Enlightening You on Mold and Environmental Contaminants
Aside from providing comprehensive mold inspection services, Holt Analytical is also dedicated to informing property owners about environmental contaminants. That is why we strive to provide invaluable resource materials about these topics.
Common Indoor Molds
- Aspergillus
- Cladosporium
- Basidiospores
- Penicillium
Allergenic Molds
These contaminants do not usually produce life-threatening health effects. They will most likely affect people who are already allergic or asthmatic.
The human system's responses to allergenic molds tend to be relatively mild. Depending on an individual's sensitivities, the typical allergic reactions include sore throats, eye and nose irritations, and rashes.
How Molds Are Considered Allergenic
Like pollen, mold spores are only significant airborne allergens if they are abundant, easily carried by air currents, and allergenic in their chemical makeup.
Mold spores are almost found everywhere. There are even some areas where they outnumber the amount of pollen in the air. Fortunately, only a few mold types are significant allergens.
Specific Molds That Are Allergenic
Mold Counts
This suggests the types and relative quantities of fungi present at a certain time and place. However, these mold counts cannot be used as a constant guide for daily activities.
One reason is that the number and types of spores present in the mold count may considerably change in 24 hours. It may be because weather and spore dispersal are directly related.
Spore Types
Many common allergenic molds are dry-spore types that release their spores during dry, windy weather. However, other fungi need high humidity, fog, or dew. Rain also causes smaller spores to spread into the air but washes out larger spores.
Aside from daily weather changes on mold counts, spore populations differ between day and night as well. It has been shown that dry spores disperse more during daytime than white wet spores spread at night.
Other Mold-Related Disorders
Fungi or their related microorganisms may cause other health problems similar to allergic diseases. Some varieties of Aspergillus may cause different illnesses, such as infections and allergies.
These fungi may stay in the airways or a distant part of the lung and grow until they turn into a compact sphere called "fungus ball." Aspergillus may use this chance to invade the lungs or whole body of people with lung damage or serious underlying illnesses.
Mold Exposure Effects
Some individuals exposed to these fungi can have an asthma attack or contract allergic bronchopulmonary aspergillosis. The latter condition only occurs in a minority of people with asthma. It is characterized by the following:
- Wheezing
- Low-Grade Fever
- Coughing Up of Brown-Flecked Masses or Mucus Plugs
Skin testing, blood tests, x-rays, and sputum examinations for fungi can help establish a proper diagnosis. Fortunately, corticosteroid drugs are usually effective in treating an allergic reaction. However, immunotherapy is not helpful.
Pathogenic Molds
These kinds of mold can produce some type of infection. They may also cause serious health effects to people with suppressed immune systems.
Luckily, healthy individuals can usually resist infection regardless of dose. Cases of high exposure may cause hypersensitivity pneumonitis as well.
Growth Rate
Colonies are moderately fast-growing organisms that effuse grey to blackish brown, suede-like floccose forms with a black reverse. Microscopic morphology has sympodial development of pale brown, pseudoseptate conidia on a geniculate or zig-zag rachis.
Additionally, conidia are produced through pores in the conidiophore wall (poroconidia). These straight, fusiform to ellipsoidal-shaped organisms are rounded at both ends with a smooth to finely roughened texture. They only germinate from the ends as well.
Species
The genus Bipolaris contains around 45 species that are mostly subtropical and tropical plant parasites. However, several species like B. australiensis, B. hawaiiensis, and B. spicifera — the most well-known pathogens — are well-documented human pathogens.
Clinical manifestations of these species include:
- Mycotic keratitis
- Subcutaneous phaeohyphomycosis
- Sinusitis
- Peritonitis in patients on continuous ambulatory peritoneal dialysis (CAPD)
- Cerebral and disseminated infections
Pathogenicity and Clinical Significance
Bipolaris is one of the causative agents of phaeohyphomycosis. It can infect both immunocompetent and immunocompromised hosts. The clinical spectrum is diverse and includes:
- Allergic and Chronic Invasive Sinusitis
- Keratitis
- Endophthalmitis
- Endocarditis
- Endarteritis
- Osteomyelitis
- Meningoencephalitis
- Peritonitis
- Otitis Media (in Agricultural Field Workers)
- Fungemia
- Cutaneous and Pulmonary Infections
- Allergic Bronchopulmonary Disease
Apart from being saprophytes on plants, Bipolaris may also be pathogenic to plant species like Graminiae and animals like dogs. It may cause nasal mycotic granuloma in the cattle as well. Luckily, Bipolaris may be isolated as a laboratory contaminant.
Macroscopic Features
Bipolaris colonies grow rapidly. They can reach a diameter of 3-9 cm following incubation at 25°C for seven days on a potato dextrose agar. The colony becomes mature within five days. Its texture is velvety to woolly.
