Sara Jahnke Sponsored by Fire-Dex
The increased risks of several types of cancer are well recognized throughout the fire service. Carcinogens as byproducts of combustion enter firefighters’ skin through PPE penetration, cross transfer from PPE to the skin, inhalation in the environment and gear off-gassing. This has become even more hazardous with the increasing use of synthetic materials in home furnishings and buildings.
It has been suggested that gross decon – cleaning gear on the fireground – may be an effective way to decrease carcinogen exposure for firefighters. However, little is known about how effective the practice is, so the question has remained: does gross decon work?
The short answer is yes.
The longer answer, and the data behind it, can be found in a recently released study in the Journal of Occupational and Environmental Hygiene by Dr. Kenneth Fent and colleagues. Their work was sponsored by the Assistance to Firefighter Grants Research and Development program in collaboration with the CDC.
Measuring carcinogen exposure
To study the question, the team burned 12 fully furnished residential structures. Each was 111 square meters with two bedrooms. They rotated firefighters through different tasks: outside command/pump operations, inside attack/search and rescue, and overhaul.
Firefighters were fully outfitted in PPE. They were instructed to use their SCBAs while fighting interior fire and to use their SCBAs outside as they typically would on the fireground.
The fires in each structure were allowed to burn until they flashed over (typically 4-5 minutes), before the firefighters were dispatched to respond.
Scientists tested both skin and surfaces for polycyclic aromatic hydrocarbons (PAHs) and then looked for volatile organic compounds (VOCs) and hydrogen cyanide (HCN) in gases and vapors.
Three types of gross decon were studied:
- Dry brush,
- Air-based (a modified leaf blower was used to blow off contaminants) and
- Dish soap/water with a brush.
They found that wet-soap decon was the most effective as it decreased contamination by 85 percent. Dry brush decon was the second most effective, decreasing contamination by 23 percent. The air-based decon was the least effective with a reduction of just 0.5 percent in contaminants.
To study skin exposure, cleansing wipes were used to clean the neck and hands ahead of time and testing was performed. After the fire, hands and the right side of the neck were tested.
Scientists found that PAHs were more frequently detected on the hands (76 percent) than the neck (41 percent). For firefighters completing interior attacks, levels of PAHs on the hands were up to four times levels found on the neck. Those completing search and rescue were also found to have significantly higher hand exposures than those just completing an interior attack.
For those conducting outside vent work, detectable PAH levels on the neck were found on 58 percent of firefighters. For firefighters in that position, post fire PAH levels were three times the levels on their hands. It is likely that those working outside are less likely to be wearing their hoods.
Field decon and off-gassing
To test the effectiveness of cleansing wipes, firefighters were instructed to clean their head and necks, and then the left side of the neck was tested. Results indicate that use of cleansing wipes reduced the PAH levels by 54 percent.
After fires, six sets of gear were placed in a 7.1 cubic meter enclosure intended to represent the typical volume of a fire truck cab. After 15 minutes (which was used to represent the average amount of time driving back to the station), testing was performed for VOCs and HCN. Half the gear was removed and decontaminated, and then it was returned for additional monitoring.
It was found that, while decon is effective at decreasing PAH contamination, field decon had no apparent effect on the concentrations of VOCs that off-gas from gear. While not a focus of the study, Dr. Fent and colleagues note that, “Because soot can be composed of semi-volatile compounds or act as a sorbent for other organic substances, field decontamination could conceivably help reduce the levels of off-gassing semi-volatile compounds.” While semi-volatile compounds were not measured in the current study, it is a hypothesis that needs further evaluation.
With all studies, there are limitations to the questions asked and the ones answered. Clearly the researchers were not able to evaluate every chemical combination and the carcinogens present were limited by what materials were used and the size of the room. They were also limited by the chemical collection techniques used. The authors indicate that they believe their measurements likely underestimate the exposures firefighters face, though what was measured presents compelling findings on its own.
Top firefighter takeaways on gross decon
The best takeaways from the findings for firefighters are these:
- Wash gear on the fireground: Washing gear on the fireground with soap and water is an effective way to decontaminate gear. Research is currently ongoing about the effectiveness of on-scene washing compared to NFPA-compliant commercial extractors but, in the mean-time, gross decon on scene is an effective measure to use in conjunction with more advanced options.
- Wipes are effective, but don't replace shower: Wipes also appear to be an effective tool for decontamination and removal of PAHs from the neck area, but cannot replace a shower. A thorough shower and hand washing should be conducted as soon as possible after an incident.
- Exposures happen anywhere on the fireground: Exposures can occur even during an exterior attack and efforts should be made for even those doing an exterior attack to keep their hoods on.
- Reducing exposure starts with prevention: Reducing exposure to carcinogens is not going to occur with any one method. Prevention has to be an ongoing effort on every scene.
More research to come.