Infectious tuberculosis

INFECTIOUS TUBERCULOSIS

TB screening

Tuberculosis is the most common opportunistic infection among people living with HIV/AIDS, and is the leading cause of morbidity and mortality in HIV-positive employees. Active TB screening forms part of annual medical examination. We have advanced environmental control measures in place in all areas where there is a high density of people, especially TB wards. This greatly reduces the risk to healthcare and other workers.

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Amplats screens employees for tuberculosis and provides comprehensive treatment to those who are infected. During 2012, we treated 635 employees with new TB infections, compared with 671 newly infected employees in 2011. 
(There were 654 new infections in 2010; 894 in 2009; and 886 in 2008.)

The incidence of TB in 2012 was 1,255 cases per 100,000 employees, compared with TB incidence rates of 1,308 cases per 100,000 employees in 2011 and 1,340 cases per 100,000 employees in 2010.

There were 61 deaths from TB in 2012, 58 of them HIV-related. This compares with 60 deaths in 2011, of which 56 were HIV-related; 77 deaths in 2010, of which 74 were HIV-related; 113 deaths in 2009, of which 100 were HIV-related; and 91 deaths in 2008, of which 81 were HIV-related.

The TB incidence rate and the TB mortality rate for 2012 are comparable to the rates in 2011. Although there was no increase in the TB incidence rate and the number of TB deaths recorded in 2012, the figures are cause for concern. In 2012, the Chamber of Mines (CoM) initiated an industry-wide review of TB prevention and treatment programmes in the mining industry. The CoM process began in November 2011 and Amplats has been participating in it. We hope to find ways of improving the outcomes of our TB programme and enhancing the quality of TB management at all 
our operations.

In 2012, one case of extensively drug-resistant (XDR) TB was diagnosed at our operations, compared with one case in 2011, three cases in 2010 and one case in 2009. 
In addition, 28 cases of multidrug-resistant (MDR) TB were diagnosed in 2012. Initial figures for the Company’s antiretroviral therapy (ART) programme show a decrease in the risk of TB among employees on ART, reflecting the efficacy of the therapy.

GRAVIMETRIC SAMPLING FOR AIRBORNE POLLUTANTS AT AMPLATS

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Jacques Blignaut fits Marc Schoeman with a personal gravimetric monitor at Khomanani

The legislation

In 2004, the Airborne Pollutants guideline replaced the guideline for Gravimetric Sampling of Airborne Particulates for Risk Assessment in terms of the Occupational Diseases 
in Mines and Works Act (No 78 
of 1973.)

The current gravimetric dust-sampling procedure for mines is designed to determine the concentration of particulates workers are exposed to during a normal eight-hour workday (as determined by the Department of Mineral Resources (DMR), 1999). 
Where significant hazards have been identified, mine managers have to implement a code of practice for occupational hygiene programmes.

The criteria for a significant hazard are as follows:

  • For airborne pollutants: ≥ 10% of the occupational exposure level.
  • For gases and vapours: ≥ 50% of the occupational exposure limit.

Occupational hygiene milestones for the elimination of silicosis were agreed to at the 2003 Mine Health and Safety Summit. The agreements stated that:

  • by December 2008, 95% of all exposure measurements results would be below the occupational exposure limit (OEL) for respirable crystalline silica quartz of 0.1 mg/m3 (these results are individual readings and not average results)
  • after December 2013 and using current diagnostic techniques, no new cases of silicosis would occur among previously unexposed individuals. (This refers to individuals unexposed prior to 2008, i.e. equivalent to new persons entering the industry in 2008)

The sampling programme

Our current gravimetric dust-sampling programme, which covers the representative shifts defined by the DMR, includes personal exposure samples taken underground at each mine. Between 90 and 120 dust samples are gathered every month. Filter and sampling trains are prepared, dispatched and post-weighed daily, based on the internal quality-assurance criteria of Amplats gravimetric weighing facility 
in Rustenburg.

Analyses for silica are done on 10% of all the personal samples taken for the month. Once calculated, exposures to silica dust are compared with the occupational exposure limit of 0.1 g/m3.

Apart from the daily monitoring described above, during 2012 an external perspective was obtained on our mines’ dust-sampling results, specifically those pertaining to alpha quartz. A snapshot study of personal sampling was conducted over a two-month period by the North-West University (NWU) at one of the conventional shafts, during which gravimetric dust-sampling equipment was issued to various groups of workers involved in mining activities.

Conclusions

Amplats has been meeting the occupational hygiene milestones for the elimination of silicosis agreed to at the 2003 Mine Health and Safety Summit.

We were able to establish that the respirable crystalline silica quartz exposures of workers sampled had been well below the OEL of 0.1 mg/m3 at all times. It was also evident from ongoing sampling that there were no significant differences in exposure levels between the two underground reefs we mine, being the Merensky and the UG2. Moreover, the results we have been obtaining found conclusive support in the findings of the 2012 NWU external survey on silica exposures.