[Soybean hull unloading in Tarragona (Spain) and asthma outbreak risk]

From 2007 to 2008, 215,000 tons of soybean hull were unloaded in the Port of Tarragona. Soybean hull was identified as the etiologic agent causing bronchial asthma outbreaks. The aim of the present study was to identify the characteristics of soybean unloading, soybean allergen dispersion, and the population risk.

Data on soybean hull unloading, carriage and storage, meteorological conditions and the number of emergency room admissions for asthma were recorded. Allergen concentrations were obtained by sampling PM(10) filters retaining particles of less than 10 microns for 24 hours in the atmospheric contamination surveillance stations. Sensitized patients underwent clinical examination consisting of skin prick test, total and specific IgE and immunoblotting to soybean extracts.

Allergen emissions were moderate at one kilometer from the unloading source (above 300 U/m(3) on 3 days, maximum 441 U/m(3)). The protein pattern of hull soybean extracts was similar to that found in asthma epidemics in Barcelona. Ninety-two percent of the patients were sensitized to soybean hull extracts. No asthma epidemic was detected during unloading days. In addition to the low molecular weight soybean proteins identified in previous studies (6 and 14-17 kDa), high molecular weight proteins were found (14-49 kDa).

There is allergen dispersion at a short distance from the unloading source, posing a risk to sensitized patients. Technical measures are required during soybean hull operations to reduce particle emissions.