATED OCCUPATIONAL HEALTH HAZARDS AND RISKS is from alumina through the process. In this an process long more than a in of or that use to the aluminum from the raw material or alumina The process in and has that A overview and are available via the IAI's Aluminium for Future Generations In this process, aluminum is by of alumina, in a of cryolite, within a series of or The are and as the to the process. have to be by a process. are of used in aluminum The cell the technology for years its initial use in the early of the however, the more common type in is known as the In the the is from a of and and contains about the used for of are at the of the cell and the in In the are from a of and material that from the cell during are during the process and must be from the cell are used their from the that such are in at about to the to and strong and have and in are from the used in the of which have been to be Alumina has basic in the a for the alumina may be older cell or in quantities at via a point a on of both the cell crust and the as a in the of cell alumina, which contains the fluoride, is used as a for the in it has a on cell and process over a major for the from and the with and sources the The of and of aluminum fluoride, fluoride, and alumina, and can be the of such as and sodium The article by and fully the of the and and the is to that article for a of considerations, including on the and cell Physical Physical hazards associated with heavy manufacturing are common during aluminum among these hazards are heat noise, and ergonomic and heat occurs because of high levels of which is compounded by ambient heat exposure, associated with the most common involved within and the use of personal protective equipment and of that heat levels may occupational exposure and is at some evidence the protective of heat in relation to within the aluminum as as other This derived from of heat-related and ambient heat as a function of and showed significant in as and for heat exposures should be considered and on the of exposure remain an important of heat and medical to personal risk for heat emergency response and on early of heat-related illness are to a and are and may include the use of personal of heat Noise is the most prevalent occupational hazard within the aluminum as it is for most other manufacturing noise is to other hazards because of its within the of mild as an occupational and in occupational from hearing and with risk for and can from occupational noise exposure. is the that as the for occupational noise of within aluminum production indicate an of standard A standard is as a significant and is by the and as an of or more at and in a given relative to a is injury risk is to be related to and to safety studies and epidemiological studies of on the and and increased and and are to risk for or aluminum production technology requires high levels of power to drive the process within the found in This used to the the and of the is within through the of workers, and personnel are thus exposed to as an however, levels of exposure in and are Epidemiological studies the potential health impacts on aluminum with exposure are very to no have been in studies at exposure and cancer because of and to with medical from and other are a manifesting as the of in by the have also been noted as occurring in aluminum workers. A number of ergonomic exist within aluminum and however, there are studies detailing the and focused on such Nevertheless, data exist within the robust injury risk ergonomic hazards are and systematically In the through a with the International on and has health which the of including ergonomics as a with other industrial hazards the most common for exposure within aluminum is a long of relative to respiratory among aluminum workers, particularly for those primary in the is of the has its in the of and workers, as primary aluminum production has been a in these case and and have important data to the of the respiratory health of aluminum production workers. health of interest have on the of and rhinitis, as as the more presence of or lung syndrome has not been reported among aluminum workers. in the primary aluminum however, has been of interest and and is as a to the industry. In this issue of the Journal, and an historical and contemporary of respiratory that have been in with occupational hazards present within the aluminum production industry. studies have a of respiratory symptoms, with exposure or employment however, the usual of such studies studies have more of both respiratory as as in workers. occupational in in this been in epidemiological and that to at as compared with historical This incidence over the or in dust and exposures over the A number of mortality studies of aluminum production have been pulmonary is the respiratory of increased pulmonary mortality has been particularly for involved in employment during the of hygiene and respiratory protection has most been linked with exposures in to the Nevertheless, the or have not been The relative of or exposures to on the of remains have been and does not seem to confer an increased for the of among workers. clinically there are no and in the the of occupational is generally as an of or The has for the diagnosis of this studies of with indicate as with other of may from further exposure. education, medical and from exposure on early are to the most of lung have also been associated with aluminum production and aluminum as in the article by that aluminum and aluminum can lead to the of lung to the to to high of alumina and among alumina manufacturing in lung has also been reported and is from by the presence of aluminum within the Epidemiological evidence for lung in primary aluminum production refining, and within the more Australia is of the of such case remains as to the with aluminum. exposures to more materials such as asbestos and in the primary production work are the human epidemiological data aluminum the a nuisance dust with of pulmonary fibrosis in beryllium has been at very low incidence in aluminum workers, owing to naturally present beryllium in ores that and the production process. Cancer is epidemiological evidence for a exposures to during primary aluminum production processes and Most of is known to operations or have been increased lung and cancer risks reported in from several but not have been the exposure linked to these In the exposure to occurs during of the and in within the of from is In exposure to within occurs during of the thus, are including during the of are present and from the or is used as a of exposure for the common in lung and cancer risks with exposure to for evidence in several for an increased risk of at other including and and most of these the with exposures has not been and further of is is that exposures to are a significant of The of other cancer however, is not as and while some risks are considered as