Zentralblatt fur Bakteriologie. 1. Abt. Originale B, Hygiene, Krankenhaushygiene, Betriebshygiene, praventive Medizin最新文献

This experiment was designed to study the degree of recovery from lead-induced neuro-behavioral deficit after normalization of blood lead-level (PbB). Female Wistar-rats were given a diet containing lead-acetate (2260 ppm Pb) for 60 d until mating, giving rise to a PbB-increase from 53 microgram/d1 (before mating) to 84 microgram/d1 (after weaning). Lead-exposure of their male offspring was continued for 4 months with their PbB levelling off at 40 microgram/d1 (table 1). Lead-feeding was discontinued thereafter for another 4 months, PbB declining to a final level of 12 microgram/d1 (table 1). These animals were then compared for neurobehavioral functions to age-matched controls with respect to discrimination-learning (Lashley jumping-stand) and motor activity (open field-test). In addition recovery from initial loss of body-weight after partial food-deprivation was measured, known to be retarded at elevated PbB. The results may be summarized as follows: Formerly Pb-treated animals subsequently raised on a lead-free diet resulting in PbB-normalization within 4 months as compared to untreated controls exhibit (1) significant retardation of recovery from initial loss of body-weight (fig 4), (2) significant increase of error-repetitions in discrimination-learning (table 4; fig. 5) indicating disturbances of learning-performance without a change in learning-speed, and (3) significant hypoactivity (ambulation) without a significant change of other variables of open field-behavior (table 5; fig. 6). These results demonstrate, that some neurobehavioral and systemic symptoms of Pb-related dysfunction persist even after normalization of PbB, thus indicating partial irreversibility of Pb-induced damage.

To evaluate products intended for disinfection of water in swimming pools a quantitative suspension test was designed based on the principle of the Dutch standard suspension test (SST). As artifical swimming pool water a buffered bovine albumin solution (BBAS) was used. The microbicidal potency of BBAS chlorinated with sodium hypochlorite (NaOC1) for 5 min to free chlorine concentractions of 0.3, 0.5 and 1 mg/1 appeared to meet the tentative standard of 4 decimals reduction (D.R.) within 5 min against the bacterial test strains used, e.g. Staph, aureus, Str. faecalis, P. aeruginosa, E. coli and Prot. mirabilis. Usually an exposure time of 30 s was sufficient to obtain this reduction. The kill C. albicans to that extent approx. 1 mg/1 free chlorine was needed. The redox potential of BBAS chlorinated as described above amounted to approx. 600 mV or higher values. When BBAS was chlorinated for 5 min with sodium dichloroisocyanurate (NaDCC) addition of 8 mg/1 of this substance was required to obtain about the same microbicidal potency as that of BBAS chlorinated with NaOC1 to 0.3 mg/1 free chlorine. The redox potential in the former solution was found to be above 600 mV. The microbicidal potency of BBAS chlorinated for 5 minutes with 2 mg/1 NaDCC was virtually zero and with 4 mg/1 NaDCC suboptimal. These findings correlated well with the redox potentials of 262 mV and 432 mV, respectively, measured in the latter solutions. Addition of cyanuric acid to BBAS before chlorination resulted in lower killing rates, although the free chlorine concentration, determined with the FAS-DPD method, seemed to be increased. It is concluded that in swimming pool water chlorinated with chloroisocyanurates the redox potential might be a better indicator for the microbicidal potency than the free chlorine concentration determined with the FAS-DPD method.

Methods are given to calculate the equilibrium concentrations of both halogene solutions (chlorine, bromine and iodine) in the presence of additional halide and of chlorine solutions in the presence of chloride and ammonia. With the aid of these values and the redoxpotentials which have been determined from them is demonstrated that there is a very complicated connection between the latters and the total as well as the equilibrium concentrations. It depends on the kind of the halogene, the pH-value and the presence of substances which can react with the halogene (halides, NH-compounds) and can not be described by the simple formula: increase of the redoxpotential approximately increase of the equilibrium concentrations of germicidal hydrolysis products and as a consequence of the death rates. On the contrary a reduction of the total halogene concentration may cause an increase of the redoxpotential as well as the addition of halide may lower the redoxpotential while the concentration of strong germicidal "free halogene" remains unchanged. The redoxpotential therefore is not a mean to make reliable predictions concerning the germicidal action of halogene solutions.

For the purpose of evaluating the stress on citydwellers by pollutants emanating from traffic sources the contents of lead and 3,4-benzpyrene in sedimentable city dust were determined in samples collected at 46 sites with different traffic densities in a city of medium size but considerable overall traffic volume (Erlangen, Bavaria). To estimate the effect of the gasoline-lead-law of Aug 5, 1971, determinations were carried out both in 1971, i.e. before this law came into effect, and in 1977 when the lead content in gasoline was finally limited to 0.15 g/1. The following results were obtained: - In city areas with dense traffic, the medium lead content dropped from 4.2 to 2.2 mg/g of dust, and the medium 3,4-benzpyrene concentration dropped from 1.3 to 0.5 microgram/g of dust. This amounts to a reduction of both the lead and 3,4-benzpyrene contents in city dust by about one half. - In the city periphery with lesser traffic density, the lead and benzpyrene contents, resp., were originally lower by about one half. In the case of lead, the concentration dropped from 1.9 mg to 1.2 mg/g dust, while 3,4-benzpyrene dropped from 0.6 to 0.4 microgram/g dust. Thus, the beneficial effect of the gasoline-lead-law was less obvious in these low-traffic parts of the city area. - The decrease in 3,4-benzpyrene with decreasing lead content is remarkable (striking, a striking pheromeron) and may be explained by lesser emission of this pollutant when burning gasoline low in lead.

Certain ethylene-oxide residues in sterilized equipment can cause toxic effects in patients. Mutagenic effects of ethylene-oxide have also been described in experimental animals, plants, and bacteria. In our studies an increase of sister chromatid exchange (SCE's) served as indicator for a mutagenic effect of this substance. We cultivated fibroblasts of healthy volunteers and added liquid ethylene oxide in concentrations of 3.6 to 3600 ppm to them. In additional cell cultures we placed endotracheal tubes containing 12 to 3900 ppm ethylene oxide residues on top of the cell layers. After 24 h reaction time the cell cultures were read microscopically and the SCE ratios determined also. Liquid ethylene oxide in concentrations of 360 and 3600 ppm caused a total destruction of the cells. At 36 ppm the cells remained alive. This concentration produced a significant rise of the SCE rate from 12.53 to 16. Tubes with residues of 200 to 600 ppm ethylene oxide brought about a consistent rise of the SCE ratio in the sense of a dose-response relationship. Ethylene oxide has besides its toxic reaction a mutagenic effect upon human fibroblasts. Many other chemical substances have mutagenic potencies also. For safety reasons ethylene oxide sterilized equipment should be aerated before its use as completely as possible.