IsIs YourYour Patient’sPatient’s WWorkplaceorkplace CausingCausing LungLung Disease?Disease? Occupational lung diseases not only have a significant health impact on the affected individual, but they often result in workplace changes and significant socio-economic impact. By Susan M.Tarlo, MB, BS, FRCPC he range and relative frequency of blasting underground. Conversely, the T occupational lung diseases has diagnosis of occupational asthma caused changed significantly in Canada over the by workplace sensitizers has risen, and past 30 years. Occupational lung diseases this is now the most common chronic that were relatively common before, such occupational lung disease in Canada.1,2 as silicosis and coal miners’ pneumoco- It is estimated that occupational asthma niosis, are now uncommon conditions in (usually due to an immunologic response Canada. Although silicosis can still be to a work agent) accounts for about 7% of caused by sandblasting and occasionally all adult-onset asthma,3 and occupational by other types of exposures, it has become factors may play a role in up to 30% of uncommon in Canadian underground min- adult asthma.4 There has been increased ers. This is due to much improved dust- recognition of the role of workplace irri- control measures, such as spraying water tants in aggravating asthma and even, at to keep dust down while drilling and times, causing asthma due to very high 74 The Canadian Journal of Diagnosis / July 2001 Lung Disease respiratory irritant exposures (termed reactive airways dysfunction syndrome [RADS], or irritant-induced asthma).5,6 Besides causing asthma in some patients, workplace respiratory irritant exposures in accidental high levels (such as nitrogen oxides from silage, or spills of chlorine in chemical plants), can also induce other acute respiratory effects in any part of the respiratory tract.7 These can include acute respiratory distress syn- drome, pneumonitis, bronchiolitis, bron- chiolitis organizing pneumonia (BOOP), bronchiectasis, bronchitis, tracheitis, laryngitis and rhinitis. Figure 1. Acute pneumonia or hypersensitivity pneumonitis? The effects are determined by several Bilateral interstitial lung disease in a worker cleaning carrots. factors, including the odor threshold, sol- ubility and hydrogen ion concentration effects. In contrast, nitrogen oxides are (pH) of the irritant, the inhaled particle odorless and poorly soluble. The effects size, the duration and concentration of the are less immediately apparent and occur exposure, and the presence or absence of mainly in the bronchoalveolar regions. underlying respiratory disease. For exam- Unless a clear exposure history is ple, ammonia has a strong odor, which obtained, the physician may find it diffi- alerts the worker to relatively low expo- cult to determine whether the indiviudal is sure conditions, and is water soluble. The suffering from the effects of an irritant or effects are, therefore, usually upper air- from coincidental non-occupational caus- way effects rather than lower airway es of respiratory disease, such as viral pneumonia or laryngitis. Another source of respiratory symp- toms in the workplace is endotoxin air- borne exposure, which can be caused by Dr. Tarlo is professor of gram-negative bacteria contaminating medicine and public health sciences, University of organic dusts on farms or in animal feed. Toronto, and respiratory Endotoxin exposure also can occur from physician, University Health Network, Gage Occupational contaminated cutting oils (i.e., metal and Environmental Health working fluids) in factories and humidi- Unit, Toronto, Ontario. fiers in buildings. This exposure can result in such flu- like symptoms as cough, chills, fever, The Canadian Journal of Diagnosis / July 2001 75 Lung Disease malaise and chest pain, which are usually such as pleural plaques, pleural calcifica- self-limited.8 Contamination of the same tion and mesothelioma, are relatively easy materials with organisms, such as fungi, to attribute correctly to asbestos exposure, can cause a similar self-limiting syn- some manifestations may mimic other drome, or may cause an immunoglobulin lung diseases, (e.g., pleural effusions, E (IgE) antibody-mediated response, lead- interstitial fibrosis and lung cancer). Lung ing to either new- cancer also can be caused by other occu- Asbestos-related onset asthma or an pational exposures, such as chromium exacerbation of pre- salts, radon, coke production, arsenic, manifestations existing asthma. IgE beryllium and nickel refining. continue to and immunoglobulin The above examples illustrate that G (IgG) antibody- occupational lung diseases may present in increase in mediated allergic many different forms beyond the more prevalence due to bronchopulmonary traditional