Human-skin

What is the critical surface tension for human skin Look up any necessary data and make a Zisman plot of contact angle on skin versus surface tension of water-alcohol mixtures. (Note Ref. 136.)... 

Plenary 79. FI G M Edwards, e-mail address h.g.m.edwards bradford.ac.uk (NIR-FTRS). A review of recent applications of RS to archeology—characterizing ancient pigments, human skin, bone, ivories, teeth, resins, waxes and gums. Aging effects and dating possibilities. Emphasizes use of microscopic Raman. 

The HYBOT descriptors were successfully applied to the prediction of the partition coefficient log P (>i--octanol/water) for small organic componnds with one acceptor group from their calculated polarizabilities and the free energy acceptor factor C, as well as properties like solubility log S, the permeability of drugs (Caco-2, human skin), and for the modeling of biological activities. 

Primary human skin irritation of tetradecanol, hexadecanol, and octadecanol is nil they have been used for many years ia cosmetic creams and ointments (24). Based on human testing and iudustrial experience, the linear, even carbon number alcohols of 6—18 carbon atoms are not human skin sensitizers, nor are the 7-, 9- and 11-carbon alcohols and 2-ethylhexanol. Neither has iudustrial handling of other branched alcohols led to skin problems. Inhalation hazard, further mitigated by the low vapor pressure of these alcohols, is slight. Sustained breathing of alcohol vapor or mist should be avoided, however, as aspiration hazards have been reported (25). 

Aromatic Hydrocarbons. These are the most toxic of the hydrocarbons and inhalation of the vapor can cause acute intoxication. Benzene is particularly toxic and long-term exposure can cause anemia and leukopenia, even with concentrations too low for detection by odor or simple instmments. The currendy acceptable average vapor concentration for benzene is no more than 1 ppm. PolycycHc aromatics are not sufftcientiy volatile to present a threat by inhalation (except from pyrolysis of tobacco), but it is known that certain industrial products, such as coal tar, are rich in polycycHc aromatics and continued exposure of human skin to these products results in cancer. 

Leather technologists have adopted the same histological techniques for the study of hide and skin stmcture as that used by the medical profession for the study of the stmcture and functions of human skin (1,2). 

Contact with elemental selenium does not injure the skin. Selenium dioxide, however, upon contact with water, sweat, or tears, forms selenous acid, a severe skin irritant. Selenium oxyhaHdes are extremely vesicant and cause bums when in contact with human skin (91,92). Hydrogen selenide affects the mucous membranes of the upper respiratory tract and the eyes (93). 

Some skin sensitization to low molecular-weight DGEBPA resins (mol wt - 340) has been shown in animals and humans. Skin sensitization decreases with an increase in molecular weight but the presence of low molecular-weight fractions in the advanced resins may present a hazard to skin sensitization (43). 

Kraeling, M. E. K., Reddy, K., and Bronaugh, R, T. (1998). Percuraneous absorption of trim rrobenzene animal models for human skin. /. Appl. Toxicol. 18, 387-392. 

Plutonium has a much shorter half-life than uranium (24.000 years for Pu-239 6,500 years for Pu-240). Plutonium is most toxic if it is inhaled. The radioactive decay that plutonium undergoes (alpha decay) is of little external consequence, since the alpha particles are blocked by human skin and travel only a few inches. If inhaled, however, the soft tissue of the lungs will suffer an internal dose of radiation. Particles may also enter the blood stream and irradiate other parts of the body. The safest way to handle plutonium is in its plutonium dioxide (PuOj) form because PuOj is virtually insoluble inside the human body, gi eatly reducing the risk of internal contamination. 

After WWI, Babcock (Ref 2) patented a mixt similar to Parazol for use m military expls. PA can be incorporated in such mixts Toxicity. The crude material is more toxic than the purified. The crude material, when applied to the human skin for 2 hours, produced hyperemia and finally small vesicles, which developed into blisters contg. a clear fluid after 48 hours. After 4 days, the latter started to heal. The dust and fumes were also toxic, and the irritant action of the fumes increased with temp (Ref 5)... 

Human skin compatibility has a high priority in manual dishwashing detergents. Recently, it was shown that there are some new possibilities to lower the Zein number by intelligent formulations. The Zein number is a common measure of the denaturation of protein under controlled conditions [84], A better... 

Alcohol and alcohol ether sulfates have also been studied to determine their toxicity by percutaneous absorption in rats and guinea pigs [354-356]. Alcohol ether sulfates penetrate in the order of 1 ng/cm2/day and alcohol sulfates are less penetrant by a factor of 10. The surfactant absorbed was metabolized. Since it is known that human skin is less permeable than animal skin, only very small amounts of alcohol or alcohol ether sulfates can be absorbed even in the case of complete body exposure. 

AOS is milder to the human skin than, for example, LAS or alcohol sulfate [145]. Safety information on AOS has been amassed and reviewed by consultants on behalf of the U.S. Soap and Detergents Association [146]. Their conclusion is that AOS, when manufactured under well-defined conditions, is entirely safe for use in household products and toiletries. 

Generally speaking, up to now the importance of a-sulfo fatty acid esters in cosmetic products has been low [1 p. 367], In the future they may become more interesting because of their mildness. a-Sulfomethyl laurate and most other ester sulfonates are mild to the skin also, they are not human skin sensitizers or primary skin irritants. Tests have shown that a-sulfomethyl laurate is mild enough to be in bath products, such as bubble bath [62]. Three patents for different applications are given to show how ester sulfonates can be used in cosmetics. 

Group 3 not classifiable as to its carcinogenicity to humans Skin notation danger of outaneous absorption A4 not classifiable as a human carcinogen... 

Sartorelli P, Aprea C, Bussani R, et al. 1997. In vitro percutaneous penetration of methyl-parathion from a commercial formulation through the human skin. Occup Environ Med 54 524-525. 

The absorption of glycolic acid in human skin is pH-, strength- and time-dependent. Seventy percent glycolic acid solutions are commonly... 

Bernstein EF, Lee J, Brown DB, Yu R, Van Scott E (2001) Glycolic acid treatment increases type I collagen mRNA and hyaluronic acid content of human skin. Dermatol Surg 27(5) 429-433... 

Moy LS, Peace S, Moy RL (1996) Comparison of the effect of various chemical peeling agents in a mini pig model. Dermatol Surg 22 429-432 Seitz JC, Whitemore CG (1988) Measurement of erythema and tanning response in human skin using a Tri-Stimulus colorimeter. Dermatologica 177 70-75... 

Kligman AM, Willis I (1975) A new formula for depig-menting human skin. Arch Dermatol 111 40-48... 

Kang et al. [23] compared the clinical, histologic, and molecular responses of normal human skin to topical retinol with that of retinoic acid. Application of retinol and retinoic acid produced epidermal thickening. However, retinol produced less erythema compared with retinoic acid. The authors suggest that these data are compatible with the idea that retinol may he a pro-hormone of retinoic acid. 

Azelaic acid is a naturally occurring dicarboxyl-ic acid (1,7-heptanedicarboxylic acid) that has demonstrated beneficial therapeutic effects in the treatment of acne and several disorders of hyperpigmentation [48]. There are minimal effects on normally pigmented human skin, freckles, senile lentigines, and nevi. The cytotoxic and antiproliferative effects of azelaic acid may be mediated via inhibition of mitochondrial ox-idoreductase activity and DNA synthesis. Disturbance of tyrosinase synthesis by azelaic acid may also influence its therapeutic effects. Azelaic acid can be used as a hypopigmenting agent in patients sensitive to hydroquinone. 

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