13 November 2017

What we don’t know about lung hazards

Public Health Respiratory

Poor data collection about occupational lung disease in Australia is hobbling efforts to head off new hazards as they arise. 

A narrative review published in the MJA asks GPs to be vigilant to sniff out work-related factors in lung disease through thorough history-taking, suggesting a set of questions to ask patients presenting with respiratory problems. 

Identifying an occupational cause for lung disease requires doctors to maintain a high level of suspicion, according to the review by respiratory physicians Dr Ryan Hoy, of Monash University, and Associate Professor Fraser Brims of Curtin University.

“Apart from the Australian Mesothelioma Registry, there is minimal systematic collection of data regarding occupational lung diseases in Australia,” they write.

“Current knowledge in Australia is based largely on extrapolation from overseas data and local epidemiological research, rather than monitoring of actual cases. This lack of efficient access to data on the distribution of diseases by occupations and exposures severely impairs development of targeted preventive interventions.” 

Reported workers’ compensation data is of limited help, as the statistics underestimate the number of cases “by at least a factor of 10 for some conditions” and fail to capture a sizeable proportion of workers.

According to international estimates, about 15% of adult-onset asthma, 15% of chronic obstructive pulmonary disease and 10% to 30% of lung cancer may be attributable to hazardous occupational exposures, the authors report. 

Jobs associated with COPD include smelter workers, machine operators, cleaners, coalminers, construction workers and bus drivers. Occupational and environmental factors should be investigated, particularly when COPD occurs in a patient who has never smoked. 

The authors say there is a pressing need to gather systematic data on the causes, prevalence, incidence and impact of occupational lung diseases, such as through a national register. 

The first case was confirmed only recently of an Australian worker with complicated silicosis associated with the cutting of artificial stone used in kitchen benchtops. In Israel, where artificial stone has been used for decades, the product is linked to 40 cases of silicosis per year. 

In the food industry, a cluster of obliterative bronchiolitis among workers at a US popcorn factory in 2000 was traced to the use of the volatile butter-flavouring agent, diacetyl. The rare condition, now known as popcorn-workers lung, was also found in workers producing chocolate, cereal and other foods.

Occupational interstitial lung diseases include hypersensitivity pneumonitis linked to bacteria (farmers, swimming pool workers); fungi (cheese makers, tobacco growers); animal proteins (bird breeders, textile workers); and low molecular weight chemicals (dental technicians, plastic industry workers). Among textile workers, disease can follow exposure to acramin and flock.  

In a separate MJA review, Professor Bill Musk of Sir Charles Gairdner Hospital in Perth, writes that Australia’s rates of mesothelioma have only just peaked and will probably remain high for decades owing to the long latency between exposure to asbestos fibres and onset. 

Australia has one of the world’s highest rates of malignant mesothelioma, as a result of asbestos mining and the widespread use of asbestos in building materials during the 20th century. 

Almost all the asbestos remaining in Australian homes and the environment is a mixture of fibre types, which vary widely in potency for causing malignant mesothelioma.  Crocidolite (blue asbestos) is five times as potent as amosite (brown asbestos), which is 10 times as potent as chrysotile (white asbestos).

“It is therefore not possible to draw general conclusions about the exact nature of ongoing exposure to asbestos in Australia today,” Professor Musk writes. 

“Individuals with a history of minor exposure, such as during small renovations at home, should be reassured that their risks are immeasurably low, and advised to avoid further exposure to asbestos and tobacco smoking.” 

MJA 2017; online 13 November