Dermal absorption anatomical site

The skin is a complex multilayered tissue with a large surface area exposed to the environment. Skin anatomy, physiology, and biochemistry vary among species, within species, and even between anatomic sites within an individual animal or human. Logically these biological factors alone can influence dermal absorption. What is consistent is that the outer layer, the stratum corneum (SC), can provide as much as 80% of the resistance to absorption to most ions as well as aqueous solutions. However, the skin is permeable to many toxicants, and dermal exposure to agricultural pesticides and industrial solvent can result in severe systemic toxicity. 

FACTORS INFLUENCING DERMAL ABSORPTION 319 Factors Related to the Skin 319 Intraspecies Differences 319 Inter-individual Differences 319 Skin Condition 319 Anatomical Site 320 Skin Metabolism 320... 

This chapter provides an overview of factors affecting dermal absorption. Factors influencing absorption are among others related to the skin (e.g. anatomical site, difference between species, metabolism, etc.) and the exposure conditions (e.g. area dose, vehicle, occlusion and exposure duration). In order to provide relevant information for the risk assessment of pesticides, dermal absorption studies should take these aspects into account. With respect to the methods being used nowadays for the assessment of dermal absorption, it is important to realize that neither in vitro nor in vivo animal studies have been formally validated. Available data from various in vitro studies, however, indicate that the use of the total absorbed dose (i.e. the amount of test substance in the receptor medium plus amount in the skin) could be used in a quantitative manner in risk assessment. Tape stripping of the skin can be adequate to give a good indication of test chemical distribution, and hence its immediate bioavailability. 

Viau and Vyskocil 1995). Van Rooij et al. (1993a) examined differences in the absorption of PAH between anatomical sites and individuals following dermal exposure of volunteers to 10% coal tar in a vehicle of zinc oxide paste. The surface disappearance of PAH and the excretion of urinary 1-hydroxypyrene after coal tar application were used to assess dermal absorption following controlled... 

Moody. R. P.. and Ritter, L. (1989). Dermal absorption of the insecticide lindane (la, 2a. 3b. 4a. 5a. 6b-hexachlorocyclo-hexane) in rats and rhesus monkeys Effect of anatomical. site, J. Toxicol. Environ. Health 28, 161-169. 

Lipohypertrophy is the result of repeated insulin injection into the same site. Insulin hypertrophy (lipohypertrophy) occurs as a soft dermal nodule with normal surface epidermis at the injection site, which has often been used for many years. This reaction may be due to the lipogenic action of insulin. This condition may be avoided by rotating the injection site, although it should be remembered that absorption of insulin may vary from different anatomical areas. 

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