OCCUPATIONAL HEALTH AND SAFETY IN URANIUM MINING AND MILLING

Dr J. Leigh

Worksafe Australia

February 1997

BRIEF

To provide a research report which:

Identifies health and safety matters relevant to employees involved in uranium mining and milling, and the transport of uranium, in the context of general health and safety matters affecting mining employees.
Includes a brief general survey of the relevant literature and findings with explicit relevance to uranium mining and associated operations. Copies of especially relevant material to be provided to the Committee Secretariat.
Identifies and, where possible and as appropriate, comments upon organisations with responsibilities relevant to health and safety of employees involved in uranium mining and milling.
Comments on the adequacy of arrangements for assuring the health and safety of employees involved in the uranium industry, and what measures, if any, might be desirable for improving such arrangements. [Responding to this part of the brief will entail visiting the mines at Ranger and Olympic Dam; and also identifying and evaluating relevant instruments used.]
Includes an evaluation of approximately 6 submissions received by the Committee (approx 40 pages) in relation to the health and safety of employees in the uranium industry.
Draws attention to any findings in relation to the above which are relevant to Committee Term of Reference (d) (health and safety of communities adjacent to mining, milling and transport of uranium). The main focus of the research report is on Term of Reference (c) (health and safety of employees).
The report will be written in plain English.

SUMMARY, CONCLUSIONS AND RECOMMENDATIONS

Summary

The report gives a review of methods of uranium mining, milling and processing, and the associated short term and long term occupational hazards. Methods for control of these hazards are described. The long term radiation-induced lung cancer hazard is dealt with in greater detail and quantitative risk assessments are given. The particular cases of ERA Ranger and WMC Olympic Dam mines and processing plants are also covered in greater detail. Mention is made of health and safety issues likely to arise at Jabiluka, if developed.

Current legislated regulatory arrangments in Australia are described.

An evaluation of selected material from the submissions relating to occupational health and safety is provided as a separate document.

Conclusions

Occupational health and safety is a prime concern in uranium mining, milling and processing. However, aside from the long term radiation hazard, the occupational risks to health and safety are similar to those in other open cut and underground hard rock mining and mineral processing operations, and with proper control can be managed to achieve an acceptably low risk, at least no higher than in otherwise comparable mining operations. Ranger and Olympic Dam, while appearing to be generally well run operations, showed a few areas where improvements could be made.

The radiation hazard is very closely monitored by the mines themselves and by a large number of regulatory authorities, who are not always in full co-operation. It is a concern that there is not a consistent method of radiation dose assessment, nor a completely adequate national register of uranium and mineral sands radiation exposed workers. If new mines are developed it would be important to rationalise and simplify the regulatory framework, and to develop a standardised register with consistent surveillance and dose criteria. This is made even more necessary by the likely higher radiation exposures expected at Jabiluka in particular.

The regulatory structure is very cumbersome and duplicative. No doubt there are historical reasons for this but the opportunity to streamline and rationalise this structure should be taken if new mines are to be developed. The unique indenture arrangement at Olympic Dam is very different from the multiple Federal and Territory legislation applying to Ranger.

There is naturally a wide variety of views expressed in the submissions evaluated, and the ideological polarizations on nuclear technology as a whole are in evidence. From a pure occupational health and safety of mining milling and processing point of view ,the concerns about the quantitative risks of low dose ionising radiation can be dealt with as with any carcinogen, namely-by frank and honest risk communication, open access to research as it emerges, and involvement of the workforce at all stages. In other words, concerns about occupational health and safety should not in themselves be a block to new mine development.

Environmental effects from tailings and waste management are likely to cause wider concern. However, from the radiation point of view, measured levels outside the minesites are very low.

Road transport of ore and product also entails definite but manageable risks both occupational and environmental.

Recommendations

1. A standardised system of radiation dose assessment should be put in place.

2. A national register of uranium mining ,milling and processing workers should be esablished, incorporating standardised radiation dosimetry and medical surveillance. This should also include mineral sands miners, millers and processors.

3. Regulatory arrangements should be reviewed and rationalised.

4. The above (1-3) should happen whether or not new mines are developed, but any such developments would increase their priority

1. HEALTH AND SAFETY HAZARDS OF URANIUM MINING, MILLING, AND TRANSPORT (INCLUDING LITERATURE REVIEW)

The health hazards of uranium mining and milling fall immediately into two main classes:

Radiation hazards due to ionising radiation from uranium and its decay products

These include lung cancer occurring ten to fifty years later due to internal exposure to alpha radiation and other delayed cancers and genetic effects due to all forms of ionising radiation. The radiation hazard exists at both underground and open cut mines but is greater at underground mines. This hazard will be the main focus of this report.

Acute and chronic hazards associated with hard rock mining in general, open cut and underground

These include explosions, fire, (kerosene is used as an extraction solvent), accidental injury (eg rockfall, manual handling, heavy vehicle, pressure accidents), acute inhalation accidents, chronic silicosis and lung cancer risk due to quartz exposure, noise-induced deafness, hazards due to vibration, diesel fumes, chemical hazards, eg acid and alkali burns from NH3, SO2, H2SO4 and acute and chronic respiratory disease from exposure to vanadium pentoxide, used as a catalyst in H2SO4 production, skin diseases due to solvent, oil and grease exposures, hazards due to heat and humidity; and possible hazards due to non-ionising radiation at power, radio and laser frequency, including both acute and long term effects.

Radiation Hazard

Methods of Uranium Mining

Underground uranium mining is in principle no different to any other hard rock mining and other ores are often mined in association (eg copper, gold, silver). Once the ore body has been identified a shaft is sunk in the vicinity of the ore veins, and crosscuts are driven horizontally to the veins at various levels, usually every 100 to 150 metres. Similar tunnels, known as drifts, are driven along the ore veins from the crosscut. To win the ore, the next step is to drive tunnels, known as raises, up and down the deposit from level to level. These raises are subsequently used to develop the stopes where the ore is mined in the veins. The stope, which is the workshop of the mine, is the excavation from which the ore is being extracted. Two methods of stope mining are commonly used. In the “cut and fill” method and open stoping method (Jabiluka proposed and Olympic Dam), the space remaining following removal of ore after blasting is filled with waste rock and cement. In the “shrinkage” method just sufficient broken ore is removed via the chutes below to allow the miners to work from the top of the pile to drill and blast for the next layer to be broken off; eventually leaving a large hole. Another method, known as room and pillar, is used for thinner flatter ore bodies. In this method the ore body is first divided into blocks by intersecting drives, removing ore while so doing, and then systematically removing the blocks, leaving sufficient for roof support. This method, also used in underground coal mining, requires the worker to enter the ore body.

Drilling the holes for blasting in crosscut or drift mining is usually done with a machine mounted drill (the “Jumbo”). Blasting operations are followed by a delay period for removal of dusts and fumes.

The method at Olympic Dam (and proposed for Jabiluka) is known as long-hole open stoping. The long-hole refers to the vertically long blocks of ore which are mined, leaving alternate blocks for support in the first pass. After backfilling, the filled stopes then provide support to reaccess the remaining support stopes. “Cut and fill” methods backfill progressively in smaller mined areas.

Ore from the stopes is moved by diesel powered loader equipment to the crusher station from where it is crushed and transported to the surface. Extensive ventilation is used to control heat, dust, diesel fumes and radioactive materials. The ventilation required is of the order of hundreds of cubic metres per second (Olympic Dam 1,400 cubic metres per second). Worker exposure to dusts and fumes is reduced by use of enclosed cabins for machine operators. Water is also extensively used for dust suppression.

In open cut mining, overburden is removed by drilling and blasting to expose the ore body which is mined by blasting and excavation via loaders and dump trucks. Workers spend much time in enclosed cabins. Water is extensively used in all dust make processes to suppress airborne dust levels.