The surface of the colony is initially white to grayish brown. It becomes olive green to black with a raised grayish periphery as it matures. The reverse is also darkly pigmented and olive to black
in color.
About Conidia (Poroconidia)
These organisms are three to six-celled, fusoid or cylindrical shaped, and light or dark brown-colored with a sympodial geniculate growth pattern. The poroconidium (30-35 µm x 11-13.5 µm) is distoseptate and has a scarcely protuberant, darkly pigmented hilum.
This basal scar indicates the point of attachment to the conidiophore. From the terminal cell of the conidium, germ tubes may develop and elongate in the direction of the longitudinal axis of the conidium.
Production and Appearance
Susceptibility
In vitro susceptibility testing procedures have not been standardized for dematiaceous fungi yet. There are limited data available on the susceptibility of Bipolaris.
This information suggests that itraconazole minimum inhibitory concentrations (MICs) are variable, and voriconazole MICs are considerably low.
Toxigenic Molds
Mycotoxins can cause serious health reactions in almost anybody. These agents have toxic effects ranging from short-term irritation to immunosuppression and possibly cancer. When toxigenic molds are found, further evaluation is recommended.
The notoriety of Stachybotrys leads some to believe it is the only “toxic mold.” However, many toxigenic mold types have been found during indoor air quality investigations in different parts of the world.
Infamous Toxic Contaminants
According to studies by Burge (1986), Smith et al. (1992), Hirsh and Sosman (1976), Verhoeff et al. (1992), Miller et al. (1988), and Gravesen et al. (1999), the most frequently found outdoor molds that exceed the acceptable levels are:
- Aspergillus
- Penicillium
- Stachybotrys
- Cladosporium
The toxicity levels of Penicillium, Aspergillus, and Stachybotrys are especially harmful when people are exposed to these contaminants indoors.
Penicillium
These mold species are common indoors, even in clean environments. According to studies by Burge (1986), Miller et al. (1988), and Flannigan and Miller (1994), they can be problematic when indoor spore levels are higher than outdoors.
Penicillium spores have the highest concentrations of mycotoxins. Mycelium, the vegetative portion of the mold, can also contain the poison. The viability of spores is not essential to toxicity. Because of this fact, a dead spore can still be a source of the toxin.
About These Toxigenic Species
A. parasiticus and A. flavus produce aflatoxins, the most extensively studied mycotoxins. It is among the most toxic substances. They can adversely affect the liver, brain, kidneys, and heart. Chronic exposure leads to potent carcinogens in the liver.
Aflatoxins are also teratogenic, according to studies by Smith and Moss (1985) and Burge (1986). Based on research by Smith and Moss (1985), symptoms of acute aflatoxicosis are fever, vomiting, coma, and convulsions.
Explore More About A. Fumigatus
It is found in many indoor spaces. This mold is often associated with an infectious disease called aspergillosis. However, the species does produce poisons that only been examined using simple toxicity tests, according to studies by Betina (1989).
Additionally, recent work has found several tremorgenic toxins in the conidia of this species, as researched by Land et al. (1994).
See More About A. Versicolor
This is a more common Aspergillus species found growing on wallpaper, wooden floors, fiberboards, and other construction materials in wet buildings. It does not produce aflatoxins but does produce a less potent toxin.
This pathogen is called sterigmatocystin, the precursor to aflatoxins according to Gravesen et al. (1994).
A. Versicolor Exposure Signs and Symptoms
Symptoms of aflatoxin ingestion are well described. However, symptoms of environmental contraction, like being in a moderately contaminated building, are not known but are undoubtedly less severe due to reduced exposure.
Additionally, the potent toxicity of these agents requires prudent prevention of exposures. This precaution is especially warranted when levels of Aspergilli indoors exceed outdoor levels by a significant amount.
Mold Sampling
Because Stachybotrys does not do well with other molds or bacteria, it is easily overgrown in a sample. This is especially true since it does not grow ideally on standard sampling media.
Its inability to compete may also result in Stachybotrys being killed off by other organisms in the sample mixture.
Sampling Precautions
Take a surface sample, such as tape or bulk, whenever evidence of black mold is found. This organism has a high moisture requirement, so it grows vigorously where water has accumulated from roof, wall, or plumbing leaks and chronically wet areas.
Black mold is often hidden within the building envelope and inside wall cavities. When Stachybotrys is detected in the air, it should be searched out in walls or other hidden spaces where it is likely growing in abundance.
Contact Us for More Info
For additional details about mold types, inspection services, and more, feel free to get in touch with us. It would be our pleasure to help you learn more about possible biological contaminants in your property and how they may affect your health.