Human hair is a potential source of cat allergen contamination of ambient air.

BACKGROUND: We have previously shown that airborne cat allergen levels are significantly lower in school classes using special school clothing or in classes with no pet owners. However, cat allergen is present and the levels are in fact two- to threefold higher on cat owners' than noncat owners' school clothing which is used, washed and stored at school only. This suggests that allergen is transferred to schools by routes other than clothing. AIM: To analyse levels of cat allergen (Fel d 1) in hair from cat owners and noncat owners among children and adults. METHODS: Samples of unwashed hair (> or =1 day prior to sampling) from adults and children with (n = 22) or without (n = 22) cats at home were collected at a hairdresser. In addition, samples of newly washed hair (adults only, n = 11) were collected. The hair sample was extracted and analysed for Fel d 1 content with ELISA. RESULTS: The geometric mean levels were more than two orders of magnitude higher in unwashed hair from cat owners, compared with noncat owners (P < 0.0001) and more than 10-fold higher in newly washed hair from adults. The allergen contamination of unwashed hair among noncat owners appeared higher in children than in adults (P = 0.045). CONCLUSIONS: Hair may be an important source for transfer and deposition of cat allergen in schools and may explain why cat allergen is found in environments with strict allergen avoidance measures. Although it may be unrealistic to apply allergen avoidance strategies against this allergen source, it is important to be aware of it.

Allergen avoidance does not alter airborne cat allergen levels in classrooms.

BACKGROUND: Some schools in Sweden offer allergen avoidance classrooms for allergic children with severe asthma. However, the measures commonly used to achieve a reduction in allergen levels have not been properly evaluated. The aim of the present prospective study was to study whether the levels of airborne cat allergen are altered after introducing feasible intervention measures in classrooms, without interfering with peoples' freedom of choice regarding pet ownership. METHODS: Twenty-five classes, including five established allergy prevention classrooms participated in the study during a school year. After one term, six classes underwent a number of intervention measures recommended by the Swedish National Institute of Public Health. Curtains, upholstery and plants were removed, bookshelves were replaced with cupboards and regular cleaning was increased. Airborne dust was collected weekly (32 weeks) using duplicate Petri dishes (n = 1574) and on six occasions using two personal air samplers in each class (n = 264). RESULTS: Airborne cat allergen levels were showing a similar variability throughout the whole study in all classes. Despite extensive measures in order to reduce allergen exposure, cat allergen levels were unaltered in the six classes after intervention. Allergen levels were not significantly lower in the established allergy prevention classes, compared with the other classes. Cat allergen levels differed, however, significantly between classes with few and many cat owners (P < 0.05). CONCLUSIONS: We conclude that the recommended allergen avoidance measures used in this study did not reduce airborne cat allergen. It seems plausible that measures that fail to reduce allergen levels also fail to influence health status in allergic children but this remains to be shown.

Evaluation of Petri dish sampling for assessment of cat allergen in airborne dust.

BACKGROUND: Dust reservoir sampling is the most commonly used method for assessment of indirect allergen exposure. Because assessment of personal exposure using person-carried pumps is time-consuming and expensive we evaluated the Petri dish sampling method for measurement of airborne cat allergen in classrooms. METHODS: Petri dish sampling was evaluated in three study parts. Part I: by comparison between Petri dish sampling and personal air sampling in 44 classrooms with many (> or = 20%) and few (< or = 10%) cat owners and by additional Petri dish sampling in 40 pet-free homes. Part II: by sampling with duplicate Petri dishes in 28 classrooms. Part III: by sampling in three classrooms at four sampling heights during different sampling times. All samples were analyzed for cat allergen (Fel d 1) content with a monoclonal antibody two-site ELISA (enzyme linked immunosorbent assay), using signal amplification when necessary. RESULTS: There was a significant correlation between Petri dish sampling and personal air sampling (r = 0.66; P < 0.0001). Levels were five-fold higher in classes with many cat owners than in classes with few cat owners, regardless of method. A corresponding difference was found in the homes. Duplicate sample values were in fair agreement (Bland-Altman test) and were correlated (r = 0.77; P < 0.0001). Cumulative levels collected weekly in one Petri dish were lower than using five daily Petri dishes, regardless of sampling height. CONCLUSIONS: Petri dish sampling can be useful as an alternative method to personal air sampling of airborne allergens.

