• comparatively small quantities are highly efficient against infestation with the larvae of moths and beetles,
• safe and lasting protection of the merchandise,
• not dangerous to humans if used properly.

Having thoroughly tested the mothproofing agent, also the German "Bundes-
gesundheitsamt" ( Federal Health Office) concludes: “[…] impregnation (i.e., mothproofing) of carpets and fitted material cannot be assumed to cause a significant health risk […]. Thus, the Berlin authority shares the opinion of the World Health Organisation (WHO) and America’s Environmental Protection Agency (EPA). The latter admitted this substance in the USA recently after a very elaborate test. The Federal Institute for the Protection of Consumer Health and Veterinary Medicine (BgVV) remarks: “[…] that, given proper impregnation, present-day knowledge does not indicate that the use of such carpets or fitted material is hazardous to human health […].

In summary: Woollen carpets must be protected against insect attack in order to safeguard indoor-room hygiene and to prevent premature destruction of the material. Consumer health is not endangered by permethrin as a preventive moth- and beetle- proofing agent.

1. Preface
Some years ago, exposition of the general population to pyrethroids, be it through vermin-killing measures or through gases emanating from moth- and beetle-proofed woollen carpets or fitted woollen materials, gave rise to thorough discussions and even to legal disputes. For example, persons affected, amongst other things, complained about chronic nerve damage and a number of unspecific symptoms. As happens so often, the result in this conflict of interests was a complex mix of potentially injured persons, of insufficient scientific data and of scientific opinions.
[…] Against this background, the Federal Ministry for Education and Research (BMBF) supported a joint research project stipulating that the industry concerned should bear the same financial share. […] two studies were conducted that, for the first time, were designed to prospectively contribute in volunteers solid data covering the incorporated impairment, the connection between exposition and impairment and possible health hazards.This research was conducted independently, and therefore […] the project was assessed by independent experts. […]
 

2. The joint project “Exposition to Pyrethroids in Indoor Rooms“
[…] One study included persons having carpets containing pyrethroid in their households and thus being permanently exposed to the insecticide. […]

In order to determine the pyrethroid concentration, the pyrethroid concentrations  in the room air were measured in the house dust of the rooms (indoor-room monitoring). In order to detect possible pyrethroid effects on human health, the persons affected were asked to indicate their complaints and were physically examined and subjected to further health-related tests. These included tests of the urine for products of the pyrethroid metabolism (bio-monitoring), of the blood along with immunological parameters as well as possible impairment of the nervous system (neurophysiological tests and measurement of the brain flows). All this was designed to find answers to such questions as:

• Does the occurrence of pyrethroids in indoor rooms lead to relevant impairment of the residents’ health?

• Is there a change in the health condition of people exposed to pyrethroids once (vermin-killing measures) or permanently (woollen carpets) […]?

3. […] Health impairment through permethrin from woollen carpets              and woollen fitted carpets?
      [..]  Basic questions of the study

• What is the extent of exposition to permethrin in the house dust and air of indoor rooms with woollen carpets?
• What is the share of particle-borne permethrin that reaches the lung?
• To what extent is permethrin bioavailable from woollen carpets, i.e., can it be found as a metabolic product in the urine of humans?
• Is there any correlation between the concentration of permethrin in the room air and the concentration of permethrin metabolites (degradation products)?
• Is there any correlation between the concentration of permethrin in the room air or the permethrin metabolites in the urine and the state of health?

4. Correlations found or not found
      [..]  Permethrin in house dust and fitted carpets

• When the permethrin concentration in the carpet fibres increases, a rising concentration is recognisable also in the house dust.
• In contrast to the carpet-fibre finish, permethrin can enrich in house dust. This means that the permethrin concentration found in house dust may be higher than that in carpet fibres.
• Compared with studies recording the “background exposition”, house dust from flats with Eulan-finished carpets shows a markedly higher permethrin rate.

• The concentration of permethrin in the air is very low; in 19 % of all cases it is below the identification limit.
• No significant correlation […]  is recognisable between the concentration of permethrin in the room air and in the house dust.
• The permethrin in the air must be attributed to a minor continual abrasion of small carpet fibres.

• The identification of permethrin metabolites in the urine basic indicates intake of permethrin. But:
• As a rule, the concentration of permethrin in the urine is very low and often below the identification limit.
• The concentration of permethrin metabolites in fitted carpets, in house dust and in the room air does not indicate a significant correlation with the metabolite concentration in the urine.

• No significant correlation is recognisable between the occurrence of a symptom and the permethrin concentration in the room air.
• The concentration of permethrin metabolites in the urine does not show a significant correlation with the indication of symptoms.
• The type and the frequency of the indication of symptoms may be compared with those of a comparative study without the influence of pyrethroids.

5. Conclusion
The results of the study covering flats equipped with Eulan-finished woollen carpets or fitted woollen carpets may be summarised as follows:

The indoor-room monitoring showed that the permethrin concentrations are very high in house dust. They are, however, very low in the toxicologically relevant room air. As, in the study under consideration, the air is the main path for the intake of permethrin, residents can be expected to be exposed only to a minor degree.

The metabolite concentrations in the urine determined through biomonitoring are comparable to those observed in other studies with general population groups. Only a small part of the samples showed values above the identification limit.

Also the frequency of the health symptoms indicated is similar to the findings of a comparative study conducted with persons that are not exposed to permethrin. The persons examined obviously perceived a range of symptoms similar to those indicated in the present study. A correlation of their state of health with the permethrin concentration in the room air and the metabolite concentration in the urine cannot be recognised. The question whether this applies also to very sensitive persons such as allergics cannot be answered due to the study’s setup.

A special label for permethrin-treated fitted woollen carpets would benefit consumers and should thus be striven for.
 

The results of the study do not indicate a hazard to the health of healthy residents of flats where woollen carpets or fitted woollen materials are used that were properly moth- and beetle-proofed by means of permethrin.