Occupational exposure to soy increases asthma risk
MedWire News: Occupational exposure to soy and soy dust is associated with an increased risk for work-related asthma and respiratory symptoms, results from a US study show.
Kristin Cummings (Centers for Disease Control and Prevention, Morgantown, West Virginia) and team explain: “Processed soybeans are the largest source of protein feed and the second largest source of vegetable oil in the world. Over the next decade, global soybean trade is projected to rise 3.5% annually. Thus, understanding the possible occupational risks of soy processing is imperative.”
The researchers therefore studied the risk for asthma and respiratory symptoms among 147 employees from a soy factory in Tennessee.
All the participants were interviewed about respiratory symptoms, asthma diagnosis, smoking history, employment history, workplace exposure to mold, and demographics. They also underwent lung function tests, skin prick allergen tests, and supplied blood samples for analysis of soy-specific immunoglobulin (Ig)E, and soy-specific IgG.
The prevalence of respiratory problems among the workers were compared with reference rates for the US adult population obtained from the Third National Health and Nutrition Examination Survey (NHANES III), while soy-specific IgE and soy-specific IgG values were compared with those from a control population of healthcare workers.
The researchers found that the prevalence rates for wheeze, sinusitis, ever-asthma, and current asthma were 2.1, 2.0, 1.8, and 1.7 times higher, respectively, in the soy plant workers than in the adult US population.
Soy plant workers also had significantly higher mean levels of soy-specific IgG (97.9 vs 1.5 mg/l) and a greater prevalence of soy-specific IgE (21% vs 4%) compared with controls.
Workers with soy-specific IgE were three times more likely to have current asthma or asthma-like symptoms, and six times more likely to have work-related asthma-like symptoms than those without soy-specific IgE.
Work-related respiratory symptoms and airway obstruction rates were significantly higher in production workers who were exposed to high levels of soy dust than in support workers who were exposed to relatively low levels of soy dust.
The researchers also note in the European Respiratory Journal that work-related sinusitis, nasal allergies, and rash were associated with exposure to workplace mold, but not with exposure to soy dust.
Cummings and team conclude: “In this study, workers at a soy processing plant had higher than expected prevalence of self-reported respiratory problems, including asthma.”
“Asthma and symptoms of asthma, but not other respiratory problems, were associated with immune reactivity to soy.”
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By Mark Cowen