Analytical Sensitivity

Analytical sensitivity is the asbestos concentration that one counted fiber or structure would represent in a given sample, based on how much air or surface was sampled and how much of the filter was examined. It sets the floor for a result: when nothing is found, the lab reports less than the analytical sensitivity, not zero.

Origin

The concept comes from fiber and structure counting by microscopy, where only a small part of a filter is examined and the count is scaled up to the whole sample. Methods such as EPA's AHERA TEM method and ISO TEM standards specify the analytical sensitivity a lab must reach.

Significance in Asbestos Context

A result of "none detected" is only as meaningful as the sensitivity behind it. If a small volume of air was sampled or only a few grid openings were examined, a single structure could represent a fairly high concentration, so a non-detect would not rule out a real exposure. If a large volume was sampled and many openings were read, a non-detect means much more. Defendants sometimes present non-detect results to suggest a product released no asbestos; plaintiffs' experts check the analytical sensitivity and detection limit to see whether the test could have found the levels that matter. The same reasoning applies to dust and wipe samples. Reading a result properly means looking at both the count and the sensitivity, which should appear on the lab report.

Example Sentence

The report listed the air sample as none detected, but with an analytical sensitivity of 0.2 structures per cubic centimeter, it could not rule out an exposure at the current OSHA limit of 0.1 fibers per cubic centimeter.

Related Terms

Structure Counting, Transmission Electron Microscopy (TEM), AHERA TEM Method, PLM Detection Limit, Air Sampling, Fibers per Cubic Centimeter (f-cc), ISO 10312

Notes

• When a test says "none detected," ask what the analytical sensitivity or detection limit was.
• Keep full lab reports, including the sample volume and the area of filter examined.