CONTENT OF TOXIC ELEMENTS IN STREET DUST AND RISK ASSESSMENT FOR HUMAN HEALTH (MEZHDURECHENSK, SOUTHERN KUZBASS)

Abstract

The relevance of the research is caused by the need for assessments of the impact of heavy metals and some other elements accumulating in urban street dust on public health. The purpose of the research is to establish the elemental composition of street dust and to assess the health risk of exposure to toxic elements accumulating in the street dust of multi-industry regions, including active coal mining and coal refining (Mezhdurechensk, Southern Kuzbass); to determine the magnitude of carcinogenic and non-carcinogenic risk to public health. Objects: street dust material obtained by sampling (29) according to the uniform network. Research methods: method of sampling street dust by means of dirt brushing; separation of granulometric fractions of 1000-100, 100-50, 50-20 20-4.5 micron diameters by sieving; determination of granulometric composition and size of dust particles (SALD-7101 SHIMADZU with semiconductor laser); method of inductively coupled plasma mass spectrometry, NexION 300D to determine the content of 57 elements in samples; methods for assessing the risk of exposure to chemicals on human health; Research results. Street dust is enriched with Fe (7,5), As (4,8), Sb (4,0), Ag (2,7), Pb (2,1), Cu (1,3), Ti (1,29), with respect to the clark of the upper part of the continental crust. Enrichment factors are given in parentheses, only those elements that are included in the risk assessment list are considered. The excess of the average contents of a number of elements in street dust over clark values, and at some points very significantly, may be due to the impact of motor transport (Pb), metalworking enterprises (Fe, Ti, Cr), coal combustion products (As, Hg), long-distance transfer from coal mining enterprises, transfer of air flows through the masses of overburden and host rocks (Sg, Si, Sb). Environmental risks to public health from exposure to street dust components (26 elements were taken into account according to the ICI data) were assessed taking into account oral, inhalation and cutaneous routes of entry and using standard exposure factors. In order of decreasing values of the total hazard coefficients, taking into account all three routes of entry of pollutants, the elements form the following series: As (1,6×10–1)>Cr (4,1×10–2)>Pb (2,4×10–2)>Mn (2,2×10–2)>Sb (1,5×10–2)>Ba (1,4×10–2)>Al (8,6×10–3)>Cu (4,4×10–3)>Co (1,7×10–3)>Cd (1,7×10–3)>Zn (1,0×10–3)>Hg (2,2×10–4); ∑ КО=29,4 ×10–2. The total hazard coefficient had a value of 0,29. This level of risk is characterized as acceptable (acceptable risk); it is at this level that the majority of foreign and recommended by international organizations hygiene standards for the population as a whole are established. However, the problem of long-term exposure to low doses of toxic elements on public health also needs to be studied. To reduce the level of carcinogenic risk, the elements form the following series: As (3,0×10–5)>Сr (VI) (2,7×10–5)>Ве (4,3×10–6)>Pb (1,6×10–6)>Cd (1,2×10–7). Values lying in the range of more than 1×10–6, but less than 1×10–4, are regarded as the maximum permissible risk. These levels are subject to constant monitoring. In some cases, at such risk levels, additional measures may be taken to reduce them. Comparison of risk indicators and geochemical characteristics of street dust indicates the need to take into account the ecological and geochemical features of depositing media when interpreting the results of risk assessment.

Keywords

• street dust
• heavy metals
• inhalation risk
• carcinogenic risk
• non-carcinogenic risk
• coal energy