Introduction to Mold Testing (Mold Sampling)

Molds are a natural and important part of our environment. They are ubiquitous and are found virtually everywhere. Molds produce tiny spores to reproduce. These spores can be found in both indoor and outdoor air and on indoor and outdoor surfaces. When mold spores land on a damp spot, they may begin growing and digesting whatever they are growing on in order to survive, leading to adverse conditions. In response to increasing public concern, a number of government authorities, including the United States EPA, California Department of Health Services and New York City Department of Health, have developed recommendations and guidelines for assessment and remediation of mold.

While it is generally accepted that molds can be allergenic and can lead to adverse health conditions in susceptible people, unfortunately there are no widely accepted or regulated interpretive standards or numerical guidelines for the interpretation of microbial data. The absence of standards often makes interpretation of microbial data difficult and controversial. The reports generated by the lab we use have been designed to provide some basic interpretive information using certain assumptions and facts that have been extracted from a number of peer reviewed texts, such as the American Conference of Governmental Industrial Hygienists (ACGIH). In the absence of standards, the user must determine the appropriateness and applicability of this report to any given situation. Identification of the presence of a particular fungus in an indoor environment does not necessarily mean that the building occupants are or are not being exposed to antigenic or toxic agents. None of the information contained in reports provided should be construed as medical advice or a call to action for evacuation or remediation unless deemed so by an authoritative party in that particular field having the credentials and experience needed to make such recommendations. Only a qualified physician should make any decision relative to medical significance.

Methods

1. Surface Samples – Swab, Dust, Tape and Bulk Samples: Swab, Dust and Tape samples are mounted on a glass slide and observed under a bright field microscope for either Qualitative or Quantitative Examination. A bulk sample is also
simultaneously observed under a stereomicroscope to look for signs of any visible discoloration or fungal growth, which is then mounted and observed under a bright field microscope for either Qualitative or Quantitative Examination. The samples are analyzed at a minimum of 200X magnification and up to a 1000X magnification. In the qualitative examination, the prepared samples are observed for the presence of any structures or skewing of spore distribution that may indicate growth in the sample being analyzed. In the quantitative examination, the mold spores detected in the sample are counted and reported as spores per cm2, spores per gram (or 1000mg), or spores per swab/wipe, etc depending on the sample type.

These methodologies do not differentiate between viable and non-viable fungal spores.

2. Air Samples- Spore Trap Device: Spore traps are a unique sampling device designed for the rapid collection and analysis of a wide range of airborne particulates, including fungal spores. While analyzing the sample, the analyst takes a number of variables into account to select the proper analytical method to accurately determine the densities of the various spores on the trace. The densities of the debris and the spores on the trace will determine the approach to analyzing the sample. In general, the sample is directly mounted under the microscope and the various airborne particles detected are counted at a minimum of 200X magnification and up to 1000X magnification, with the entire trace (100% of the sample) being analyzed at 200X or 600X. This method does not differentiate between viable and non-viable fungal spores. This technique does not allow for the differentiation between Aspergillus and Penicillium spores. Additionally, depending on morphology, other non-distinctive spores are reported in categories such as ascospores or basidiospores. All slides are graded with the following debris scale for data qualification.

Data Interpretation

According to ACGIH, “Data from individual sampling episodes is often interpreted with respect to baseline data from other environments or the same environment under anticipated low exposure conditions.” In the absence of established acceptable exposure limits, it is often necessary to use a comparison standard when interpreting data. In this instance, it will be necessary to sample the suspect area as well as a non-suspect area. According to ACGIH, “…active fungal growth in indoor environments is inappropriate and may lead to exposure and adverse health effects.”

Total Fungal Spores
According to ACGIH, “…. differences that can detected with manageable sample sizes
are likely to be in 10- fold multiplicative steps (e.g., 100 versus 1000…)”. Following
this logic, if total fungal spores are ten (10) times greater in the sample from a suspect
area than in the negative control sample collected from a non-suspect area, then that
sample area may be a fungal amplification site.

Mycelial Fragments
Mycelium is a fungal mass that constitutes the vegetative or living body of a fungus.
Following the same logic above, if total mycelial fragments are ten (10) times greater in
the suspect sample than in the negative control, then the sample area is considered to be
a fungal amplification site. The presence of mycelial fragments provides evidence of
microbial growth.

Mycotoxins
Molds can produce toxic substances called mycotoxins. More than 200 mycotoxins have been identified from common molds, and many more remain to be identified. Some of the molds that are known to produce mycotoxins are commonly found in moisture-damaged buildings. Exposure pathways for mycotoxins can include inhalation, ingestion, or skin contact. Although some mycotoxins are well known to affect humans and have been shown to be responsible for human health effects, for many mycotoxins, little information is available, and in some cases research is ongoing. Some molds can produce several toxins, and some molds produce mycotoxins only under certain environmental conditions. The presence of mold in a building does not necessarily mean that mycotoxins are present or that they are present in large quantities.

Water Indicator Molds
Certain authorities identify certain molds whose presence indicates excessive moisture. The presence of a few spores of indicator mold should be interpreted with caution. Additionally, it should be recognized that these named molds are not necessarily the only ones of potential significance.

Mold Glossary
Specific characteristics of the individual molds listed in the report are presented in Table 1.