significant there is a for further in this Other potential exposures can include some metals and involved in can be exposed to and and in some In the International Agency for Research on Cancer of Chemical and including a Aluminium This that in evidence from epidemiological studies of a of occupational exposure in production on a large number of studies that showed a excess of cancer of the and a less excess of lung further of the in the is evidence in for the of occupational exposures during exposures during production cancer of and of the exposures during production are to is important to however, that the aluminum production exposure of in International Agency for Research on studies have been out with to cancer in the aluminum industry. and up the data in that however, to in in the present The first a brief of on in The mortality and incidence data for with to the a significant excess or a not significant In the on the evidence of a work in production and cancer of the of the has been to and use one that is material must have several have low have low in the chemical be and to Other important include low that there is for it should the of the cell and have a that aluminum work on the for an is by compared with the for of as as material cell environmental and issues related to employee health through a risk Nevertheless, a of in lead to of interest remain in the of and or issues still remain to be either of these can be considered as a The potential are however, that work to be the of the of The process uses and heat in a process, than an process, to alumina to aluminum. the the process has through several with the initial that and that to the to in several have focused on the production on aluminum. work is in to an which be to aluminum. the production of the and the of the to the further in the for a process, be to a in over through with a potential on electrical and such be to power from sources, a of the can be and used in other AND HEALTH Alumina risk is a that can be used to or the or health of chemical exposures on a population, such as the in which industrial operations are present. In has been increasingly used to potential health impacts to the in to alumina refineries, and refineries in noted by Donoghue and in this issue of the significant and in the process. the type of industrial for refineries is the of an is requires significant to and and this must be used to fully and potential health The point for a is the of or potential sources and followed by an of and of sources are more easily than there are from or ambient sources, which significant A of the process is the of for chemical of In with should be used to the relative to exposure the thus, are inherent in The of chemical concentration to available and and hazard hazard are to an and a are further the The the and health health cancer risk is in a cancer risks cancer risk using the of 1 out by such as the Agency and the a in the and health these are the however, in have in excess of the for potential risk to the at the most in these have been less than of more than among the for the to the a and given the in the The process is cancer risk the Agency as by but epidemiological of at the refineries in Australia no increased cancer incidence or In and have been the of the Aluminium risk are in the potential impacts of process or and control and also for appropriate community health risks from including noise, can be on the of occupational health studies and on other community health from aluminum from the use of the production process, a process with hazards that have the potential to on the health of workers. The article by and reviewed studies in using relevant to and the aluminum process. also to include other data as a of personal in the aluminum industry. A number of community studies reviewed with to potential the health risks from This to a by using or community exposure levels and those associated with adverse in the studies to risk in hazards in aluminum and their risks to is described in of this the hazard aluminum (Al2O3), dust and and and noise, and and hazards one of risk the of an industrial to health impacts in a community is a is first a to the industrial processes to have data related to to the and to be to the of the industrial being described in relation to alumina In the more the the is the that there be and sources for the is the use of occupational health data to the population, as these may of more and no compared with The have reviewed available on potential health hazards that may also community health risks because of the of the to aluminum note that there is the potential for materials such as and noise to community health The of risk however, is on the of a number of both and including and to the Public The the that aluminum exposure is involved in the of in the article by this its to from the of these that aluminum in the of This to an initial on the of aluminum in Although it still to the of a small of and aluminum to be with concern by some of the the has been by most The for this of the and for the public concern are Although to the of very are at the Consequently, there is a of on the The by and and and showed that aluminum the of with like the in The also showed of This in in response to an in another that with to and showed aluminum levels in of with and to of by aluminum. The on the of these to the in these not aluminum to for several not lead to that are to those in The and of by not the as those of levels of aluminum in the with have no known The are frequently used to there is solid evidence a diseases and and Although the have been as to with to neurocognitive such as the and the in the not lead to the or with high levels of aluminum in their to not the of of is an and lack of studies by as reported by the of exposure to and of long the of the decades epidemiological studies have exposure and of in impacts of one of more than noted that aluminum can than biologically important and adverse on the in or those with and of the studies in aluminum can in that are to those of In the of other from those of and the of is very to aluminum in studies that the issue have of the in that not one of the to with to neurocognitive such as has been the of is and are more the public is to to lead to concerns about the aluminum and and the are and occupational health hazards and risks within the primary aluminum production industry. the of environmental and some of these risks in also to the evidence for this is less health protection programs have generally been throughout the to and to the the hazards and include industrial hygiene and medical programs and the use of technologies and possible. process and have also potential risks for The of the has been a and in and for the protection of in the aluminum and those in including the of applicable health The IAI's has also and to an interest in the of the by aluminum with to human health.