RT Journal Article SR Electronic T1 High exposure to endotoxin in farming is associated with less new-onset pollen sensitisation JF Occupational and Environmental Medicine JO Occup Environ Med FD BMJ Publishing Group Ltd SP 139 OP 147 DO 10.1136/oemed-2017-104384 VO 75 IS 2 A1 Grethe Elholm A1 Vivi Schlünssen A1 Gert Doekes A1 Ioannis Basinas A1 Anneli Clea Skjelmose Bolund A1 Charlotte Hjort A1 Pernille Milvang Grønager A1 Øyvind Omland A1 Torben Sigsgaard YR 2018 UL http://oem.bmj.com/content/75/2/139.abstract AB Objectives Little is known about risk factors for new onset and loss of atopic sensitisation in adulthood. The aim is to examine the longitudinal effect of quantitatively assessed endotoxin exposures on changes in specific allergen sensitisation in young adults.Methods The cohort consisted of 1113 young Danish farmers and rural controls, with a mean age of 19 years at baseline. Sensitisation to birch pollen, grass pollen, cat dander and house dust mite was measured by specific IgE levels in serum samples from baseline and at 15 years’ follow-up. Changes in sensitisation were analysed in relation to cumulative endotoxin exposure during follow-up, considering early life farm exposure.Results Endotoxin exposure during follow-up was significantly associated with less new onset of specifically grass and birch pollen sensitisation. For the highest versus lowest quartile of cumulative endotoxin exposure, the OR for new-onset IgE sensitisation was 0.35 (0.13–0.91) for birch and 0.14 (0.05–0.50) for grass. On the other hand, loss of pollen sensitisation showed a positive, although mostly non-significant, association with increased levels of endotoxin exposure. Endotoxin exposure was not associated with significant changes in cat dander and house dust mite sensitisation.Conclusions High exposure to endotoxin during young adulthood appears to protect against new onset of pollen sensitisation, independent of childhood farm exposure.