Occupational lung disease. 95/5
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Introduction
For many years, there has been interest in work as a potential
cause of ill health, especially as occupational diseases are often
preventable. In particular, respiratory diseases may be caused
by a wide range of dusts, gases and fumes. However, effective
prevention of work-related diseases relies on information about
exposure to possible causal agents. In 1989, a scheme was set
up with the participation of members of the British Thoracic Society
and the Society of Occupational Medicine for the voluntary reporting
of new cases of occupational respiratory illness. This has become
known as the SWORD project (Surveillance
of Work Related and Occupational Respiratory Disease). This
factsheet about occupational respiratory disease summarises some
of the data collected by the project. The reporting system is
described in the footnote.
Diseases
Figure 1:Proportion of reported cases
in main diagnostic categories
This shows the proportion of new cases of occupational respiratory
disease in the main diagnostic categories from 1990 to mid-1995
(1989 is omitted as inhalation accidents and benign pleural disease
were not included then). Asbestos-related disease represented
half of all cases reported by the chest physicians. The majority
of reports from occupational physicians were for asthma and inhalation
accidents. Occupational lung cancer was thought to be seriously
under-reported. During this period, chest physicians reported
over twice as many cases as occupational physicians. From 1992
onwards, the reporting system for chest physicians changed - some
continue to report new cases monthly, and the remainder report
for one month a year chosen at random (see footnote). The estimated
total of new cases seen by chest physicians is 13,609.
Causal agents
Figure 2: Suspected causes of acute
respiratory disease
Figure 2 shows the distribution of suspected causal agents for
selected acute respiratory diseases reported to the surveillance
of work related and occupational respiratory disease in 1989-91.
Organic materials such as hay, laboratory animals, proteins and
flour accounted for over 60% of cases of allergic alveolitis and
a quarter of asthma cases. Chemical agents were cited for 36%
of asthma cases and 65% of inhalation accidents. Welding fumes,
included in the miscellaneous category, was the agent most frequently
reported for bronchitis (47%).
For long-latency diseases, asbestos was the most common suspected
cause - 78% of all cases, including nearly all malignant and non-malignant
pleural disease. Of the pneumoconiosis cases, 49% were attributed
to agents other than asbestos, including silica (22%) and coal
(20%).
Occupations of reported cases
Figure 3:Occupations of cases of acute
respiratory disease
This shows the distribution of occupation group for acute respiratory
disease. Almost half the cases of allergic alveolitis were among
farm workers, and 60% of the cases of occupational bronchitis
were in metal and electrical processor workers. More than half
the asthma and inhalation accident cases were experienced by material
processors, including metal and electrical processors.
Figure 4:Occupations of cases of long
latency respiratory disease
The distribution of occupation group for occupational respiratory
diseases of long latency is shown here. Shipyard workers and engineers
(including insulation workers) were the groups most represented
in mesothelioma. In contrast, benign pleural disease showed a
greater pre-dominance of construction workers and engineers, with
a lower proportion of shipyard workers, although the attributed
agent was the same for both diseases.
Incidence rates by occupation
Annual incidence rates for selected occupational groups are shown
in Figure 5. These take into account the size of the workforce
employed in different occupations as reported by the 1989 and
1990 Labour Force Surveys. For the acute diseases, the highest
rates occurred among spray painters and chemical processors (756
and 728 per million workers per year, respectively). Most of the
illness among spray painters was due to asthma; among the chemical
processors, there was an equal split between asthma and inhalation
accidents. For diseases of long latency, the highest rates were
experienced by shipyard and dock workers, mainly due to mesothelioma
and benign pleural disease.
Footnote
The SWORD reporting system
The SWORD system is based on the regular reporting of new cases
of respiratory illness, believed to be due to occupational or
work-related exposure. The participating physicians are sent reporting
cards to be filled in and returned, asking for information on
diagnosis (twelve categories), age, sex, place of residence, type
of work and suspected agent. In 1992, a system of sampling was
introduced for the chest physicians: a core group continue to
report monthly, and the remainder are divided into twelve groups
which report for one month a year each. The occupational physicians
continue to report monthly, quarterly, bi-annually or annually.
The estimated number of new cases each year is then calculated
based on the sampling system. There are currently about 800 chest
and occupational physicians participating in the scheme.
Reference
Meredith SK, Mcdonald JC. Occupational
Medicine 1994; 44:183-89
We are grateful to the SWORD project, in particular Dr David
Ross, for help and advice in preparing this factsheet.
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