Types of ILD
In 2000 in Europe, it was estimated that a total of 7200 cases of pneumoconiosis were related to occupational exposures to asbestos, silica and coal dust.
Silicosis should be a disease of the past, and it has indeed become relatively uncommon in industrialised countries thanks to dust control in the workplace. However, hazardous exposures to free crystalline silica (quartz or cristobalite) may still occur in the following areas: mining, tunnel drilling or stone quarrying; processing stone or sand; building and demolition; foundries; pottery or ceramic manufacture; the abrasive use of sand (sandblasting); the manipulation of calcined diatomaceous earth; as well as other, sometimes unexpected, settings. A tragic recent example was seen in Turkey, where hundreds of young workers contracted silicosis as a result of sandblasting denim jeans.
Small workshops represent a particular risk and in countries where occupational standards are not adequately enforced, the risk of silicosis is still significant. The construction industry also requires specific attention because there are indications that silicosis has re-emerged in this industry since the introduction of mechanical hand tools, which have resulted in high dust and silica exposures.
It is important to appreciate that silicosis is also associated with other conditions such as COPD, TB, lung cancer and systemic sclerosis.
Coal worker’s pneumoconiosis
In many European countries, thousands of coal miners have developed more or less advanced degrees of coal worker’s pneumoconiosis. In some countries, this disease is labelled and registered in official statistics as (anthraco) silicosis. Although substantial silica exposure may occur in underground mines, coal worker’s pneumoconiosis differs from silicosis. Incidence has declined in recent decades and complicated coal worker’s pneumoconiosis (or progressive massive fibrosis) should become a rarity, at least in western European countries.
Asbestosis (pulmonary fibrosis caused by asbestos) has become uncommon. It is generally found in patients who were heavily exposed to asbestos in the past – during the manufacture of asbestos-cement products, friction materials or fireproof textiles, or when using asbestos for heat insulation or fire protection purposes in construction, heating systems, power stations, furnaces, shipyards and railroads, etc. The incidence of asbestosis will continue to decrease in countries in which asbestos use has been forbidden. Nevertheless, the risk of asbestosis will remain for those engaged in asbestos removal and waste handling, as well as in developing countries where the use of asbestos is still allowed and is poorly regulated.
A realistic target for labour and health authorities should be to aim for a decrease in the incidence of silicosis, coal worker’s pneumoconiosis and asbestosis, until their complete disappearance in all European countries. This should be achievable by appropriate occupational legislation, rigorous enforcement of dust-control measures and adequate medical surveillance.
Berylliosis, hard metal lung disease and other metal-related disorders
Lung disease caused by sensitisation to beryllium (i.e. chronic beryllium disease, or berylliosis) is clinically and pathologically similar to sarcoidosis. Exposure to beryllium is not frequent, but this light metal is increasingly used in modern technology. In a series of 84 patients with suspected sarcoidosis from Germany and Israel, a diagnosis of chronic beryllium disease was made in 34 subjects.
Hard metal lung disease
Hard metal lung disease is caused in susceptible individuals by a reaction to cobalt, which is a constituent of hard metal. In its most typical presentation, the disease is characterised by giant cell interstitial pneumonia. Interestingly, the same disease occurred among Belgian diamond polishers after the introduction of polishing disks made of diamond–cobalt. Hard metal lung disease is uncommon, but cases have been described in small workshops where hard metal or diamond–cobalt tools are manufactured or sharpened. Cobalt is also a possible cause of occupational asthma, which may coexist with interstitial lung disease.
Other metal-related disorders
Many other metals have been associated with interstitial lung disease, which sometimes masquerades as sarcoidosis. However, the epidemiology of these rare conditions is rather poorly understood.
More effort should be made at a European level to recognise, register and prevent these conditions.
Extrinsic allergic alveolitis (see chapter 22)
Occupational causes of EAA are quite diverse. The more common aetiological agents are organic dusts, originating from microorganisms (farmer’s lung, humidifier lung) or from birds (pigeon breeder’s lung, bird fancier’s lung). However, it should be considered that there is potential for EAA in all environments in which bio-aerosols may be inhaled. These include mushroom farms, composting installations, wood processing, vegetable stores and machining shops (through the use of machining fluids). Some chemicals, most notably isocyanates, may also cause the condition.
Occupational EAA has been most frequently studied in farmers, and is caused by sensitisation to (thermophilic) microorganisms that grow in hay or other organic substrates. The frequency of farmer’s lung varies considerably geographically, depending on climate and farming practices, and the causative antigens also differ between regions. It is most frequent in the cold, humid climates of northern Europe or in mountainous areas, such as the Doubs in France. Reported prevalence figures vary between 10 and 200 cases per 100 000 inhabitants, and 4 to 170 per 1000 farmers, depending on area and diagnostic criteria. Yearly incidences have been estimated to be 2–6 cases per 1000 farmers in Sweden and 5 per 1000 farmers in Finland in the 1980s. These figures may be underestimates because of diagnostic problems and the use of hospital data.
Outbreaks of EAA have also been described among workers exposed to metal working (or machining) fluids, e.g. in the manufacture of car engines. The exact causative agent cannot always be identified but mycobacteria have been implicated.
Other occupational ILDs
In the 1990s, outbreaks of ILD caused by synthetic agents demonstrated that novel causes of occupational disease can still emerge. The most spectacular outbreak was Ardystil syndrome, a severe form of organising pneumonia in textile workers that was caused by aerosolised paints. Another outbreak was caused by the inhalation of nylon microfibres in nylon flock workers. These outbreaks should serve as reminders that workers should never be exposed to aerosolised compounds unless appropriate inhalation testing has shown that this can be done safely.
Prevention is particularly relevant to the new ‘nano-materials’ (including carbon nanotubes, insoluble metallic agents, polymers or composites) that are being increasingly produced for various applications. Although no overt pulmonary or other disease has hitherto been attributed convincingly to occupational (or other) exposure to engineered nano-materials, many properties of these materials (including their intended chemical activity), as well as some experimental studies in vitro and in laboratory animals, are a cause of justified concern for human health in case of exposure. This is an important responsibility for occupational legislation at a European level.