House-dust mites and their allergen are widely recognised as a key contributor to the onset of asthmatic attacks, rhinitis and atopic dermatitis. Studies have shown that sheepskins used for bedding provide an ideal habitat for the accumulation of house-dust mite populations and allergen, and hence may provide a significant risk factor for people who suffer from House-dust mite allergy.
House-dust mites are those species of the family Pyroglyphidae that are regularly found throughout the world – Dermatophagoides pteronyssinus, Dermatophagoides farinae and Euroqlyphus maynei. These species constitute 90-100% of the mite population found in mattresses and 70-90% found in carpets and furniture dust.
Over two million Australians suffer from asthma.
Dust mites are a major cause of asthma and allergies.
Mould and animals are also common allergens.
Sheepskins and wool pile underlays are commonly used for both residential and medical bedding because of their superior comfort and cushioning attributes. Whilst medical sheepskins are manufactured such that they are able to be washed at a temperature of 80ºC, well over the 55ºC required to kill dust mites, manufacturers recommend that domestic sheepskins and wool underlays be washed at luke-warm temperatures (35-45°C). This will remove the majority of allergen present, but is unlikely to kill mites.
One approach to overcoming this shortfall is to introduce an acaricide as a wash additive or in a detergent to increase mite mortality during washing. A number of products, which are claimed to do so, are currently on the market. However these products contain Benzyl Benzoate, which is a chemical pesticide and therefore not as appealing to the consumer as a washing product containing an essential oil.
Tests carried out by Lindy G McDonald BSc(Hons) & Euan Tovey PhD demonstrated the effectiveness of Benzyl Benzoate and some essential plant oils as laundry additives for killing house dust mite. These tests showed Benzyl Benzoate killed all the mites and the essential plant oils killed 80% of the dust mites. However the concentration of the acaricide was relatively high at 250ml per 30lt water and the wash time 30 minutes. In real terms these concentrations would prove to be relatively expensive and the odour very concentrated. The relatively long wash time would not be ideal for fibres such as wool and sheepskin. Washing at high temperature above 55°C will kill house-dust mite however some fibres shrink or are damaged at these temperatures.
For more information on House Dustmite go to House Dustmite Information Website.
Page last updated: 29 Apr 2009