Uranium Milling and Processing

The hazards in the crushing area are similar to those in the mine itself, with possible exposure to radiation, controlled by enclosure , ventilation and use of respiratory protective equipment in certain high risk jobs. The products include ammonium diuranate and concentrates ofuranium oxide (UO2 2UO3 or U3 O8), both known as “yellowcake”.

Mineral processing is a more automated process, requiring less human exposure. Most uranium mills use an acid leach process. The ore is crushed wet to a slurry and, thickened, sedimented using a flocculant and passed to leaching tanks. Acid leaching takes about 24 hours, and involves sulphuric acid with hydrogen peroxide (Caro's acid) or pyrolusite. Then the uranium-bearing solution (pregnant liquor) is separated from the solid tailings by counter-current decantation and passed to a solvent extraction process, using kerosene containing a tertiary amine and an alcohol, isodecanol. The uranium is transferred from the loaded solvent to an ammonium sulphate solution from which it is precipitated as ammonium diuranate by addition of ammonia. The diuranate is then dried and calcined (roasted in a furnace) to drive off the ammonia, leaving a uranium oxide product containing in excess of 90% U308. Apart from the initial crushing stage, all subsequent processing up to the calciner involves wet chemistry in sealed vessels or water-covered tanks. Consequently, there is very little release of dust or radon in the mill. A potential for dust raising occurs at the calcining stage and in product packing, but these operations are normally controlled remotely or automated, requiring very little human occupancy of those areas. These compounds are toxic as metals to many organs but mainly the kidney (Tarasenko 1983). This hazard can be prevented by enclosure and exhaust ventilation of the drum filling and weighing process. Workers in this area should be monitored for uranium in urine. Samples should be taken when workers come on shift, to avoid sample contamination. Respiratory protective devices should be worn in the packing areas. Uranium oxide is packed in sealed labelled drums in covered containers and transported by road to port where conventional container handling procedures load it on to ships. In the absence of serious transport accident, the radiation hazard at this point would be low. Appendix 5 of the Jabiluka Draft EIS (1996) gives detailed data and references of accident risk in truck haulage operations, both on unsealed and sealed roads, private and public. The risk cover both ore and product road transport.

The Radiation Hazard

Although deliberate mining for radioactive ores, first for radium, and then uranium, has been going on for only about 95 years, miners must have been exposed for centuries to air in mines with higher than background levels of radioactivity. Old chronicles (cited by Lorenz 1944) make it apparent that the metal miners of Schneeberg and Joachimsthal situated in the Ore Mountains separating Saxony and Bohemia, were aware as early as the 16th century that many miners died of a respiratory disorder “Bergkrankeit” or mountain sickness. The symptoms were cough, chest pain and shortness of breath. It is probable that these symptoms represented more than one disease and included silicosis, tuberculosis and lung cancer. Lung cancer was first diagnosed as an occupational disease of Schneeberg miners by Harting and Hess (1879). A similar finding in relation to Joachimsthal miners was made by Sikl (1930). Ludewig and Lorenser (1924) were the first to suggest that airborne radon might be responsible for the high lung cancer mortality and this view was supported by Sikl (1930). However, in a critical review, Lorenz (1944) expressed the opinion that radon was not the sole cause of lung cancer in the miners; he listed pneumoconiosis, chronic respiratory disease, arsenic and genetic factors as other contributing factors, not mentioning smoking.

Uranium ores generally contain less than 0.5% uranium (U3O8) (eg Jabiluka No. 2 0.46%, Ranger 0.3%, Olympic Dam 0.15%,Nabarlek 1.9%). Occasionally pockets of ore with 5% or even more are found. The most abundant isotope is uranium 238 (99.3%) and uranium 235 makes up 0.7%. Uranium 238 decays through thorium 234, proactinium 234, uranium 234, thorium 230, via alpha, beta and gamma emissions to radium 226. Radium 226 was the reason for mining uranium before the discovery of nuclear fission (eg Radium Hill in SA). Radium 226 has a long half life of 1,620 years and emits a rich spectrum of gamma radiation as well as alpha in decaying to radon 222. Radon 222 decays through polonium 218, lead 214, bismuth 214, polonium 214, lead 210, bismuth 210, polonium 210 to lead 206 which is stable. In this decay chain, alpha, beta and gamma emissions occur but polonium 218, 214 and 210 are alpha emitters (214, 210 emit gamma as well). The decay products of radon are known as radon daughters or radon progeny. They are dangerous to health because they are relatively short-lived and , if inhaled, decay before lung clearance processes can eliminate them. Mostly they attach themselves to aerosols but they also exist as unattached atoms. th unattached fraction is typically 0.5-2%.The short range but heavily ionizing alpha particles can damage the DNA (genetic material) of bronchial and alveolar epithelial cells and possibly other lung cells, leading to carcinogenesis (cancer formation) after a latency period of ten to fifty years. Both underground and open cut uranium miners and millers are also exposed to alpha, beta and gamma radiation from inhaled ore dust, containing the heavier longer lived isotopes and are also subject to external gamma radiation from the ore body, concentrates and other radioactive materials on the mine site. The relative contributions to the total absorbed dose of radiation depend on the type of mining, the ventilation and dust suppression procedures in use. Gamma radiation is much more penetrating but about 20 times less damaging than alpha which delivers the same dose. Beta radiation is somewhat more penetrating than alpha, but about as damaging as gamma. Biological damage is a function of linear energy transfer a measure of ionisation density along the track of an ionising particle (ICRP 60 (1991) p6).

Uranium 235 decays through radon 219 (actinon), which has a half life of 3.92 seconds and so will not diffuse from the ore in sufficient quantities for its progeny to be able to make a significant contribution to airborne radiation exposure in an underground mine. The concentration of radon progeny is generally expressed in a unit known as the Working Level (WL). One WL is any combination of radon progeny in one litre of air that ultimately releases 1.3 x 105 million electon volts of alpha energy during decay. Exposure to one WL for 170 hours gives a dose of one WL month (WLM). The relationship between the dose in WLM and the actual dose in Sieverts to the target tissues in the lung is extremely complex and depends on physical factors such as the characteristics of the carrier aerosol and the proportions of attached and unattached progeny, the radon progeny equilibria, the pattern of respiration, the pattern of particle deposition and clearance, and the sites of the cells likely to become malignantly transformed. The conversion of WLM (the measured exposure which has been epidemiologically related to human lung cancer) to Sieverts, the effective radiation dose unit (applying to all types of radiation by use of a weighting factor for ionising quality) in relation to which which all other dose-related radiation risks are expressed, is thus complex. An earlier conversion in accepted use is 1 WLM = 10 millisieverts (mSv) based on dosimetric modelling but there is argument on this point and more recent work (eg ICRP65 (1993), ICRP66 (1994)) suggests that an epidemiologically derived conversion of 1 WLM = 5 millisieverts should be used for occupational exposures. The ARL submission suggests that this would underestimate doses by up to 40% and recommends using 10 mSv/WLM but it has become the practice at Olympic Dam to use 5 mSv /WLM. It should be emphasised that the calculation of the total millisievert effective dose (on which national standards are based) from primary measurements can dramatically affect the final reported result. For example, other studies give a ten fold range for the WLM to mSv conversion (see eg James 1992), and Olympic Dam allows for a protection factor of 10 when airstream helmets or respirators are worn whereas Ranger does not. The evidence from human studies for radon and radon progeny-induced lung cancer has been supported by extensive animal experiments (eg Cross et al 1981,82). A number of analyses of cohorts of underground miners concerning radiation and lung cancer have been conducted, and are continuing, examining dose-response relationships and effects of modifying factors. The BEIR IV and V reports (1988, 1990) and ICRP 60 (1991) examined lung cancer risks associated with the principal underground mining populations. These included uranium miners in Colorado (Hornung and Meinhardt 1987); Ontario (Muller et al 1985); Saskatchewan (Howe et el 1986) and Czechoslovakia (Sevc et al 1988) and an iron mine in Sweden (Radford and Reynard 1984). In some cases later follow-up data is available. There are also studies in New Mexico uranium mines (Samet 1984, 1989), Radium Hill in SA (Woodward et al 1993), fluorspar miners in Newfoundland (Morrison et al 1988) and niobium miners in Norway (Langard et al 1991) confirming the dose-response relationship. A comprehensive joint analysis of all uranium miner studies has recently been published by the US National Cancer Institute (Lubin et al, NIH Publication 94-3644 1994). An earlier review proposing exposure standards was prepared by US National Institute of Occupational Health and Safety (NIOSH) (NIOSH 1988).The International Agency for Research on Cancer (IARC) classified radon and progeny as a category 1 human carcinogen in 1988 (sufficient evidence in humans) giving a comprehensive review (IARC 1988).

