Coal miners' respiratory disease litigation

The recognition of lung disease in coal workers: The role of Gough–Wentworth whole lung sections

From the identification of a specific lung disease caused by coal dust exposure in miners in 1831 until the demonstration of the association of that exposure to risk of emphysema in 1984, there was continuous argument about the harmfulness of coal dust. Ill health in miners was attributed variously to tuberculosis, quartz exposure or cigarette smoking. An acceptance that coal dust was harmful only started with investigative radiology and pathology in the 1920s, and physiology in the 1950s. Most of the early investigations were in South Wales, the centre of the most important coal field in Great Britain. Among the investigators was Professor Jethro Gough who, with his technician James Wentworth, introduced a technique for making thick sections of whole, inflated lungs on paper backing. Here, we describe this method and its central role in understanding the relationships between coal dust exposure, pneumoconiosis, emphysema and lung dysfunction in miners.

Profusion of Opacities in Simple Coal Worker's Pneumoconiosis Is Associated With Reduced Lung Function

BACKGROUND

A large body of evidence demonstrates dose-response relationships of cumulative coal mine dust exposure with lung function impairment and with small-opacity profusion. However, medical literature generally holds that simple coal worker's pneumoconiosis (CWP) is not associated with lung function impairment. This study examines the relationship between small-opacity profusion and lung function in US underground coal miners with simple CWP.

METHODS

Miners were examined during 2005 to 2013 as part of the Enhanced Coal Workers' Health Surveillance Program. Work histories were obtained, and chest radiographs and spirometry were administered. Lung parenchymal abnormalities consistent with CWP were classified according to International Labor Organization guidelines, and reference values for FEV1 and FVC were calculated using reference equations derived from the third National Health and Nutrition Examination Survey. Differences in lung function were evaluated by opacity profusion, and regression models were fit to characterize associations between profusion and lung function.

RESULTS

A total of 8,230 miners were eligible for analysis; 269 had category 1 or 2 simple CWP. Decrements in FEV1 % predicted were nearly consistent across profusion subcategories. Clear decrements in FVC % predicted and FEV1/FVC were also observed, although these were less consistent. Controlling for smoking status, BMI, and mining tenure, each 1-unit subcategory increase in profusion was associated with decreases of 1.5% (95% CI, 1.0%-1.9%), 1.0% (95% CI, 0.6%-1.3%), and 0.6% (95% CI, 0.4%-0.8%) in FEV1 % predicted, FVC % predicted, and FEV1/FVC, respectively.

CONCLUSIONS

We observed progressively lower lung function across the range of small-opacity profusion. These findings address a long-standing question in occupational medicine and point to the importance of medical surveillance and respiratory disease prevention in this workforce.

BaySTDetect: detecting unusual temporal patterns in small area data via Bayesian model choice

Space-time modeling of small area data is often used in epidemiology for mapping chronic disease rates and by government statistical agencies for producing local estimates of, for example, unemployment or crime rates. Although there is typically a general temporal trend, which affects all areas similarly, abrupt changes may occur in a particular area, e.g. due to emergence of localized predictors/risk factor(s) or impact of a new policy. Detection of areas with "unusual" temporal patterns is therefore important as a screening tool for further investigations. In this paper, we propose BaySTDetect, a novel detection method for short-time series of small area data using Bayesian model choice between two competing space-time models. The first model is a multiplicative decomposition of the area effect and the temporal effect, assuming one common temporal pattern across the whole study region. The second model estimates the time trends independently for each area. For each area, the posterior probability of belonging to the common trend model is calculated, which is then used to classify the local time trend as unusual or not. Crucial to any detection method, we provide a Bayesian estimate of the false discovery rate (FDR). A comprehensive simulation study has demonstrated the consistent good performance of BaySTDetect in detecting various realistic departure patterns in addition to estimating well the FDR. The proposed method is applied retrospectively to mortality data on chronic obstructive pulmonary disease (COPD) in England and Wales between 1990 and 1997 (a) to test a hypothesis that a government policy increased the diagnosis of COPD and (b) to perform surveillance. While results showed no evidence supporting the hypothesis regarding the policy, an identified unusual district (Tower Hamlets in inner London) was later recognized to have higher than national rates of hospital readmission and mortality due to COPD by the National Health Service, which initiated various local enhanced services to tackle the problem. Our method would have led to an early detection of this local health issue.

Review series: Occupational and environmental lung disease: Chronic obstructive pulmonary disease and the workplace

Chronic Obstructive Pulmonary Disease (COPD) is a progressive respiratory disease associated with increasing morbidity and mortality worldwide. Whilst tobacco smoking is the important cause, other cuases are regognised. This article discusses the contribution that harmful inhaled occupational exposures make to the overall burden of COPD, and goes on to discuss other aspects of the COPD workplace interface. Prevention is key. All healthcare professionals have a resposibility to consider workplace issues when dealing with their COPD patients.

