There are three significant occupational health risks at our operations. In order of frequency of exposure, they are:
- High levels of noise. This stressor can result in noise-induced hearing loss among exposed employees.
- Ergonomic stressors. These include vibration from machinery, manual handling and
- sedentary tasks.
- Airborne pollutants and chemical stressors in the working environment that target specific organs and impede the normal functions of the human body.
During the reporting period, one case of sino-nasal carcinoma and four cases of platinum-salt sensitivity were reported. (See the sections on “Exposure to nickel, aerosols and acid mist” and “Platinosis” below.)
Noise-induced hearing loss
Looked at together with the risk-assessment data for occupational hygiene exposures, our medical surveillance research clearly indicates that noise remains the number one occupational health risk at Amplats. Our risk mitigation strategy is to control the noise at source, i.e. by reducing the sound-pressure levels of noise-emitting equipment. Over the years we have concentrated on silencing pieces of equipment emitting noise levels above 110 dB(A). Over 98% of the equipment identified for silencing at the start of 2007 has been silenced over the past five years. Of the 2,063 pieces that required silencing in 2007, only 26 pieces remain. The pieces remaining are either fans that are located in remote areas where no one is exposed to the noise, or specialised drills that are in the process of
The mining industry’s milestone for achieving the objective of silencing all equipment to below 110 dB(A) is December 2013. Amplats is thus well within the targeted date. The Company has now set itself a new goal – that of further reducing the risk of NIHL to its employees by silencing equipment emitting in excess of 100 dB(A).
The inventory Amplats has completed has identified approximately 11,326 pieces of equipment fitting the description. Most of this equipment consists of rock drills, and to achieve this objective will require an innovative approach by all the stakeholders involved. Presently no percussion-type rock drill available achieves this noise level: the best available emits approximately 103.5 dB(A). The electric-type drills that are in use in our Eastern Limb operations also emit above this limit. The industry will thus need to develop new technology to achieve its aims.
Amplats reported 46 cases of NIHL in 2012, compared with 53 new cases in 2011, 19 cases in 2010, 42 cases in 2009 and 28 cases in 2008. These fluctuations can be explained by
- variability in susceptibility to hearing deterioration and
- the length of service of employees in different cohorts.
The South African system of compensation for hearing loss uses the criterion of percentage loss of hearing to assess an employee’s level of hearing impairment. The details are captured in Circular Instruction No 17: Noise, which falls under the Compensation for Occupational Injuries and Diseases Act (No 130 of 1993). In line with this instruction, 101 employee dossiers were submitted to the Rand Mutual Assurance for compensation for NIHL in 2012, compared with 32 in 2010, 79 in 2009 and 68 in 2008.
Despite this mixed picture, which is generally common in the industry, the Company is confident that its interventions will ultimately be reflected in future data on hearing deterioration. Given the long latency period of this occupational disease, it is too early to evaluate the impact of the recent risk-management strategies on hearing deterioration.
DEAFENING THE IMPACT OF NOISE
A number of interventions aimed at mitigating the impact of noise exposure have either been implemented or are currently under investigation at Amplats.
The Company has revised its Group procedure on the selection of hearing-protection devices (HPDs). Key features that have been added include the use of the octave-band method to estimate the effectiveness of HPDs; the adoption of an HPD matrix in line with the recommendations of the Best-Practice Adoption System developed by the Mining Industry Occupational Safety and Health (MOSH); and the procurement of HPDs that meet the accepted standards, i.e. ANSI, ISO,
BS and SANS.
Other leading noise-attenuation initiatives are taking place in the following areas:
Engineering: Our first-generation rock-drill silencers are in the process of being replaced by second-generation silencers. This silencing programme follows an implementation schedule that is fully on track. The related noise registers are updated on a quarterly basis. Currently, further tests are being conducted on three types of rock drills in order to identify the best machine for the purpose.
Administrative: Comprehensive hearing-conservation regimes are in place, including the use of noise-source registers. Also employed is a noise-attenuation tracking register. Group standards pertaining to hearing-conservation programmes and respiratory protection equipment are currently being revised to ensure that we conform to best practice.
Personal protection equipment (PPE): A detailed PPE matrix is in place, which sets out the required standards for personal hearing protectors and also lists those vendors that are approved by Amplats.
Noise monitoring: A dosimeter has been developed for our “Type 2” cap-lamp, in collaboration with two suppliers. This effective, practical piece of equipment requires neither time nor manpower to record noise-exposure measurements.
All instances of noise exposure above the legislated occupational exposure limit of 85 dB(A) are linked to the IRM.Net action manager, and result
in the appropriate action taking place. All identified shifts in hearing of 5%
or more above the baseline are formally investigated.
