Occupational Exposure and 25-Year Incidence Rate of Non-Specific Lung Disease: The Zutphen Study

Abstract

Information gathered in the Zutphen Study, the Dutch contribution to the Seven Countries Study that started in the 1960s, was used for the present study. In 1960 878 men participated in the physical examination and they were followed for 25 years until 1 July 1985. During this follow-up, their morbidity status was verified regularly. With this information the occurrence of chronic non-specific lung disease (CNSLD) at a specific time was coded by one physician, using strict criteria. The CNSLD diagnosis was based on the following criteria: episodes of respiratory symptoms such as regular cough and phlegm for longer than three months or episodes of wheezing and shortness of breath reported to the survey physician, or: diagnosis of CNSLD, including chronic bronchitis or emphysema by a clinical specialist. Occupation in 1960 was coded and used to generate specific occupational exposures with a Job Exposure Matrix. Because the exact time of diagnosis of CNSLD was known, incidence densities could be calculated. For 804 men a complete set of data was available. A Poisson regression analysis was used to analyse the relationships between the incidence density and independent variables like age, calendar period, occupation and specific occupational exposures. Blue collar workers had a significantly elevated incidence density ratio (IDR) compared to white collar workers (1.82, 95% confidence limits (CL): 1.35, 2.46). Subgroups of blue collar workers, wood and paper workers, textile workers, and tailors, construction workers and transport workers had significantly elevated IDRs also. Of the specific exposures heavy metals, mineral dust and adhesives had a significantly elevated IDR.(ABSTRACT TRUNCATED AT 250 WORDS)

Performance of odds ratios obtained with a job-exposure matrix and individual exposure assessment with special reference to misclassification errors

“…Our results concern job-exposure matrices whose entries are probabilities of exposure, thought to be more informative than dichotomic (6), and which are now being developed and used to analyze the results of epidemiologic studies (13)(14)(15)(16). In using such matrices the most commonly used statistical method of analysis of the data is as follows.…”

Respiratory symptoms and intensity of occupational dust exposure

“…Studies conducted in other community-based groups have also noted an association between occupational dust exposure and respiratory symptoms (8,(18)(19)(20)(21)(22)(23)25,32). Unlike the present study, only a few studies had sufficient information to address the question of an exposureresponse relationship and one other study compared current to past exposures.…”

“…Results in studies with occupational histories assessed prior to the ascertainment of respiratory symptoms or obtained by a review of job histories (18,21,22,24) are not subject to this bias. These studies have similar results compared to studies where measures of selfreport were used to assess exposure as in the current study (19,20,23,25).…”

“…Self-report of dust exposure was based on simple categories. Many large cohort studies have used a more detailed questionnaire or structured interview to obtain job and exposure history (18,20,22,25) together with an expert assessment (21,24). The method used in the current study could potentially lead to an underreporting of exposure.…”

“…Specifically, exposure to inorganic dusts such as those found in the coal (1)(2)(3)(4), gold (5,6), and hard rock (7) mining industries, or to organic dusts such as found in cotton processing (8)(9)(10)(11) or associated with various farm related and agricultural jobs (12)(13)(14)(15)(16)(17) may result in an excess of these symptoms. General population surveys conducted in six US cities (18), Europe (8,(19)(20)(21)(22)(23)(24), and China (25) found elevated risks of respiratory symptoms attributable to occupational dust exposure. In veterans treated at US Department of Veterans Affairs (DVA) Medical Centers, potentially significant occupational exposures have been noted (26,27), but the relationship between occupational exposures and respiratory health has not been assessed in this population.…”