Occupational endotoxin exposure in association with atopic sensitization and respiratory health in adults:Results of a 5-year follow-up

<div><p>The objective of the present longitudinal study was to investigate the effects of occupational endotoxin exposure on respiratory health and atopic sensitization in adults. Health outcomes and personal endotoxin exposure estimates were determined for 234 farmers and agricultural workers both at baseline and 5 years later. A questionnaire was used to assess respiratory symptoms, spirometry tests were performed and total and specific IgE levels were measured in serum.</p><p>A twofold increase in personal endotoxin exposure was associated with less hay fever (OR 0.68, 95%CI 0.54-0.87) and grass IgE positivity (OR 0.81, 95%CI 0.68-0.97) at both time points (“persistent” versus “never”). Although not statistically significant, a consistent protective pattern was observed for an increased loss of hay fever symptoms (OR 2.19, 95%CI 0.96-4.99) and grass IgE positivity (OR 1.24, 95%CI 0.76-2.02), and for less new-onset of hay fever (OR 0.87, 95%CI 0.65-1.17), grass IgE positivity (OR 0.83, 95%CI 0.61-1.12) and atopic sensitization (OR 0.75, 95%CI 0.55-1.02). Endotoxin exposure was not associated with changes in lung function.</p><p>We showed that occupational endotoxin exposure is associated with a long-term protective effect on hay fever and grass IgE positivity. Results on longitudinal changes in hay fever, atopy and grass IgE positivity in adulthood were consistent with a protective effect of endotoxin exposure, but results need to be confirmed in larger cohorts. An effect of endotoxin exposure on lung function decline was not found.</p></div

Changes in reported health symptoms and IgE positivity between baseline and follow-up.

<p>Participants are categorized as never (absent at baseline and follow-up), new onset (negative at baseline and positive at follow up), loss (positive at baseline and negative at follow up) and persistent (positive both at baseline and follow up) health symptoms.</p

General characteristics of the study population at baseline and follow-up.

<p>Differences between baseline and follow-up are tested for statistical differences: paired t-test for continuous variables, McNemar’s paired chi squared test for binary outcomes. The number of persons included in each analysis depends on the source of the outcome data: questionnaire (n = 234), lung function (n = 161), or serological data (n = 212).</p

General characteristics of the study population at baseline and follow-up.

<p>Differences between baseline and follow-up are tested for statistical differences: paired t-test for continuous variables, McNemar’s paired chi squared test for binary outcomes. The number of persons included in each analysis depends on the source of the outcome data: questionnaire (n = 234), lung function (n = 161), or serological data (n = 212).</p

Odds of loss, new onset and persistence of allergic outcomes during follow-up in association with endotoxin exposure.

<p>Analyses are adjusted for potential confounders (age, gender, smoking and farm childhood). A consistent protective pattern is observed for hay fever, grass IgE sensitization and atopy, although not all associations meet statistical significance.</p