13

Conclusions and Recommendations

The American Conference of Governmental Industrial Hygienists has not recommended exposure limits for the military fuels that are the subject of this report. The Occupational Safety and Health Administration and other regulatory agencies also have not promulgated standards for these fuels.

The toxicity data on military fuels are sparse. No reliable information was found to indicate a need to change the Navy's proposed PEL of 350 mg/m3. The findings in Swedish jet-motor factory workers of chronic CNS effects—performance degradation and neurasthenic symptoms—attributable to long-term exposure to jet fuels at TWA concentrations of 300 mg/m3 were considered questionable for reasons discussed above. The studies of hepatotoxicity in experimental animals were also considered to be of questionable significance. The PEL of 500 mg/m3 was based on a slight increase in liver weight in rats—an effect that was reversible and not accompanied by any histopathological change. Based



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OCR for page 109
Permissible Exposure Levels for Selected Military Fuel Vapors 13 Conclusions and Recommendations The American Conference of Governmental Industrial Hygienists has not recommended exposure limits for the military fuels that are the subject of this report. The Occupational Safety and Health Administration and other regulatory agencies also have not promulgated standards for these fuels. The toxicity data on military fuels are sparse. No reliable information was found to indicate a need to change the Navy's proposed PEL of 350 mg/m3. The findings in Swedish jet-motor factory workers of chronic CNS effects—performance degradation and neurasthenic symptoms—attributable to long-term exposure to jet fuels at TWA concentrations of 300 mg/m3 were considered questionable for reasons discussed above. The studies of hepatotoxicity in experimental animals were also considered to be of questionable significance. The PEL of 500 mg/m3 was based on a slight increase in liver weight in rats—an effect that was reversible and not accompanied by any histopathological change. Based

OCR for page 109
Permissible Exposure Levels for Selected Military Fuel Vapors on the available information from studies in humans and animals and based on expert judgment, the subcommittee concludes that the Navy board's 8-hr PEL of 350 mg/m3 for JP-5, JP-8, and DFM is adequate to protect the health of naval personnel occupationally exposed to military fuels. Due to the uncertainty surrounding (1) the CNS effects observed in Swedish jet-motor factory workers from chronic exposure to jet fuel at TWA concentrations of 300 mg/m3 and (2) the NOAEL of 500 mg/m 3 derived from liver toxicity studies in rats and mice, the subcommittee recommends that the PEL of 350 mg/m3 be considered interim until further research is completed. Data needed to evaluate the adequacy of the Navy's 15-min STEL of 1,800 mg/m3 for the three fuels are sparse. The subcommittee considered the acute CNS effects (e.g., dizziness, headache, nausea, and fatigue) in the Swedish jet-motor factory workers to be the most critical health effects for determining the adequacy of the STELs. Based on the limited information on exposure concentrations and the attribution of CNS symptoms to peak exposures of approximately 1,000 mg/m3 or higher, the subcommittee recommends that the Navy's current STEL be lowered from 1,800 mg/m3 to 1,000 mg/m3 to avoid acute CNS toxicity. The STEL of 1,000 mg/m3 should also be considered an interim recommendation until further research is completed. The subcommittee also recommends the following: Appropriate protective clothing should be worn to reduce dermal exposure because of the evidence of the carcinogenic potential of DFM via the dermal route. Because respirable aerosols of military fuels are much more toxic than vapors, naval personnel should avoid exposure to aerosolized fuel. If a potential for exposure to aerosolized fuel exists, protective clothing and respiratory equipment should be worn. The Navy should complete the following research to improve its ability to assess the health risks associated with the use of military fuels:

OCR for page 109
Permissible Exposure Levels for Selected Military Fuel Vapors Obtain information on exposures occurring during operational procedures, including exposures to respirable aerosols of unburned fuels. Samples should be taken in the breathing zone of the service personnel. Breath analysis of exposed personnel is recommended to determine the extent of individual exposures to fuel vapors. Conduct studies on the possible effects of high-level acute and low-level chronic exposure to military fuel vapors on the CNS, including the effects on the performance of personnel. At present, very little information exists. Anecdotal accounts do not provide adequate documentation of exposures leading to reduced performance. Conduct further research on the effect of military fuel vapors on hepatotoxicity in experimental animals; this research would help to identify the NOAEL with greater confidence