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New study assesses effectiveness of decon to reduce exposure to PAHs

Feb. 27, 2023, Canada – A new study based on live fire training shows skin decontamination methods vary in their effectiveness to reduce internal PAHs in firefighters.

From the Journal of Occupational and Environmental Hygiene, the study, called “Effectiveness of dermal cleaning interventions for reducing firefighter’s exposures to polycyclic aromatic hydrocarbons (PAHs) and genotoxins” investigated which method of dermal cleaning PAHs would be most effective out of four post-fire cleansing methods.

“Firefighters are exposed to PAHs through their skin, post-exposure removal of dermally deposited PAHs could potentially reduce overall exposure and internal dose,” the study reported. “As such, dermal decontamination has been suggested as an effective means of removing PAHs deposited on skin.”

Researchers recruited firefighters from the Ottawa Fire Service and the Canadian Armed Forces to participate in the study. Firefighters were randomly assigned to one of four post-fire decontamination methods on the day of sampling with a minimum of four participants recruited per fire. These methods included one of two commercial wipes, detergent and water and a control group where no dermal cleaning was conducted.

Sampling was conducted during particle board training fires in modified shipping containers. Samples were collected from 88 firefighters – six female, 82 male – during 21 training fires held on eight days between October 2018 and November 2019.

On the day of sampling, firefighters were randomly assigned to one of the four post-decontamination methods.

Skin wipe, air and urine samples were taken before and after each fire as a method of control and analysis.

The sampling process saw instructors near the fire at one end of the shipping container, controlling the fire’s growth. The other firefighters were in groups of six to eight in the same container in a static position, moving occasionally in a circular pattern to take turns applying water on the fire with a nozzle.

Activity, fuel load, and conditions were identical for all fires to ensure equivalent exposure.

The results of the sample studies were broken down by method: skin wipe, air and urine.

Skin wipe samples results saw participants who used detergent remove the most PAHs, deeming it the most effective in terms of this study. Data showed decreases in all 14 individuals’ PAHs with reportable levels observed, 10 of them decreased significantly and 6 significantly lower than the control group. Researchers noted that this could be attributed to one of three factors: to the concoction being most effective, the vehicle (wash cloth) being most effective or the familiarity of the process being the reason this method was most effective at removing PAHs from the skin.

Air samples of PAH air concentrations during fires provided a snapshot of the environment firefighters were exposed to during the training exercises. Twenty-seven personal air samples were collected. The average duration of these samples was 43.9 minutes. Researchers reported higher proportions of possible carcinogenic PAHs (77 per cent versus 51 per cent).

Researchers explained the difference could be due to “a result of fuel difference.”

“Training fires utilize a single fuel type, whereas emergency fires are composed of multiple fuel types and complex mixtures. This is consistent with a study by Banks et al. (2021) that presented data indicating higher proportions of possible and probable carcinogenic PAHs in personal air from fires with different fuels (i.e., particleboard fires vs. diesel pan fires), calculated using their reported data.”

Urine analysis found that post-fire dermal decontamination efforts occur too late to prevent absorption into the body, citing “a lack of difference between urinary OAH metabolite increases between intervention groups and the control group show that the post-fire dermal cleaning steps did not have a measurable effect on the internal dose of PAHs that firefighters received during the live fire training exercise.”

Researchers suggest that future studies should focus on “preventing initial exposure through improved compliances in use and quality of personal protective equipment to prevent a combustion by-product onto skin.”