Penicillium species are common contaminants on various substances. This organism causes food spoilage and colonizes on leather objects and is an indicating organism for dampness indoors. Some species are known to produce mycotoxins. If health effects are noticed by occupants or workers, in an environment that evidences an amplification of Penicillium, identification of species is helpful.

Mycotoxins can affect the immune system, nervous system, liver, kidneys, blood and blood clotting. Some mycotoxins are known to be carcinogens. Killing spores does not disable the toxicity of mycotoxins. In fact, mycotoxins can be present on or in spores, whether the spores are dead or alive. Stopping fungal growth does not stop adverse medical symptoms. Both spores and hyphae can be allergenic and/or toxic.