All the above studies show a proportionate increase in excess lung cancer frequency with cumulative exposure to radon progeny, up to exposure levels of about 500 WLM. Such a proportional relationship is in agreement with animal experiments. There is a statistically significant excess detectable at 20 WLM. Lung cancer following alpha radiation exposure has a latency of at least ten years and up to fifty years. (The same is generally true for other cancers and whole body irradiation. Leukaemia has a minimum latency of about two years.)

Although risk of lung cancer in relation to exposure can be expressed in a number of ways and various forms of modelling the dose-response relationship can be used, the clearest measure of a long term health risk is often expressed as a lifetime risk, or lifetime excess risk when the occupational adverse outcome can also be caused by non-occupational factors. This represents the probability of developing cancer in a lifetime or work lifetime for a given dose and although probability applies to an individual, its interpretation under the frequency theory of probability leads to an absolute estimate of cancer cases in a population of known size. For example, if the lifetime risk is 0.01 (1%) then there would be expected to be one case in the lifetimes of 100 persons.

In the relationship between radon progeny and lung cancer the studies above give estimates of lifetime excess risk of lung cancer ranging from 130-730 per million per WLM cumulative dose or if 1 WLM = 10 mSv, 1.3% -7.3% per Sv with an average figure of 3.5%/Sv. The Radium Hill study falls at the high end of this range. If the exposures and population sizes of proposed and present uranium mines and mills are known, these risk coefficients can be used to estimate expected numbers of excess cases over a lifetime or any desired period. For example, at Olympic Dam, 371 miners are exposed to an average 4.4 mSv per year alpha radiation (radon progeny plus dust) so the expected number of excess lung cancers in this workforce from these exposures for a 47 year working lifetime would be (0.035 x 4.4 x 47 x 371)/1000 = 2.7. At the proposed Jabiluka mine with a predicted alpha dose from radon progeny and alpha emitting dusts of 12.5 mSv/year(ARL estimates), assuming a workforce of 380, the corresponding figure would be 0.035 x 12.5 x 47 x 380/1000 = 7.8. If the workforce were less and the doses less , this figure would be lower. If the mine life were less than 47 years a further lowereing would be involved. However 47 years is used for comparability with ICRP.

To these radiation risks must be added the risk of fatal cancer from whole body gamma irradiation. ICRP 60 gives a final overall figure of risk of all fatal solid cancers for a 47 year working life of 0.04 (4%)/Sv and for leukaemia 0.004 (0.4%)/Sv (fatal cancers plus a contribution for non-fatal). These estimates are based on studies of 76,000 (originally 150,000), Japanese A-Bomb survivors with appropriate dosimetry (the exposure was virtually instantaneous gamma and high energy neutron) and rely among other things on a factor of two in assumption that low dose rate radiation risk is half as harmful as high dose rate radiation risk for the same cumulative dose (the DDREF factor). In a more recent analysis of 95,000 UK radiation workers (Kendall et al 1992 ), the central estimates of dose-related gamma risk were higher (0.1 (10%)/Sv) for fatal solid cancers and 0.0076 (0.76%)/Sv for fatal leukaemia. Other UK and US studies of subgroups of nuclear industry workforces also gave greater estimates of risk than ICRP (Beral et al 1985, 1988, Smith and Douglas 1986, Wing et al 1991, Gilbert et al 1989-1990, Checkoway 1985, Binks et al 1989). Applying the more conservative ICRP figure to Olympic Dam and Jabiluka would give a further excess lifetime fatal solid cancer estimate of 0.04 x 2.6 x 47 x 371/1000 = 1.8 (Olympic Dam); 0.04 x 20 x 47 x 380/1000 = 14.2 (Jabiluka) and excess fatal leukaemia cases of 0.1 (Olympic Dam) and 1.4 (Jabiluka).( ARL dose estimates). As above the Jabiluka figure would be lower for a smaller workforce and shorter mine life.

Similar calculations for Ranger, assuming workforce = 300, alpha radiation from radon progeny and dust = 5.7 mSv, gamma radiation = 0.2 mSv give lifetime excess lung cancers 0.035 x 5.7 x 47 x 300/1000 = 2.8; lifetime excess solid cancers = 3.2; lifetime excess leukaemias = 0.32. Inclusion of non-fatal cancers would increase these estimates by about 20% (NCRP Report No. 11 1993). However the estimates have 90% confidence intervals of about plus or minus 25% and the DDREF factor has been disputed.

Alternatively, the risks could be calculated by adding the lung alpha dose (dust and radon progeny) to the external gamma dose and using the ICRP figures for total cancer risk. The rationale for this would be that the 20 mSv dose limit is a total dose for all forms of exposure and the ICRP risk calculation is based on this, even though the atomic bomb survivors received external doses only (mainly gamma).

Smoking is thought to have a multiplicative or near multiplicative synergy with alpha radiation in causing lung cancer. The risk of lung cancer in smoking uranium miners is more than the sum of the risks of smoking and of uranium mining. Thus uranium miners and millers should be advised not to smoke and companies should implement no smoking policies. This is not currently the practice and workers can even smoke underground.

The excess risk of hereditary effects is estimated by ICRP to be 0.008 (0.8%)/Sv. This is the probability of radiation hereditary defects in the first two generations, eg for 10 years exposure at 20 mSv, the cumulative dose is 200 mSv = 0.2 Sv so the excess risk is 0.8% x 0.2 = 0.16%. The natural incidence of hereditary disorders as defined by ICRP is about 10%.

The Australian national standard for occupational exposure to ionizing radiation is based on ICRP 60 and is no more than 20 mSv/year from all sources averaged over 5 consecutive years, with no more than 50 mSv in any one year. Risks greater than that associated with this exposure are regarded as “intolerable”. From the other point of view,the risk associated with this exposure is regarded as “acceptable” ie over 50 years 1 Sv can be accumulated, giving a lifetime excess solid cancer risk of 4%.

Methods of Radiation Exposure Measurement

Radon progeny

These are sampled by area sampling with a powered sampler which draws a known volume of mine air through a filter, which traps the attached progeny, both attached and unattached and radioactive dust. No size selective cyclone is used so the dust measured is inhalable dust. The radioactivity on the filter is then subsequently analysed by appropriate counters. Applying appropriate conversion factors, and knowing hours worked and assuming breathing rate (volume/time), a mSv dose can be derived. The conversion factor for doses allows for some beta dose as well. For longer term sampling at Ranger the device used is an Alphanuclear Series 500 Alpha PRISM. The alpha detection is based on ion pair production in a solid state detector. At Olympic Dam scintillation photomultiplier methods are used. Although the device samples dust as well the radon progeny activity effectively swamps the alpa activity of the dust. Personal sampling to measure individual exposure is also possible using passive (unpowered) film badge like devices which give a record of alpha activity, although this method is currently more of a research tool. For spot sampling (< 10 min sampling time) Ranger use the Kusnetz method (Kusnetz 1956), Olympic Dam the Borak method (Borak 1987), succeeding the Rolle method (Rolle 1972). Both methods give total progeny activity and do not allow the determination of individual progeny. The Rolle and Borak methods have much the same sensitivity as the Kusnetz . More detailed descriptions of the methods may be found in ARL TR095 (1990), TR011 (1979).

