Some species of Penicillium can present a danger, as they produce toxins known as mycotoxins. These are especially dangerous for those with allergies or compromised immune systems. Other species of Penicillium are useful in the food and drug industry and have beneficial effects of humans.
There are 200 species of Penicillium known. Penicillium chrysogenum is the most common specie found in indoor environments and is responsible for many allergic reactions in those with a sensitivity. Other species can produce toxins that damage internal organs and are potential carcinogens. One of the most widely known uses of Penicillium is the production drugs that halt the grow of bacteria, known as antibiotics.