Cholinesterase Inhibition and Exposure to Organophosphate Esters in Aircraft Maintenance Workers

Abstract

INTRODUCTION: Aircraft maintenance workers may be exposed to organophosphates in hydraulic fluid and engine oil. Previous research has indicated that inhalation may not be the primary exposure route. This study sought to measure dermal contact and inhalation in conjunction with cholinesterase inhibition and determine if Air Force Specialty Code serves as an exposure predictor.METHODS: Aircraft maintenance workers were sampled for changes in acetylcholinesterase and butyrylcholinesterase. Dermal contact was measured using wrist-worn silicone passive dosimeters and inhalation exposure was measured using thermal desorption tube air sampling.RESULTS: Overall prevalence of any cholinesterase inhibition in the study population was 25.33%. Prevalence of inhibition of acetylcholinesterase and butyrylcholinesterase was 18.67% and 6.67%, respectively. The mean tributyl phosphate result was 1.71 ng of tributyl phosphate per gram of wristband (ng g1) [95% confidence interval (CI): 5.63, 9.05]. Triphenyl phosphate was more prevalent, with only one sample below the limit of detection (mean 1386.26 ng g1; 95% CI: 7297.78, 10,070.31), and tricresyl phosphate was found in every sample (mean 4311.65 ng g1; 95% CI: 8890.24, 17,512.31). No organophosphates were detected via air sampling.DISCUSSION: Workers experienced organophosphate exposure and cholinesterase inhibition, but the study was not large enough to establish a statistically significant association between exposure and disease. Exposure to organophosphate esters is more likely to occur through contact and absorption of chemicals through the skin than through inhalation of oil mists. Air Force Specialty Code does not appear to be a good predictor of exposure to organophosphates. Future studies should consider using a larger sample size.Hardos JE, Rubenstein M, Pfahler S, Sleight T. Cholinesterase inhibition and exposure to organophosphate esters in aircraft maintenance workers. Aerosp Med Hum Perform. 2020; 91(9):710714.

Comparative Assessment of Pesticide Exposures in Domestic Dogs and Their Owners Using Silicone Passive Samplers and Biomonitoring

“…Silicone samplers are being used increasingly as passive monitoring devices for assessing multipollutant exposures in a variety of settings including occupational, − vulnerable populations (such as children − and pregnant women , ), pet cats and dogs, beehives, wild frogs, and their habitats . Furthermore, previous studies have demonstrated that chemicals measured on wristbands are significantly associated with human and canine exposure biomarkers, reinforcing their utility. ,,,,, Silicone wristbands are a useful tool for investigating personal exposures that occur via inhalation and through dermal routes .…”

Occupational exposure and markers of genetic damage, systemic inflammation and lung function: a Danish cross-sectional study among air force personnel

“…In our study, the TPHP median levels for crew chiefs were 434 ng/g normalized for 24 h with maximum level of 2584 ng/g per 24 h (corresponding to approximately median levels of 2300 ng/band and maximum level of 13,700 ng/band with equivalent band weights in both studies), which is considerably higher taking the shorter sampling period into account (1 day vs 5 days), in turn suggesting occupational exposure. A recent study investigated OPEs levels among US military aircraft maintainers, also using silicone bands as passive samplers, measuring an average of 1.67 ng/g of TNBP, 832.4 ng/g of TPHP, and 2352.1 ng/g of TMPP for a shift work of crew chiefs (n = 14) 29 , 30 , showing a similar trend in prevalence and level as the crew chiefs in our study (mean exposure levels were 49 ng/g TNBP, 622 ng/g TPHP and 959 ng/g TMPP, respectively). However, in the Hardos et al report, crew chief was not the job function with the highest mean levels for any of these three OPEs assessed, since aerospace propulsion, fuel system repair and avionics presented higher or equivalent mean levels for each of the OPEs 29 .…”

“…However, in the Hardos et al report, crew chief was not the job function with the highest mean levels for any of these three OPEs assessed, since aerospace propulsion, fuel system repair and avionics presented higher or equivalent mean levels for each of the OPEs 29 . Overall, Hardos et al suggested that the use of job functional career code system for aircraft maintenance employees was not a good predictor of exposure 30 .…”

Silicone wristbands as personal passive sampling devices: Current knowledge, recommendations for use, and future directions

“…Lastly, significant positive and negative associations existed between several PBDEs, and NFRs concentration and free thyroxine (FT4), free triiodothyronine (FT3), and thyroid-stimulating hormone (TSH) ( Wang et al, 2020 ). Two other studies focused on occupational exposure of aircraft workers, which included evaluating the association between OPE exposure with cholinesterase inhibition ( Hardos et al, 2020 ), and evaluating OPE as well as PAH exposure on lung function, systemic inflammation, and genetic damage ( Andersen et al, 2021 ); but in both instances significant associations were not seen.…”

“…Multiple studies demonstrated the usefulness on using silicone wristbands to assess exposure both in rural setting ( Varnell et al, 2021 ; Vidi et al, 2017 ) and in children ( Lipscomb et al, 2017 ; Vidi et al, 2017 ). Additionally, silicone wristbands have been successful exposure assessment tools when deployed only in occupational settings ( Varnell et al, 2021 ; Andersen et al, 2021 ; Hardos et al, 2020 ) and have demonstrated the relationship between occupational exposure to environmental contaminants and adverse health outcomes ( Varnell et al, 2021 ). If silicone wristbands are deployed only while an individual is in an occupational setting, occupational exposure can be separated from total exposure.…”