Abstract:

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. To date, however, no studies have been performed on nasal aspiration of allergen particles directly off textile surfaces or from hand to nose transfer. If the hypothesis of allergen inhalation from direct contact with surfaces can be supported then future studies to evaluate factors that affect respiratory uptake of allergen from surfaces would be warranted.

Short ragweed pollen (20 mm diameter) was used as a surrogate for dust mite allergen exposure because of its ease of radiolabelling and similar aerodynamic and physiological properties to the dust mite fecal particle. Pillows and a section of linoleum (followed by a hand press) were embedded with 99MTechnetium 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. 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 13–39% of the total activity localized in the pharyngeal region. 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.