Introduction
Mining is an ancient occupation, long recognized as
being arduous and liable to injury and disease [1,2].
The lifecycle of mining consists of exploration, mine
development,mine operation, decommissioning and land
rehabilitation.
Mining is a multi-disciplinary industry, drawing on
several professions and trades. To ensure precision in
clinical and epidemiological work, it is important to
enquire about the details of tasks, as the term ‘miner’ is
relatively non-specific.
Mining is traditionally classified as metalliferous or
coal, and as surface or underground. Metalliferous
mining can also be classified according to the commodity
being mined.
Some degree of minerals processing is usually
undertaken at mine sites. For metalliferous mining, many
of the occupational health hazards relate to these
metallurgical processes and for this reason I will include
comments on metallurgical hazards.
The In-depth Reviews in this issue are intended to
cover the topics that remain most important in miningtoday.
These are: noise induced hearing loss, ergonomics,
respiratory disease and system safety/risk management.
Physical hazards
Traumatic injury remains a significant problem and
ranges from the trivial to the fatal [3,4]. Common causes
of fatal injury include rock fall, fires, explosions, mobile
equipment accidents, falls from height, entrapment and
electrocution. Less common but recognized causes of
fatal injury include flooding of underground workings,
wet-fill release from collapsed bulkheads and air blast
from block caving failure. The systematic application of
risk management techniques has contributed to a
substantial decline in injury frequency rates in developed
nations. Further improvement, however, is required to
reach rates tolerable to the broader community. The
review by Joy in this issue (pp. 311–315) covers system
safety and risk management in mining.
Noise is almost ubiquitous in mining. It is generated by
drilling, blasting, cutting, materials handling, ventilation,
crushing, conveying and ore processing.Controlling noise
has proven difficult in mining and noise-induced hearing
loss remains common [5,6]. The review by McBride in
this issue (pp. 290–296) gives a detailed account of noise
and noise-induced hearing loss in mining.
Heat and humidity are encountered in tropical
locations and in deep underground mines, where the
virgin rock temperatures and air temperatures increase
with depth, due principally to the geothermal gradient
and auto-compression of the air column [7]. Fatal heat
stroke has been a significant problem in the South African
deep underground gold mines and heat exhaustion
remains a contemporary problem in deep underground
mining [7–13]. Miliaria rubra, colloquially also known as
‘mucker’s mange’ is problematic in deep underground
mines [14].
Whole body vibration is commonly experienced whilst
operating mobile equipment, such as load–haul–dump
units, trucks, scrapers and diggers. This can cause or
exacerbate pre-existing spinal disorders. Poorly maintained
roads and vehicles contribute to the problem.
Hand–arm vibration syndrome is also encountered
with the use of vibrating tools such as air leg rock drills
[15–19].
Radon daughter exposure in underground mining has
increased the risk of lung cancer, but is now generally
controlled by mine ventilation [20–27].
Solar ultraviolet exposures in surface mining operations
are likely to contribute to the occurrence of squamous cell
and basal cell carcinomas, although this is an inference
drawn from studies of outdoor workers in other industries
[28–30]. Occupations involving substantial outdoor work
appear not to be associated with an increased risk of
melanoma [28,31–35].
Infra-red exposures in pyrometallurgical processes
contribute to heat stress and may induce cataracts.
Electromagnetic fields are encountered in electrolytic
smelting and refining processes.
Barometric pressure is elevated in deep underground
mines and reduced at high altitude mines in South
America. Chronic intermittent hypoxia at altitude has
been reported to induce physiological adaptations and
symptoms of benign acute mountain sickness (AMS) in
mine workers [36]. High altitude pulmonary oedema
(HAPO) and high altitude cerebral oedema (HACO)
were not seen. Increased barometric pressures in deep
mines increase air temperatures, increase convective heat
exchange and reduce sweat evaporation rates [37].
Chemical hazards
Crystalline silica has long been a serious hazard in
mining, with the risk of silicosis at its worst during dry
drilling late in the nineteenth century [38]. Silicosis
has been subject to considerable investigation [39–46].
Axial water-fed rock drills, wet techniques, ventilation,
enclosed cabins and respiratory protection have largely
controlled silicosis in developed nations. However,
silicosis remains a problem in developing nations and
silico-tuberculosis is important in Africa, where the high
prevalence of HIV infection among miners increases the
risk. Prolonged exposure to crystalline silica can also
cause chronic obstructive pulmonary disease [47,48].
There is some evidence for accelerated silicosis in
rheumatoid arthritis and of renal disease following
prolonged silica exposure [49,50].There is also now good
evidence that prolonged exposure to crystalline silica
increases the risk of lung cancer [51].
Coal dust has also been a serious hazard in mining,
causing coal workers’ pneumoconiosis or ‘black lung’ and
chronic obstructive pulmonary disease [52–69]. The risks
have now been largely controlled in developed nations by
dust suppression, ventilation and respiratory protection
[70,71]. Vigilance is, however, required to maintain
effective control.
Although largely historic in the developed world, the
mining and milling of asbestos has caused a legacy of
asbestos-related diseases, which continue to occur today.
The review by Ross and Murray in this issue
(pp. 304–310) gives a detailed account of respiratory
diseases in mining.