Inhaled dust

This is sampled by powered personal samplers, four hole at Ranger rather than the Australian Standard 7 hole used at Olympic Dam, which sample over a full shift at 1.9 litres/minute, depositing dust on a filter which can then be analysed for alpha radioactivity, and given an assumed breathing rate and hours worked, applying a conversion factor a mSv dose can be derived. This factor depends on the particle diameter and type of the inhaled dust, the bigger the particle size the lower the mSv per activity unit. No size selective cyclone is used so the dust measured is inhalable dust. At Ranger a standard slide-drawer alpha counter (scintillation-photomultiplier counter) is used. At Olympic Dam, a standard scintillation/photo-multiplier alpha counter is used. Area sampling using high volume samplers is also carried out. Solid state detectors are more sensitive for smaller samples (ARL reports above) but are rarely used for dust sampling.

External gamma

This is monitored by the program run by ARL using thermoluminescent (TLD) badges. These depend on emission of light following heating of irradiated material and record personal gamma exposure. The badges are analysed by ARL and reported to the mine. TLD badges also record beta exposure. Routine area gamma measurements are also made, using, at Ranger, the very sensitive Alnor Gammameter (detection limit 1 microroentgen = 1.61 x 106 ion pairs/gram of air). Some portable gamma dosemeters are also used for spot checks and alpha and beta contamination checks are also done with the PCM5 portable photomultiplier/scintillator device. ARL calculate, report on, and maintain records of cumulative dose in the individual. Badges can be re-used after heat annealing, but start accumulating a record of exposure from zero again (ARL TR 065, 1990).

Proposed for Jabiluka is a combined radon progeny/dust sampler/analyser, which is an active (requiring a pump) personal sampler which measures dust and progeny on one filter by a track edge material for progeny followed by total alpha counting for dust. It may be possible to add TLD material to get gamma as well.

There is also environmental alpha sampling with alpha samplers more sensitive to the low background rate (20 counts/day compared to 20 counts/hr at the mine itself).

Internal dose assessment via the inhalation pathway.

This is not routinely measured except in accidents involving suspected heavy exposure, as occurred at Ranger in 1983, when two workers attempted to clear a blockage in the product drum load feed. This measurement is available through ARL.

Urine monitoring

This is not routinely done.

Adverse Outcomes other than Radiation-Induced Cancer

In addition to lung cancer, other adverse chronic long term effects have been postulated in underground miners as a result of radon progeny exposure. In general,other malignancies have not been found to occur in excess, but one report from Czechoslovakia demonstrated increased skin cancer in uranium miners (Sevcova et al 1978). The authors estimated that the skin could receive high alpha doses from radon progeny.

The occurrence of nonmalignant respiratory diseases has been examined only in miners from the Colorado Plateau. Several papers from the US Public Health Service Study reported excess mortality from nonmalignant respiratory diseases (Archer et al 1976, Waxweiler et al 1981). Between 1950 and 1977, a five-fold excess of deaths occurred from nonmalignant respiratory diseases exclusive of tuberculosis, bronchitis, influenza and pneumonia. Causes of death were primarily emphysema, fibrosis, and silicosis. The effects of cigarette smoking were not considered.

These mortality data and respiratory surveys of uranium miners have led to statements that radon progeny cause interstitial fibrosis and emphysema (Archer et al 1973, Archer et al 1964, Trapp et al 1970). Animal studies are consistent with this hypothesis (Cross et al 1981, 1982). For the US Public Health Service Study, physical examinations and lung function testing were performed in 1957 and 1960. However, data were neither collected nor analyzed with techniques that are currently accepted. Thus, the finding that uranium mining apparently contributed to the development of emphysema should not be regarded as definitive. Trapp et al 1970 performed more detailed studies on 34 uranium miners and found evidence of pulmonary dysfunction, both restrictive and obstructive. More recently, Samet et al 1984 surveyed 192 long term New Mexico uranium miners. Duration of underground mining was significantly associated with reduction of spirometric flow measures. Chest X-ray abnormalities were found in 9% and were compatible with silicosis.

These investigations have not separated the effects of radon progeny exposure from those of other atmospheric contaminants in a uranium mine: silica, engine exhaust, and blasting fumes. In fact, without good exposure data, epidemiological methods cannot assess contributions of all possible exposures. These findings are based on exposures received before extensive use of enclosed operator positions in mining machines.

Primarily descriptive data have resulted in speculation that uranium mining is associated with adverse reproductive outcomes (Weise 1981 a,b). Changes in the secondary sex ratio (males to females at birth) have been found in New Mexico countries where uranium mining is prevalent and in the offspring of miners. Birth certificate and hospital record data indicate the possibility of increased congenital malformations in children of uranium miners. However, the evidence is currently incomplete and largely descriptive and hypothesis-generating.

As in all mining, noise and vibration hazards are unavoidable. Appropriate noise control and hearing protection programs are required to minimise the risk of noise-induced hearing loss and appropriate ergonomic interventions and attention to design parameters of mining equipment will reduce the risk of vibration-induced back and neck injury as well as classic vibration-induced vascular conditions. Heat stress could also be a problem in both NT, WA and SA potential mine sites (Owers and Wetzel 1994). At Ranger contractors in daytime shifts were offered night work, but declined. Fluid replacement and rest periods are now used.

Silica-induced diseases

Exposure to crystalline silica (silicon dioxide as quartz ) dust is a worldwide occupational hazard causing disability and death among workers in industries such as mining, quarrying, glass making, and metal founding. Inhaled silica can accumulate in the body and cause diseases of the respiratory system and other organs (eg, the kidney). The biological effects of exposure to respirable silica can be modified by concomitant exposure to other minerals. Prolonged exposure to elevated levels of silica over many years can cause an extensive build-up of fibrous tissue in the lung and result in chronic restrictive lung disease (silicosis). More recently the question has arisen of whether silica and silicosis are related to the occurrence of lung cancer (Nurminen et al 1992).Lung cancer after silica exposure has a latency of at least ten years.

IARC (International Agency for Research on Cancer) has recently (late 1996) classified silica as a Category 1 human carcinogen (ie sufficient human and animal evidence exists). Estimates of the lifetime risk of silicosis and lifetime excess risk of lung cancer at various exposure levels are given in the tables below (Leigh et al 1997).

Table 1

Average lifetime risk (%) of silicosis 1/1 ILO (X-ray category)

Current exposure <0.2 mg/m3 <0.1 mg/m3 <0.05 mg/m3

27 25 12 1.4

Table 2

Average lifetime excess risk of lung cancer % (95% confidence interval)

Current exposure <0.2 mg/m3 <0.1 mg/m3 <0.05 mg/m3

1.87(0.21-31.3) 1.34(0.20-3.98) 0.83(0.15-1.92) 0.47(0.09-0.98)

Silica levels should be controllable by the same methods used to control radioactive dust and radon progeny, ie ventilation and water sprays.

2. REGULATORY ARRANGEMENTS IN RELATION TO HEALTH AND SAFETY

Acts which may have relevance to radiation protection in the mining and milling of radioactive ores

Commonwealth

Environment Protection (Alligator Rivers Region) Act 1978

Environment Protection (Impact of Proposals) Act 1974

Environment Protection (Northern Territory Supreme Court) Act 1978

Environment Protection (Nuclear Codes) Act 1978

Under the Environment Protection (Nuclear Codes) Act 1978, three codes have been published with two of these being later revised. The three codes, with the latest dates of publication are:

Code of practice on the management of radioactive wastes from the mining and milling of radioactive ores (1982 (`Waste Management Code')
Code of practice on radiation protection in the mining and milling of radioactive ores (1987) (`Radiation Protection Code')
Code of practice for the safe transport of radioactive substances (1990) (`Transport Code').

Series of guidelines relevant to the first two codes have also been developed and published. The most important guidelines are the guideline on Assessment of doses and control of exposure to meet the radiation protection standards (1989) and the guideline on Health Surveillance (1982) reissued 1987.

