Case Studies

Chemical treatment of carpets to reduce allergen: A detailed study of the effects of tannic acid on indoor allergens

Journal of Allergy and Clinical Immunology, Vol. 94, Issue 1, p19–26, Published in issue: July, 1994

Judith A. Woodfolk, MB, ChB  •  Mary L. Hayden, RN  •  Jeffrey D. Miller, MD  •  Gail Rose, BS  •  Martin D. Chapman, PhD  •  Thomas A.E. Platts-Mills, MD, PhD


Tannic acid (TA), a protein-denaturing agent, has been reported to reduce allergen levels in house dust and is marketed for that purpose as 1% and 3% solutions. We investigated the effects of TA on dust allergens by using monoclonal antibody-based ELISAs for mite (Der p I, Der f I, and group II) and cat (Fel d I) allergens. Initial studies confirmed that TA reduced allergen levels in carpet dust. However, when dust samples from treated carpets are extracted in saline solution, residual TA redissolves and may interfere with the assessment of allergens. In the laboratory, concentrations of TA as low as 0.1% inhibited the assays, but this effect may be prevented by addition of 5% bovine serum albumin (BSA). After treatment of dust samples in the laboratory with 3% TA, the apparent reductions in Der p I and Der f I levels were 89% and 96%, respectively, but when the samples were extracted in 5% BSA the reductions were 74% and 92%. Similar effects were seen with dust samples from carpets treated with TA. In an extreme case in which a carpet had been repeatedly treated with TA, the apparent concentration of Der p I was < 0.05 μg/gm without BSA and 2.1 and 8.4 μg/gm when extracted in the presence of 1% and 5% BSA, respectively. Our testing of the ability of TA to denature Fel d I demonstrated an 80% reduction in allergen, but only in samples with an initial concentration of less than 200 μg Fel d I/gm dust. In samples with high levels of Fel d I (≈1 mg/gm) TA had little effect. The interpretation of this was that Fel d I itself could block the effects of TA. In keeping with this, Fel d I inhibited the effect of TA on Der p I. The results confirmed the profound denaturing effects of TA, but demonstrated that high levels of protein blocked the effect of TA on dust allergens. In addition, without added protein, residual TA in dust samples could interfere with the assay of allergens in vitro. (J ALLERGY CLIN IMMUNOL 1994;94:19-26.)

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Cat antigen in homes with and without cats may induce allergic symptoms

Journal of Allergy and Clinical Immunology, Vol. 97, Issue 4, p907–914, Published in issue: April, 1996

Mary Elizabeth Bollinger  •  Peyton A. Eggleston  •  Elizabeth Flanagan  •  Robert A. Wood


Although Fel d 1, the major cat allergen, has been found in settled dust samples from homes both with and without cats, the clinical relevance of this allergen has never been studied. In this study we measured airborne concentrations of Fel d 1 in homes both with and without cats and then attempted to relate these levels to those obtained in our experimental cat challenge model to assess their clinical significance. In baseline samples we found measurable levels of airborne Fel d 1 in all 37 homes with cats (range, 1.8 to 578 ng/m3; median, 45.9 ng/m3) and in 10 of the 40 homes without cats (for detectable samples: range, 2.8 to 88.5 ng/m3; median, 17 ng/m3). Fel d 1 was present in the settled dust of 38 of 40 homes without cats (range, 39 to 3750 ng/gm; median, 258 ng/gm), although these levels were only weakly predictive of airborne levels. Repeat samples obtained weekly from 12 homes without cats yielded measurable airborne Fel d 1 in at least one of the four samples from all homes. When compared with challenges performed in our cat room facility at low levels of airborne Fel d 1 (<500 ng/m3), these home levels are within the range capable of causing upper and lower respiratory symptoms in subjects allergic to cats. We therefore conclude that the low level cat exposure that occurs in many homes without cats is capable of inducing symptoms in some patients who are sensitive to cats. The assessment of cat exposure should not be based solely on the presence or absence of a cat in the home.

