STUDIES ON THE PERMEABILITY OF THE SKIN TO MERCURY 98 •5. 'Effect of Aging Generally speaking, reassay of ointments after standing for months gave check results. In ointments containing lard, however, a measur- able increase in penetration of mer- cury was observed. The work of Menschel (10) indicates that inter- action between mercury and the lard base may take place with for- mation of mereuric oleate. Accord- ing •o our results, mercuric oleate gives by far the best penetration. In Table 14 are shown two assays of a lard containing calomel ointment, with an interval of 16 months inter- vening. It can be seen that after the prolonged contact between calo- mel an'd lard, significantly greater penetration of mercury occurred than (rom the freshly prepared ointment. By contrast no change occurred.in the petrolatum vehicle. TABLE 14--EFFECT oF A6tN6 ON THE PENE- TRATION OF MERCURY FROM TWO CALOMEL OINTMENTS The measure of penetration is the storage of mercury in the kidneys of the rat Micrograms Mercury per Gram of Wet Kidney Assayed Assayed After Immediately 16 Months 30% Calomel 70% Benzolin- atedlard 30% Calomel 70% Petrola- rum 11 17 5.6 5.5 The results are the averages of six animals on each treatment. SUMMARY A new method for determini.ng penetration of mercury through the skin has been worked out. This method depends on the principle that the quantity of mercury which accumulates in the kidney during a 24-hour cutaneous exposure to mer- cury is a measure of the penetration of this metal through the skin. The results of a study of a number of factors concerned in cutaneous pene- tration of mercury are as follows: 1. Covering the site of the skin inunction increases penetration nearly fourfold. 2. Lo(•ation of the inunction site appears to have no effect on penetration. 3. Penetration through the skin of the rat and rabbit is approxi- mately equal. 4. "Clean inuncti0n" reduces penetration. 5. Skin conditioning has no marked effect on penetration. 6. Adjustments of the size of the exposure area alie not critical for penetration. 7. Sex, litter, and weight have no significant'influence on penetra- tion. 8. The vehicle has the greatest influence on penetration, the com- pound of mercury less, and the con- centration of mercury least. 9. Reduction in the particle size of calomel i'ncreases penetration. 10. "Stiffening" of an ointment tends to reduce penetration. 11. The effectiveness of wetting agents in increasing penetration is dependent on the type of vehicle. 12. There is evidence to show that the aging of certain calomel ointments, notably those contain- ing lard, increases penetration.

94 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS BIBLIOGRAPHY 1. Cole, H. N., Schreiber, N., and Soil- mann, T., Arch. DermatoL and SyphiloL, 21,373 (1930). 2. Cole, H. N., DeWolf, H. F., Schreiber, N., Soilmann, T., and Cleve, J. V., Ibid., 27, 1 (1933). 3. Soilmann, T., Cole, H. N., and Schrei- ber, N. E., Ib/d., 32, 242 (1935). 4. Laug, E. P., J. Lab. and Clin. Med., 29, 308 (1944). 5. Laug, E. P., and Nelson, K. W., 2. Assoc. O•c. Agric. Chem., 25, 399 (1942). 6. Rothman, S., Arch. Dermatol. u. Syphi- lis, 131,549 (1921). 7. Cole, H. N., Gainreel, J. A., Rausch- kolb, J. E., Schreiber, N., and Soilmann, T., Arch. Dermatol. and SyphiloL, 17, 625 (1928). 8. Moncorps, C., Arch. f. Exper. Path. u. Pharmacol., 155, 51 (1930). 9. Dueruling, W. W, Arch. Dermatol. and Syphilol., 43, 264 (1941). 10. Menschel, H., Blochem. Ztschr.• 137, 193 (1923).