| It is estimated that each person may spend more than 80% of the time of a day in an indoor environment (including living at home or working in office). Obviously, indoor air quality is very important to human health. In China, with the living standard improving, room (or named house ) decoration is becoming more and more popular in recent years, which results in a dramatic increasing of indoor air pollution especially the pollutions of volatile organic compounds (VOCs). In addition, changes in building designs in order to get better energy efficiency lead the "modern" living homes or offices to be more airtight than that of the old one. Furthermore, studies have demonstrated that a large number of decoration or building materials sold in the markets in China now contain numbers of high toxic chemical substances such as benzene, formaldehyde or ammonia etc. In this study, investigation on the indoor air quality in the newly decorated rooms in Nanjing was conducted firstly. Secondly, based on the results of indoor air pollution investigation, combination characterization of the toxicities of several major harmful indoor air chemical components polluted by decoration materials was studied by in vivo and in vitro models. Classic toxicology and cytotoxicology test techniques were used to study the patterns of combination effects of several major volatile compounds (including ammonia, benzene, ethyl, toluene, xylene, and formaldehyde). Combination reaction of genotoxicity of formaldehyde with benzene was studied by molecular biology technology. The tests mainly conducted in this study include mice actual toxicity test through respiration and gastrointestinal contamination, 50% cell growth inhibitory concentration in cultured cells, genotoxicity detection using cultured cells and oxidant damage effects detected by cultured cells.Investigation results demonstrated that formaldehyde, benzene, ammonia, toluene, xylene and ethyl were the major indoor air pollutants in the newly decorated rooms. Concentrations of ammonia, formaldehyde, benzene, toluene and xylene in the indoor air detected by high-performance liquid chromatographic were 67.5 times,37.9 times,2.6 times,10.0 times and 21.5 times respectively comparing with national indoor air hygienic standards respectively.The actual mouse test results indicated that additive effect existed when contaminating using formaldehyde with benzene and ammonia, or formaldehyde with benzene , or formaldehyde with ammonia, or formaldehyde, benzene, toluene, xylene combined with ethyl benzene whilst an antagonistic combination was observed when contaminating using benzene with ammonia.Results of in vitro studies indicated that treatments with formaldehyde or/ and benzene could induce cells growth inhibition. Furthermore, the cell growth inhibition effect showed a synergistic interaction. These results also indicated that exposure to formaldehyde or/ and benzene after 24 hours produced a dose-dependent genotoxicity, which was demonstrated by the significant increase in the numbers or rates of apoptosis, DNA strand break, DNA cross-link, lipid peroxidation, or decrease in the amounts of antioxidant substances such as glutathione(GSH) and superoxide dismutase(SOD). The cellular DNA damage showed a similar tendency with cellular oxidant damage. Results analyzed by ANOVA statistical analysis indicated that cellular DNA damage and cellular oxidant damage have statistical significant comparing with that of control (P<0.05).In conclusion, pollutions of ammonia, formaldehyde, benzene, toluene and xylene in the indoor air in newly decorated rooms in Nanjing show heavily. Several major volatile chemical pollutant components in indoor air exhibit an additive reaction, while formaldehyde with benzene can produce a synergistic combination in cytoxicity and genotoxicity on cultured cells.Therefore, we suggest that the values of the hygienic standards of some indoor air chemicals in China should be decreased according to our combination studies on different chemical compon...
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