There are more than 160 species of Aspergillus,
16 of which have been documented to cause disease in humans. They are among the most
common groups of environmental fungi and many species are isolated from a variety of
substrates, including grains, nuts, cotton, organic debris and water damaged, organic
building materials. The most frequently encountered opportunistic Aspergillus
pathogen is A.fumigatus, which is seen most abundantly in decomposing organic materials.
Aspergillus fumigatus and A.niger have been identified as the more harmful species of the
Aspergillus is considered a common environmental mold that
can pose health risks when it is present in elevated levels. Health problems due to
Aspergillus exposure may include headaches, eye and skin irritation, asthma, aggravation
of existing respiratory conditions, other typical allergic symptoms, and hypersensitivity
pneumonitis. Hypersensitivity and allergic responses can be triggered by minimal
exposure and especially in people who have an existing sensitivity to mold allergens and
toxins or who have compromised or suppressed immune function. Aspergillus can
proliferate successfully indoors when conditions become favorable resulting in an increase
in the number of spores, and therefore, mycotoxin concentrations that can be harmful.