The influence of pH on the in vitro permeation of rhodium through human skin.
Workers in precious metals refineries are at risk of exposure to salt compounds of the platinum group metals through inhalation, as well as through the skin. Rhodium salt permeation through the skin has previously been proven using rhodium trichloride (RhCl3) dissolved in synthetic sweat at a pH of 6.5. However, the skin surface pH of refinery workers may be lower than 6.5. The aim of this study was to investigate the influence of pH 6.5 and 4.5 on the in vitro permeation of rhodium through intact Caucasian skin using Franz diffusion cells. A concentration of 0.3 mg mL-1rhodium was used and analyses were performed using inductively coupled plasma mass spectrometry and inductively coupled plasma optical emission spectrometry. Results indicated a cumulative increase in permeation over 24 h. Rhodium permeation after 12 h was significantly greater at pH 4.5 (1.56 ± 0.24 ng cm-2) than at 6.5 (0.85 ± 0.13 ng cm-2; p = 0.02). At both pH levels, there was a highly significant difference ( p < 0.01) between the mass of rhodium remaining in the skin (1428.68 ± 224.67 ng cm-2at pH 4.5 and 1029.90 ± 115.96 ng cm-2at pH 6.5) and the mass that diffused through (0.88 ± 0.17 ng cm-2at pH 4.5 and 0.62 ± 0.10 ng cm-2at pH 6.5). From these findings, it is evident that an acidic working environment or low skin surface pH may enhance permeation of rhodium salts, contributing to sensitization and adverse health effects.
1 Occupational Hygiene and Health Research Initiative, North-West University, Potchefstroom, South Africa.
Sané
S
Jansen Van Rensburg
1 Occupational Hygiene and Health Research Initiative, North-West University, Potchefstroom, South Africa.
Anja
A
Franken
2 Centre of Excellence for Pharmaceutical Sciences, North-West University, Potchefstroom, South Africa.
Jeanetta
J
Du Plessis
1 Occupational Hygiene and Health Research Initiative, North-West University, Potchefstroom, South Africa.
Johannes Lodewykus
JL
Du Plessis
D000328:Adult; D004781:Environmental Exposure; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D012238:Rhodium / Q000378:metabolism*; D012867:Skin / Q000187:drug effects / Q000378:metabolism; D012869:Skin Absorption / Q000187:drug effects*; D044465:White People
D012238:Rhodium
Franz diffusion cells; occupational health; permeability; platinum group metals; rhodium trichloride