SEARCH · PubMed Health
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
A short-time exposure on the concentration--time relationship base, a classification of substances according to the degree of hazard and the program for assessing safety coefficients have been suggested in order to predict the basic toxicometric parameters (chronic exposure thresholds, maximum allowable concentrations, safety coefficients, and others).
Blood levels and exhalation bag contents of FC-11 and FC-12 from dogs and humans were used to elucidate the pharmacokinetic model describing the time-course of these agents. The derived pharmacokinetic parameters were in good agreement with the physicochemical properties of these substances. The model was used to estimate the percentage of dose absorbed, which averaged 77 per cent for FC-11 and 55 per cent for FC-12, and to predict the level of FC-11 and FC-12 under a variety of conditions simulating both short- and long-term exposure to the maximum allowable concentrations of these agents. With similar doses, an 8-hour continuous exposure was estimated to produce levels of FC-11 and FC-12 that are much lower than the corresponding levels reported to induce cardiac sensitization in dogs.
As a contribution to the discussion on the "Verordnung uber Umweltkontaminanten" (draft) we examined 73 double samples of the frequent types of edible fish and 2 samples each of fish oil and fish meal for their content of arsenic (As), cadmium (Cd), lead (Pb) and mercury (Hg). Arsenic was determined photometrically, cadmium and lead by anodic stripping voltammetry and mercury by flameless atomic absorption spectrometry. We found the following average contents (ppm): 0.84 As, 0.003 Cd, 0.08 Pb, 0.06 Hg. The limits (ppm) set up in the draft for a German "Höchstmengenverordnung" (regulation specifying the maximum concentrations allowed) were by far not reached in the case of Cd, Pb, and Hg with all samples while they were fulfilled in the case of As by only 18% of the samples. It seems that the limit for As of 0.5 ppm has been set up too low. In the average, the following proportion applies for the trace contents found: Cd:Hg:Pb:As = 1:20:27:280. Correlations between the contents of trace metals on the one hand and fishing grounds or trawler or sample piece on the other could not be found.
In order to evaluate the load of heavy metals (Cd, Cu, Hg, Ni, Pb, Zn) imposed on the River Leine by the city of Göttingen (medium-sized town) the content of heavy metals in fish samples (which had been collected at two points on the River Leine, upstream, respectively downstream of Göttingen--Fig. 1) were determined by Atomic Absorption Spectroscopy. Analysis of heavy metals in brook trout (total fish, flesh, and liver) showed a statistically significant definite increase in some heavy metals, caused by the sewage from the city of Göttingen. In the flesh only Cd in the liver Cd, Hg and Zn and in the total fish Cd, Cu and Zn had been increased significantly. All the values of heavy metals in the flesh were lower than the suggested maximum allowable concentrations.
Epidemiology, including occupational tumors and other groups at risk; experimental studies; and physiochemical methods of evaluation of environmental carcinogens form the basis of cancer prevention. Hygienic measures of limitation (maximum allowable concentrations) are also discussed.
Published studies of the toxicity of sodium hydroxide aerosols are few. These studies were generally marred by inadequate characterization of particle size and chemical compositon and of the ambient humidity. Because NaOH aerosols can readily undergo reaction with carbon dioxide to form sodium carbonate, a much less alkaline (and less hygroscopic) compound, these shortcomings may warrant a reconsideration of the NaOH standard and the consideration of a Na2CO3 standard.
Beaf-peptone broth and some of its modifications, one of which is a simple and in expensive one to a leser extent binding to antibiotics, such as penicillin, oxytetracycline and streptomycin and providing sufficient growth of the test microbes were used to determine the antibiotic activity with the methods of serial dilutions. The simple modification was recommended for practical use. The MIC of the antibiotics in the above simple medium was less than that in the control. The results of the antibiotic activity determination on both media coincided.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Blood-lead level (Pb-B), erythrocyte delta-aminolevulinic acid dehydratase (ALAD) activity, free erythrocyte porphyrin (FEP) concentration, delta-aminolevulinic acid concentration in urine (ALAU), hematocrit value, and hemoglobin concentration were compared for groups of children 10-13 years old from areas differently polluted by lead (rural area and lead smelter area). The biological responses of the children were also compared with those observed in adults similarly exposed to lead (Pb-B: 10-40 mug/100 ml). Compared with the rural children, children living less than 1 km from the smelter exhibited a significant increase of Pb-B and FEP, a significant inhibition of ALAD, and a slight positive correlation of ALAU with Pb-B; however, they showed no biological signs of anemia. In children living approximately 1.5 km from the smelter, there was still a significant increase of Pb-B and a concomitant inhibition of ALAD, but no change in FEP concentration. Comparison of the dose-response curves between Pb-B and FEP in adult males, adult females, and children indicates that the sensitivity to lead is in the order of children larger than or equal to women greater than men. Based on the FEP response, it is proposed that 25 mug Pb/100 ml blood be regarded as the maximum biologically allowable concentration of lead in blood of school-age children.
The character and level of benzylpenicillin toxic effect was studied in accordance with the methodic instruction for performance of the experiments on toxicological estimation and hygienic norms of antibiotics in the air of working areas in production premises. It was shown that the antibiotic was of low toxicity under conditions of a single exposure, did not cumulate and had no local irritating and resorbing effect. It was shown to be an allergen. Prolonged inhalation of benzylpenicillin in a concentration of 14 mg/m3 resulted in reversible changes in the function of the kidneys and liver of the animals, their sensitization and development of pronounced dysbacteriosis of the mouth and intestine mucosa. In a concentration of 1 mg/m3 benzylpenicillin had no general toxic and sensitizing effect but induced reversible changes in the normal autoflora. This allowed the authors to consider the above concentration to be maximum with respect to the antibacterial effect. On the basis of the experiments the maximum permissible norm (MPN) of the aerosol of benzylpenicillin disintegration was recommended at the level of 0.1 mg/m3.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.