Useful Resources

i. Guidelines on Assessment and Remediation of Fungi in Indoor Environments, New York City Department of Health.
www.ci.nyc.ny.us/html/doh/html/epi/moldrpt1.html

ii. Facts about Mold, New York City Department of Health. www.ci.nyc.ny.us/html/doh/html/epi/epimold.html

iii. Mold Resources, United States Environmental Protection Agency. www.epa.gov/iaq/pubs/moldresources.html

iv. Mold in My Home, What do I do? California Department of Health Services. www.asbestos.org/Microbial/index.html

Summary of Specific Mold Characteristics

Alternaria

Alternaria is one of the more common fungi found in nature. It is found growing indoors on a variety of substrates including wallboard, painted walls, etc.

Arthrinium

Arthrinium is a saprobe and is found on plants. It is rarely found growing indoors.
     
Ascospores 

Ascospores are ubiquitous in nature and are commonly found in the outdoor environment. Some fungi that belong to the ascomycete family include the sexual forms of Penicillium/Aspergillus, Chaetomium, etc that may be frequently found growing on damp substrates.

Aureobasidium

Aureobasidium is commonly found in a variety of soils. Indoors, it is commonly found where moisture accumulates, especially bathrooms, and kitchens, on shower curtains, tile grout, windowsills, textiles, and liquid waste materials.

Basidiospores

Basidiospores are Saprophytes and plant pathogens and are commonly found in gardens, forests, and woodlands. They also include organisms that are the agent of “dry-rot,” and other fungi that cause white and brown wood rot, which may grow and destroy the structural wood of buildings.

Bipolaris/Dreschlera

Bipolaris and Dreschlera are usually found associated with plant debris, and soil. They are plant pathogens of numerous plants, particularly grasses. Bipolaris and Dreschlera can grow indoors on a variety of substrates.

Botrytis

Botrytis is commonly found in tropical and temperate climates growing on vegetative matter. They may be found indoors in conjugation with indoor plants, fruits and vegetables.

Chaetomium

Chaetomium is often found on materials containing cellulose such as sheetrock paper, or other wet materials.

Cladosporium

Cladosporium is a common outdoor mold. They are commonly found on dead plants, food, textiles, and a variety of other surfaces. Indoors, they can grow on a variety of substrates including textiles, wood, moist windowsills, etc. It can grow at 0oC and is associated with refrigerated foods.

Curvularia

Curvularia is found on plant materials and is considered a saprobe. Indoors, they can grow on a variety of substrates.

Epicoccum

Epicoccum is a saprophyte and considered a weekly parasitic secondary invader of plants. They tend to colonize continuously damp materials such as damp wallboard and fabrics.

Fusarium

Fusarium requires very wet conditions and is frequently isolated from plants and grains. They colonize continuously damp materials such as damp wallboard and water reservoirs for humidifiers and drip pans.

Memnoniella

Memnoniella can be found growing on a variety of cellulose-containing materials.

Nigrospora

Nigrospora is especially abundant in warm climates and is rarely found growing indoors.

Oidium/ Peronospora

Oidium and Peronospora are plant pathogens and are not found growing indoors.

Penicillium/ Aspergillus

Penicillium and Aspergillus are ubiquitous in environment. Aspergillus tends to colonize continuously damp materials such as damp wallboard and fabrics. Penicillium is commonly found in house dusts, wallpaper, decaying fabrics, moist clipboards, etc.

Pithomyces/Ulocladium

Pithomyces is commonly found on grass and decaying plant material and are rarely found growing indoors. Ulocladium has a high water requirement and therefore colonizes continuously damp materials such as damp wallboard and fabrics.

Rusts

Rusts are plant pathogens and only grow on host plants.

Smuts/Periconia/Myxomycetes

Smuts and Myxomycetes are parasitic plant pathogens that require a living host. Smuts do not usually grow indoors. Periconia are rarely found growing indoors. Myxomycetes are occasionally found indoors, but rarely growing.

Stachybotrys

Stachybotrys are commonly found indoors on wet materials containing cellulose, such as wallboard, jute, wicker, straw baskets, and other paper materials.

Stemphylium

Stemphylium is either parasitic or saprophytic and is rarely found growing indoors.

Torula

Torula can grow indoors on cellulose containing materials such as wallboard, jute, wicker, straw baskets, and other paper materials.

Other brown/colorless

An uncharacteristic fungal spore that does not lend itself to classification via direct microscopy

Mold News & Info

• Tue, 15 Nov 2011 05:00:00 +0000: Maryland College Students Take to Floating Dorm
  After an outbreak of mold shut down two dormitories at St. Mary’s College in Maryland, students moved on to the Sea Voyager, a cruise ship docked at the nearby waterfront.
• Tue, 05 Jul 2011 04:00:00 +0000: NYC Housing Authority Neglects Mold
  New York City’s public housing towers are the shame of the city, ungainly and forgotten stepchildren.
• Sun, 13 Feb 2011 05:00:00 +0000: Battling Mold Infestations - Posting
  New York City’s Department of Housing Preservation and Development issued 14,290 violations for mold in residential buildings last year.
• Wed, 12 May 2010 04:00:00 +0000: New York Anti-Asthma Program Would Cite Landlords
  The City Council in New York plans to introduce legislation requiring landlords to battle garbage, mold and vermin, all factors that have been linked to asthma.
• Tue, 26 Jan 2010 05:00:00 +0000: Slime Mold Proves to Be a Brainy Blob
  In Japan, researchers showed that in only a day, slime molds could design a complex network as efficient as the Tokyo rail system.