Determining Severity of Illness
Exposure to certain types of airborne molds and their spores can cause allergic reactions, episodes of asthma, extreme illness, and other respiratory complications in individuals who are genetically and immunologically predisposed. Greater impacts on health may occur when individuals are exposed to large doses of the chemicals produced by molds. These are more commonly known as mycotoxins.
Mycotoxins generated by fungal spores can enter the body through the respiratory tract, thereby inducing local toxicity. This cytotoxicity to the lung may seriously affect the physical defense mechanisms of the respiratory tract, damage the alveolar macrophages, and decrease the ability of the air passages to filter bacteria, viruses, and other particulate matter from the air we breath in. Neurotoxic symptoms (possibly related to airborne mycotoxin exposure in a heavily contaminated environment) have also been reported at very low levels.
Higher concentrations may induce toxic effects that range from severe irritation to immunosuppression and cancer. The immunosuppressive and cancer-inducing mechanism of mycotoxins causes damage by interfering with vital cellular processes, such as protein, RNA, and DNA synthesis. The combined outcome of these immunosuppressive and cytotoxic activities of mycotoxins (including T- and B-cell, helper or suppressor cells) increases the susceptibility of the exposed person to infectious diseases and possibly, cancer.
Molds can have a negative impact on human health. The specificity of the impact depends on the nature of the species involved, the metabolic products produced by the species, the amount and duration of the individualís exposure to the actual mold or its byproducts, and the specific susceptibility or state of health of the person exposed.
Health effects generally fall into seven categories:
Type-1 Allergy or Immediate Type Hypersensitivity
The most common response to mold exposure may be allergy. People who are atopic, that is, people who are genetically capable of producing an allergic response, may develop allergic symptoms when their respiratory system or skin is exposed to mold or mold products to which they have become sensitized. Sensitization may occur in atopic individuals with sufficient exposure. This reaction is IgE mediated and occurs within minutes after exposure to molds. Delayed Type Hypersensitivity Reaction
This type of reaction occurs hours or days after exposure to molds. It is mediated by IgG, IgM, IgA or immune complexes and is referred to as Type-2 and Type-3 allergic reaction. Finally, direct lymphocyte reaction to mold antigens may result in delayed type hypersensitivity or Type-4 allergic reaction. This reaction is mediated by lymphocyte reaction to mold antigens.
Infection from molds that grow indoors is not a common occurrence, except in certain susceptible populations, such as individuals who have compromised immune systems as a result of disease or drug treatment. A number of Aspergillus species that can grow indoors are known to be pathogens. Aspergillus fumigatus is a weak pathogen that is thought to cause infections (aspergillosis) only in susceptible individuals.
Mucous Membrane and Trigeminal Nerve Irritation
A fourth group of possible health effects from fungal exposure derives from the volatile compounds (VOC) produced by means of fungal primary or secondary metabolism, and subsequently released into the air indoors. Some of these volatile compounds are continuously produced as the fungus consumes its energy source in the course of the primary metabolic processes. Such compounds, in low yet sufficient aggregate concentration, can irritate the mucus membranes of the eyes and the respiratory system. Adverse Reactions to Odor or Pseudoallergy
Odors produced by molds may also adversely affect some individuals. The ability to perceive odors and respond to them is highly variable among people. Some individuals can detect extremely low concentrations of volatile compounds, while others require high levels of perception. An analogy to music may give perspective to odor response. What may be beautiful music to one individual could be unbearable noise to another. Some people derive enjoyment from odors of all kinds. Others may develop negative symptoms, such as headache, nasal stuffiness, nausea or even vomiting to certain odors, including perfumes, cigarette smoke, diesel exhaust, or moldy odors.
Toxicity or Neurotoxicity by Molds and Mycotoxins
The spores of many molds are capable of producing secondary metabolites, such as antibiotics and mycotoxins, some of which are extremely toxic. Depending on the route of entry, they may do damage to the skin, the lungs, the gut, the vascular system, the urinary system, the reproductive system, and the neuroimmunological systems. The spores from Stachybotrys chartarum, a mold capable of producing some of the most toxic substances known to mankind, can survive temperatures of up to 500 degrees Fahrenheit, as well as acid, caustics, and bleach without being destroyed.
In heavily contaminated environments, neurotoxic symptoms related to airborne mycotoxin exposure have been reported. Recently for example, highly abnormal brainstem auditory evoked response (BAER) was tested in adolescents with acoustic mycotic neuroma due to environmental exposure to toxic molds. This abnormal, evoked response correlated with objective findings, such as headaches, loss of memory, hearing loss, lack of concentration, fatigue, sleep disturbance, facial swelling, rashes, nosebleeds, diarrhea, abdominal pains, and respiratory difficulties. In addition, antibodies to neuron-specific antigens have been detected by our laboratory in the majority of patients exposed to toxigenic molds. This may be due to compromised blood brain barriers in the patients.
The exact mechanism by which molds and particularly mycotoxins induce neurotoxicity is yet unclear. As a result of the assault of mycotoxins on the nervous system and the degenerative process, proteins, which act as antigens to provoke humoral responses in the form of IgG, IgM and IgA, are liberated. It can therefore be said that promising candidates for monitoring neurotoxicity caused by mycotoxins are the presence of autoantibodies against neurotypic and gliotypic proteins.
While the mechanisms have yet to be elucidated, we believe that antibodies against neuron-specific antigens and their cross-reactive epitopes may play a role in the pathogenesis of neurotoxicity induced by mycotoxins.
Immunotoxicity Induced by Molds and Mycotoxins
The exposure of animals to molds have shown a significant effect on the immune system. In animals, this was manifested as increased susceptibility to infectious diseases.
It is important to note that almost all mycotoxins have an immunosuppressive effect, although the exact target within the immune system may differ. Many are also cytotoxic, so that they have route of entry effects that may be damaging to the gut, the skin, or the lung. Such cytotoxicity may affect the physical defense mechanisms of the respiratory tract, decreasing the ability of the airways to clear particular contaminants (including bacteria or viruses). It may also damage alveolar macrophages, thus preventing the clearance of contaminants from the deeper lung cavity.
Studies on the adverse immunological effects of fungal bio-aerosol on individuals were conducted and both cellular and humoral immune abnormalities were detected. The cellular abnormalities included abnormal T-cell function, B-cell function, and NK cell activity, as well as abnormal helper-suppressor ratios and cytokine production. Humoral abnormalities were observed in levels of anti-nuclear antibodies, anti-tissue antibodies, anti-neuronal antibodies, anti-thyroid antibodies, anti adrenal antibodies, rheumatoid factor, immune complexes, C3 and C4 complements, and fungal and mycotoxin antibodies.