Toxicity, Regulation, Product Safety, and Skin Irritation

Several methods have been described to evaluate dandruff, such as brushing off the hair and/or the scalp with various devices and weighing the scruf [162,173], However, the most popular approach involves partitioning the scalp into several areas, rating each area for dandruff severity, and analyzing the combined data statistically [174], The scalp-partitioning method using appropriate statistical procedures provides a powerful tool to evaluate dandruff severity and the efficacy of antidandruff products. 

Toxicity, Regulation, Product Safety, and Skin Irritation 

Several toxicity, irritation, and sensitization phenomena will be summarized in this section with special reference to hair care products that contain surface active agents. Skin irritation by surfactants will be covered in some depth providing a few fundamental principles and useful relationships of skin irritation to surfactant molecular structure to provide guidance for formulating milder hair care products. A few important regulatory statutes will be summarized and referenced for further follow up as needed. 

The Food, Drug, and Cosmetic Act of 1938 provided definitions for cosmetics and drugs and prohibited interstate commerce for cosmetics that are adultered or misbranded. By definition, adultered means that the product contains a poisonous or deleterious substance, a nonpermitted color additive, or a filthy, putrid, or decomposed substance or that it was manufactured or held under nonsanitary conditions. Misbranded means that it contains false labeling, does not contain the required labeling, or is not truthfully packaged. 

By this act, cosmetics are those articles (or their ingredients) that are applied to the human body for cleansing, beautifying, promoting attractiveness, or altering the appearance without affecting the body s structure or function. On the other hand, those articles promoted as cosmetics, but 

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Toxicity, Regulation, Product Safety, and Skin Irritation 301 y = 17.971 - -042x + 2.665E-5x2... 

Health and Safety Factors. Some of the Vazo products are mild skin or eye irritants in laboratory animals (Table 9) but none are skin sensitizers. In the absence of a polymerizable vinyl polymer, tetramethylsuccinonitrile [3333-52-6] (TMSN) is the principal decomposition product of Vazo 64. TMSN is highly toxic orally (rat oral LD50 of 39 mg/kg) and by inhalation (29). OSHA regulations require that an employee s exposure to TMSN in any 8-h shift does not exceed an 8-h time-weighted average of 0.5 ppm in air (=3 mg/m3). Because both TMSN solid and vapor are capable of penetrating the skin and mucous membranes, control of vapor inhalation alone may not be sufficient to prevent absorption of an excessive dose. 

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