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Domestic control of house dust mite allergen in children’s beds

Journal of Allergy and Clinical Immunology, Vol. 105, Issue 6, Part 1, p1130–1133, Published in issue: June, 2000

Carl H. Vanlaar  •  Jennifer K. Peat  •  Guy B. Marks  •  Janet Rimmer  •  Euan R. Tovey


Background: House dust mite allergen levels in humid coastal regions of Australia are high, particularly in beds. Because high allergen levels in beds are associated with more severe asthma, reduction of levels may be important for asthma control. Objective: We tested the effectiveness of an acaricidal treatment of bedding in combination with occlusive mattress and pillow encasings in reducing allergen levels in children’s beds in a community setting. Methods: A total of 14 beds of children were selected for the active intervention. In each home the bed of a sibling of nearest age was selected as the control. Dust was vacuumed from beds by using a standard protocol, and Der p 1 levels were measured by using ELISA. Adjacent settling dust was collected by using opened Petri dishes. The intervention consisted of encasing mattresses and pillows in occlusive covers and washing all bedding with Acaril, an acaricidal additive. The acaricidal wash was repeated twice in 7 households at 2-month intervals. Control beds were not treated. Results: The mean Der p 1 concentration at baseline was 27.9 μg/g in the active beds and 18.1 μg/g in the control beds. At 4 days after intervention, Der p 1 decreased to 3.2 μg/g and 15.7 μg/g in active and control beds, respectively. The average difference (active minus control) over the first 8-week cycle was 78.5% (P < .0001), and the difference over 3 washing cycles was 125.1% (P < .05). The mean rate of settling Der p 1 adjacent to the actively treated beds decreased from 24.4 ng·m–2·d–1 at baseline to 10.0 ng·m–2·d–1 after intervention (P < .01). Conclusion: A substantial reduction in Der p 1 levels in beds and in airborne dust in a humid region with naturally high house dust mite allergen levels can be achieved and sustained in a community setting with use of occlusive covers and a rigorous washing routine. (J Allergy Clin Immunol 2000;105: 1130-3.)

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Exposure to mite and cat allergens on a range of clothing items at home and the transfer of cat allergen in the workplace

Journal of Allergy and Clinical Immunology, Vol. 106, Issue 5, p874–879, Published in issue: November, 2000

Sandra D. De Lucca  •  Timothy J. O’Meara  •  Euan R. Tovey


Background: Clothing has been proposed as an additional source of exposure to mite and cat allergens. Dispersal of allergen into public places has also been attributed to clothing. Objectives: We sought to study the contribution of various types of clothing on mite and cat exposure in a domestic environment. Also, we studied the ability of clothing to transfer allergen in a workplace. Methods: Personal exposure to mite and cat allergen from a range of clothing was measured by using intranasal air samplers in 11 homes. Five categories of clothing were tested. Wearing no upper clothing was the sixth category tested to distinguish the contribution of clothing over ambient background exposure. An adhesive tape was used to sample allergen from the surface of clothing, and reservoir dust samples were also collected. The above techniques were also used in the workplace to examine the amount of cat allergen transferred from cat owners to non-cat owners. Results: The amount of mite and cat allergen inhaled differed among the clothing types worn and whether they had been washed recently. Wearing a woolen sweater increased personal allergen exposure to cat and mite allergen by a mean of 11 and 10 times, respectively. Clothing items that were less frequently washed carried more allergen whether assessed by vacuuming or sampled with adhesive tape. This corresponded to the amount of allergen inhaled. We also found that cat levels on non-cat owners’ clothing increased significantly at the end of a working day, which lead to the increase in their personal allergen exposure to cat. Conclusions: These studies strongly support the emerging model that personal clothing is an important source of both mite and cat allergen exposure. This article also demonstrates the importance of clothing as a means of distributing cat allergen into cat-free environments. (J Allergy Clin Immunol 2000;106:874-9.)

