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Camphor, menthol, and methyl salicylate occur in numerous over-the-counter products. Although extensively used, there have been no estimates of human exposure following administration via dermal application. Furthermore, there is little information about the pharmacokinetics of those compounds. The authors report the plasma concentrations of the intact compounds as a function of dose following dermal patch application. Three groups of 8 subjects (4 male, 4 female) applied a different number of commercial patches (2, 4, or 8) to the skin for 8 hours. Plasma samples were assayed using sensitive and selective gas-chromatographic methods. For the 8-patch group, the average maximum plasma concentrations (Cmax +/- SD) were 41.0 +/- 5.8 ng/mL, 31.9 +/- 8.8 ng/mL, and 29.5 +/- 10.5 ng/mL for camphor, menthol, and methyl salicylate, respectively. The corresponding values for the 4-patch group were 26.8 +/- 7.2 ng/mL, 19.0 +/- 5.4 ng/mL, and 16.8 +/- 6.8 ng/mL. The harmonic mean terminal half-lives were 5.6 +/- 1.3 hours, 4.7 +/- 1.6 hours, and 3.0 +/- 1.2 hours for camphor, menthol, and methyl salicylate, respectively. The 2-patch group had measurable but low plasma concentrations of each compound. Low-dose dermal application for an extended time results in low plasma concentrations of all 3 compounds. Four and 8 patches, when applied for 8 hours, gave measurable and nearly proportional plasma concentrations. Although unable to determine the absolute dermal bioavailability of these compounds, there appears to be relatively low systemic exposure to these potentially toxic compounds, even when an unrealistically large number of patches are applied for an unusually long time.

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Seven simulated eyes with varying pupil size to eye ratios were tested for their effects on the duration of tonic immobility. A pair of eyes with a ratio of approximately 11/20 mm was the only configuration which produced reliable increases in response duration. The results were discussed as they relate to the possible role of eye contact in predator-prey encounters.Tonic immobility (TI) appears to function as the terminal response in a series of distance-dependent predator defenses (Ratner, 1967; Sargeant & Eberhardt, 1975). The response, which is produced by some form of physical restraint, occurs in a wide variety of species and is characterized by a catatonic-like state of physical immobility and muscle hypertonicity. Attempts to produce TI in the laboratory eventuate in immobility episodes that vary in duration from a few seconds to several hours.Among the most potent agents for increasing the duration of TI are stimuli which are thought to produce fear (Gallup, 1974). Prominent in this list are stimulus characteristics of potential predators. In a series of studies, it has been shown that (a) the opportunity to view a stuffed hawk or a human experimenter increases the duration of TI in chickens (Gallup, Cummings, & Nash, 1972;Gallup, Nash, Donegan, & McClure, 1971) and lizards (Edson & Gallup, 1972; Gallup, 1973), and that (b) the effects of simulated predation on TI are due almost exclUSively to the visibility of the predator's eyes. Of such singular importance are eyes in sustaining TI that merely suspending artificial glass eyes over immobilized chickens (Gallup, Nash, & Ellison, 1971) or crabs (O'Brien & Dunlap, 1975) results in a marked increase in response duration.The preceding findings, when considered together, strongly suggest that eye contact plays a powerful and fundamental role in the maintenance of tonic immobility. A logical next step would be an attempt to determine which feature(s) of such eyes is critical for sustaining the reaction. 0 'Brien and Dunlap (1975) found that artificial eyes potentiated TI in crabs, but eyes of different sizes all yielded comparable effects. One likely candidate for remaining investigation is the size of the pupil relative to the rest of the eye.Requests for reprints should be sent to G. G. Gallup, Jr., Department of Psychology, State University of New York at Albany, Albany, New York 12222. METHOD SubjectsThe subjects were 86 straight-run, Production Red chickens (Gallus gallus) obtained from a local hatchery at 1-2 days of age. All birds were housed in commercial brooders and maintained on artificial light for 14 h/day . Purina Chick Chow (Growena) and water were continuously available during rearing. ApparatusThe apparatus consisted of an upright stand, fitted with a pair of 1.27-cm wooden dowels which could be suspended over an immobilized bird. Small magnets were attached to the ends of the dowels and provided a means by which stimulus materials could be attached and replaced.The stimulus materials consisted of seven pairs of circular paper eyespo...