Although major route of absorption for benzidine and benzidine dihydrochloride are known to be skin, the skin penetration rates for benzidine and benzidine dihydrochloride are not known well at all. In order to provide basic data on effective management for worker's health and workplace environment, we used the skin of Sprague Dawley rat to obtain the skin penetration rates for benzidine and benzidine dihydrochloride, and studied the possibility of the skin penetration for Direct Black 38.
The penetration rates of benzidine at 250, 500 and 1000㎍/㎖ were 15.57㎍/Hr/㎤(84.49 nmole/hr/㎤), 29.47 ㎍/hr/㎤ (159.96nmole/hr㎤), and 47.12 ㎍/hr/㎤ (255.77nmole/hr/㎤) respectively. The penetration rates of benzidine showed a concentration dependent increase, and from 22.92 to 30.76% of total benzidive penetrated within 12 hours. The penetration rates of benzidine dihydrochloride at 250, 500, 1000㎍/㎖ were 8.92 ㎍/hr/㎤ (20.22 nmole/hr/㎤), 9.64 ㎍/hr/㎤(21.85 nmole/hr/㎤), and 10.22 ㎍/hr/㎤ (23.15 nmole/hr/㎤) respectively. The penetration rates of benzidine dihydrochloride did not show a concentration dependent increase as show in benzidine. Because benzidine is more lipid soluble but benzidine dihydrochloride is more water soluble, benzidine is absorbed more rapidly than benzidine dihydrochloride. The reduction of benzidine dyes to benzidine has been known to be possible in an anaerobic condition only. The skin penetration of benzidine dye might be impossible because of the aerobic nature of skin. Further studies on the possibility of skin penetration of benzidine dye be needed.