Hohenstein Institute uses genuine dust mite excrement for the first time to test allergen resistance of mattress covers – seams and zips are the weak points - New quality label "House dust and mites barrier" will help consumers and retailers

BOENNIGHEIM (dh) Special mattress covers called encasings are intended to provide relief for people who are allergic to dust mites. They are used to prevent contact with the allergens and, ideally, their surface construction (sometimes a laminate) forms a physical barrier between the dust mite excrement and the human respiratory system. The technical challenge for producers is to design the structure of the woven fabric and the bond in the laminate in such a way that it remains sufficiently resistant to dust mite excrement even as people turn over in their sleep. Scientific studies do show that the number of allergens can be reduced by putting an encasing over the mattress (Tereehorst et al.. N Engl J Med. 2003 Jul 17;349(3):237-46.), but nonetheless, depending on the quality of the cover, a sufficient volume of excrement to cause an allergic reaction escapes and is inhaled by the person sleeping in the bed - and this has health consequences.

In Germany, 4.5 million people now suffer from an allergy to house dust. The main cause of this allergy is the house dust mite, a small arachnid found mainly in mattresses but also in bedding, carpets, upholstered furniture and other textile surfaces. 66% of all the dust mites in the home are to be found in beds. However, it is not the mites themselves but their tiny balls of excrement which contain the main allergens. When it dries, the fresh excrement, measuring just 40µm, breaks down into lots of even smaller particles which are then dislodged from the mattress by movements during sleep, and can be inhaled via the respiratory system. For millions of people in Germany, this makes every night an ordeal as they suffer from a runny nose, shortness of breath or asthma.

The various barrier properties of encasings against dust mite excrement have been confirmed by recent tests carried out in the specialist Hygiene, Environment & Medicine department of the Hohenstein Institute in Bönnigheim, where the encasings currently available on the market have been tested using a new and realistic test method. The encasing test simulates the movements of a sleeper in all phases of their night-time sleep. The scientists are even using genuine dust mite excrement from specially bred dust mites in the test for allergen-resistance, instead of using the synthetic particles that are normally used but can only simulate the larger particles of excrement. All parts of the encasing, i.e. the flat surface, the seams and the zip were impregnated with real dust mite excrement and then the movements of a sleeping person were simulated for 8 hours. The scientists measured the number of particles of the dust mite excrement allergen "Der P1" which were of the critical size to penetrate through the structure of the fabric during the test. The interesting feature of the test is the use of the actual allergy trigger, dust mite excrement. This, together with the way the experiment is set up, means that it can be established accurately for the first time whether the so-called sensitisation threshold of 2µg of allergen is exceeded during a single night. This threshold set by doctors indicates the level of allergens at which the majority of allergy-sufferers start to react with typical allergic symptoms like a runny nose, streaming eyes, asthma. "Many of the encasings perform really well, but on some it is the zip and the seams that are still the weak points. These weaknesses did not show up with synthetic particles, but only with the significantly smaller fragments of genuine dust mite excrement," said Prof. Dirk Höfer of the Hohenstein Institute. "We are now able to draw up a definite list ranking the mattress covers that are currently available on the market in terms of their barrier performance."

From now on, the scientists will be endorsing the materials they have tested with a new quality label: "Tested quality – house dust and mite barrier. Only those encasings will be given the label which receive a mark proving that they keep the dust mite allergen "Der P1" away from the sleeping person so effectively that the sensitisation threshold is not reached during any phase of their sleep. This will provide allergy-sufferers with a reliable aid to decision-making when they are selecting a medically-tested mattress cover. The hospitality industry, for example modern hotel businesses, will also now be able to tell their customers that they use allergy-proof bedding which has passed a realistic and effective test.

Background:
Dealing with questions relating to allergies and textiles is an important focus area for the department of Hygiene, Environment & Medicine at the Hohenstein Institute. The scientists have already succeeded in developing a dust-mite-free mattress. During that project, a mattress was developed in which a heatable knitted fabric is used to create an environment inside the mattress that is permanently hostile to dust mites, and this largely eliminates them.
An environment hostile to dust mites is achieved when the hygrothermal target values of a temperature of 55° C and humidity of less than 40% are guaranteed in all parts of the mattress. Current findings suggest that it is quite enough to activate the flexible textile heating mat that is built into the mattress for about an hour two to three times a week. These heating mats are designed so that, at a low voltage of 24 volts, they can produce very high temperatures in a very short time, without generating any additional electromagnetic fields (electrosmog). Dangerous electric shocks are also prevented. Since the temperature to which it is heated can be controlled, the mattress is a useful alternative to an electric blanket in winter, and so may also be of interest to non-allergy-sufferers. The "Allergomed" mattress is sold by the bed company Gailing & Co through specialist retailers.