Sensory Irritating Potency of Some Microbial Volatile Organic Compounds (MVOCs) and a Mixture of Five MVOCs

Abstract

The authors investigated the ability/potencies of 3 microbial volatile organic compounds and a mixture of 5 microbial volatile organic compounds to cause eye and upper respiratory tract irritation (i.e., sensory irritation), with an animal bioassay. The authors estimated potencies by determining the concentration capable of decreasing the respiratory frequency of mice by 50% (i.e., the RD₅₀ value). The RD₅₀ values for 1-octen-3-ol, 3-octanol, and 3-octanone were 182 mg/m³ (35 ppm), 1 359 mg/m³ (256 ppm), and 17 586 mg/m³ (3 360 ppm), respectively. Recommended indoor air levels calculated from the individual RD₅₀ values for 1-octen-3-ol, 3-octanol, and 3-octanone were 100, 1 000, and 13 000 μg/m³, respectively—values considerably higher than the reported measured indoor air levels for these compounds. The RD₅₀ value for a mixture of 5 microbial volatile organic compounds was also determined and found to be 3.6 times lower than estimated from the fractional concentrations and the respective RD₅₀s of the individual components. The data support the conclusion that a variety of microbial volatile organic compounds may have some synergistic effects for the sensory irritation response, which constrains the interpretation and application of recommended indoor air levels of individual microbial volatile organic compounds. The results also showed that if a particular component of a mixture was much more potent than the other components, it may dominate the sensory irritation effect. With respect to irritation symptoms reported in moldy houses, the results of this study indicate that the contribution of microbial volatile organic compounds to these symptoms seems less than previously supposed.