Alternative method for checking toxicity of hair dyes

Photocatalytic degradation of p-phenylenediamine with TiO2-coated magnetic PMMA microspheres in an aqueous solution

This study investigates the photocatalytic degradation of p-phenylenediamine (PPD) with titanium dioxide-coated magnetic poly(methyl methacrylate) (TiO2/mPMMA) microspheres. The TiO2/mPMMA microspheres are employed as novel photocatalysts with the advantages of high photocatalytic activity, magnetic separability, and good durability. The scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), and transmission electron microscopy (TEM) images of the TiO2/mPMMA microspheres are used to characterize the morphology, element content, and distribution patterns of magnetite and TiO2 nanoparticles. The BET-specific surface area and saturation magnetization of the TiO2/mPMMA microspheres are observed as 2.21 m(2)/g and 4.81 emu/g, respectively. The photocatalytic degradation of PPD are performed under various experimental conditions to examine the effects of initial PPD concentration, TiO2/mPMMA microsphere dosage, and illumination condition on the eliminations of PPD and chemical oxygen demand (COD) concentrations. Good repeatability of photocatalytic performance with the use of the TiO2/mPMMA microspheres has been demonstrated in the multi-run experiments. The photocatalytic kinetics for the reductions of PPD and COD associated with the initial PPD concentration, UV radiation intensity, and TiO2/mPMMA microsphere dosage are proposed. The relationships between the reduction percentages of COD and PPD are clearly presented.

Simultaneous determination of oxidative hair dye p-phenylenediamine and its metabolites in human and rabbit biological fluids

A liquid chromatography with an electrochemical detector method has been developed for the quantitative measurement for three diamine derivatives (p-phenylenediamine, N,N(')-p-phenylenebisacetamide, and 4-aminoacetanilide) in human urine and rabbit blood, urine, and feces. The detection cell consisted of a glassy carbon electrochemical signal obtained with a supporting electrolyte containing 20% methanol-5mM octylammonium orthophosphate (pH 6.30) as the mobile phase. A comparison of the results obtained from HPLC-UV shows agreement.

Comprehensive outlook of in vitro tests for assessing skin irritancy as alternatives to Draize tests

In vitro alternative methods have been verified for the possibility to assess cutaneous irritancy because humans cannot be direct initial experimental subjects and animal experimentation could be forbidden in the near future. Many kinds of cell cytotoxicity assays have been tried, revealing their own advantages and limitations. Cell function-based tests have been used less frequently than cytotoxicity assays. Three-dimensional culture systems are promising because they are closer to the actual in vivo skin, and some of them are commercialized nowadays. The ultimate objective of in vitro irritancy tests, which is the high degree of correlation with human in vivo test results, has been accomplished in many experimental settings. Before applying these in vitro methods we must consider several points, including cell sources, irritant characteristics, exposure time, endpoint of experiment, extrinsic factors affecting irritation, etc. In vitro skin irritancy tests have been developed continuously, and in the future they could assume a heavy responsibility of estimating the irritancy in human skin in vivo.

Survey of the QSAR and in vitro approaches for developing non-animal methods to supersede the in vivo LD50 test

Quantitative structure-activity relationship (QSAR) studies and in vitro studies in which correlations with LD50 have been sought are reviewed. QSAR methods have shown some success in relating LD50 to certain physicochemical properties of the compound, particularly lipophilicity, but have been less successful in correlating LD50 with electronic properties of molecules (related to reactivity) or structural variables. It is concluded that insufficient evidence is available to determine whether QSAR methods can be of general use in predicting the acute toxicity (LD50) of chemicals, and that until further work is undertaken to develop QSARs for a much wider range of homologous series of compounds, this situation is unlikely to be resolved. New chemical descriptors that are more directly relevant to the mechanism of toxic action of the chemical should be identified. Cytotoxicity in vitro is poorly correlated with LD50, but good correlations have been obtained between toxicity in vivo and in vitro, using systems in which the toxic endpoint reflects the probable mechanism(s) of acute toxicity of the test chemical (e.g. the assessment of neurotoxins using neural cell systems). Therefore, it seems that the successful application of in vitro methods requires a better understanding of the mechanisms of acute toxicity in vivo and the development of mammalian cell culture systems that can model more closely the metabolic fate of the chemicals in vivo.