which at high concentrations are central nervous system (CNS) depressants and can produce anesthesia or asphyxia at high absorbed doses (Andrews and Snyder 1986; Marshall and Wollman 1985). The effectiveness of vapors as CNS depressants depends principally upon the volatility of their component hydrocarbons.
The Subcommittee on Permissible Exposure Levels for Military Fuels found that data on potential nervous system effects of jet fuels are sparse. In several Swedish studies conducted by Knave and his colleagues, acute CNS symptoms were reported in workers who were employed in jet factories where they were potentially exposed to jet fuels designated Jet A-1 and JP-1 (Knave et al. 1976, 1978, 1979). Industrial-hygiene measurements of up to 3,200 mg/m3 were reported for a variety of job activities. Although the one-time air measurements reflected various activities, the exposures were not well characterized over time or by individual.
In a study of 30 Swedish workers potentially exposed to jet fuels at a motor factory for an average of 17 years (yr), workers reported acute symptoms of exposure to vapors and performance degradation associated with long-term exposure (Knave et al. 1978). The study reported an approximate time-weighted average (TWA) of 300 mg/m3. The findings of performance degradation said to be attributable to long-term exposure were considered unreliable for a number of reasons, including weak and inconsistent evidence of impairment, inadequate methods of evaluation, inadequate consideration of confounding, a small cohort of workers, and a lack of quantitative information on exposure over time.
Acute exposure to jet fuels has been associated with neurologic effects in humans, including headache, nausea, vomiting, dizziness, fatigue, in coordination, irritability, problems with attention and memory, narcosis, and gait disturbances (Knave et al. 1976; Knave et al. 1978; Porter 1990; Anger and Storzbach 2001; Gibson et al. 2001b) (see Table 5-1). Persistent effects can include peripheral neuropathy and behavioral changes, such as reduced performance on tests of attention and psychomotor speed.
In a preliminary assessment of data, Anger and Storzbach (2001) reported significant behavioral disturbances characterized by impaired performance on digit-span (forward), digit-symbol, and finger-tapping tests among workers who had high JP-8 exposure at the beginning of their workshifts compared with workers who had no significant JP-8 exposure. Exposure was determined by median breathing-zone concentrations of two components of JP-8,