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Cause of intoxications with nano spray not yet fully elucidated

10/2006, 12.04.2006

Scientific discussions at BfR did not produce any clear results

At an expert meeting on 7 April 2006 experts from poison control and treatment centres, science, industry, federal state authorities and the Federal Institute for Risk Assessment, analysed the cause of 97 intoxication cases, some of them severe, following the use of novel sealing sprays with nano particles. "These incidents have demonstrated that the introduction of new technologies in consumer products must be coupled with an assessment of the possible risks arising from their use. It is incumbent on science to communicate this message to consumers as well", said BfR President Professor Dr. Dr. Andreas Hensel. The experts assume that the observed health disorders were caused by inhalation of the very fine aerosol spray. Aerosol sprays with a droplet size of 10 micrometres are only formed when the product is applied from spray cans containing a propellant. Droplets of this size penetrate deeply into the lungs and can impair pulmonary function. It was not possible for the experts to determine in a definitive manner whether the nano particles, a component of the aerosol, also contributed to the health problems observed because of the lack of data on both toxicological properties and the nano scale of the particles.

Between 27 and 30 March 2006 97 incidents involving, in some cases, severe respiratory disorders and even pulmonary oedemas were reported following the use of two "nano" sealing sprays in aerosol cans from the manufacturer Kleinmann. Thanks to concerted action by the poison control and treatment centres, federal state authorities, the Federal Institute for Risk Assessment (BfR), manufacturers and distributors, the suspicious products were very quickly withdrawn from the market in Germany. In press releases consumers were warned not to use these products. No further incidents were notified after 30 March 2006.

At an expert meeting on 7 April 2006 60 experts from science, clinics, public agencies, industry and the Federal Institute for Risk Assessment analysed whether the health disorders like respiratory distress or pulmonary oedemas were triggered by the nano particles in each of the two products or whether other known noxae or hazardous substances from traditional impregnating sprays were responsible.

The distributors of the two sealing sprays were unable to supply the full formulations because information was missing from their upstream suppliers. A definitive toxicological assessment of the acute pulmonary disorders following use of the two products was not, therefore, possible in the scientific discussions.

The experts also pointed out that a classical toxicological assessment of the individual components in a product is not enough when the product is applied in an aerosol spray containing a propellant. Physical characters like the droplet size of the spray are the main deciding factors whether and, if so, which toxic effects could occur in the respiratory tract.

We know from intoxication incidents involving classical impregnating sprays in Germany, Holland and Switzerland that products do not cause severe health problems like respiratory distress or pulmonary oedemas until they penetrate the alveolar tissue in the lung. In order to reach these areas the droplets must be very small. This droplet size is only achieved when the product is applied using a propellant and a correspondingly small nozzle in the spray head. When, however, these liquids are applied using a pump mechanism, the droplets are no smaller than 100 micrometres and do not reach the alveolar tissue.

The experts do not rule out the possibility that the toxic effects observed in connection with the application of the two nano sealing sprays containing a propellant during the period in question may have been caused solely by application as an aerosol spray. As it is not known whether nano particles in the aerosol also reached the patients’ lungs and damaged the alveolar tissue, a possible involvement of these particles has to be elucidated.

The experts agreed that the health effects of products in the form of propellant sprays can only be determined in a test strategy which simulates real application conditions indoors. Toxic effects only occur when the product itself, i.e. the entire substance mixture in the formulation, is inhaled as fine mist with a corresponding small droplet size. This applies both to products with and without nano particles.

The manufacturers of propellant sprays should, therefore, undertake and document toxicological tests of this kind before placing products on the market. Only then will they comply with the requirements formulated in the Equipment and Product Safety Act / GPSG) which stipulate that "in the case of correct use or foreseeable incorrect use, the safety and health of users or third parties are not endangered."

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