Lonia Maclean

Follow-up study of 232 patients with occupational asthma caused by western red cedar (Thuja plicata).

A total of 232 patients with red cedar asthma diagnosed by inhalation provocation tests were observed an average of 4 years after the initial diagnosis. The status during the follow-up examination was as follows: 96 patients continued to work with red cedar, and 136 left the industry and had no further exposure to red cedar in their jobs or hobbies. Of the 136 patients who left the industry, only 55 (40.4%) recovered completely, whereas the remaining 81 (59.6%) continued to experience attacks of asthma of varying severity. The initial pulmonary function tests were significantly higher among the asymptomatic group compared to the symptomatic group (FEV1 99.3 +/- 2.7% versus 90.5 +/- 2.2% predicted, respectively). Methacholine PC20 during the initial examination was higher among the asymptomatic group than in the symptomatic group (1.46 +/- 3.96 mg/ml versus 0.77 +/- 4.52 mg/ml, respectively). These findings indicate that the patients in the asymptomatic group were diagnosed at an earlier stage of the disease. This observation was confirmed by the significantly shorter duration of symptoms before diagnosis among the asymptomatic patients compared to the symptomatic patients (1.6 +/- 1.9 versus 2.6 +/- 4.3 years). Race, smoking status, immediate skin reactivity, and presence of plicatic acid-specific IgE antibodies did not influence the outcome of these patients. Of the 96 patients who continued to work with red cedar, 47 were exposed daily, whereas 41 were exposed intermittently.(ABSTRACT TRUNCATED AT 250 WORDS)

A Follow-up Study of the Grain Elevator Workers in the Port of Vancouver

Abstract A second respiratory survey was conducted on 587 grain elevator workers in the Port of Vancouver and on 111 civic workers, 25 years after the first health survey. The prevalence of respiratory symptoms and lung function findings among grain elevator workers in the second survey were almost identical with those in the first health survey, even though the dust concentration was lower in the elevators during the second survey. The longitudinal study in 396 grain workers showed that the prevalence of respiratory symptoms increased slightly during the second health survey among workers who had the same smoking habits during both surveys. Of the smokers who had respiratory symptoms or lung function impair-ment in the first survey, 23.5% followed our advice and gave up smoking; the prevalence of cough and sputum pro-duction decreased among these workers. The annual decline in function was greater for grain workers than civic workers particularly among workes over the age of 50 years when the differences...

Comparison of cellular and protein changes in bronchial lavage fluid of symptomatic and asymptomatic patients with red cedar asthma on follow‐up examination

Seventeen patients with occupational asthma due to western red cedar had bronchial lavage during follow‐up examination after removal from exposure for at least 1 year. Seven patients were asymptomatic while ten continued to have symptoms of asthma requiring treatment. Symptomatic patients had evidence of airway inflammation, as reflected by a significantly higher total cell count, neutrophils and eosinophils, as well as an increase in protein and albumin in their bronchial lavage fluid compared to those without symptoms. Asymptomatic patients had no evidence of airway inflammation in the lavage fluid. There was no correlation between the degree of non‐specific bronchial hyperresponsiveness and the number or percentage of inflammatory cells to suggest that cellular infiltration is the sole cause of persistent bronchial hyperresponsiveness.

Respiratory health at a pulpmill in British Columbia

The respiratory parameters of 392 white male pulpmill workers were measured by standardized procedures and compared with those of 310 white male rail yard workers. The pulpmill workers complained more frequently of wheezing and chest tightness and missed work more commonly because of chest illness as compared with the rail yard workers. Significant airflow obstruction was noted in nonsmokers who worked in the bleach plant, and it was most striking in the younger members of this group. The principal environmental contaminant in this area was chlorine at levels generally below current permissible concentrations. Members of the maintenance group--especially older members--demonstrated significantly lower forced vital capacity compared to the rail yard workers.