Whilst the first two codes are specific to the mining and milling of radioactive ores, the third code applies to all radioactive substances of which the natural radionuclides contained in radioactive ores are only a very small fraction.

These three codes of practice are intended to provide a sound basis for radiation safety in the mining and milling of radioactive ores and the transport of radioactive materials. In those states or territories where uranium mining has been carried out since the Ranger enquiry in 1977, these codes have either been adopted as regulations or used as the basis of regulations which maintain their spirit.

For the management of uranium mill wastes, it is important to revisit the waste code to ensure firm control over environmental contamination. This code is now fourteen years old and, apart from the need to bring it into line with present day standards, should take advantage of industry experience in the intervening years.

Carriage of the 1978 Act rested with the Department of Environment, Sport and Territories until July 1994 when the responsibility was transferred to the Australian Radiation Laboratory (currently part of the Department of Health and Family Services).

On 8 May 1996, a meeting of the Commonwealth/State Consultative Committee on Nuclear Codes of Practice (CSCC) was convened. After the preliminaries, the meeting considered what actions might be taken to advance a revision of the three codes.

A very useful course on the application of the codes was organised by ARL in 1987 and the very informative notes were published in 1990 (Radiation Protection in the Mining and Milling of Radioactive Ores ARL TR095 1990).

NOHSC Act 1985

National Occupational Health and Safety Commission Standards:

Exposure Standards for Atmospheric Contaminants in the Occupational Environment 1990

National Standard for Control of Major Hazardous Facilities 1996

National Standard for Plant 1994

ACT

Radiation Ordinance 1983

Occupational Health and Safety Act 1989

NSW

Mining Act 1973

Radioactive Substances Act 1957, 1961, 1967, 1976 (Radioactive Substances Regulations as amended 1977)

Occupational Health and Safety Act 1983

Victoria

Environment Effects Act 1978

Environment Protection Act 1970

Extractive Industries Act 1966

Health Act 1958 (Health (Radiation Safety) Regulations 1984 and Amendments 1985)

Mines Act 1958

Occupational Health and Safety Act 1985

Queensland

Mining Act 1968-83

Radioactive Substances Act 1958-1978

Workplace Health and Safety Act 1989

South Australia

Explosives Act 1936

Mines and Works Inspection Act 1920-1978

Controlled Substances Act 1984

Dangerous Substances Act 1979

Radiation Protection and Control Act 1982 (as amended 1986)

Roxby Downs (Indenture Ratification) Act 1982 (A unique piece of legislation which allows Olympic Dam to comply with ICRP recommendations and which gives it some immunity from State and Federal legislation)

Occupational Health and Safety and Welfare Act 1986

Mining Act 1971

Environment Protection Act 1993

Public and Environmental Health Act 1987

Environment Protection Act 1971-1980

Mines Safety and Inspection Act 1994 ; Mines Safety and Inspection Regulations 1995 (Code of Practice on Radiation Protection in the Mining and Processing of Mineral Sands (1982))

Radiation Safety Act 1975-1981

Nuclear Activities Regulation Act 1978

Explosive and Dangerous Goods Act 1961

Occupational Health , Safety and Welfare Act 1984 (proposed only and very contentious)

Tasmania

Mining Act 1929

Radiation Control Act 1977

Tasmania

Industrial Safety, Health and Welfare Act 1977

Environment Assessment Act 1982

Mining Act 1982-1985

Mines Safety Control Act (1977-83)

Mines Safety Control (Radiation Protection) Regulations (1981)

Radiation (Safety Control) Act 1978

Radioactive Ores and Concentrates (Packaging and Transport) Act 1980

Uranium Mining (Environment Control) Act 1979-1981

Work Health Act 1986

The principal agencies administering this legislation are well described in the submission from the Department of Minerals and Energy WA, in particular the paper by Hewson et al 1992. The main difficulties seem to be in the desire of states to retain control rather than Commonwealth and the desire of mining departments to retain control rather than occupational health and safety departments. The 1996 Jabiluka Draft EIS p1-9- 1.17 also gives a good account of the legislative controls in the Northern Territory.

3. CURRENT ARRANGEMENTS FOR ASSURING HEALTH AND SAFETY

Situation at Ranger

Health and safety statistics at Ranger show a lost-time injury frequency rate of 16 one day lost-time injury per million man hours in 1994/95. This compares favourably with all NSW open cut coal mines for the same period (43)(Joint Coal Board 1996). The rate at Ranger has fallen noticably from a high of 123 in 1984/85 and has been fairly stable since 1991 when there was a large downsizing from 310 to 170 workers. The first and only fatality was in late 1996 (an excavator tipped over, crushing the driver). A National Safety Council Audit was carried out in 1996 with a resultant 4 star rating (down from 5 stars). My own impression was of a clean well organised operation. I did notice a few things however:

1. Sprays not operating at primary crusher dump point.

2. Was able to drive straight through front gate without challenge.

The management were exceptionally frank and helpful. A comprehensive health and safety program is in place. The features include:

Health and Safety Policy

Central Health and Safety Committee (CH&SC)

Two management, employee representatives (operator, trades - Mill and Engineering, clerical, supervisor) and Occupational Health and Safety adviser
Meet monthly

Safe Work Procedures

Attached to Work Order
Some in area

Incident Reporting and Investigation

Incidents which cause injury and/or equipment damage
Near misses
Full investigation for all Lost Time Injuries (LTIs) or serious near misses

Hazard/Risk Identification, Assessment and Control

Incident/Hazard Reports
Risk Management Audits
- Introduce Hazard Logging system via Work Requests in Engineering Information system (EIS)

Health Monitoring

Commencement, biennial and termination medicals
Commencement, three- or five-yearly, termination X-ray
Site visits twice a week by doctor
First aid treatment
Radiation monitoring

Claims Management

Injury/illness reporting and investigation
Rehabilitation
Return to work or non-return to work
Costing

Emergency Action Plan

Exercises

Induction

Workplace specific (supervisor)
Radiation (SHARP) (Safety Health and Radiation Protection)
General (SHARP)
“First Contact” video

Occupational Health and Safety Training

Monthly safety topics (chosen by workgroup, run by group)
Specific topics (given by SHARP)
Annual compulsory topic for all personnel (Radiation reinduction)
Voluntary topics (Fire prevention, CPR)
Monthly Fire and First Aid training for shift crews
Weekly Fire training for day crew
Ongoing First Aid training for Security (Occupational First Aid)
- Special training - Central Health and Safety Committee (CH&SC), supervisors, etc

National Safety Council of Australia (NSCA) - 4 Star

Review audits quarterly
Annual grading
- Look at management systems, housekeeping, chemicals, machinery, tasks, attitudes, etc

Policies and Procedures

Manual (supervisors)
Via personal computer
Separate Occupational Health and Safety section

Engineering Information System

Checklists via Preventative Maintenance (PM) program
Review/monitoring via PMs
Corrective Maintenance (CM) to be linked to Incident Report number
Costing
- Safety priority on Work Request at present. Introducing separate Hazard Logging system
Safe work procedures and permits attached to Work Order when initiated

Permits

Hot Work (Type 1 - trades personnel, Type 2 - supervisor)
Dig
High Voltage Access
Confined Space/Vessel Entry

Meetings

CH&SC (monthly)
Managers and Superintendents (monthly)
Following LTIs or serious near misses
Monthly workgroup meeting
Workgroup weekly communication meeting

Surveys/Investigations

Biennial for noise
Biennial for signs
Chemicals to update registers
Special as required, eg ergonomic

Hazardous Substances

Hard copy register in all work areas
Database on SHARP personal computer (Infosafe)
Material Safety Data Sheet (MSDS) attained and reviewed prior to new substance being brought on site

Measurement of Safety Performance

Monthly Statistics Report
Performance Index (LTIFR x average duration of lost time)
- Occupational Health and Safety included in Performance Appraisal for personnel from supervisors up
External rating - NSCA (National Safety Council of Australia)

- MINEX (Minerals Industry Safety Excellence Awards)

I was provided with a copy of the ERA 1995 Radiation Protection Monitoring Program Report for 1995 and all exposures were well within the 20 mSv limit. The highest annual effective dose equivalent was 8.6 mSv in mill maintenance.

