Medical scientists:Parents should chill over house dust mites

Parents wanting to help their children avoid asthma and other allergies are being told to give their toys a frosty reception by sticking them in the freezer. Medical scientists in New Zealand and Taiwan have discovered that freezing children's soft toys can kill almost all house dust mites (HDMs), the microscopic bugs associated with a range of allergies, including asthma. Other effective remedies for killing HDMs, commonly found in children's soft toys, were tumble drying and washing with eucalyptus oil and detergent, the scientists from New Zealand's University of Otago and Taiwan's Changhua Christian Hospital found. HDMs were strongly associated with the development of asthma in children, and the severity of asthma was in proportion to the number of house dust mites a child was exposed to when sleeping with soft toys, said a statement from the university Monday. "Children frequently sleep with their favorite toys close to their airways and this may be important for HDM-sensitized asthmatic children," said University of Otago Associate Professor Rob Siebers. The scientists tested the three different cleaning methods on 36 toys divided into three groups of 12. Freezing toys for at least 16 hours at minus 15 degrees centigrade resulted in a 95-percent reduction of HDMs, as did soaking in an emulsion of eucalyptus oil and liquid detergent for one hour before rinsing and drying. Hot tumble drying for one hour reduced mites by 89 percent, the study found. "Washing and soaking with eucalyptus oil and detergent is very effective in not only reducing live mites, but also reducing house dust mite allergens, compared to freezing and tumble drying," said Siebers. Ten of the 12 toys cleaned this way showed no live mites at all. Siebers said all three methods were more effective than just washing toys, because water needed to be above 55 degrees centigrade to kill HDMs, but this usually damaged the toys. "My advice for parents is to either tumble dry for one hour, or freeze the soft toy overnight, and then wash it in a cold wash to remove any allergens." Siebers said the thickness of the material used in making the toys could alter the effectiveness of the three methods. The scientists would conduct further research to determine how quickly HDMs recolonized soft toys and how often toys should be treated. The study has been published in the European journal, Paediatric Allergy and Immunology.