Evaluation of metabolic endpoints of acute cytotoxicity in V79 fibroblasts

The key constituents underlying the combined toxicity of eight cosmetic contaminants towards Vibrio qinghaiensis

Cosmetic additives (ADDs) and packaging plasticizers (PLAs) probably present potential risks and dangers to the environment and human body as emerging pollutants. To investigate their potential risks and dangers, five ADDs including methyl paraben (MET), ethyl paraben (ETH), propyl paraben (PRO), butyl-hydroxy anisole (BHA), and salicylic acid (SAL), as well as three PLAs including bisphenol A (BPA), bisphenol S (BPS) and tris(2-butoxyethyl) phosphate (TBEP) were selected as research objects, and ten mixture rays (R1-R10) composed of the eight components were designed by the uniform design ray (UD-Ray) method. The toxicities of the eight cosmetic pollutants and their eight-component mixture system towards Vibrio qinghaiensis sp.-Q67 (Q67) were systematically determined by the time-dependent microplate toxicity analysis (t-MTA) method. The three-dimensional (3D) surface of deviation from the concentration addition model (dCA) was utilized to qualitatively and quantitatively analyse the toxicity interaction of the mixtures and the correlation between toxicity interaction and the components' concentration ratios. Finally, eight individual pollutants and representative rays with significant inhibitory and interactive effects were selected to analyse DNA and soluble proteolysis as well as the microstructure and morphology of Q67 after treatment with single chemicals and their mixtures. The results showed that the eight cosmetic pollutants had conspicuous concentration-dependent toxicity and acute toxicity, and none of them, except BPS, BPA and ETH, had time-dependent toxicity. All rays had time/concentration-dependent toxicity and acute toxicity. At the same time, the toxicity interaction of these mixture rays was predominantly antagonism and the strongest antagonism appeared at high concentrations at 12 h. Nevertheless, the components' concentration ratio (pi) was the decisive factor for the type of mixture interaction. The correlation analysis revealed a significant positive linear correlation between mixture toxicity and pETH and pBPA, which indicated that ETH and BPA were the key components of the toxic effects. However, there was a significant negative linear correlation between the antagonism intensity and pBPA and pTBEP, which demonstrated that BPA and TBEP were the key components of the antagonism intensity. Pollutants and their mixtures can also damage cellular structures, and mixtures can exacerbate the dissolution of DNA and soluble proteins.

ECITTS: An Integrated Approach to the Application of In Vitro Test Systems to the Hazard Assessment of Chemicals,

As a result of a workshop held at Täljöviken, Åkersberga, Sweden, on 27–29 May 1991, a multicentre collaborative research project was established, with the purpose of developing the concept of integrated in vitro toxicity testing. The first priority was the selection of tests within eight appropriate areas: basal cytotoxicity, irritancy, developmental toxicity, hepatotoxicity, nephrotoxicity, immunotoxicity, neurotoxicity and biokinetics. An ideal battery of tests for each area was identified. Since it was realised that it would not be feasible to include the full ideal list of tests in the project, a minimum test list was also agreed. For each area, ten calibration chemicals were selected. From these 80 compounds, 30 were selected for inclusion, together with 20 of the OECD test programme chemicals, in a first test set of chemicals. The toxicity of these 50 test set chemicals will be investigated in the minimum integrated test scheme.

The aim of the project is to employ non-animal methods to assess the toxicological properties of chemicals, and to improve this assessment through the use of knowledge about mechanisms of toxic action. The information produced will contribute to the establishment of a more-scientific and more-efficient toxicological procedure for hazard assessment. Questions concerning which parameters need to be investigated and combined to make hazard assessments, and which parameters relevant to in vivo toxicity can be determined in non-whole animal test systems, will also be addressed.

Established cell lines for safety assessment of food contaminants: differing furazolidone toxicity to V 79, HEp-2 and Caco-2 cells

In vitro models, preferentially derived from human tissues, may be valuable tools to study the biotransformation and toxicity of compounds that may be present as residues in food products. Such residues may represent a risk to human health, and therefore call for increased testing. Three established cell lines were used to study the toxic effect of furazolidone (FZ), a widely used veterinary drug: HEp-2 cells, derived from a human larynx carcinoma, previously used in toxicity screening of several compounds; Caco-2 cells, derived from a human colon adenocarcinoma, able to differentiate partially in culture, and V 79, a fibroblast cell line derived from Chinese hamster lung, widely used to assess direct toxicants. Various toxicity parameters were used, primarily dealing with cell death and cell proliferation. In all cell lines FZ at a concentration of 5 micrograms/ml caused a marked decrease in cell viability and especially in cell proliferation. Inhibition of DNA synthesis has also been observed, even if at higher concentrations. However, only in V 79 cells was the decrease in cell number accompanied by a marked increase in lactate dehydrogenase leakage due to membrane damage. Moreover, the surviving V 79 cells, after removal of FZ, fully recovered from the effect of the drug, as shown by their full capacity to attach to dishes and to form colonies. Surviving cells of the other two cell lines showed much poorer colony-forming ability. Exposure of Caco-2 cells and, to a lesser extent, HEp-2 cells, caused a marked increase in oxygen consumption, that possibly was due to redox cycling of the initially formed radical nitro anion. Biotransformation of the drug by all three cell lines was accompanied by the formation of protein-bound metabolites, HEp-2 being the most active cells. The toxic effects recorded show that cell lines provide a sensitive system in toxicity assessment. Moreover, it may be suggested that a battery of cell lines, including some of human origin, as well as a battery of endpoints, may be of help in addressing further specific mechanistic investigations.