Environmental Engineering Reference
In-Depth Information
C. Nonallergenic illness
1. Fungal MVOCs
Because of their ubiquitous presence in mold-infested buildings, fungal
MVOCs have been the subject of scientific speculation related to their poten-
tial role in causing nasal irritation and stuffiness. Reports linking fungal
MVOCs to illness symptoms have been anecdotal, and studies to test the
effects of fungal MVOCs on humans have yet to be conducted. Limited
laboratory studies indicate that MVOCs produced by
Paecilomyces variotii
are
ciliatoxic (adversely affect the hair-like structures, i.e., cilia, in the respiratory
tract that are responsible for removing foreign particles). In other studies,
MVOCs from
Penicillium
sp. and
Trichoderma veride
increased ciliary beat
frequency in respiratory airway cells of animals.
It is likely that fungal MVOCs do have significant biological effects. At
present there is little scientific data to indicate that such biological effects
occur at the relatively low exposure concentrations present in mold-infested
buildings.
2. Mycotoxicoses
Mycotoxin intoxication or poisonings have historically been associated with
contaminated livestock feed and human foodstuffs. Outbreaks of mycotox-
icoses in animals are associated with climatic or seasonal conditions favoring
fungal growth on grain and other crops.
Mycotoxins have a broad range of toxic potentials. Substances such as
saratoxin H and cyclochorotine have LD
50
s (dose required to kill 50% of
animals under test) of <1 mg/kg (1 ppm w/w) and are extremely toxic.
Other mycotoxins have LD
50
s as high as 800 mg/kg.
The primary route of mycotoxin exposure in humans is ingestion. How-
ever, there is increasing evidence that airborne mycotoxin exposure may be
important (particularly to certain mycotoxins). Inhalation exposure may
cause more severe toxic responses for a given dose.
Mycotoxins are very large molecules and, as a consequence, not volatile.
Therefore, mycotoxin exposure must result from inhalation of particulate-
phase substances. Exposure may occur when mold spores that have high
mycotoxin concentrations are inhaled. Such spores have aerodynamic diam-
eters in inhalable/respirable ranges.
Mycotoxins have a variety of adverse health effects. The mycotoxin
ochratoxin A, for example, causes both kidney and liver damage; liver dam-
age is caused by exposure to aflatoxin B, which is also a potent liver carcin-
ogen. Ochratoxin A is produced by several different species of
Aspergillus
and
Penicillium
. Mycotoxins citroviriden and verruculogen, produced by
P.
verrucossen,
are neurotoxic. Mycotoxins patulin (produced by
Aspergillus
and
Penicillium
sp.) and saratoxin H (produced by
Stachybotrys chartarum
) cause
lung hemorrhaging in animals.