Diesel particulate exposures occur in underground
mines because of diesel powered mobile equipment, used
primarily for drilling and haulage. Diesel particulate is an
IARC Group 2A probable human carcinogen and several
epidemiological studies from other industries suggest
there is an excess risk of lung cancer [72–83]. Control
measures include the use of low sulphur diesel fuel,
engine maintenance and mine ventilation [84].
Arsenic is sometimes a contaminant of metal ores and
has been commercially extracted during copper smelting
with an accompanying risk of lung cancer [85–88].
Exposures to nickel compounds in some nickel
refineries have been reported to increase the risk of lung
cancer and nasal sinus cancer [89–92]. However, these
risks have declined substantially with improving hygiene.
Several other metal ores, including those of lead,
cadmium, manganese, platinum and cobalt, present
health hazards [93–97]. The risks are usually greatest
during metallurgical processing, when air concentrations
exceed those experienced during mining of the ore.
Appropriate control measures are required.
Exposures to coal tar pitch volatiles in Soderberg
aluminium smelters have been reported to increase the
risk of lung cancer and bladder cancer [98–102].
Occupational asthma has also been a problem in the pot
rooms of aluminum smelters [103–105].
Coal dust and methane gas explosions in underground
coal mines remain a serious risk requiring comprehensive
monitoring and management [106]. Some underground
coal mines also have problems with carbon dioxide and
hydrogen sulphide gas.
Cyanide is used as a solvent for metals such as copper
and gold in hydrometallurgical processes. Exposure to
hydrogen cyanide gas can occur during cyanide solution
preparation. Skin splashes with cyanide solutions are
hazardous, although the risk is minimized by the use of
low concentration solutions. Cyanide solutions are
usually alkalinized to reduce the risk of hydrogen cyanide
gas being evolved on contact with water.
Xanthates are reagents commonly used in hydrometallurgical
processes. They evolve carbon disulphide
gas on combustion or on mixing with water. Suspected
acute carbon disulphide toxicity has been reported during
xanthate reagent preparation at a gold mine [107].
Mercury is still used in some gold mining operations,
especially in developing nations, to extract gold through
the formation of mercury–gold amalgams [108–112].
Toxicity can result from inhalation of mercury vapour
during preparation of amalgam, retorting or smelting
[108].
Hydrofluoric acid is used in the analysis of core
samples taken during exploration drilling.
Smelting of sulphide ores produces sulphur dioxide
gas, which can cause acute bronchospasm.
Irritant dermal exposures are common in mining and
often result in dermatitis [3].
Biological hazards
The risk of tropical diseases such as malaria and dengue
fever is substantial at some remote mining locations.
Leptospirosis and ankylostomiasis were common in
mines, but eradication of rats and improved sanitation has
controlled these hazards effectively in the developed
world [113].
Cooling towers are commonly found on mine sites.
Regular microbiological analysis of the water is necessary
to detect Legionella contamination or high concentrations
of other heterotrophic microorganisms [114].
Ergonomic hazards
Although mining has become increasingly mechanized,
there is still a substantial amount of manual handling.
Cumulative trauma disorders continue to constitute the
largest category of occupational disease in mining and
often result in prolonged disability [3]. Overhead work is
common underground, during ground support and
during the suspension of pipes and electrical cables. This
can cause or exacerbate shoulder disorders. Broken
ground is often encountered and can cause ankle and
knee injuries.
Most mines operate 24 h per day, 7 days per week, so
shiftwork is very common. There has generally been a
trend towards 12 h shifts in recent years.
Fatigue in relation to shiftwork has been subject to
considerable investigation in the industry [115]. Sleep
deficits, which might be expected in hot locations, have
been shown to cause impairments of cognitive and motor
performance among drivers from other industries [116].
The remote control of mobile equipment in
underground mining has been introduced to reduce the
risk of fatal injuries from rock falls. This has required
attention to cognitive ergonomic issues, many of which
are similar to those found in metallurgical plant control
rooms. Proximity safety devices have also been developed
[117].
The review byMcPhee in this issue (pp. 297–303) gives
a detailed account of ergonomic issues in mining.
Psychosocial hazards
Drug and alcohol abuse has been a difficult issue to deal
with in mining, but policies and procedures are now in
place in most large mining operations. Debate continues
about how to measure psychophysical impairment.
Nevertheless, mining operations commonly require the
measurement of urinary drug metabolites and breath
or blood alcohol on pre-employment and following
accidents.
Remote locations are common in mining. Massive
ore-bodies, such as those at Mount Isa in Queensland,
Australia that have been mined for 80 years, justify the
establishment of a city. Contemporary finds, however,
tend to be smaller and do not justify establishment of
permanent townships. As a result, there has been a trend
towards ‘fly-in-fly-out’ operations, with mine employees
separated from their families and communities during
work periods.
Expatriate placements are also common in mining and
the associated psychosocial hazards have been reviewed
recently [118].
Unfortunately, fatal and severe traumatic injuries
continue to occur in mining and often have a profound
impact on morale. Post-traumatic stress disorders
sometimes develop in witnesses, colleagues and
managers. Registered managers often feel personally
responsible for such injuries, even in the absence of
negligence, and face the ordeal of government inquiries
and legal proceedings.
