Introduction. Oxidizing methods are most widely used for water disinfection with such reagents as chlorine, chlorine dioxide, sodium, and calcium hypochlorite. However, the regulatory instruments of the sanitary and epidemiologic legislation do not fully reflect the requirements for monitoring of their use. Materials and methods. We analyzed the research, regulatory and methodological literature concerning water disinfection issues in the process of water treatment and the parameters of water disinfection efficiency as well as the quality of drinking water of three water treatment stations based on production control data (Perm, Russia) and the results of own research (the towns of Nizhny Tagil (Russia) and Curitiba (Brazil)). Results. A comparative analysis of regulatory documents governing the parameters of the efficacy and safety of drinking water disinfection with chlorine in different years showed that, after the completion of the disinfection process of drinking water, residual free chlorine should be kept within 0.3–0.5 mg/L after 30 minutes of contact or residual bound chlorine – within 0.8–1.2 mg/L after 60 minutes of contact. With the simultaneous presence of free and bound chlorine in water, their total concentration should not exceed 1.2 mg/L. When analyzing the production control data for drinking water in the city of Perm, where chloramination was used for water treatment, we established that the concentration range of 1.04–1.44 mg/L of only the residual bound chlorine ensured high efficiency of water disinfection according to microbiological indicators. The examples of water treatment plants in the towns of Nizhny Tagil and Curitiba demonstrated that water treatment with 0.3 and 0.4 mg/L of chlorine dioxide formed no new dangerous organochlorine compounds but the disinfected drinking water contained residual amounts of chlorine dioxide, as well as chlorite and chlorate anions. Conclusion: These indicators should be included in the regulatory documents to monitor the safe use of chlorine dioxide for water disinfection.
Introduction. According to the legislation, the water quality of reservoirs should be monitored not only by one index for all water bodies of the country but also according to the priority list pollution specific for a particular region. However, the choice of priority pollution is not always correct. The aim of the work is to develop proposals for optimizing the list of monitored water quality indices of a water body using the example of the Moscow River. Material and methods. The studies are conducted in two stages: a retrospective analysis of the results of three-year observations of the quality of water in the Moscow River and its tributaries of the three controlling organizations (the Analytical Laboratory of the Department for Environmental and Environmental Safety, Mosvodokanal and Mosvodostok); and own research of the water quality of the rivers Moscow and Gorodnya. The article does not present the results of extended studies of the content of organic chemical compounds in water. mean, median and maximum values were determined by statistical methods. Results. Indices are constantly exceeding standards: pH, suspended solids, turbidity, dissolved oxygen, COD, BOD, sodium, aluminum, calcium, manganese, iron, nickel, cadmium, lead, ammonium ion, phosphate ion, and chloride ion. Conclusion. It is proposed recommendations to optimize the list of monitored indices: •include mercury in the mandatory list; •It should be conducted additional research if the standards of organoleptic indices, COD and BOD are exceeded; •exclude mineralization, total hardness, potassium and magnesium from constantly controlled indices; •increase the frequency of monitoring the content of calcium and sodium in water in the winter-spring period; •oblige enterprises to transfer samples at the legislative level for research to an independent, unified laboratory; •carry out continuous monitoring of the purity of the water of the Moscow River directly at the site of the release of wastewater for pollution sources of all types, as well as at the mouths of small rivers, flowing into the Moscow River within the city.
Introduction. The use of road deicing reagents (RDR) is an effective measure to reduce winter traumatism and requires enhancement of methods for evaluation of deicers safety. The aim of investigation: to study markers of oxidative stress in rat blood samples during intranasal (i/n) administration of RDR solutions, as a model of intake under natural conditions, using liquid commercial RDR (22% CaCl2; 6% NaCl). Material and methods. Male Wistar rats (10 rats per group) were daily injected into the nasal cavity with 100 μl of RDR solutions in concentrations (C) 0; 0.75; 7.5 and 75 ml per liter of tap water. 5 and 28 days after the start of the experiment, the content of malondialdehyde (MDA), GSH, the activity of SOD, catalase, glutathione peroxidase (GPO) and glutathione reductase (GR) in the hemolysates were determined. Logarithmic transformation x=lg(C+0.01)+2 was used for regression analysis of dose - effect relations. Results. 5 days after the start of the experiment, adaptive dose-dependent changes in activities of SOD (R = -0.504; p=0.001); GR (R = 0.548; p<0,001) and catalase (R=0.725; p<0,001) were revealed, and after 28 days these effects were replaced by dose-dependent increase in MDA content (R=0.617; p<0,001) and GPO activity (R=0.326; p=0.04). The revealed effects, apparently, are due to the presence of additional RDR components (such as detergents, corrosion inhibitors, etc.), since significant differences with corresponding control groups were found also during administration of 0.75 ml RDR per liter (CNa+ 200 times lower than in saline solution; CCa2+ equivalent to its serum content). In particular, sharp increase in catalase activity after 5 days may be indirect evidence of anticorrosive formates metabolism (commonly used anti-corrosive additive) in the conditions of their entry bypassing the portal vein. Conclusion. I/n administration of the studied RDR solutions (0.75-75 ml/L) gave distinct dose-dependent signs of compensated (5 days) and decompensated (28 days) oxidative stress, presumably due to the presence of additional components besides of basic chlorides.
Introduction. When new industrial enterprises appear, whose activities are related to the use and/or production of chemicals, pollutants that do not have approved hygiene standards may appear in the air of the working area. We note that the introduction of new chemicals into the production process does not always require the development of a hygienic standard in the air of the working area, since conditions can be met for these compounds, namely compliance with hygienic criteria, under which the development and approval of hygienic standards is not required. The study aims to demonstrate a practical approach to the application of hygienic criteria for substances that do not need to establish hygienic standards in the air of the working area on the example of paraformaldehyde. Materials and methods. The theoretical basis of the work was the methods of substantiating the need to develop hygienic standards: maximum permissible concentration (MPC) and approximate safe level of exposure (ASLE) to harmful substances in the air of the working area. The practical basis of the work was methodological guidelines for measuring mass concentrations of formaldehyde in the air of the working area by a photometric method based on the reaction of formaldehyde with acetylacetone in an ammonium acetic acid medium and subsequent photometric measurement of the optical density of the yellow-colored reaction product. Results. The conducted experiment simulating the processes of formaldehyde emission from paraformaldehyde in various production conditions showed that paraformaldehyde under the influence of temperature releases formaldehyde, while the rate of formaldehyde release increases with increasing temperature. Conclusion. Analysis of the technology of production (application) of paraformaldehyde, toxicological data, as well as an experiment modeling the processes of formaldehyde emission from paraformaldehyde in various production conditions allows us to conclude that the development of a hygienic standard for paraformaldehyde in the air of the working area is impractical, according to paragraph 2.1.1. GN 1.1.701-98 "For substances containing the ingress of which into the air of the working area in the form of vapors and aerosols or a mixture thereof is excluded due to the physico-chemical properties, as well as production and application conditions" and p.2.1.3. GN 1.1.701-98 "For substances that easily hydrolyze in the air with the formation of hydrolysis products, the toxicity of which has been studied and the hygienic standards of which have been established".
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