When it comes to testing firefighter turnouts for contamination, which we outlined in part one, there are also limitations of the sampling itself. Testing turnout gear for contamination levels involves taking small samples from selected areas of the garment. These samples generally measure around 6" x 6" square.
Analyses are done on each of these individual samples, yielding separate findings which may not correspond to the findings from other squares.
The organization responsible for sampling must be judicious as to where the samples are taken from. Unless there is specific knowledge of where the chemical contact has occurred to the clothing, the laboratory will attempt to select sample areas that are most likely to have come in contact with the chemicals.
For example, coat sleeves and knee areas of pants are common sections of garments that might be contaminated. However, selected areas might not represent the area where contamination has actually occurred so some guesswork is required to be done during sampling.
Even when results are provided for analysis of specific samples taken from turnout gear, there can be some uncertainty as to how to interpret those results. The types of findings provided in analysis include the identification of a chemical and its concentration in the sampled section of the garment.
That concentration is usually reported as micrograms or nanograms, depending on the sensitivity of the analytical method for that particular chemical found in the solution that was used to extract a sample piece of material.
The background
To give some meaning to the concentration reported, there has to be an understanding for how much chemical could be harmful and how much chemical might be expected simply as background contamination from everyday wearing of the clothing.
This part of the analysis is most complicated because it requires expertise in evaluating how a particular chemical might be harmful. It is made more difficult because there are relatively few documented exposure limits for skin exposure to many chemicals.
Therefore, the general rule of thumb is to consider concentrations that are two or more times greater than background concentration as being significant and thus at undesirable levels. It is also important to pay attention to the specific nature and hazards of the chemical(s) involved.
Effective chemical analyses of turnout clothing materials also require testing fabrics that are not contaminated, but are representative of the gear’s relative condition.
These additional samples are useful for showing the background levels of certain types of contaminants. For example, there are many harmful metals that include substances like arsenic, chromium, lead, and mercury.
Surprisingly, very small levels of some of these metals may show up ordinarily in turnout clothing. Other elements such as calcium, magnesium, or sodium can be expected to show up relatively large quantities.
Therefore, getting a good background on the clothing assists in making the determination of whether certain substances are present at significant concentrations or not.
All chemical analyses, with the exception of some tests that can be done via water-based extraction, are destructive in nature. This is because portions of the outer shell, and sometimes underlying layers, must be removed and cut into sample size specimes.
The extraction step, in which the chemicals are removed from the material, involves subjecting the fabric swatches to some chemical solvent or an acid, which dramatically affects the material.
Weigh things up
Fire departments considering the testing of their turnout clothing should weigh the loss or sacrifice of a clothing item in making a decision as to whether analysis should be conducted. There may be circumstances in which limited sampling can be justified when it is a choice between disposing of several sets of gear versus getting a potential test result that shows the absence of contamination.
However, it must also be noted that the analysis of one single set of gear may or may not be representative of the presence of chemicals in other clothing, even when all of the clothing was worn at the same incident.
It is important for the fire service to realize that chemical testing of turnout gear for contamination levels is by no means foolproof.
For example, the samples analyzed might not be in the exact location of where the gear was contaminated. Further, the gear selected for analysis might not be the best set for representing an entire group of gear that is suspected of having been contaminated.
The specific chemicals of interest might not be captured in the analysis and background contamination levels may confuse the interpretation of results. Finally, and most importantly, it can be difficult to interpret the results with clear, conclusive information that enables an informed decision.
If you are a department that believes that a chemical analysis is necessary to help you decide whether your turnout clothing is safe or properly decontaminated, it is important to select a competent organization, which has the necessary expertise for interpreting chemical analysis results.
Many laboratories may be able to perform analyses but have little understanding of fire service responses. It is critical to the success of the organization’s investigation that you provide as much information as possible to focus the analysis on those contaminants that are likely to yield useful findings.
This information includes identification of possible suspected contaminants, how the exposure might have occurred, the activities of the responders at the emergency scene, the potential length of the exposure, and why you suspect that contamination is an issue.
As mentioned in an earrlier article, all fireground exposures are “mini” hazardous materials incidents, but the severity of exposures vary dramatically. Testing, if properly performed when appropriate, can provide valuable information.