Dose levels to the public at Jabiru and Jabiru East are mainly from radon progeny and in 1995-96 were 0.03 mSv/yr (child) and 0.02 mSv/yr (adult) well below the ICRP limit of 1 mSv/yr.

Silica exposures were low (< 0.02 mg/m3).

SO2 and sulphuric acid mist exposures were low.

Situation at Olympic Dam

The most interesting finding was that Olympic Dam have radiation doses calculated in a different way to Ranger and in a way not consistent with the methods recommended in the Code. For example they use a conversion of 5 mSv per WLM rather than 10; they use a very large particle size (20 microns) for plant dust, giving a much lower conversion factor; they use consistently lower conversion factors for other dusts, and they apply a protection factor of 10 to 40 employees required to be wearing airstream helmet respirators. All of these procedures greatly reduce the dose estimation.

The WMC handout Occupational and Environmental Radiation Dose Review 1995-96 and other data supplied by WMC showed that all occupational doses, calculated as above were under 20 mSv/yr (90% < 5.0 mine; 90% < 2.7 plant) with the maximum in the mine 8.6 mSv and plant 8.4 mSv. The highest 5 year cumulative dose was 48.6 mSv (mine); 34.4 mSv (plant). These doses have reduced considerably from 1983-85 when maxima of 18 mSv/yr were recorded and mean values were also higher (Hondros 1987, Sonter and Hondros 1987, 1988, Sonter 1987) ( Rolle method for radon progeny). How much of this reduction is due to change of method needs further investigation. The methods of dose estimation at Jabiluka and Kintyre, if developed, will need careful scrutiny.

Public mean dose at Roxby Downs town was 0.02 mSv/yr and at Olympic Dam village 0.03 mSv/yr. These doses were well under the ICRP 1 mSv limit.

The accident lost time injury frequency rate was extremely low (4 per million man hours in the mine and 9 per million man hours in the plant). However it was frankly admitted that the procedure for classifying an injury as lost time was designed to minimise this by giving injured workers other jobs so that time was not lost. One fatality had occurred (premature detonation). My impression was that Olympic Dam are somewhat less open than Ranger and Jabiluka with the details of their operations, including health and safety. They seemed more defensive in interview and less forthcoming with details requested. Although our inspection was on a maintenance day, I noticed vehicles regularly exceeding stated speed limits, a casual approach to hearing protection and lack of units on the hand contamination monitor in the change rooms.

Silica exposures were under 0.1 mg/m3, with only one work category (open air loader operator) reaching this level.

Olympic Dam have documented a clear hazard assessment and control program and have a clear Health and Safety policy. Workplace hazards and their control are summarised below:( adapted from WMC Submission 8 July 1996)

Underground Materials Handling, Hoisting and Services

***Chronic Hazards* *Control Method***

Noise	standard more stringent since project startup (90dB now reduced to 85dB eight hour-equivalent to 83dB (12 hour) (dB= decibel))
	enclosed insulated cabins; personal hearing protection
Silica dust	ventilation; enclosed filtered cabins; personal respiratory protection
Diesel smoke etc	more emphasis on air conditioned cabins
	Ceramic filters; enclosed ventilated filtered cabins; personal respiratory protection
Dust-long lived radionuclides	ventilation; filtered cabins, personal respiratory protection (Airstream helmet etc)
Radon daughters	ventilation; filtered cabins, personal respiratory protection (Airstream helmet etc)
Chemicals sensitisation	choice of chemicals; procedures; personal protective equipment
Acute hazards	Control method
Vehicle accident/impact	one way traffic; `block' lights; back-up alarms, rear-view cameras; procedures
Rockfalls	routine roof bolting for strata support
	regular checking
Mechanical entanglement or impact	guarding; design for exclusion of personnel
Electrical shock	enclosure; AS 3000 rules, electric leakage circuit breakers on all 240V AC outlets
Fire	fuel bay:
	- elimination of ignition sources; aqueous film forming foam systems
	- ventilation to exhaust
	on mobile equipment
	- hydraulic oil leaks
	- tyre fires
Heat stress	air conditioned cabs; ventilation to maintain air cooling power >>150 W/m2; `spot' cooling when needed
Trips, slips,falls	from mobile equipment
	-access/egress design; non slip treads
	from fixed plant - handrails,steps on roadways-muckpiles etc
Blasting: accidents/explosive	low sensitivity detonators
Blasting: fume exposures	ventilation; re-entry procedures
Burns (thermal, chemical)	work practices and personal protective equipment

Concentrator

This section includes the ore stockpile through to flotation and including reagents.

Chronic Hazards	Control Method
Noise	grinding - personal protective equipment
	flotation fans - enclosure etc
Dust (long lived radionuclides)	washdown of slurry spillages to sumps etc
Chemical sensitisation	personal protective equipment and automated mixing
Radon	the existing natural ventilation is thought to be adequate
Acute Hazards	Control Method
Slip/falls hazards	walkways, good access, clean-up
Vessel entry (tanks, mill maintenance, flotation cells etc	procedure, lockouts etc
Electrical	AS3000 and enclosure; electical leakage circuit breakers on all 240V AC circuits
Chemical	fire (at reagents area) - fixed equipment

Hydromet and Solvent Extraction Plants

Concentrate Leach

Chronic Hazards	Control Method
Skin sensitisation from slurry etc	personal protective equipment

Acute Hazards	Control Method
H2SO4; NaOH; ore process reagents: - corrosive etc	automated mixing and metering; physical containment
Entrapment in pressure filter	lockout procedure
Vessel entry	Safe Work Permit for confined space work

Tailings leach, counter- current decantation, and clarification


Acute Hazards	Control Method
Vessel entry	Safe Work Permit for confined space work
Manual handling during maintenance	crane access, monorails, lifting points
High temperature, burns	personal protective equipment
NaOH for wash of sand filters	personal protective equipment

Uranium and copper solvent exchange


Chronic Hazards	Control Method
Chemical exposure - sensitisation? (diluent, amine and oxime)	personal protective equipment

Acute Hazards	Control Method
Ammonia, weak and strong acid; NaOH; kerosene; oxime; amine; skin contact; asphyxiation	personal protective equipment
Fire	Aqueous film forming foam system
Solvent vapour intoxication	ventilation in enclosed spaces
Vessel entry	Safe Work Permit for confined space work

Ammonia and Diluent Storage, Yellowcake Precipitator, Calcination

Chronic Hazards	Control Method
Airborne U3O8 (chemical toxicity and radiation dose)	personal protective equipment
Surface U3o8(including skin and clothing)	shower and change facilities
Noise (calciner building)	personal protective equipment (ear protection)
Acute Hazards	Control Method
U3O8 poisoning (kidney damage)	personal protective equipment
NH3 - corrosive	personal protective equipment
Heat stress (top level calciner)	appropriate ventilation
Fire (oil burner mishap etc)	fire appliances, extinguishers
Fire (diluent)	fire appliances, extinguishers

Tailings Handling

Chronic Hazards	Control Method
Lime exposure; slurry exposure (skin irritation)	personal protective equipment
Noise (pumps)	personal protective equipment (ear protection)

Acute Hazards	Control Method
High pressure fluid (release)	goggles essential
Lime contact with eyes etc	goggles essential
Vessel entry	Safe Work Permit for confined space work

