Abstracts from the brochure published by the Federal Ministry for Research and Education covering the joint project "Exposure to Permethrin in Indoor Rooms"

Impairment of human health through pyrethroids (insecticides) in living and working rooms

Results of study conducted on the bio-, effect- and indoor-room monitoring of pyrethroids

 

No health risk identifiable

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.

1. Preface

Some years ago, exposure 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 impairment involved, the connection between exposure and impairment and possible health hazards. This research was conducted independently, and therefore […] the project was assessed by independent experts. […]

2. The joint project “Exposure 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:

3. […] Health impairment through permethrin from woollen carpets and woollen fitted carpets?

[..]  Basic questions of the study

4. Correlations found or not found

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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.

A hazard to human health is not identifiable

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.