Acute toxicity of radiation-sterilised propylene glycol

Final Report on the Safety Assessment of Propylene Glycol and Polypropylene Glycols

Propylene Glycol is an aliphatic alcohol manufactured as a reaction product of propylene oxide and water. Polypropylene Glycol is a polymer formed by adding propylene oxide to dipropylene glycol. Propylene Glycol is reportedly used as a skin-conditioning agent-humectant, solvent, viscosity-decreasing agent, and humectant in thousands of cosmetic formulations. Polypropylene Glycols of various polymer lengths are reportedly used as miscellaneous skin-conditioning agents in far fewer formulations. Acute, subchronic, and short-term animal studies suggested little toxicity beyond slight growth and body weight decreases. Little ocular or skin irritation was observed in animal studies, and no sensitization was seen. Small increases in fetal malformations were seen in mice injected subcutaneously with Propylene Glycol, but a continuous breeding reproduction study in mice showed no reproductive toxicity following oral administration. A wide range of mutagenesis assays were negative, and studies in mice and rats showed no evidence of carcinogenesis. Clinical data showed skin irritation and sensitization reactions in Propylene Glycol in normal subjects at concentrations as low as 10% under occlusive conditions and dermatitis patients at concentrations as low as 2%. A careful evaluation of skin irritation and sensitization data as a function of disease state of the individual, occlusion, and concentration was done. On the basis of that analysis, it is concluded that Propylene Glycol and Polypropylene Glycol are safe for use in cosmetic products at concentrations up to 50%.

An Evaluation of Sterilisation Processes

A sterile environment is one of the basic elements of in vitro cell culture. When choosing an appropriate sterilisation method, the possibility that the physical and chemical properties of the sterilised material could be altered by the sterilisation process itself, should be considered. Avoiding any potential problems of toxicity arising as a consequence of the sterilisation process is essential, not only in in vitro cell culture procedures, but especially in the case of the sterilisation of medical devices which come into contact with human tissue (e.g. catheters, surgical tools, and containers used for transplant preparation and storage). As it is not possible to predict the potential effects of every combination of test material and sterilisation process, we have designed a simple test, which can be easily performed to ensure the absence of cytotoxicity. The test involves the culturing of a non-adherent cell line in direct contact with the test material, in micro-wells attached to the surface of the test device. By using this novel test method, three sterilisation procedures were compared for each material. The results indicated that, neither ionising irradiation nor ethylene oxide left toxic residues on the surface of polystyrene; and that, in the case of steel, neither steam sterilisation nor ethylene oxide left toxic residues on the metal. The cold plasma system, which left toxic residues on the surface of both materials, required a post-sterilisation period of 24 hours in the case of steel, and 10 days in the case of polystyrene, in order to eliminate toxic residues prior to their use.

A review of the effects of gamma radiation on pharmaceutical materials

This review on the radiation effects on pharmaceutical materials, with a view to their sterilization by gamma radiation, attempts to cover all the pertinent literature published over the period 1975 to 1992.