Smelter

General Operations

Chronic Hazards	Control Method
Concentrate dust (radiation dose by inhalation)	spot fume extraction and general building ventilation
Smelter dust (radiation dose by inhalation)	as above
Polonium 210 fume (radiation dose by inhalation)	as above
Polynuclear aromatic hydrocarbons (PAH)(Carcinogens)from electric furnace (also Polonium 210)	as above
Noise	personal protective equipment
SO2 (sulphur dioxide)(long term respiratory hazard)	containment within process; ventilation as necessary
Acute Hazards	Control Method
SO2	Containment within process; ventilation as necessary
Heat stress	cool refuges
Smelter dust	enclosure, ventilation and personal protective equipment
Burns (from hot metal/ slag during tapping, from hot equipment	continuous tappers - personal protective equipment
High pressure steam	engineering, goggles
Vessel entry	Safe Work Permit for confined space work
Entanglement in machinery	engineering, lockout procedures
Fire	procedures, protection systems

Specific Plant Areas (Smelter)

Hazard	Control
Feed Preparation
Dust	engineering - personal protective equipment
High pressure steam	goggles
Mechanical failures, entrapment	engineering, lockout procedures
Oxygen Plant
Cold, Nitrogen, high pressure gases	procedures, engineering, goggles
Fire	procedures protection systems
Flash Furnace
Hot metal, fume, SO2	engineering, ventilation extraction systems
Heat stress	ventilation extraction systems, cool refuges
Anode Furnace and Casting Wheel
Noise	personal protective equipment
Heat stress	cool refuges
Electric Slag Cleaning Furnace
Fume, SO2, carbon monoxide, PAH	fume extraction systems
Waste Heat Boiler
Dust, vessel entry protocol, maintenance	personal protective equipment, procedures
Electrostatic Precipitator
Dust, dust handling system	personal protective equipment procedures
Equipment entry	lockout system, Safe Work Permit
Boilers
Chemicals	engineered dosing systems, personal protective equipment
Acid Plant
SO2, SO3,(sulphur trioxide), acid, vessel entry, sulphur fires	engineered containment, protective apparel, procedures

Tankhouse and Gold Room

Chronic Hazards	Control Method
Mist suppression	extraction ventilation
Radionuclides in slimes	clean up of spills
Noise	detail design to combat noise
Fumes in gold room, nitrogen oxides (respiratory hazards), selenium, polonium, lead etc	ventilation design
Arsenic in slimes (also cadmium and chromium (all carcinogens)	clean up of spills

The main regulatory audits at Olympic Dam mine and plant are inspections from the SA Health Commission. Radiation measurements are reviewed three monthly by the SA Health Commission, SA Department of Minerals and Energy, SA EPA, and ARL.

In order to see the extent to which Ranger and Olympic Dam followed the 1987 Code of Practice health surveillance guidelines (actually intended for the 1980 Code of Practice but never revised) the following letter was sent as part of a NOHSC/ARL project to establish a national radiation worker register and to explore the possibility of future epidemiological studies:

1. Does your mining/processing operation follow the Code of Practice on Radiation Protection in the Mining and Milling of Radioactive Ores (1987)? If not, what alternative occupational health surveillance requirements apply?

2. When conducting health surveillance under Clause 17(1) of the Code (or otherwise), do you use the pro-formas (Form 1 & 2) suggested in the Guideline: Health Surveillance (1982) for (i) personal history and (ii) medical examination?

3. Do you conduct any periodic health surveillance examinations of your employees? (Forms 3 & 4).

4. Have any special examinations been carried out at your site? (Form 5).

5. Do your termination-of-employment examinations follow the Guideline pro-formas? (Forms 6 & 7).

6. If you do not use the Guideline pro-formas, please provide advice to a similar level of detail on the form of examination carried out and the information recorded.

7. Finally, please give details of where health surveillance records are kept (specific names and addresses are not sought - `health department', `company doctor', etc will suffice).

A summary of the responses follows:

Table 3

RADIATION HEALTH SURVEILLANCE PRACTICES

TO BE COMPLETED BY THE EMPLOYEE

QUESTIONS CODE OF SA HEALTH RANGER

PRACTICE COMMISSION MINE

_________________________________________________________________________

PERSONAL HISTORY (FORM 1)

Questions related to:

1. Name Yes Yes Yes

2. Sex Yes Yes No

3. Date of Birth Yes Yes Yes

4. Place of Birth Yes Yes Yes

5. Permanent Address Yes Yes No

6. Name of Spouse Yes Yes No

7. Name of Employing

Company Yes Yes No

8. Member of Trade Union

Professional Association Yes Yes No

9. Current medical problem No No Yes

10. Absence from work due to

illness or injury No No Yes

11. Exercise taken No No Yes

12. Medication taken No No Yes

13. Consumption of alcoholic

beverage No No Yes

SMOKING STATUS

Questions related to:

1. Pipe smoking Yes Yes No

2. Cigar smoking Yes Yes No

3. Cigarette smoking Yes Yes Yes

4. Smoking status Yes Yes Yes

5. No. of cigarettes smoked Yes Yes Yes

6. Length of period smoked Yes Yes Yes

7. Giving up smoking Yes Yes Yes

PAST EMPLOYMENT HISTORY

Questions related to:

1. Employment status Yes Yes No

2. Exposure to radiation Yes Yes Yes

3. Exposure to asbestos Yes Yes No

4. Periods of exposure Yes Yes No

5. Name and location of

company where exposed Yes Yes No

6. Exposure to noise No No Yes

7. Exposure to chemical No No Yes

8. Exposure to dust No No Yes

9. Details of previous jobs Yes Yes No

10. Employment in a uranium

mining company Yes Yes No

PAST MEDICAL HISTORY

1. Questions related to:

Past medical history Yes Yes Yes

FAMILY MEDICAL HISTORY

1. Questions related to:

Family medical history No No Yes

TO BE COMPLETED BY THE EMPLOYEE

QUESTIONS CODE OF SA HEALTH RANGER

PRACTICE COMMISSION MINE

_________________________________________________________________________

MEDICAL EXAMINATION (FORM 2)

Results related to:

1. Height Yes Yes Yes

2. Weight Yes Yes Yes

3. BMI No No Yes

4. Urinalysis Yes Yes Yes

5. Visual Acuity Yes Yes Yes

6. Spirometry Yes Yes Yes

7. Audiometry Yes Yes Yes

8. Blood pressure Yes Yes Yes

9. Respiratory diseases Yes Yes Yes

10. Nose/Sinus check No No Yes

11. Spine Check No No Yes

12. Limbs check No No Yes

13. Chest check Yes Yes Yes

14. Chest X-ray Yes Yes No

15. Abdomen check No No Yes

16. Skin check No No Yes

17. Neurological check No No Yes

Questions related to:

1. Undergoing radiotherapy Yes Yes No

2. Having barium meal, I.V.P.,

or other specialised-

x-ray procedure Yes Yes No

3. Injury requiring five

attendances for X-ray or

nuclear scan Yes Yes No

FAMILY MEMBERS

Questions related to:

1. Out come of pregnancy Yes Yes No

2. Health status of the

child Yes Yes No

3. Difficulty in conception Yes Yes No

4. Details of children born

in the last two years No Yes No

5. Details of children born

since previous

examination Yes No No

CONSENT OF EMPLOYEE

Requiring:

1. Release of information

from subject's previous

medical practitioner Yes Yes No

MEDICAL OFFICERS' ASSESSMENT

The employee (applicant) is:

1. Fit (no health problems) Yes No Yes

2. Unfit Yes No Yes

3. Fit with treatment Yes No No

4. In need of treatment or

further investigation Yes Yes No

The above tabulation is the comparison of questions in the General health questionnaire (GHQ) of the Energy Resources of Australia Ltd Ranger mine (the GHQ is developed by the company and approved by appropriate authority for the purpose of health surveillance under clause 17(1) of the code and is used for all medical examination) and the Single multi-purpose questionnaire of the South Australian Health Commission of the radiation protection branch (Single multi-purpose questionnaire (covering Olympic Dam) which is very similar to Form 1&2 of the Code, is a combination of Pre-employment and Periodic- questionnaires which were used until 1991 for collecting personal and medical history data), with the questions in the Code of Practice on Radiation Protection in the Mining and Milling of Radioactive Ores (Forms 1 & 2).

