Document 6wnr1MvJKXRNe1o3Mdm03E0Ld

1 /?/!/ ip.5J - SI' M M A RY Characteristics of Cl. Perfringens Strains as Causative Agents of Toxinfections O. E. Goeva, G. I. Sidorenko, E. B. Borovik The pape r deals with a com pa rative investigation of 235 C 1 . perfrin gens strains isolated f rom cases of food toy infections, caused by C 1. per fringens (29 strains), from cases of food poisoning of unknown etiology (56 strains) and from faeces of healthy persons (150 strains). In case of food toxinfections, caused by Cl .perfringens, the recove red strains were of type A and revealed a slight toxigenic, lecithinase and haemolytic activity. As a rule the spores of these strains were highly thermostable. A compara tive study of the properties of strains, recovered from cases of food poisoning, and those of other investigated strains did not show any significant differ ences in respect to their toxigenicity and production of lecithinase, thetatoxin, hyalurodinase and collagenase. The main distinction between the strains was their thermostability. UDC 613.5:645.1:678.743 HYGIENIC ASSESSMENT OF POLYVINYL CHLORIDE FLOORING FOR PRESCHOOL INSTITUTIONS (K gigienicheskoi otsenke polikhlorrinilovykh pokrylii dlya polov v doshkol'nykh uchrezhdeniyakh) Z. A Pluzhnikova, Candidate of Medical Sciences, and M. N. Kuz'micheva Ensinari Research Institute of Hygiene, Moscow Polymer materials. Including polyvinyl chloride, are used in the building of children1 s and especially preschool institutions. We carried out a hygienic assessment of polyvinyl chloride flooring in such institutions. For this purpose, we performed (in 1965 --1966) chemical analysesof air in the premises, determinations of the thermoinsulating properties of the flooring, and measurements of the charges of static electricity on the floor surfaces, as well as investigations of the children's functional state. Control obser vations were derived from premises with parquet floors. Our observations included 15 apparently healthy children aged 5 -- 6. In the institutions investigated, the floors were covered withunbacked poly vinyl chloride tiles laid on chipboard. The tiles, manufactured by the Mytishchi factory, contained polyvinyl chloride resin (39.07 %), dibutyl phtha- late (1 5.12 %), talc (41.68 %) and zinc white (2.6 2 %), as well as boiled oil, rosin, lead silicate, calcium stearate and pigment. In the light of the formula of the polymer and certain published sources (Khrulev), we tested the indoor air for vinyl chloride, chlorinated hydrocarbons, dibutyl phthalate and hydrogen chloride, using the colorimetric, nephelometric and spectrophotometric methods recommended for the analysis of outdoor and indoor factory air. For the purpose of laboratory investigations, samples of the polyvinyl ^ chloride tiles were placed in desiccators (2 m2 sample per 1 m3 volume) at v room temperature, 20 --25. We succeeded in detecting only dibutyl- phthalate, in concentrations of 3.3 -- 7.5 mg/m3, but could not detect hydrogen V chloride, vinyl chloride or chlorinated hydrocarbons. Similar results ft were elicited by investigations of the indoor air in children's institutions during the : from 18.4 t probably was pci sampling, results sttgf present in mg/m3 in th. the the rmo i based on stu and Solonm t including po tions of a rlu i partial coo1 floorings in temperatm * before and . on the feet > in that of a- Parquet . . . Polyvinyl chi. f tiles . . It is r ^ childrei group room thetic floor' Thus, poly'v the children The pro* the use of p. studies by h\ by the "Tek and voltage < The instrurr The instrum over static * N. N. Komai The voltawas 40 to 80r found higher found at low< 50 i-en C ^0 nFG04327 15 Cl. perfrinaused by C 1. perinknown etiology is). Ln case of food '-ed strains were of nimolytic act ivity. .stable, A comparases of food poisoning, significant differeithinase, thetaion between the 1.5:645.1:678.743 used in the building arried out a ~h. institutions. For ialysesof air .in the .-ties of the flooring, a the floor surfaces, te. Control obser;. Our observations ed with unbacked polyctured by the i7 %), dibutyl phthaas boiled oil, rosin, the formula of the d the indoor air for p and hydrogen -trophotometric ndoor factory air. es of the polyvinyl :ier 1 m3 volume) at only dibutvllot detect hydrogen Similar results dren's institutions during the season when heating is used, when the indoor air temperature varied from 18.4 to 21.6 at the children's respiration level, i.e., 0.75 cm [should probably read "0.75 m"J above the floor. It should be noted that the group room was periodically aired, and the windows were closed only half an hour before sampling. The music room had not been aired for 24 hr prior to sampling. The results suggested that dibutyl phthalate was major air pollutant; this was present in a concentration of0.5 -- 0.15 mg/ m3 in the group room and 0.1 -- 0.4 mg/m3 in the music room. There are some published data on the evaluation of the thermoinsulating properties of floors made of different polymer materials, based on studies both in the laboratory and in dwellings. For instance, Tsiper and Solomatova recommended the use of thermoinsulated polymer floorings, including polyvinyl chloride linoleum laid on wood wool slabs. In his observa tions of adults, Stankevich demonstrated that polyvinyl chloride tiles caused partial cooling of the feet. For a comprehensive assessment of the synthetic floorings investigated, we studied the children's thermal state. The skin temperature was measured on different parts of the body with Mishchuk's device before and afte r a 50--70-min stay in the group room. The skin temperature on the feet of the children in the room with synthetic flooring was lower than in that of children in a group room with parquet floors (Table 1). TABLE 1 Skin temperature on the feet of children in group rooms with different flooring (mean data). Flooring Number of observations Time of investigation Skin temperature on foot, *C on arrival in group room after stay in group room Parquet ................... Polyvinyl chloride tiles ...................... 34 32 After walk '* daytime sleep " walk '* daytime sleep 26.1 28.8 27.5 27 8 28.0 30. 4 27.7 26.6 It is seen from Table 1 that the skin temperature on the feet of the children in the control group became somewhat higher after their stay in the group room. No such trend was exhibited by children in the room with syn thetic flooring, and in some cases there even was an appreciable lowering. Thus, polyvinyl chloride laid on chipboard is capable of drawing heat from the children's bodies, thus creating conditions of discomfort. The presence of static electricity in children's institutions as a result of the use of polymer materials constitutes a new physical factor requiring studies by hygienists. For this purpose, we used a charge meter manufactured by the "Tekstilmashpribor"factory, for measurements of the surface density and voltage of charges and their sign on areas no smaller than 50X100 mm. The instrument's range includes electrostatic charges from 0.5 to 50 kV. The instrument is portable and convenient and possesses certain advantages over static voltmeters. In our use of the instrument we were advised by N. N. Komarov, Candidate of Physico- Mathematical Sciences. The voltage of charges (negative) on the surface of polyvinyl chloride flooring was 40 to 800 V. In our fairly numerous measurements of static electricity we -found higher Voltages (> 500 V) rather infrequently. The highest voltages were found at lower relative air humidities (< 35%) in winter and early spring.