Evidence of large particle allergen inhalation from contact with surfaces

Background: To establish a more accurate relationship between dust mite all ergen on surfaces such as bedding with respiratory uptake, an exposure meth od is needed which correlates exposure of allergen on surfaces with respira tory dose. Objectives: Assess if aerodynamically large allergen particles (>10 mu m), similar in nature to dust mite allergen, is inhaled into the nose from dire ct head-and-hand contact with allergen contaminated surfaces. Methods: Short ragweed pollen (20-mu m diameter) was used as a surrogate fo r dust mite allergen exposure because of its similar aerodynamic and physio logic properties. Pillows and a section of linoleum (followed by a hand pre ss) were embedded with (99M)Technetium labeled pollen. Particles on the lin oleum were transferred to the sampler after a hand press to the surface. Si mulated human exposure was performed by surface-sampling particles, at a ca pture velocity of the nose, onto a filter. Human evaluation of hand transfe r to the nose or direct inhalation from a pillow was performed with three s ubjects. Percentage respiratory uptake and deposition location was determin ed by gamma camera imaging. Results: Simulated respiratory uptake of pollen by hand-to-nose transfer an d directly off pillows was 20% and 1.4%, respectively. Human subject respir atory uptake by hand-to-nose transfer and directly off pillows was 6.6% and 1.5%, respectively. Most of the regional activity was found immediately in the nasal vestibule with 13% to 39% of the total activity localized in the pharyngeal region. Conclusions: Aerodynamically large allergen particles (pollen) are inhaled and deposited into the anterior nose and pharyngeal areas of the respirator y tract from direct contact with allergen-containing surfaces.