Laboratory animal workers are at high risk of developing occupational allergy. Little is known about the relationship between levels of exposure and the risk of developing laboratory animal allergy. A cross-sectional study was performed in 540 workers at eight facilities to quantify the exposure-response relationship for allergy to rats, while controlling for determinants like atopy, gender, and smoking. All participants completed a questionnaire, underwent skin prick testing with common and occupational allergens, and total IgE as well as occupational allergen-specific IgE antibodies were serologically measured. Personal air dust samples were taken during full-shift periods to estimate the rat urinary aeroallergen exposure levels. In the whole study population no clear exposure-response relationship was observed. However, in the group of workers with less than 4 yr of working experience with laboratory animals the prevalence rate of sensitization to rat allergens was clearly associated with exposure levels. The exposure-response relationship was steepest for workers with atopy-associated risk factors, i.e., self-reported allergy or sensitization to cats or dogs, or elevated total serum IgE. The prevalence rates of sensitization to rat allergens for these workers were about 15, 9.5, and 7.3 times higher in the high, medium, and low exposure group, respectively, compared with internal reference group.
The influence of various filter types and extraction conditions on the quantitation of airborne endotoxin with the Limulus amebocyte lysate test was studied by using airborne dusts sampled in a potato processing plant. Samples were collected with an apparatus designed to provide parallel samples. Data from the parallelsampling experiment were statistically evaluated by using analysis of variance. In addition, the influence of storage conditions on the detectable endotoxin concentration was investigated by using commercially available lipopolysaccharides (LPS) and endotoxin-containing house dust extracts. The endotoxin extraction efficiency of 0.05% Tween 20 in pyrogen-free water was seven times higher than that of pyrogen-free water only. Two-times-greater amounts of endotoxin were extracted from glass fiber, Teflon, and polycarbonate filters than from cellulose ester filters. The temperature and shaking intensity during extraction were not related to the extraction efficiency. Repeated freeze (؊20؇C)-and-thaw cycles with commercial LPS reconstituted in pyrogenfree water had a dramatic effect on the detectable endotoxin level. A 25% loss in endotoxin activity per freeze-thaw cycle was observed. Storage of LPS samples for a period of 1 year at 7؇C had no effect on the endotoxin level. House dust extracts showed a decrease of about 20% in the endotoxin level after they had been frozen and thawed for a second time. The use of different container materials (borosilicate glass, ''soft'' glass, and polypropylene) did not result in different endotoxin levels. This study indicates that the assessment of endotoxin exposure may differ considerably between groups when different sampling, extraction, and storage procedures are employed.
Objective-Extensive IgE serology in occupational or environmental health studies is often hampered by a lack of technical facilities and finance. The use in population studies of relatively simple and inexpensive enzyme immunoassays (EIAs) was therefore evaluated for the assessment of total serum immunoglobulin E (IgE), and of specific IgE reactions with various common (house dust mites, grass and birch pollen, and cat) or occupational (fungal a-amylase and rat urinary protein) allergens. pollen, birch pollen, and cat) were remarkably high (> 80%/o-90%) in the series of 116 children's serum samples. In a population of bakery workers the specificity of the EIAs was also very high (> 90%). The sensitivity was notably lower (30°/o-70%) in this adult population, which is, however, in agreement with results reported for conventional IgE tests. Conclusion-As the costs were estimated to be at least five to 10-fold lower than those of commercial test kits, the EIAs for total and specific IgE may be very useful tools in epidemiological studies of atopic respiratory or other disorders.
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