Tape Lift and Bulk Sample for Mold
Tape Lift and Bulk Sample for Mold
When investigating a potential mold problem, a surface sample may need to be collected especially if it’s not clear whether the contamination is mold. Sometimes the surface could be contaminated with soot, dust, dirt or old flaking insulation. Collecting a sample for direct examination under a microscope can provide a confirmation whether the sample is mold. Two main methods for collecting a sample for direct examination include: a tape lift and bulk sampling. Both methods are described in more detail below. A direct microscopy exam by a microbiology laboratory provides an immediate determination of the presence of fungal spores including the types of fungi present. Direct examinations are best utilized to sample visible mold growth. Sampling a random area will likely result in a mix of various spores since fungal spores are ubiquitous in the environment. The lab report should indicate the species of mold and the range of concentration, usually low, medium or high. The laboratory may also discern if there is active growth occurring on the bulk material (e.g. on a piece of wood).
An example of collecting a bulk sample for mold analysis can occur when investigating potential mold growth in the attic or basement. Wooden rafters or beams may have some dark (or other color) discoloration and it may not be clear whether its of microbial origin. To confirm whether the discoloration is mold growth a sterile knife would be used to scrap the top of the wooden surface including the wood. The sample would be placed into a sterile bag using sterile gloves. The microbiological laboratory would be able to confirm whether the sample is mold. Prior to considering whether remediation needs to be conducted it’s a good idea to confirm that what you are looking at is in fact mold contamination and not something else like soot. Especially since mold remediation is costly, multifaceted and time intensive. Typically soot will wipe off more easily from the surface than mold. Mold contamination will embed itself into the wooden surface to feed of the carbon source. Mold growth will not wipe off as easily as surficial dirt.
When deciding on this type of sampling, you need to consider the advantages and disadvantages. The advantages and disadvantages of collecting a tape lift or bulk sample for mold are described below:
- The direct exam is relatively inexpensive, and can be conducted quickly.
- It’s a useful test for initial site sampling.
- Direct examination of a surface provides a good picture of all mold present in a given area.
- Direct sampling may disclose indoor reservoirs of spores that are not airborne yet.
- Areas of fungal growth are often small and scattered, so they may not be picked upon sampling.
- Health problems related to indoor microbial growth are generally caused by the inhalation of substantial numbers of airborne spores, sometimes over a long period of time. The presence of biological materials on a specific surface, is not a direct indication of the spores that may be in the air.
- Not all the spores seen under the microscope may be viable (alive). It is advisable to combine direct exam samples with culture methods to get a better picture of what molds are present.
- Tape lifts are not able to be cultured.
- Direct examinations of dirt/soil and dust samples can not be performed.
For all sampling, latex/nitrile gloves need to be used when collecting mold samples. Samples need to be properly labeled and a chain of custody completed and enclosed with the samples.
For Tape lift:
- Clear (transparent) Scotch or other brand tape (frosted tape hides the spores). 2. New plastic bag to hold specimen(s). Sometimes a lab may provide you a tape lift kit
- Sterile container or new plastic bag. to hold and transport specimen.
An example of sampling procedures are provided below:
1.Take a few inches of clear tape (not frosted tape). Avoid touching the sticky side, especially the part touching the mold. Do not fold tape onto itself.
2.Wearing gloves, apply the central inch of tape to the suspect area (choose one that is free of extraneous debris). Apply light pressure to the non-adhesive side.
3.Pull tape off surface with slow, steady pressure, holding the tape edges only.
4.Apply sticky side of tape to the inside of the plastic bag.
5.Ensure there are no folds or creases in the tape.
- Place only one sample in each bag.
1.Wearing latex gloves, take a small piece of the suspect material.
2.Place piece inside clean sterile container or new plastic bag or whirl-a-pack bag.
3.Close bag or cap container.