Nasal air sampling used for the assessment of occupational allergen exposure and the efficacy of respiratory protection.

BACKGROUND: Occupational exposure to rodent allergens may cause laboratory animal allergy. Personal exposure to occupational allergens is measured by collecting airborne dust on filters using person-carried pumps. This technique cannot be used to evaluate personal protective respiratory equipment. Recently developed intranasal air samplers collect inhaled particles by impaction on adhesive strips within the samplers. OBJECTIVE: The aims were to compare rodent aeroallergen exposure assessment using nasal air samplers with personal air sampling, and to evaluate the efficacy of using respiratory protection during rodent work using nasal air samplers. METHODS: Aeroallergen exposure was assessed during rodent work using both nasal air samplers and personal air samplers. The efficacy of respiratory protection (P2 facemasks and fresh-air helmets) was studied in subject pairs working side by side, one person with protection, the other without. Right nostril samples were laminated with protein-binding membrane and immunostained for rat urinary allergen-containing particles. Left nostril samples and air samples were eluted in buffer and analysed in amplified ELISAs for rat (RUA) and mouse (MUA) urinary allergen content (detection limit 10 pg/mL). Allergen collection efficacy of the nasal air samplers was tested at high and low exposure levels and at different flow rates using static sampling. RESULTS: P2 facemasks decreased the amount of inhaled allergen by about 90%, and verylittle allergen was inhaled using fresh-air helmets. Allergen levels in air and nasal samples correlated well (r(s) was about 0.8 for both RUA and MUA). The number of RUA-positive particles and nasal allergen levels measured in ELISA also correlated significantly (r(s) = 0.8). Collection efficacy of the nasal air sampler was better during high exposure (cleaning cages, median 73% of allergenic particles collected), than during low exposure (undisturbed room, 49% of particles). CONCLUSION: Nasal air sampling is a relevant and sensitive complement to personal air sampling and enables evaluation of personal respiratory protection equipment. Use of P2 facemasks and fresh-air helmets may substantially reduce occupational exposure to inhaled allergens.

Comparison of four allergen-sampling methods in conventional and allergy prevention classrooms.

BACKGROUND: Several allergen-sampling methods are used to assess level of personal or indirect exposure to cat in homes, schools and other public buildings and working environments. OBJECTIVE: To compare four different allergen-sampling methods (dust collectors, Petri dishes, person-carried pumps and intranasal samplers) by simultaneous sampling in classrooms and to compare the cat allergen levels between conventional classrooms and allergy prevention classrooms. Another aim was to relate the results to self-reported frequency of allergy and asthma symptoms among the children, to their perception of the school environment. METHODS: Among all compulsory schools (n = 257) in the Stockholm suburban area, 35 classrooms (five with implemented allergy prevention measures, seven with additional cleaning and 23 with normal cleaning routines) were chosen for allergen-sampling. Dust collectors (two models), Petri dishes, person-carried pumps and intranasal samplers were used simultaneously. All children (n = 829) received a self-administered questionnaire which included questions about home and school environment, allergic disease, asthma symptoms and pet contact. RESULTS: The correlation between sampling methods was generally poor.Furthermore, there was no significant difference in allergen levels between allergy prevention and allergen avoidance classes compared to conventional classes. Median levels were generally, but not significantly, lower in classes with few cat owners, compared to classes with many cat owners. Children in allergy prevention classes were more satisfied with the indoor air quality and cleaning than children attending classes with fewer or no allergy prevention measures (P < 0.0001). Nine per cent of all children reported allergic symptoms while at school. CONCLUSION: The lack of correlation between sampling methods used simultaneously demonstrates the difficulty in assessing allergen levels in schools and similar environments. The implemented intervention measures (allergy prevention/allergen avoidance) did not influence cat allergen levels at school.

