Occupational Asthma Reference

Larsen AI, Johnsen CR, Frickmann J, Mikkelsen S, Incidence of respiratory sensitisation and allergy to enzymes among employees in an enzyme producing plant and the relation to exposure and host factors, Occup Environ Med, 2007;64:763-768,

Keywords: enzyme, smoking, atopy, air measurement, longitudinal study, IgE, asthma, rhinitis, urticaria

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Abstract

Objectives: Belonging to the group of high molecular weight respiratory sensitisers, microbial enzymes have been reported as a well known cause of occupational allergy, typically manifesting itself as rhinitis and/or asthma. High exposure to such high molecular weight sensitisers, and possibly also peak exposures, implies a higher risk than low exposure, but the exact relation between exposure, sensitisation and clinical allergy remains to be clarified. The authors sought to estimate the risk of respiratory enzyme allergy in an enzyme producing plant and to assess the relation between exposure indices and allergy.

Methods: Retrospective follow-up study based upon data gathered from health surveillance since 1970. 1207 employees from production and laboratories were included. The level of enzyme exposure in the relevant departments was estimated retrospectively into five exposure levels based on 10-fold increments/decrements of the threshold limit value and other exposure information. The risk was estimated in an exponential regression survival model fitted with constant intensity for subperiods of time using maximum likelihood estimation.

Results: During the first three years of a person's employment, the enzyme sensitisation and allergy incidence rates were 0.13 and 0.03 per person-year at risk, respectively. In the fitted models, exposure class did not correlate with the outcome variables. The risk of sensitisation decreased along the three decades, whereas the risk of allergy remained unchanged. The risk of sensitisation and allergy was doubled among smokers. Pre-employment atopy was only associated with sensitisation risk.

Conclusion: Sensitisation to enzymes decreased during the study period, possibly reflecting improvements in the working environment. A similar decrease could not be demonstrated for allergy to enzymes. Neither of the two outcomes correlated with exposure estimates, possibly because of the low precision of the estimates.

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Associated Questions

Registered users of this website have associated this reference with the following questions. This association is not a part of the BOHRF occupational asthma guidelines.

What is the frequency of occupational asthma?
burgeps A study of manufacturers of a mixed (and unspecified) group of enzymes studied prospectively. The incidence of sensitisation and disease was measured for the first 3 years of exposure only. The incidence for sensitisation was 0.13/person year at risk and for disease (asthma, rhinitis or urticaria) 0.03/person year at risk. There was no relationship betweem measured exposure and incidence, but incidence reduced over time (1970-2002), during which time more atopics were employed. Atopy was a risk factor for sensitisation but not disease, smoking was a risk factor for disease and sensitisation (x2). It is likely that the air measurement did not fully represent exposures, and that the initial exclusion of atopics was a confouding factor. Within the first 3 years 10-5% developed disease (decreasing over time); of those with disease 55% had asthma.
Which agents cause occupational asthma and which workers are at risk?
burgeps Manufactureres of enzymes are at risk. A study of manufacturers of a mixed (and unspecified) group of enzymes studied prospectively. The incidence of sensitisation and disease was measured for the first 3 years of exposure only. The incidence for sensitisation was 0.13/person year at risk and for disease (asthma, rhinitis or urticaria) 0.03/person year at risk. There was no relationship betweem measured exposure and incidence, but incidence reduced over time (1970-2002), during which time more atopics were employed. Atopy was a risk factor for sensitisation but not disease, smoking was a risk factor for disease and sensitisation (x2). It is likely that the air measurement did not fully represent exposures, and that the initial exclusion of atopics was a confouding factor. Within the first 3 years 10-5% developed disease (decreasing over time); of those with disease 55% had asthma.
What are the risk factors for developing occupational asthma?
burgeps Smoking increased the risk x 2, atopy increased sensitisation but not disease. No obvious relationship between measured exposure and disease, but better processes reduced incidence. A study of manufacturers of a mixed (and unspecified) group of enzymes studied prospectively. The incidence of sensitisation and disease was measured for the first 3 years of exposure only. The incidence for sensitisation was 0.13/person year at risk and for disease (asthma, rhinitis or urticaria) 0.03/person year at risk. There was no relationship betweem measured exposure and incidence, but incidence reduced over time (1970-2002), during which time more atopics were employed. Atopy was a risk factor for sensitisation but not disease, smoking was a risk factor for disease and sensitisation (x2). It is likely that the air measurement did not fully represent exposures, and that the initial exclusion of atopics was a confouding factor. Within the first 3 years 10-5% developed disease (decreasing over time); of those with disease 55% had asthma.
Is atopy a risk factor for developing occupational asthma?
burgeps Atopy a risk for sensitisation but not disease A study of manufacturers of a mixed (and unspecified) group of enzymes studied prospectively. The incidence of sensitisation and disease was measured for the first 3 years of exposure only. The incidence for sensitisation was 0.13/person year at risk and for disease (asthma, rhinitis or urticaria) 0.03/person year at risk. There was no relationship betweem measured exposure and incidence, but incidence reduced over time (1970-2002), during which time more atopics were employed. Atopy was a risk factor for sensitisation but not disease, smoking was a risk factor for disease and sensitisation (x2). It is likely that the air measurement did not fully represent exposures, and that the initial exclusion of atopics was a confouding factor. Within the first 3 years 10-5% developed disease (decreasing over time); of those with disease 55% had asthma.
Is smoking a risk factor for developing occupational asthma?
burgeps Smoking doubled the risk of disease and sensitisation A study of manufacturers of a mixed (and unspecified) group of enzymes studied prospectively. The incidence of sensitisation and disease was measured for the first 3 years of exposure only. The incidence for sensitisation was 0.13/person year at risk and for disease (asthma, rhinitis or urticaria) 0.03/person year at risk. There was no relationship betweem measured exposure and incidence, but incidence reduced over time (1970-2002), during which time more atopics were employed. Atopy was a risk factor for sensitisation but not disease, smoking was a risk factor for disease and sensitisation (x2). It is likely that the air measurement did not fully represent exposures, and that the initial exclusion of atopics was a confouding factor. Within the first 3 years 10-5% developed disease (decreasing over time); of those with disease 55% had asthma.

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