Evidence of large particle allergen inhalation from contact with surfaces

Background: To establish a more accurate relationship between dust mite allergen on surfaces such as bedding with respiratory uptake, an exposure method is needed which correlates exposure of allergen on surfaces with respiratory dose. Objectives: Assess if aerodynamically large allergen particles (> 10 μm), similar in nature to dust mite allergen, is inhaled into the nose from direct head-and-hand contact with allergen contaminated surfaces. Methods: Short ragweed pollen (20-μm diameter) was used as a surrogate for dust mite allergen exposure because of its similar aerodynamic and physiologic properties. Pillows and a section of linoleum (followed by a hand press) were embedded with (99M)Technetium labeled pollen. Particles on the linoleum were transferred to the sampler after a hand press to the surface. Simulated human exposure was performed by surface-sampling particles, at a capture velocity of the nose, onto a filter. Human evaluation of hand transfer to the nose or direct inhalation from a pillow was performed with three subjects. Percentage respiratory uptake and deposition location was determined by gamma camera imaging. Results: Simulated respiratory uptake of pollen by hand-to-nose transfer and directly off pillows was 20% and 1.4%, respectively. Human subject respiratory 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 respiratory tract from direct contact with allergen-containing surfaces.