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Airborne dust and allergen generation during dusting with and without spray polish

Journal of Allergy and Clinical Immunology, Vol. 109, Issue 1, p63–67, Published in issue: January, 2002

Karen L. Jerrim  •  Lindsey F. Whitmore  •  John F. Hughes  •  Malcolm T. McKechnie


Background: Dusting is a commonly used method for dust removal from surfaces in the home. However, the process of dusting may contribute to airborne dust levels by disturbing dust particles from a surface and failing to remove it from the indoor environment. Objective: We sought to measure the quantity of allergen-laden dust disturbed into the air during dusting and discover whether applying spray polish to either the dusty surface or the cleaning cloth reduced this amount. Methods: A common furniture polish was tested for its ability to prevent dust particles and major house dust mite (Der p 1) or major cat (Fel d 1) allergen from becoming airborne during dusting. Tests were completed with a repeatable mechanized dusting procedure with polish sprayed onto either a cleaning cloth or directly onto a surface, and this was compared with a control procedure with a standard duster. Airborne dust was measured with an air-particle counter and by means of anti-Der p 1 or anti-Fel d 1 ELISA. Results: Considerable quantities of dust became airborne during dusting. When polish was sprayed onto the cleaning cloth, the concentration of airborne dust particles was reduced by a mean of 83.4%, house dust mite allergen by 50.3%, and cat allergen by 57.4% when compared with dry-cloth controls. Spraying polish directly onto the surface was even more effective at reducing the generation of airborne particles (92.9%) and allergens (Der p 1 by ≥95% to below the sensitivity of the ELISA and Fel d 1 by 95%). All reductions were significant when compared with dry-cloth controls (P < .01, Mann-Whitney U test). Conclusions: This study showed that application of a polish spray to either the surface or the cloth during dusting greatly reduced dust and allergen evolution into the air, which should reduce exposure to airborne allergens in the home. (J Allergy Clin Immunol 2002;109:63-7.)

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Methods and effectiveness of environmental control

Journal of Allergy and Clinical Immunology, Vol. 103, Issue 2, p179–191, Published in issue: February, 1999

Euan Tovey  •  Guy Marks


In recent years the role of allergen exposure and atopy, and the interaction between them in the clinical expression of allergic disease, has been examined in a quantitative manner in epidemiologic studies. Such analyses suggest that avoidance of exposure to domestic allergens is a critical element in integrated strategies for both the prevention and the management of asthma. The promise of primary intervention in high-risk infants, as shown in the Isle of White study, has been confirmed in a recent study in Japan, and at least 4 similar trials are in progress. Applying these principles to the management of symptoms in patients with chronic asthma has proved more difficult, and it is likely that many earlier studies were poorly designed to test the hypothesis that allergen avoidance was clinically useful. Recent studies with patients moved to high altitudes during seasonal reductions in mite exposure and randomized controlled interventions in houses have all shown improvements in clinical manifestations of asthma. These recent trials have also demonstrated something that was less certain—that massive reductions in domestic allergen exposure can be achieved and that people will adopt the significant changes to their domestic environment and lifestyles if the risks and benefits are known. In the future, it seems likely that better study designs, as well as improvements in methods to monitor exposure and clinical outcomes, will provide further support for the role of allergen avoidance in the prevention and management of asthma. (J Allergy Clin Immunol 1999;103:179-91.)

The role of intervention in established allergy: Avoidance of indoor allergens in the treatment of chronic allergic disease

Journal of Allergy and Clinical Immunology, Vol. 106, Issue 5, p787–804, Published in issue: November, 2000

Thomas A.E. Platts-Mills  •  John W. Vaughan  •  Melody C. Carter  •  Judith A. Woodfolk


Avoidance of exposure to indoor allergens is an important element in the treatment of allergic disease. The results of several studies provide strong evidence in support of a role for allergen avoidance; however, strategies that optimize allergen reduction in houses have not been determined. Complex issues regarding the efficacy of physical and chemical measures that target house dust mite, pet, and cockroach allergens in the home are discussed. The greatest challenge is to educate allergic patients so that they can play an important role in controlling their own disease. (J Allergy Clin Immunol 2000;106:787-804.)