Occupational exposure to asthmagens and adult onset wheeze and lung function in people who did not have childhood wheeze: A 50-year cohort study

Abstract

Background:  There are few prospective studies that relate the development of adult respiratory disease with exposure to occupational asthmagens.  Objective:  To evaluate the risk of adult onset wheeze (AOW) and obstructive lung function associated with occupational exposures over 50 years.  Methods:  A population-based randomly selected cohort of children who had not had asthma or wheezing illness, recruited in 1964 at age 10-15 years, was followed-up in 1989, 1995, 2001 and 2014 by spirometry and respiratory questionnaire. Occupational histories were obtained in 2014 and occupational exposures determined with an asthma-specific job exposure matrix. The risk of AOW and lung function impairment was analysed in subjects without childhood wheeze using logistic regression and linear mixed effects models.  Results:  All 237 subjects (mean age: 61 years, 47% male, 52% ever smoked) who took part in the 2014 follow-up had completed spirometry. Among those who did not have childhood wheeze, spirometry was measured in 93 subjects in 1989, in 312 in 1995 and in 270 subjects in 2001 follow-up. For longitudinal analysis of changes in FEV1 between 1989 and 2014 spirometry records were available on 191 subjects at three time points and on 45 subjects at two time points, with a total number of 663 records. AOW and FEV1 < LLN were associated with occupational exposure to food-related asthmagens (adjusted odds ratios (adjORs) 95% CI: 2.7 [1.4, 5.1] and 2.9 [1.1, 7.7]) and biocides/fungicides (adjOR 95% CI: 1.8 [1.1, 3.1] and 3.4 [1.1, 10.8]), with evident dose-response effect (p-trends < 0.05). Exposure to food-related asthmagens was also associated with reduced FEV1, FVC and FEF25-75% (adjusted regression coefficients 95% CI: -7.2 [-12.0, -2.4], -6.2 [-10.9, -1.4], and -13.3[-23.4, -3.3]). Exposure to wood dust was independently associated with AOW, obstructive lung function and reduced FEF25-75%. Excess FEV1 decline of 6-8ml/year was observed with occupational exposure to any asthmagen, biocides/fungicides and food-related asthmagens (p < 0.05).  Conclusions:  This longitudinal study confirmed previous findings of increased risks of adult onset wheezing illness with occupational exposure to specific asthmagens. A novel finding was the identification of food-related asthmagens and biocides/fungicides as potential new occupational risk factors for lung function impairment in adults without childhood wheeze.