Ranger Mine and SA Health Commission conduct health surveillance under Clause 17(1) of the Code but they do not use the pro-formas (Forms 1 & 2) as per guideline (Code of Practice), but use their own questionnaire (General Health Questionnaire and The Multipurpose Questionnaire).

SA Health Commission uses The Multi-Purpose Questionnaire not only for conducting health surveillance under clause 17(1) of the Code but also for conducting periodic health surveillance (Forms 3 & 4), special examination on work site (Form 5 of Code of Practice) and for termination of employment examination (Forms 6 & 7 of Code of Practice).

Ranger Mine does not carry out special examination on work site (Form 5 of Code of Practice) but uses its own questionnaire to conduct periodic health surveillance (Forms 3 & 4 of Code of Practice) and termination of employment examination (Forms 6 & 7 of Code of Practice). Ranger Mine like SA Health Commission uses its General Health Questionnaire for all medical examination.

Since the Forms 3 & 4, 5, and 6 & 7 are similar to the Forms 1 & 2 of the Code of Practice the questions in the GHQ of the Ranger Mine and the Multi-Purpose Questionnaire of the SA Health Commission are compared to the questions in the Form 1 (personal history) and Form 2 (medical examination) of the code.

Differences and Similarities of Forms 3&4, 5, 6&7 with Forms 1&2

Form 3 of the Code (periodic health surveillance --personal history

Same as Form 1. Questions on Past Employment History are omitted. In its place there are questions eliciting information on the present occupation of the respondent.

Form 4 of the Code (periodic health surveillance--medical examination)

Same as Form 2. Except all the questions in this form starts or ends in `since previous examination'.

Form 5 of the Code (special medical examination

Same as form 2.

Form 6 of the Code (termination of employment--personal history)

Same as form 3.

Form 7 of the Code (termination of employment--medical examinations)

Same as Form 4 except there is a question asking `reason for termination'.

Ranger medical records are kept by the company and by NT Department of Health and Community Services. Olympic Dam records are kept by the company and the Epidemiology Branch of the SA Health Commission.

Thus, both Ranger and Olympic Dam essentially follow the guidelines with a few omissions. The importance of this lies in the availability of standardised confounder data which is essential to any future epidemiological study, ie data on other exposures (eg smoking, asbestos, chemical) which can cause cancer or lung disease which may distort any epidemiological attempt to relate radiation exposure to future cancers or other disease.

The proposal for Jabiluka involves underground mining by a similar method to that used at Olympic Dam, which will have similar hazards and control mechanisms. Higher ventilation to deal with the higher radon progeny levels may be required. Ore is to be transported by road to the existing mill and processing plant at Ranger, so no new processing hazard, other than a quantitative increase in throughput will be introduced. The transport hazard has been mentioned above.

Feasibility of epidemiological studies in Australian uranium and mineral sands miners and millers

The main aim of the ARL National Radiation Dose Register is to maintain data on exposure to ionising radiation experienced by Australian uranium and mineral sands workers to act as a resource should epidemiological studies to determine an increased risk of lung cancer become feasible in the future. Health surveillance according to the Code of Practice on Radiation Protection in the Mining and Milling of Radioactive Ores (Guideline on Health Surveillance 1982) by companies, State and Territory authorities will continue.

Published dose-related risk estimates for lung cancer in uranium and mineral sands workers suggest a mean dose-related increase of relative risk of lung cancer (risk as a ratio compared to the risk in the non-radiation exposed) of approximately 1.01 per 10 mSv effective dose (the risk/dose coefficient). This estimate has a wide range of variation in different studies (1.003-1.04). Table 4 shows the calculated relative risks under different assumptions.

About 2,000 uranium and mineral sands workers are exposed to external gamma radiation and internal alpha radiation from inhaled radioactive dust and radon progeny products.

The average lung dose for Australian uranium and mineral sands workers has been estimated a 3 mSv/yr. Doses in the period 1979-1986 were higher (but of unknown magnitude), at least in the mineral sands industry. Because of uncertainties in the actual dose (see eg NRC 1995 for the difficulties of retrospectively estimating dose for epidemiological studies) the risk/dose coefficient (for total dose), and the number of workers available for follow-up, a series of power calculations, for a range of values for these variables, were undertaken. Table 5 shows the likely relative risks, based on previous studies, and the minimum relative risk detectable at the conventional 5% alpha one side level (ie less than 5% likely to be due to chance, with a power of 80% (ie 80% probability of detecting a significant effect if it exists; this is a commonly used power level).

Table 4

Relative risk expected on the basis of previous studies and different

assumptions of annual lung dose, risk/dose coefficient and duration of

exposures

Annual Rel Duration of exposure

lung Risk/10 mSv

dose (risk/dose

coefficient)

_______ ___________ ______________________________________

10 20 30 40

3 mSv 1.003 1.009 1.018 1.03 1.04

1.01 1.03 1.06 1.09 1.13

1.04 1.13 1.27 1.42 1.60

10 mSv 1.003 1.03 1.06 1.09 1.13

1.01 1.10 1.22 1.35 1.49

1.04 1.48 2.19 3.24 4.8

20 mSv 1.003 1.06 1.13 1.20 1.27

1.01 1.22 1.49 1.82 2.22

1.04 2.19 4.80 10.52 23.1

Table 5

Minimum relative risk detectable (alpha = 0.05

one sided, power 80%)

Population for Duration of follow-up (years)

follow-up

____________ _______________________________________________

10 20 30 40 50 60

400 3.50 2.50 2.25 1.95 1.88 1.78

2,000 1.85 1.57 1.46 1.39 1.36 1.31

3,000 1.67 1.46 1.37 1.31 1.28 1.25

4,000 1.57 1.39 1.31 1.27 1.24 1.22

This calculation assumes that we are only interested in an increase in lung cancer incidence and does not take account of confounders like smoking, asbestos, and other carcinogens, all of which weaken the power or increase the minimum detectable increased risk.

Thus, assuming current exposures (3 mSv/year) and the mean risk/dose coefficient (1.01) applies, the expected relative risk for 20 years exposure from now would be 1.06 (Table 4). The minimum detectable relative risk at the given power and significance levels for 60 years follow-up of 2,000 people is 1.31 (Table 5). Hence the study would require more than 60 years follow-up and is thus infeasible.

These calculations show that if we accept the mean risk/dose coefficient relating lung cancer risk to exposure from previous studies, then detection of increased lung cancer risk in Australian uranium and mineral sands workers will not be feasible at the 80% power level, even if the actual exposures were higher in the past, giving a mean exposure of, say, 10 mSv/yr. If a lower level of power or higher alpha levels were acceptable, the proposed study would become more feasible.

Similarly, applying the Japanese A-bomb survivor risk/dose estimates, the likely increased incidence of all solid cancers at the current whole body radiation exposures is such that it would not be detectable at the given power and alpha levels within 60 years of follow-up.

However, there are justifications for maintaining a dose register for its own sake. Future studies of large populations elsewhere (A-bomb survivors, nuclear industry workers, uranium and mineral sands miners) may point to a higher dose/risk coefficient. With the passage of time, the increased total number of workers whose exposure histories have been recorded may make the detection of increased risk more feasible and it would be therefore desirable to conserve the dosimetry and medical data against this contingency. In addition, once the numbers have become large enough, even a negative result, which puts an upper limit to the risk in the Australian context, would be a valuable outcome.

Further, it is important to maintain cumulative dose measures to ensure that the new exposure standards are not exceeded. If the higher grade uranium ore project at Jabiluka is approved, dose levels will very probably be higher than those found at Ranger and Olympic Dam. Cumulative dose measures are also sometimes required as evidence in compensation claims by employees with cancer.

REFERENCES

Archer VE, Brinton HP, Wagoner JK (1964) Pulmonary function of uranium miners. Health Physics 10:1183-94.

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