Airborne exposure to laboratory animal allergens: 2005-2022

Exposure to laboratory animal allergens has been a significant cause of IgE-mediated allergic symptoms and occupational asthma (OA). Mice are the predominant species used in medical and scientific facilities. We have previously published a review of our air monitoring data of mouse and rat major allergens (mus m 1 and rat n 1) expressible in ng center dot m-3 from 2005-2016. We have now reassessed all this largely United Kingdom (UK) air monitoring data from 2005-2022, which include 77% and 47% additional mouse and rat results, respectively. Where possible, we have categorized the results to specific tasks and areas to identify those associated with higher exposures and explored temporal trends in exposure together with an estimation of the annual incidence of OA in 2005 and 2018. A downward shift in mouse results for personal samples was apparent from 2014, with evidence of a decrease in the 90th percentile, but both personal and static rat samples confoundingly showed an apparent increase from 2017. Activities of "cage changing", "cage cleaning", and "cage washing, dirty side" suggested substantial personal exposures in some facilities, while "bedding dumping" and "cage scraping" suggested generally high exposures, albeit modified by any respiratory protective equipment worn. Individually ventilated cages reduce exposure, but filter changing/cleaning can still lead to high exposures. Exposure from experimental and husbandry duties were generally lower, but in some facilities activities where animals are handled outside of cages can cause significant exposures. The reduction in personal exposure to the predominant species is consistent with an estimated 55% decrease in the UK annual incidence rate of OA in 2018 from 2005. The data may help facilities to improve exposure control by identifying higher risk activities, benchmarking their own monitoring data and help further reduce the risk of sensitization and subsequent allergic respiratory ill-health.