Allergen exposure, atopy and smoking as determinants of allergy to rats in a cohort of laboratory employees

Abstract

This study aimed to examine the relationship between exposure to rat urinary allergens, atopic status, smoking and the development of allergic symptoms and specific sensitization.It is a case-referent analysis of a cohort of 342 newly employed laboratory animal workers. Cases comprised persons developing symptoms of laboratory animal allergy or a positive skin prick test to rat urinary allergens; each was matched with up to two asymptomatic referents. Subjects were assigned to categories of exposure based on measurements of airborne rat urinary allergens.Of the cases, 80% reported that their symptoms started within 2 yrs of employment. The odds ratio (OR) for development of each symptom type (respiratory, eye or nose and skin) and of an immediate skin test reaction was increased in those with direct contact with rats. A gradient of increasing OR for the development of any such symptom across exposure categories was found; for respiratory symptoms and skin test reactions the OR for subjects in the highest exposure category were lower than those in intermediate categories, a pattern attenuated when the analysis was confined to outcomes developing within 2 yrs of first exposure. Atopy increased the OR of most outcomes as did cigarette smoking, although there was no evidence of a relationship between smoking and the development of a specific skin test reaction.In conclusion, allergen exposure was confirmed as the most important determinant of laboratory animal allergy; by implication, measures to reduce exposure may be the most effective means to reduce its incidence. Eur Respir J 1999; 13: 1139±1143. Allergy to inhalable, animal-derived proteins is a common occupational health problem among employees working with small laboratory animals. In a prospective study of new staff at a large toxicological laboratory with several animal species, the incidence of clinically-diagnosed laboratory-animal allergy in the first year was 9% and that of specific immunoglobulin (Ig)E development~22% [1].Figures from the surveillance of work-related and occupational respiratory disease (SWORD) national surveillance scheme indicate that laboratory animal proteins are the commonest high molecular weight cause of occupational asthma seen by chest and occupational physicians in the UK [2]; the annual incidence of new cases of laboratory animal asthma in the UK, estimated from the same source, is at least 188 per million exposed employees [3].With the development of immunoassays [4] it has become possible to measure directly the relationship between intensity of exposure to airborne animal allergens and sensitization and allergic disease. This relationship has been studied in a cohort with occupational exposure to laboratory rats; in a previous report of the initial, cross-sectional phase [5] weak associations between allergic symptoms and rat urinary aeroallergen exposure, modified by atopic status were described. The present study describes the findings of a full longitudinal study, analysed using a nested case-referent approa...

Host determinants for the development of allergy in apprentices exposed to laboratory animals

“…Eur Respir J 2002; 19: 96-103 Exposure to laboratory animal-derived allergens carries a significant risk for immunoglobulin (Ig)-Emediated sensitization and development of oculonasal and respiratory symptoms as well as occupational rhinoconjunctivitis (RC) and asthma (OA) [1]. In a prospective assessment of 342 laboratory-animal workers, CULLINAN et al [2] found that 46 (13%) developed skin reactivity to rat urine over a 3.5-yr period. In a prospective study of 417 apprentices starting exposure to laboratory animals and seen for a 32-to 44-month period, 85 (20%) incident cases of sensitization to at least one laboratory-animal-derived allergen were identified [3].…”

Have the prevalence and incidence of occupational asthma and rhinitis because of laboratory animals declined in the last 25 years?

“…In all other cross-sectional studies all workers who were exposed to LA were recruited. In the four longitudinal studies it was not possible to show a reduction of incidence over time also because in three, study years were overlapping (Table 2) (24)(25)(26)(27). Only a strong negative cohort effect seemed to emerge in one study, as incidences of OA and OR was inversely correlated with follow-up duration and age (25).…”

“…Between 1983 and 2005 four longitudinal studies evaluated OR and/or OA in workers exposed to LA, allowing incidence estimates (Table 2) (23)(24)(25)(26)(27). Two publications were treated as a single study because the reported analysis came from the same cohort of animal health apprentices (26,27).…”

“…The incidence of symptoms of OA and OR/100 person years was 2.0 and 10.1, respectively; it was 1.4 and 4.7/100 person years, respectively, based on symptoms and positive serum IgE to LA (Table 2). Cullinan et al (24) studied a cohort of 342 employed workers with a participation rate >80%. Prior exposure to laboratory rats ranged from 1 month to 4 years.…”

“…To investigate trends in the prevalence and incidence of OA and OR over time, we reviewed the available published literature for both (8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27).…”