Relative absorption and dermal loading of chemical substances: Consequences for risk assessment.
Quantification of skin absorption is an essential step in reducing the uncertainty of dermal risk assessment. Data from literature indicate that the relative dermal absorption of substances is dependent on dermal loading. Therefore, an internal exposure calculated with absorption data determined at a dermal loading not comparable to the actual loading may lead to a wrong assessment of the actual health risk. To investigate the relationship between dermal loading and relative absorption in a quantitative manner, 138 dermal publicly available absorption experiments with 98 substances were evaluated (87 in vitro, 51 in vivo; molecular weight between 40 and 950, logP between -5 and 13), with dermal loading ranging mostly between 0.001 and 10mg/cm(2). In 87 experiments (63%) an inverse relationship was observed between relative dermal absorption and dermal loading, with an average decrease of factor 33+/-69. Known skin irritating and volatile substances less frequently showed an inverse relationship between dermal loading and relative absorption.
Buist
Harrie E
HE
Department of Food & Chemical Risk Analysis, TNO Quality of Life, P.O. Box 360, Utrechtseweg 48, 3700 AJ Zeist, The Netherlands. harrie.buist@tno.nl
Schaafsma
Gerwin
G
van de Sandt
Johannes J M
JJ
D000818:Animals; D006801:Humans; D007287:Inorganic Chemicals / Q000493:pharmacokinetics / Q000633:toxicity; D009930:Organic Chemicals / Q000493:pharmacokinetics / Q000633:toxicity; D018570:Risk Assessment; D012869:Skin Absorption; D023422:Skin Irritancy Tests / Q000379:methods*
D007287:Inorganic Chemicals; D009930:Organic Chemicals