Possible concerns in case of chronic respiratory exposure
The appropriate use of some microbial cleaner products leads to exposure scenarios which deserves particular attention. Spray application leads to aerosol formation, especially in closed rooms (e.g. toilets). Repeated application on carpets and upholstery can lead to an accumulation of spores and formation of dust-containing spores. Used in daily cleaning, chronic respiratory exposure therefore has to be considered in a health risk assessment. There is evidence in the scientific literature of sensitising properties and of hypersensitivity pneumonitis. In its microbial pesticide programme, the United States Environmental Protection Agency (US EPA) generally recognises that micro-organisms may be respiratory sensitisers. At the present time, in the course of its voluntary partnership environment label programme, Design for the Environment (DfE), the US EPA has generally excluded from consideration microbially based products intended for use on carpets, hard surfaces and other indoor environments until further information on their safety can be obtained (United States Environmental Protection Agency, 2009). Allergenic properties are also described for the mould species Aspergillus oryzae which is also being used in some cleaners.
It is not clear whether and to what extent these hazards are caused by the microbial enzymes and/or on other components of microbial cells and spores. Sensitising and allergenic properties of microbial enzymes, as well as some microbial cells, are well documented. A difficulty is that there is no agreed upon test for respiratory sensitisation. In the European Union, microbial enzymes are therefore voluntarily considered by industry as respiratory sensitisers and labelled and handled accordingly (R42) (see Federal Environment Agency Austria and Inter-University Research Center for Technology Work and Culture, 2002). Further investigation of this question was, however, beyond the scope of this study.
In order to check to what extent and in what particular cases these concerns are also valid for microbiological cleaners, an in-depth scientific review needs to be conducted and quantitative data or robust estimates on the concentration of cells and spores in aerosols or dust, and the effects of those concentrations, would be required.
Environmental risks of the microbes
Little can be said on the environmental risks of the microbes used. While producers are generally keen to use safe microbes only, the risk group scheme for classifying microbes does not specifically consider plant or animal (in case there is no human) pathogenicity. The risk group scheme also does not consider toxicity to animals. Some companies referred to standard OECD oral toxicity tests on rodents as well as to eco-toxicity tests conducted with the Bacillus strains they are using and which did not - according to these producers - identify any environmental risks. This type of information does not seem to be available from all manufacturers or for all microbes.