Our hearing team has been exploring the use of an in-ear dosimeter that measures the noise inside the ear when HPDs are in place or inserted. This technology is used to determine the actual protection afforded by HPDs; and to assess the use of HPDs among employees exposed to noise.
Vibration and ergonomics
We have started to record quantification measurements in the assessment of ergonomic risk in sedentary work and in manual handling tasks. High-risk occupations are being identified, and appropriate engineering and/or administrative controls are being sought to minimise or mitigate the various risks. This will be an area of growth and specialisation over time.
The production of chloroplatinates during the refining of precious metals continues to pose a health risk to employees working at Precious Metals Refiners (PMR). Medical surveillance – on at least a quarterly basis – is used to monitor the possible accumulation of platinum salts in the body. Over the years, PMR has recorded a significant decline in the number of cases of platinum-salt sensitivity.
Four cases were reported in 2012.
A task team is investigating these cases to try to prevent future occurrences of platinosis. Once an employee is removed from the source, all symptoms of platinosis cease.
Exposure to nickel, aerosols and acid mist
Exposure to nickel in the metallurgical processes at Rustenburg Base Metal Refiners (RBMR) has been greatly reduced, to below the legal limit of
0.1 mg/m³. This was achieved through the introduction of a tank house equipped with leading-edge enclosure and extraction technology. The tank houses are engineered with forced-extraction cell hoods that improve aerosol capture, thereby further limiting exposure to the metal and the acid mist. It has also been compulsory to wear the approved respiratory protective equipment in this facility since the early 1990s.
Although these exposures have been reduced to acceptable levels, one case of sino-nasal carcinoma was reported in 2012. This carcinoma is a malignant tumour of the epithelial lineage, observed as a soft-tissue mass that invades and destroys the sinus wall. The affected employee had worked as a processor in the copper tankhouse at RBMR for a period of 35 years, and had been exposed to soluble nickel mist in much higher concentrations in earlier years. The employee is currently receiving all medical, palliative and supportive care possible. A surveillance plan has been developed and implemented, together with an ear, nose and throat specialist, to monitor and support employees potentially at risk of sino-nasal carcinoma following longer periods of employment at the facility.
Exposure to airborne dust
Ongoing occupational-hygiene measurements reflect that occupational exposures to airborne platinum dust and silica in our mining operations are at levels below set occupational-exposure limits of
2.0 mg/m3 and 0.1 mg/m3 respectively. Furthermore, detailed analysis has indicated that alpha quartz forms only a trace constituent of Merensky and UG2 rock, meaning that silica is not an issue.
Occupational exposure to airborne dust is thus deemed not to be a significant health hazard at our mining operations. A number of factors and control measures contribute to the low dust levels, including:
- the high humidity of underground environments
- sound ventilation principles, designs, standards and practices
- comprehensive watering-down procedures
- wet-drilling methods
- dust suppression on operations and equipment (e.g. water sprays, dust filters, cyclones)
- low-velocity ventilation over conveyor belts (<3.0 m/s)
- re-entering periods (calculated on the basis that no exposure to any significant airborne pollutant associated with blasting will occur)
- the nature of the ore deposits
Exposure to diesel particulate matter
Occupational exposure to diesel particulate matter (DPM) in mechanised underground sections is a potential risk, and as a result a comprehensive baseline occupational hygiene assessment was completed in 2009. Results indicated moderate exposure above international occupational exposure limits, with concentrations at their highest in work areas situated at the back-end of return airways. During 2011 and 2012, DPM formed part of our mines’ occupational hygiene sampling programme. A baseline review of
DPM revealed measurements of between 0.1 mg/m³ and 0.19 mg/m³. The international benchmark is set
at 0.16 mg/m³.
We continually explore means of reducing employees’ exposure to DPM. These include awareness-creation and training programmes, better ventilation, the use of low-sulfur diesel fuel, and the purchase of “Tier 3” machines as a minimum. Tier 3 diesel machines contain engine technology that ensures compliance with environmental regulations related to Tier 3 exhaust gas emissions in Europe and the USA. In June 2012, the International Agency for Cancer Research classified diesel engine exhaust (including DPM) as a known human carcinogen (Group 1) and Amplats is in the process of developing a more comprehensive strategy to mitigate the risks associated with exposure to it.
Other occupational diseases
Two cases of occupational dermatitis were reported in 2012.
In addition, some 80 people were diagnosed with other occupational diseases. Of these cases, 70 were not attributable to conditions at Amplats and were instead linked to employees’ previous places of work.
Medical surveillance and monitoring programmes
All our operations run medical surveillance and monitoring programmes for occupational exposure to known risks, and offer comprehensive medical-care facilities to both employees and contractors.
In 2012, Amplats’ health team continued to focus on the enhancement of risk-based medical surveillance.