Evidence based Code of Best Practice for animal research facilities: results of the SPIRAL study

Background: In the UK c.12,000 people have occupational exposure to laboratory animals and are at risk of developing laboratory animal allergy (LAA) with potentially serious consequences. Recent changes in animal research have rendered much of the LAA literature outdated, with mice replacing rats as the main animal model and individually ventilated cages (IVC) used to reduce cross-infection and produce a controlled microenvironment in place of conventional cages (CC). Aim: To design an evidence based code of practice to reduce occurrence of LAA in contemporary animal research facilities. Methods: The SPIRAL study comprised a cross-sectional survey of 750 laboratory animal workers exposed to mice at UK research institutions and over 500 exposure measurements of Mus m 1 (mouse urinary protein), the major risk factor for LAA. Results: Prevalence of sensitisation to mice was lower in IVC units compared with CC units (2.6% vs 9.6%); some units had no recently sensitised workers. Mus m 1 levels were lower in IVC compared with CC units with both personal sampling and background monitoring but varied 8 fold between different IVC units. Certain tasks e.g. handling soiled bedding were associated with highest Mus m 1 levels. Regression analysis found around half of an individual’s Mus m 1 exposure was explained by a combination of unit, job title and tasks performed. Conclusion: LAA now appears to be preventable. Whilst IVCs are important, units should not become complacent and other factors such as strict adherence to local guidelines e.g. for use of respiratory protection for high exposure tasks, and access to a high quality occupational health service unit, are likely to be key.