End point/Concentration/Rationale: Absence of mortality.
Uncertainty factors/Rationale:
Total uncertainty factor: 10
Interspecies: 3
Intraspecies: 3
A total uncertainty factor of 10 was considered sufficient because the effects are attributed to n-hexane itself and no relevant differences in kinetics are assumed. Mortality from n-hexane exposure is preceded by CNS depression, and variation in susceptibility for CNS-depressing effects is not very great in the human population.
Modifying factor: None
Animal-to-human dosimetric adjustment: Not applicable
Time scaling: Because a steady-state blood concentration will be reached within 30 min of exposure, no increase in effect-size by exposure duration is expected from 30 min to 8 h. Therefore, the AEGL-3 values for the 1-h, 4-h, and 8-h durations are set equal to the 30-min AEGL-3 value. The 10-min AEGL-3 value was derived from the 30-min AEGL-3 value by time-scaling using the equation Cn × t = k, with n = 3.
Data adequacy: The database is very poor. Available data for derivation of AEGL-3 values were predominantly from toxicokinetics studies. Adequate toxicity studies are lacking.

aThe 10-min AEGL-3 value of 12,000 ppm (42,240 mg/m3) is higher than the lower explosive limit of n-hexane in air of 1.1% (11,000 ppm). Therefore, extreme safety considerations against the hazard of explosion must be taken into account.

bThe AEGL-3 values for the 30-min, 1-h, 4-h, and 8-h durations are each 8,600 ppm (30,000 mg/m3), which is higher than 50% of the lower explosive limit of n-hexane in air of 1.1% (11,000 ppm). Therefore, extreme safety considerations against the hazard of explosion must be taken into account.



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