Utilisation des gènes humains du stress pour détecter la présence de substances non biocompatibles dans l'eau destinée à la consommation : Les tests biologiques applicables à la surveillance de la qualité de l'eau de consommation

Industrial needs in toxicology are well identified and in fine, focus on a better evaluation of risk assessment. The development of a rapid, flexible and large scale waming detection system (bioalert) is of paramount importance to companies intempting to manufacture high quality water supplies. An overall risk evaluation needs to integrate complex interactions between one or several contaminants, the environment and the living organism. Moreover, the global approach should assess not only the presence of nonbiocompatible substances found but also their biological effects in order to evaluate their varying impacts on water bioquality. When necessary, traditional analytical methods can be used afterwards to identify and characterize the biotoxic compound(s). We selected human cellular and molecular probes that can be used as danger sentinels for detecting low doses of biotoxicants in water intended for human use. Indeed, most living organisms, from bacteria to man, in response to a variety of physical, chemical and biological toxic stressors, rapidly synthesize a set of new proteins (stress proteins) implicated in protein folding, detoxification and/or resistance. Not surprisingly, most noxious compounds cause damage to several cell macromolecules and functions and thus induce a number of stress responses. Initially, we used a human T cell line as biotoxicological device by measuring the transcription of native stress genes such as the metallothionein-2A (MT2A) and the Heat Shock Protein 70 (HSP70). This requires no genetic manipulation prior to assessing biotoxicity. Here, we used a RT-PCR (Reverse Transcriptase - Polymerase Chain Reaction) assay and synthesized specific oligonucleotides to detect and quantify mRNA transcripts of these genes. Experimentally, the final medium for the cell line cultured was reconstituted with samples of water from different origins or distilled water as a reference in the absence or presence of different cadmium concentrations. Cells were cultured for 6 to 18 hr and metabolic activity, cell viability or gene expression was then analyzed. Direct toxicity was observed only in cells cultured with various water samples and low doses of cadmium : water polluted by industrial wastes < polluted water < surface or distilled water (100 %). By contrast, with or without cadmium, expression of MT2A and HSP70 transcripts was highly induced in cultures using water polluted by industrial wastes as compared to nonpolluted water, the latter being still more active in inducing MT2A gene than distilled water. MT2A expression was observed by 18 hr whereas HSP70 expression was already apparent by 6 hr and maintained up to 18 hr. We believe that these new approaches will add greater certainty to risk assessment screening for the presence of nonbiocompatible compounds in potable water samples, and will help promote more efficient and effective safety regulation in their manufactures. This may be of interest to industrial groups participating in the development of environmental, health, and safety regulations. Also, they may be useful in evaluating and shaping new classification schemes for toxic compounds based upon various cellular and molecular responses rather than on toxicant structure.