pneumoconioses. Often now, their long latency mycoses (e.g., aller- these diseases present to physicians in gic bronchopul- ways that mimic non-occupational lung period. monary aspergillo- diseases. Without an accurate occupation- sis) also may present al history in all patients with respiratory initially as an exacerbation of asthma. disease, the correct diagnosis will easily Thermophilic actinomycetes or fungi also be missed. can cause a Type IV hypersensitivity The importance of a missed occupa- response (T-lymphocyte-mediated), tional diagnosis can have implications, resulting in hypersensitivity pneumonitis not only for the individual patient, whose (e.g., farmer’s lung), which may clinically condition may worsen if he/she continues mimic pneumonia.9 to work in the same conditions, but also True respiratory infections may have for co-workers. Medical screening of an occupational cause, such as tuberculo- other workers after diagnosis of an “index sis in health-care workers; legionnella case” may lead to earlier diagnosis and pneumonia from contaminated workplace treatment. Awareness of the “index case” humidification systems; anthrax in farm- and sending notification to the Provincial ers; and respiratory viral infections spread Ministry of Labour and/or workplace by close contact among office workers. occupational hygienist, as appropriate Asbestos-related manifestations con- with the consent of the patient, also may tinue to increase in prevalence due to their allow preventive measures to be taken in long latency period, despite the reduced the workplace. use of asbestos—especially the reduced The following cases illustrate the use of the most hazardous types of importance of thinking and asking about asbestos: crocidolite, amosite and antho- workplace exposure in all patients, but phyllite. Although most manifestations, especially in those with lung disease. 76 The Canadian Journal of Diagnosis / July 2001 Lung Disease Case 1 Recurrent viral infections, humidifier fever or mass psychogenic illness? Eight out of 40 underground nickel min- ers, seen by the same local family physi- cian, presented with recurrent cough, chest discomfort, difficulty breathing, chills and malaise. These symptoms occured within a few hours of working underground, and improved away from work within hours. No abnormalities were found on physical examination, chest radiographs or pulmonary function test- ing, although all tests were performed several hours after leaving the mine. Peak Figure 2. Sarcoidosis or berylliosis? Bilateral hilar lymphadenopathy and right lower lobe infiltrate. expiratory flow (PEF) readings were slightly reduced underground, but would ed by the miners were initially elevated, be expected to fall somewhat due to though later samples collected in a sterile underground pressure manner were normal. Mold counts under- Without an changes. Some miners ground were significantly higher than out- accurate had a mild neutrophil- door levels.10 ia on blood counts It was considered most likely that symp- occupational performed a few hours toms were due to “humidifier fever,” history of patients after mining. The min- induced by endotoxin and/or mycotoxins, or ers attributed their other fungal irritants, such as beta 1-4 glu- with respiratory symptoms to diesel cans from fungal walls. However, viral disease, the fumes underground. infections or mass psychogenic illness could Subsequent investiga- have caused symptoms in some of the min- correct diagnosis tions at the mine ers. Occupational hygiene changes in the will be missed. showed that water was mine were associated with resolution of sprayed underground symptoms. to reduce levels of silica and other dust, especially when blasting. The water had Case 2 been obtained from a tailings pond produced by damming a river. The surrounding area Pneumonia or hypersensitivity pneu- had been used as a sewage dump site, and the monitis? water was treated to kill bacteria (but this A 24-year-old-man worked for five years would not destroy endotoxin). Measured lev- in a plant where carrots and onions were els of endotoxin in the water sample collect- cleaned and packed. He was seen in the The Canadian Journal of Diagnosis / July 2001 77 Lung Disease Figure 3. Left upper lobe lung cancer, due to smoking or chromium? emergency department with a three-day history of dry cough, dyspnea and mild fever. He was found to have severe hypox- ia and bilateral infiltrates on his chest radiograph (Figure 1). He was admitted to Figure 4. Left upper lobe lung cancer, due to smoking or chromium? the intensive care unit and rapidly improved with supplemental oxygen. Five no symptoms, except when he re-visited days later, he was discharged after treat- the onion room, where symptoms would ment with