Epidemiology and Pulmonary Response To Organic Dust Exposure

Sponsor
National Heart, Lung, and Blood Institute (NHLBI) (NIH)
Overall Status
Completed
CT.gov ID
NCT00005288
Collaborator
(none)
59

Study Details

Study Description

Brief Summary

To characterize the nature of pulmonary responses to organic dust exposures in order to gain insight into patterns of respiratory disease in agricultural workers.

Condition or Disease Intervention/Treatment Phase

    Detailed Description

    BACKGROUND:

    In 1986 when the study began, agriculture was one of the largest employers in the United States, comprising nearly 12 million people. Farm workers were hospitalized more frequently than other occupational groups and were found to have the highest number of restricted activity days due to injury and illness. Much of this was due to frequent and disabling farm related accidents which made agriculture the most hazardous occupation in the United States. Agricultural workers were also found to have high rates of respiratory disability, compared with other industrial sectors, based on Social Security disability records.

    The common denominator for respiratory disorders among agricultural workers was exposure to organic dust which was recognized to be a complex mixture of vegetable particles and fragments, microorganisms and their products, insects and insect fragments, feed additives including fish meal and antibiotics, and avian and rodent proteins. While the vegetable dust itself was by far the most important exposure, individual circumstances of growing, storage and subsequent use of the product from which the organic dust arose, influenced specific exposures. In certain situations, like animal confinement housing, irritant gases including ammonia and hydrogen sulfide co-existed with an organic dust to further vary respiratory exposure.

    Workers exposed in Iowa swine production units were known to be significantly exposed to grain dust, endotoxin, animal danders and other proteins, ammonia and hydrogen sulfide gas, and a variety of microorganisms including fungi and thermophilic actinomycetes. Cross-sectional epidemiological surveys had documented a high prevalence of respiratory symptoms including chronic cough, phlegm and wheezing, but also prominent constitutional symptoms including fever, myalgias and malaise. This study was one of several projects supported by a Specialized Center of Research in Occupational and Immunologic Lung Disease.

    Funding represents approximately 35 percent of the dollars of the Specialized Center of Research in Occupational and Immunologic Lung Disease (P50HL37121) used to support epidemiologic studies.

    DESIGN NARRATIVE:

    A nested case-control study was carried out on a previously studied cohort. Members of the cohort were resurveyed in the first year of the study. All participants received a routine physical examination, chest x-ray, electrocardiogram if over 40 years of age, routine laboratory tests, methacholine challenge, intradermal skin testing, and bronchoalveolar lavage. Cases for the swine confinement farmer cohort were selected if they had FEF50 of 60 percent or less of predicted for age, sex, height, and race. Three referents for each case were randomly selected from all swine confinement farmers not selected as cases, non-confinement farmers, and blue collar workers. Measurements were repeated in the fourth year, finishing in the fifth year of the study. The study determined: the extent to which epidemiological studies underestimated pulmonary responses and impairments among agricultural workers; the environmental risk factors significantly related to cases; whether atopy and heightened airway reactivity were significantly associated risk factors. The subproject was not renewed in 1992.

    The study completion date listed in this record was obtained from the "End Date" entered in the old format Protocol Registration and Results System (PRS).

    Study Design

    Study Type:
    Observational
    Study Start Date :
    Dec 1, 1986
    Actual Study Completion Date :
    Nov 1, 1991

    Outcome Measures

    Primary Outcome Measures

      Eligibility Criteria

      Criteria

      Ages Eligible for Study:
      N/A to 100 Years
      Sexes Eligible for Study:
      Male
      Accepts Healthy Volunteers:
      No

      No eligibility criteria

      Contacts and Locations

      Locations

      No locations specified.

      Sponsors and Collaborators

      • National Heart, Lung, and Blood Institute (NHLBI)

      Investigators

      None specified.

      Study Documents (Full-Text)

      None provided.

      More Information

      Publications

      Responsible Party:
      , ,
      ClinicalTrials.gov Identifier:
      NCT00005288
      Other Study ID Numbers:
      • 2009
      First Posted:
      May 26, 2000
      Last Update Posted:
      Jan 16, 2017
      Last Verified:
      Apr 1, 2001

      Study Results

      No Results Posted as of Jan 16, 2017