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Photograph of animal dander and debris. Accuracy Limitations of Allergy Tests: Animals or Mold

  • ALLERGY TEST ACCURACY - CONTENTS: Limits of Allergy Exposure & Allergy Sensitivity Testing Mean Building Tests May Be Appropriate in Some Cases
  • When to Perform Building Particle Screening Surveys for Evidence of Allergens, Molds, Other Particles
  • POST a QUESTION or READ FAQs about the limits of animal or mold allergy tests performed on humans & about when to screen a building for allergens
  • REFERENCES
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Accuracy limits of allergy tests:

This article describes the accuracy and limitations of allergy tests and allergy exposure tests on humans. During building air quality inspections we often find evidence of un-recognized problematic mold reservoirs, or prior occupancy of cats, dogs, mice, birds, and other animals who have been frequently present in a home even though the human occupants didn't know it.



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Limits of Allergy Exposure & Allergy Sensitivity Testing Mean Building Tests May Be Appropriate in Some Cases

OPINION-DJF: Above at Skin Testing for Allergies and again at Immunoassay Allergy Testing we noted a few accuracy, false positive, and false negative concerns with allergy testing. While those tests have been used successfully by experienced allergists literally millions of times, they are not foolproof. Summarizing:

False positive allergy tests: Some types of skin tests for allergies can give a false positive result, suggesting that a person is allergic when they have not reacted to the material in the environment

False negative allergy tests: Skin tests for allergies, while they cover a very broad range of foods, grasses, pollen, trees, animals, and even some molds, do not and cannot test for all of the possible allergens and allergen sources in the environment nor in buildings. Furthermore, Sheryl B. Miller and others have raised questions about the actual accuracy of ELISA test results and about the absence of a comparative standard.

Human sensitivity to specific allergens varies widely: while there is no simple standard for acceptable exposure level for allergens, such as molds, there are commonly accepted rules of thumb or general exposure levels.

See MOLD EXPOSURE STANDARDS for example of mold exposure standards around the world, and for a list of reasons why a simple mold exposure standard would be technical nonsense. Most IH and mold experts agree that low levels of problematic molds (toxic, pathogenic, or allergenic molds) in the hundreds of spores per M3 of air are not considered a "mold-contaminated" environment.

Yet we have instrumented and actually measured individuals and their environments to demonstrate that some people who are hypersensitive to mold or other environmental irritants can experience severe allergic reactions to very low levels of the problem material. For example, a client who was very mold-sensitive had difficulty breathing in minutes when exposed to airborne Pen/Asp spores at just 600 spores M3 in her home - a level well below that usually defined as "mold contaminated" in buildings.

Human sensitivity to allergens can change over time: some people who suffer chronic exposure to mold or other indoor irritants can become hyper sensitized, subsequently suffering severe reactions to much lower exposure levels than normal. The author (DJF) developed hypersensitivity to Memnoniella echinata (a close relative to Stachybotrys chartarum) following high exposure during a series of building investigations.

Animal allergens and molds are ubiquitous at low levels in buildings and sometimes are present at much higher levels than a simple visual inspection would suggest. For example, mold contaminated building insulation can form a significant problem mold reservoir but might look "clean" to the naked eye.

See INSULATION MOLD for details.

We can find at least some animal dander, dog, cat, and mouse, nearly everywhere. Experience with seeing levels in dust from various buildings may be helpful in interpreting those findings.

Human exposure to any indoor contaminant is very difficult to quantify: because people are complex organisms with varying body mass, respiration rate, health vulnerabilities, etc. and because building conditions that affect the level of airborne or other contaminants vary widely often from minute to minute, it is very difficult, often cost-prohibitive to attempt an accurate estimate of the actual exposure to indoor contaminants experienced by a specific person.

At MOLD TESTING METHOD VALIDITY we offer examples of causes of high variability in indoor particle or other contaminant levels - conditions that make airborne measurements and other indoor air quality samples inaccurate.

Also see MOLD LEVEL IN AIR, VALIDITY.

Most IH and building environmental consultants take a simpler approach: if inspection or testing detect a large reservoir or problem material in a building, such as a large mold reservoir, that material should be removed, the area cleaned, and the cause of its occurence should be corrected.

See MOLD CLASSES, HAZARD LEVELS and also MOLD EXPOSURE STANDARDS.

When to Perform Building Particle Screening Surveys for Evidence of Allergens, Molds, Other Particles

In general we do not recommend mold testing nor allergy screening in all buildings as a general practice and certainly not where the visible mold or allergen problem is small in size (less than 30 sq.ft. of contiguous problem material).

Ordering environmental inspections and tests or high-cost environmental cleanup work when they are not justified is unethical and wastes consumers's money and laboratory operators' time.

But when there are building related occupant complaints, occupants at high risk, or on advice from a physician, there may be a place for simple dust screens for the presence of visible animal dander and visible animal hair.

But if you are ordering a lab test of indoor particles to determine an estimate of the level of detectable animal allergenic particles, be sure that the lab will identify the actual particles such as dog dander, cat dander, insect fragments, animal hair, or even specific kind of animal hair (dog, cat, rodent, etc. - also see FIBER & HAIR IDENTIFICATION).

Some laboratories simply give a "skin cell" count that includes human skin cells - a useless result.

See MOLD EXPERT, WHEN TO HIRE for advice on determining when it is appropriate and justified to order inspections and tests of a building for mold or allergens.

Check With Your Doctor About Allergens and About Whether or Not Building Tests for Allergens or Mold are Recommended

Of course since individual sensitivity to allergens varies, we suggest that anyone suffering from allergies and considering steps to further clean their home should also consult with their allergist and their general physician.

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