Policy challenges from the "White" Senate inquiry into workplace-related health impacts of toxic dusts and nanoparticles

On 22 June 2005 the Senate of the Commonwealth of Australia voted to establish an inquiry into workplace harm related to toxic dust and emerging technologies (including nanoparticles). The inquiry became known as the "White" Inquiry after Mr Richard White, a financially uncompensated sufferer of industrial sandblasting-induced lung disease who was instrumental in its establishment. The "White" Inquiry delivered its final report and recommendations on 31 May 2006. This paper examines whether these recommendations and their implementation may provide a unique opportunity not only to modernize relevant monitoring standards and processes, but related compensation systems for disease associated with workplace-related exposure to toxic dusts. It critically analyzes the likely role of the new Australian Safety and Compensation Council (ASCC) in this area. It also considers whether recommendations related to potential workplace related harm from exposure to nanoparticles could commence a major shift in Australian healthcare regulation.

Dust related risks of clinically relevant lung functional deficits

AIM

To quantify the risks of clinically important deficits of FEV1 in coal miners in relation to cumulative and average concentrations of respirable dust.

METHODS

Data were studied from over 7000 men who had been surveyed in the late 1970s. Linear regression equations for the association between FEV1 and self-reported breathlessness on mild exertion were used to define clinically important levels of FEV1 deficit, and the probabilities that individuals with different dust exposures would experience these deficits were calculated.

RESULTS

Levels of FEV1 were lower among breathless men than among others, with a large overlap of the distributions. The relations between standardised FEV1 and breathlessness were constant over all age and smoking groups. A decrease of 100 ml in FEV1 was associated with an increase of 1.12 in the odds of reporting breathlessness. FEV1 deficits of -0.367, -0.627, and -0.993 l (designated as "small", "medium", and "large" deficits) were, on average, associated with proportional increases of risks of breathlessness by factors of 1.5, 2.0, and 3.0 respectively. Cumulative respirable dust exposure ranged up to 726 gh/m3, mean 136 gh/m3 (British Medical Research Council measurement convention). An increase of 50 gh/m3 was associated with an increase of about 2% in the proportion of men with small deficits in FEV1. For medium deficits the increases ranged from 1.5% to 2%, depending on age. A similar pattern was seen for large deficits, but with smaller increases.

CONCLUSIONS

In the unlikely event of continuous exposure at the proposed new maximum respirable dust limit for British mines of 3 mg/m3 (ISO-CEN measurement convention) for a working lifetime, the risk of a medium deficit of FEV1 for a non-smoker at age 60 would be estimated to be 34%, compared with 25% for zero dust exposure; for smokers, about 54% compared with 44%.

Respiratory disease in aggregate quarry workers related to risk factors and Pi phenotype

OBJECTIVE

To evaluate the respiratory health and its relationship with exposure to silica, smoking, alpha 1-antitrypsin, and Pi phenotype in aggregate quarries workers.

METHODS

In a prevalence study, 378 subjects were studied, x-ray opacities and pulmonary function was analyzed in relation to cumulative dust exposure, smoking, alpha1- antitrypsin, and Pi phenotype.

RESULTS

The adjusted odds ratio (OR) of round opacities (> or =0/1) was significantly related to smoking (P <0.001). The predicted forced expiratory volume in 1 second (FEV1) percentage had a negative relationship with the product dust. pack-years (P = 0.005). The OR of FEV1 <90% was 3.03 for smokers exposed to dust versus nonexposed nonsmokers (P = 0.049). The criteria for dust-tobacco interaction are satisfied. A subgroup with the highest level of alpha1-antitrypsin presented more opacities and worse pulmonary function.

CONCLUSIONS

Radiologic alterations are found in relation to tobacco. The FEV1 has a negative relation with the product dust-tobacco. No alterations related to Pi phenotype are found. A subgroup with the highest alpha1-antitrypsin levels had more radiologic alterations and worse function.

Update on respiratory disease from coal mine and silica dust

Coal mine and silica dust cause significant respiratory disease in spite of modern dust control regulations. Susceptible individuals in exposed populations may develop fibrosing lung disease, obstructive airways disease, including chronic bronchitis and emphysema, or lung cancer. A careful occupational history that elicits exposure to respiratory hazards is the cornerstone of an accurate diagnosis. Treatment involves removal from exposure, supportive care, pulmonary rehabilitation, and when disabling disease is present, assistance obtaining compensation.

Characterisation of airborne particles collected within and proximal to an opencast coalmine: South Wales, U.K

Airborne particulate matter has been collected from within, and proximal to, an opencast coal mine in south Wales. This work forms the first part of a three year project to collect and characterise, then determine the possible toxicology of airborne particles in the south Wales region. High-resolution Field Emission SEM has shown that the coal mine dusts consist largely of an assemblage of mineral grains and vehicle exhaust particles. SEM-EDX has shown that the mineralogical make-up of the PM10 is complex, heterogeneous, and constantly changing. These findings are supported by analytical TEM-EPXMA. However, patterns can be determined relating the mineralogical composition of the airborne particles to collection locations and mining activities within the opencast. At our study opencast, Park Slip West, quartz, which has known health effects, never exceeded 30% of the total collection mass, and average levels were much less. Vehicle exhaust emissions was the largest source in terms of particle numbers. The mass of airborne particulate matter within the pit averaged approximately twice that of outside the pit: importantly however, this higher mass was due to relatively large, and non-respirable, mineral grains. This study demonstrates that the physicochemical and mineralogical characterisation of airborne particles from mining and quarrying is essential to quantify the respirable fraction, and to identify potentially hazardous components within the PM10.