Chronic Effects of Mercury on Organisms:

Problems of secondary contamination by mercury of the air of production sites


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PROBLEMS OF SECONDARY CONTAMINATION BY MERCURY OF THE AIR OF PRODUCTION SITES Secondary mercury contamination is also well known in transformer stations, all types of scientific and technical laboratories, school, dental offices, etc. Presently new materials and processes can release mercury into the air of factories, offices and even homes. The wide use of mercury lamps in plants have shown the need for special demercurializing procedures (E. I. Gol'dman, 1964). Other data as well as ours show that structural elements of buildings serve to maintain the circulation of mercury for prolonged periods. The current specialized literature does not describe cases of domestic mercury contamination although it occurs. From 1948 to 1951 we inspected the first and second stories of a Lugansk apartment house incorporating the so-called Gas Laboratory of the trust "Luganskuglegeologiya." Personnel of this laboratory used metallic mercury widely (as a degasser) in gas analysis. For years thereafter mercury smears were taken from the floors and ventilators of the building. According to laboratory personnel, several kilograms of mercury had been used, and significant quantities lost, during this period. The living quarters were in a four-story marl covered pre-war building divided into five sections and the laboratory occupied the first and second sections of the first floor. In 1951, after four years next to the apartments, the laboratory moved to another building and five apartments were made of the former laboratory site. Before tenants moved in there "had been extensive renovations" (repainting, replastering, floor finishing, repairs to sills, sashes, moldings, etc.) By the end of 1954, three years after opening the apartments, personnel of the sanitary-epidemiological station analyzed samples collected there and found mercury (L. S. Perederniy, P. F. Tashci, 1964.) All air samples contained mercury vapor from 0.0025 - 0.006 mg/m3. The air of one apartment in the second section contained a maximum content of 0.0187 mg/m3. Simultaneous sampling analysis for mercury from the walls and ceilings showed that in all samples there was from 0.004 - 0.006 mg/g. In apartment 9, where the mercury concentration was highest, there was the highest wall content (up to 0.0042 mg/g.) Especially interesting is data on the presence of mercury in the plaster of apartments in which no earlier work with mercury had occurred. The fact that 83 of 99 locations were contaminated with mercury show the significant secondary contamination of the whole building. The Lugansk Sanitary - Epidemiological Station showed that in 31 cases the mercury content in the plaster was about 0.000015 mg/g; in 47 cases, from 0.000015 - 0.00015 mg/g; in 5, above 0.00015 mg/g. Mercury was not detected in sixteen locations. Conclusive secondary mercury contamination was shown by analysis of wall samples taken two years after the plaster samples from depths of two to five cm and then at eight cm. The average mercury content in these materials was 0.00004 - 0.00034 mg/g; at 2 and 5 cm, 0.000014 - 0.00013 mg/g. The mercury content of walls and plaster diminished in a direction from the first to the second section, where the laboratory had been, to the fifth section where mercury was not detected in wall material. Control analysis of 45 composition marl wall material samples showed no mercury. This confirmed the contamination of the building by the laboratory. The possibility of contamination of apartments located with dental offices in a building was described by I. D. Krupitskaya and I. L. Pisarevskiy (1956), illustrating the dangers of use of even insignificant quantities of mercury. Attempts at demercurialization and installation of mercury barriers were not effective because of mercury penetration deep into structural members. M. N. Korshyn, at an instrument building plant, confirmed these observations. Less than two years of shop operation, even with recommended mercury barriers, produced massive mercury contamination of structural elements of the building. The mercury content of an asphalt linoleum-covered cement floor was an average of 0.001 - 0.002 mg/g, varying within limits of 0.0005 - 0.4 mg/g; wall plaster covered with a recommended oil base paint (No. 81/8 -7) contained an average of 0.0002 - 0.01 mg/g. average 0.002 - 0.0003 mg/g. contamination was highest in plaster, then in wood and least in cement floors. Special wall paints and plaster were more permeable to mercury than linoleum. Cement was more porous than plaster. As the mercury penetration decreases, so does the number of positive tests and the quantities observed therein. M. N. Korshun showed that secondary depots could maintain aerial mercury vapor levels of up to 0.05 - 0.07 mg/m3. In a chemical viscose production site mercury was detected in the air for three months despite complete removal of the primary mercury source. In industrial laboratory studies, it was shown that the aerial mercury concentration (in mg/m3) is one order higher than the mercury content in structural elements (in mg/g). This relationship is used in classifying mercury deposit sources. Thus, there are three degrees of contamination; primary (insignificant intensity) - mercury content on the order of ten thousandths of a mg/g; secondary (average intensity) - thousandths of mg/g, tertiary (high intensity) - hundredths mg/g and higher. Depending on the presence of mercury supporting structures can be a massive contamination source spreading the contamination through internal elements, conduits, foundations, etc., and also can be surface contamination sources, accumulating mercury on walls, floors, etc. The hygienic significance of such depots is based not only on hygienic investigations, but on data of medical surveys of persons who had no direct mercury contact but who had spent long periods in mercury contaminated sites. Fifty seven percent of persons studied displayed functional CNS disturbance of the asthenic type, asthenovegetative syndrome and vegetative-vascular dystonia. "Mercury erethism" appeared, changes in olfactory sensitivity, hematological shifts and increased urinary mercury contents, indicative of micromercurialism, connected with primary aerial mercury contamination were noted. "Tertiary level sources" can be generated from spillage and absorption, although primary contamination plays its role. Secondary sources are the determining factor in contamination of new objects and sites in the laboratory and in industry and explain mercury level maintenance and circulation between the air and objects at a site.