Working with male rodents may increase risk of allergy to laboratory animals.

BACKGROUND: Our aim was to study the risk of laboratory animal allergy (LAA) among research staff working in laboratories separate from the animal confinement area. The roles of atopy and exposure intensity in LAA were studied with special regard to exposure to male rodents, who excrete higher levels of urinary allergens than female rodents. METHODS: Eighty rodent-exposed subjects gave blood samples for the analysis of total IgE, Phadiatop, and specific IgE against rat (RUA) and mouse urinary allergens (MUA), and answered questionnaires. Air samples were collected for RUA and MUA aeroallergen measurement in both laboratories and animal confinement facilities. RESULTS: Twenty percent of the subjects had IgE >0.35 kU/l to RUA and/or MUA, and 32% had experienced animal work-related symptoms, although 90% of aeroallergen samples from the research department laboratories were below the detection limit (<0.26 ng RUA per m(3) and <0.8 ng MUA per m(3)). Atopy (positive Phadiatop), total IgE >100 kU/l, other allergies (especially to other animals), or more than 4 years of exposure significantly increased laboratory animal sensitization and symptoms. Working with mainly male rodents gave odds ratios (95% CI) of 3.8 (0.97-15) for sensitization and 4.4 (1.4-14) for symptoms. Subjects with both exposure to mainly male rodents and atopy or elevated total IgE had a 10-fold higher frequency of sensitization than exposed subjects with neither risk factor. CONCLUSION: A majority of subjects with a combination of exposure to mainly male rodents and atopy or elevated total IgE developed sensitization to and symptoms from laboratory animals. Current low exposure seems to maintain the presence of specific IgE. Further measures must be undertaken to provide a safe workplace for laboratory animal workers.

Exposure-response relationships for work-related sensitization in workers exposed to rat urinary allergens: results from a pooled study.

BACKGROUND: Recent studies in a few industries have shown that the likelihood of IgE-mediated sensitization increases with increasing exposure. The shape of the exposure-response relationships and modification by age, sex, and smoking habit has hardly been studied. OBJECTIVE: The purpose of this study was to determine exposure sensitization relationships for rat sensitization and to evaluate the influence of atopy, smoking habits, and sex. METHODS: Data from 3 cross-sectional studies in The Netherlands, the United Kingdom, and Sweden were used and involved 1062 animal laboratory workers. Selection criteria were harmonized, and this resulted in a study population of 650 animal laboratory workers (60.6% female) with less than 4 years of exposure. Air allergen levels were assessed previously and converted on the basis of an interlaboratory allergen analysis comparison. Available sera were analyzed for the presence of specific antibodies against common allergens (house dust mite, cat, dog, and grass and birch pollen) and work-related allergens (rat and mouse urinary proteins). Questionnaire items on work-related respiratory symptoms, hours worked with rats per week, job performed, smoking habits, and sex were used in this analysis RESULTS: The prevalence of work-related sensitization to rat urinary allergens (IgE >0.7 KU/L) was 9.7 % (n = 63). Thirty-six of the sensitized workers had work-related symptoms (asthma or rhinitis). Two hundred forty-eight workers (38.2%) were atopic (defined as specific IgE to 1 of the common allergens). The sensitization rate increased with increasing air allergen exposure. Atopic workers exposed to low levels of allergen had a more than 3-fold increased sensitization risk compared with nonexposed atopic workers. For atopic subjects, the risk increased little with increasing exposure, whereas for nonatopic subjects, a steadily increasing risk was observed. Smoking and sex did not modify the sensitization risk. CONCLUSION: Rat urinary allergen-sensitization risk increased with increasing exposure intensity. Workers who were atopic had a clearly elevated sensitization risk at low allergen exposure levels.