Groundbreaking UCT Study Exposes Lingering Toll of Asbestos on Former Miners
A recent study from the University of Cape Town has shed light on the enduring health crisis facing former asbestos miners in South Africa, revealing mortality rates 17% higher than expected among women decades after exposure. Published in the American Journal of Industrial Medicine, the research draws from a 20-year analysis of over 11,000 ex-miners, highlighting how historical mining practices continue to claim lives through respiratory diseases and other complications.
Lead researcher Dr. Yumna Williams-Mohamed, from UCT's Division of Occupational Medicine, emphasized the overlooked role of women in these hazardous environments. 'This is reflective of gender-specific job tasks, aboveground asbestos work, and inadequate protective measures in historical mining settings,' she noted. The findings underscore the need for targeted health interventions long after South Africa's 2008 asbestos ban.
South Africa's Asbestos Mining Legacy: A Major Global Supplier
South Africa was once the world's leading producer of crocidolite (blue asbestos, 97% of global supply) and amosite (brown asbestos), alongside chrysotile (white asbestos). Mining peaked in the mid-20th century across the Northern Cape, Limpopo, and Mpumalanga provinces, fueling industries worldwide but at a devastating human cost. Operations involved extracting fiber-bearing rock from open pits and underground, with processing generating massive dust clouds.
The industry employed tens of thousands, many as migrant laborers under apartheid-era systems. Mines closed by 2002, and a full ban on mining and use followed in 2008 amid growing evidence of asbestos-related diseases like asbestosis, mesothelioma, and lung cancer. Yet, legacy exposures persist through contaminated sites, buildings, and unmonitored health in ex-workers and communities.
Women's Crucial Yet Invisible Roles in Asbestos Processing
Women formed up to half the asbestos workforce from the late 19th century to the 1980s, often undocumented and informal. Their primary task was 'cobbing'—manually breaking ore with rocks or hammers to liberate fibers—performed aboveground in open air, creating intense airborne dust without respirators or protective gear. Other duties included sorting fibers by length, bagging, sweeping mills, and domestic work in mine compounds.
This labor was gender-segregated: men handled underground extraction, while women managed surface processing. Home-based secondary exposure occurred as women washed contaminated clothing, affecting families. Such roles exposed women to high fiber concentrations, explaining their elevated risks despite shorter formal employment.
Methodology: Analyzing Two Decades of Ex-Miner Data
The UCT study utilized the Inyosi database from the Asbestos and Kgalagadi Relief Trusts, covering claimants from ~85% of SA asbestos mines (2004–2023). The cohort included 11,343 individuals (75.8% aboveground workers, 67.4% <5 years exposure), tracked for 136,549 person-years, yielding 5,106 deaths (45%).
Researchers calculated standardized mortality ratios (SMRs) against general population rates, using Cox regression for predictors like International Labour Organization (ILO) radiographic profusion (lung scarring severity), spirometry (FEV1/FVC), BMI, and smoking. Data encompassed occupational histories, chest X-rays, and lung function tests from compensation seekers.
Overall Mortality: Modest Excess Masking Deeper Issues
All-cause SMR was 1.04 (4% excess; 95% CI 1.01–1.07), with crude mortality rate (CMR) 37.4/1,000 person-years. Remarkably, 43.7% of deaths occurred before age 55, signaling premature loss. SMRs declined over time, possibly due to interventions, but incomplete records limit conclusions.
Key predictors included worsening ILO profusion (aHR 1.13–2.42), severe low lung function (FEV1 z-score <-3: aHR 1.60; FVC z-score <-3: aHR 1.26), low BMI (<18.5: aHR 1.46), and ex-smoking (aHR 1.43).
| Risk Factor | Adjusted Hazard Ratio (aHR) |
|---|---|
| ILO Profusion 1/1 | 1.13 (1.05–1.23) |
| ILO Profusion 3/3+ | 2.42 (1.58–3.71) |
| Low FEV1 (<-3 z-score) | 1.60 (1.41–1.81) |
| Low BMI (<18.5) | 1.46 (1.36–1.58) |
| Ex-smoker | 1.43 (1.35–1.53) |
Gender Disparity: Why Women Faced 17% Higher Mortality
While men's SMR was non-significant (1.02), women's reached 1.17 (17% excess; 95% CI 1.09–1.25), CMR 33.0/1,000. Aboveground cobbing generated peak dust levels; lack of PPE amplified risks. Women often combined mining with childcare, heightening vulnerability. Dr. Williams-Mohamed noted this 'highlights the often-overlooked experiences of women in asbestos-related occupations.'
The gendered pattern demands inclusive surveillance, recognizing informal roles historically invisible in records.
Declining Trends Amid Data Gaps
- Annual SMRs fell progressively 2004–2023, suggesting surveillance/compensation benefits.
- However, underreporting (e.g., no cause-of-death data) cautions interpretation.
- 43.7% deaths pre-55 years indicate ongoing premature mortality burden.
Improvements may stem from Trusts' medical evaluations, but national gaps persist.
Health and Policy Implications for Ex-Miners
The study advocates risk-stratified surveillance: intensive monitoring for high ILO/spirometry risks, routine for mild cases. Core care includes vaccinations, smoking cessation, respiratory management, family compensation support. For women, gender-sensitive approaches address overlooked exposures.
Without national policy under the Occupational Diseases in Mines and Works Act, late diagnoses prevail. Enhanced diagnostics, training, and community outreach are urgent.UCT's CEOHR leads such efforts.
UCT's Pivotal Role in Occupational Health Research
UCT's School of Public Health, via CEOHR and Division of Occupational Medicine, pioneers mining health studies. Prof. Rodney Ehrlich's silico-TB work, Dr. Jim teWaterNaude's radiological innovations, Assoc. Prof. Shahieda Adams' contributions, and Dr. Williams-Mohamed's dissertation exemplify institutional commitment. This research translates to policy, aiding Trusts and government.
Such studies position SA universities as global leaders in environmental justice and epidemiology, informing worldwide asbestos legacies.
Photo by Moulaye Sidi Aly on Unsplash
Future Outlook: Surveillance, Compensation, and Equity
Addressing SA's asbestos crisis requires sustained university-led research, national surveillance, equitable compensation, and remediation of contaminated sites. Integrating gendered perspectives ensures no group is left behind. As Dr. Williams-Mohamed concludes, 'The effects do not end when a mine closes'—vigilant action can mitigate ongoing suffering.
Explore the full study here for deeper insights.
