A flow-through diffusion cell system for percutaneous absorption studies has been developed. The results of initial studies with a limited number of compounds are reported. The cells were constructed from Teflon and contained a glass window in the bottom for viewing the receptor contents. A flow rate of at least 5 mL/h is required through the receptor (volume, 0.4 mL) for accurate results. The skin permeation of water, cortisone, and benzoic acid was determined in the flow-through cell and a standard static-diffusion cell. The absorption profiles and quantitative values obtained were similar for the two types of cells. The permeation of cortisone and benzoic acid applied in a petrolatum vehicle was determined in vivo in rats and with rat skin in the flow-through and static-diffusion cells. Good agreement was obtained between the results of the in vivo and in vitro procedures. The percutaneous absorption of a hydrophobic compound [3-phenyl-2-propenyl 2-aminobenzoate (cinnamyl anthranilate)] was enhanced with normal saline receptor solution in the flow-through cell when compared with results in the static cell. Maximum in vitro absorption was obtained with either cell using a 6% solution in water of the nonionic surfactant polyethylene glycol 20 oleyl ether (PEG-20 oleyl ether).
Considerable media attention has recently been given to novel applications for products that contain nanoscale materials. These products could have utility in several industries that market consumer products, including textiles, sporting equipment, cosmetics, consumer electronics, and household cleaners. Some of the purported benefits of these products include improved performance, convenience, lower cost, as well as other desirable features, when compared to the conventional products that do not contain nanoscale materials. Although there are numerous likely consumer advantages from products containing nanoscale materials, there is very little information available regarding consumer exposure to the nanoscale materials in these products or any associated risks from these exposures. This paper seeks to review a limited subset of products that contain nanoscale materials, assess the available data for evaluating the consumer exposures and potential hazards associated with these products, and discuss the capacity of U.S. regulatory agencies to address the potential risks associated with these products.
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