Polish journal of occupational medicine and environmental health最新文献

Thermal degradation of heated chrysotile results in dehydration and changes in its crystalline structure. The impact of heat treatment at 150-1200 degrees C on the biological activity of chrysotile was tested in rats. Heating the chrysotile produced an increase in its biological aggressiveness measured in terms of animal survival rate and fibrogenic activity after intratracheal administration of the dust. The highest death rate (100% of the animals) was noted after administration of chrysotile heated at 600 degrees C. Moreover, increased fibrogenic activity of chrysotile heated at 150 degrees C up to 800 degrees C was found. The biological effect of chrysotile heated at 1200 degrees C did not differ from the effect exerted by unheated chrysotile. After intraperitoneal administration of the dust, the most violent reaction could be observed when chrysotile dust was heated at 600 degrees C, which resulted in symptoms of nervous system impairment (of the hind legs, no reaction to nociceptive stimuli, drop of internal body temperature) and death of the test animals. In male rats, the period between dust administration and the manifestation of symptoms and death was found to be longer than in females.

The disposition of butyl-(2,3-14C)-acrylate has been studied following intraperitoneal and oral administration to rats. Most of the administrated acrylate underwent rapid metabolism and excretion with expired air (more than 70% of the dose) and urine (15-22%). Most of 14C found in tissues was associated with the liver and kidneys. The level of 14C associated with most of the examined tissues remained unchanged, at least, for the first 8-10 hours, followed by its fairly rapid loss. The only exception was erythrocytes, fat and the sciatic nerve. Significant differences in the rate of 14C loss from tissues were found in relation to the route of its administration.

G6PD activity in erythrocytes was examined in 129 people with malignant neoplasms (83 males, 46 females). In all these subjects G6PD activity in erythrocytes was markedly higher than in the controls. Tumour surgery resulted in decreased activity of that enzyme in the erythrocytes. The controls were 53 healthy persons (38 males, 15 females) not exposed occupationally to carcinogens.

Effects of repetitive exposure (ten times in a period of two weeks) to chlorphenvinphos (CVP), at daily doses of 0.5 and 1.0 mg/kg, i.p., were studied in adult male Wistar rats of imp-DaK stock. It was found that 3 hrs after the last exposure, the cholinesterase (ChE) activity in the blood and brain was close to 50% of the control value in the 0.5 mg/kg group and less than 50% in the 1.0 mg/kg group. In both groups, normalization of ChE activity in plasma took less time than in erythrocytes, and the normalization of ChE activity in erythrocytes proceeded faster than in the majority of the brain areas studied. Electrophysiological investigations revealed a retardation of age-related epileptic-like cortical activity. This effect, however, was present only in the 1.0 mg/kg group, and only in the period of decreased ChE activity in the brain. Spectral analysis revealed an increase in 1-4 Hz activity in the cortical EEG of the 0.5 mg/kg group and heightened theta activity (4-7 and 7-9 Hz bands) in the hippocampal EEG of the 1.0 mg/kg group. The later effects were detected after a time sufficient for full normalization of ChE activity and manifested themselves most clearly in the presence of an acoustic stimulus associated with pain. The above results are in agreement with earlier observations on rabbits exposed repetitively to CVP. Data from both species suggest that, in the case of repetitive exposure to CVP, neither plasma nor erythrocyte ChE activity is a reliable indicator of toxicity, and that such exposure to this OP may lead to changes in EEG outlasting the period of lowered ChE activity in the blood and brain.

The efficiency of Brainstem Auditory Evoked Potentials (BAEP) as an indicator of susceptibility to hazardous noise was investigated. In earlier studies, subjects were exposed to very intense occupational noise and temporary threshold shift (TTS) was produced by high intensity noise of 115 dB. Correlations between experimental TTS and the BAEP changes were investigated. BAEP indices, which significant correlations with the eventual hearing loss, were found. Similar criteria, which were found significant in the earlier work, were investigated in 94 industrial workers with normal hearing, without past exposure to noise, using a more moderate TTS-producing noise of 110 dB SPL. Under these conditions, no significant correlation between the noise susceptibility index and BAEP changes during TTS was found. The results of this study demonstrate the limitation of determining individual susceptibility to noise-induced hearing loss using BAEP. TTS-producing noise levels must be high enough. Their predictive value holds only for hearing losses typical of high intensity occupational exposures.

The study was designed to investigate the usefulness of some biochemical indices for determination of lead toxicity. In exposed and control groups, the following parameters were measured: concentration of lead in the blood, level of free erythrocyte protoporphyrins and delta-aminolevulinic acid dehydratase activity of erythrocytes. Levels of sodium, potassium, calcium, magnesium, copper and zinc in the serum and erythrocytes as well as of iron in the serum were determined. The chelation test was performed and excretion of lead, coproporphyrins and delta-aminolevulinic acid (in 24 hour urine sample before and after EDTA injection) identified only in the exposed group. Absorption of lead was significantly higher in the exposed group (increased blood lead level (Pb-B), free erythrocyte protoporphyrin (FEP) and decreased erythrocyte ALA-dehydratase (ALA-D) activity. Levels of copper and calcium in the serum and red blood cells were significantly lower in comparison with the controls. Iron and sodium concentration in the serum as well as levels of potassium, magnesium and calcium in erythrocytes were significantly higher in the exposed group. The chelation test in the exposed group showed a significantly increased excretion of lead in 24 hour urine sample. Concentration of delta-aminolevulinic acid in 24 hour urine sample was lower after EDTA injection.

Type-III-procollagen peptide (P-III-P) concentration and angiotensin-converting-enzyme (ACE) activity were measured in the serum of asbestos workers. The subjects were classified into four groups (A, B, C, D) according to the duration of exposure (in years). A gradual increase of ACE activity in group B and P-III-P concentration in group C was found. The increase in ACE activity can be regarded as the response to the progressing inflammatory state, and the increase in P-III-P concentration may be related to the fibrosis of the lung tissue.

A method for the determination of microsomal phenacetin O-deethylase activity in the rat liver was described. Optimum conditions in which phenacetin is enzymatically converted to N-acetyl-p-aminophenol were determined. The product of enzymatic reaction was acid-hydrolyzed while heating. The amount of p-aminophenol formed was determined by means of indophenol reaction. The described method was applied to assess activity of phenacetin O-deethylase in normal rats and rats treated with inducers or inhibitors of microsomal monooxygenases, phenobarbital, 3,4-benzpyrene, SKF 525-A and cobaltous chloride, respectively.

The possibility of evaluating occupational exposure to toluene at low levels (50-150 mg/m3), based on the determination of unchanged substances in capillary blood, was investigated. The volunteers were exposed in a toxicological chamber; during and after exposure venous and capillary blood samples were analysed by gas chromatography using the headspace technique. Toxicokinetic data point out that determination of toluene should be performed in blood samples collected 15-20 min after termination of exposure. The toluene concentration in capillary blood may reflect the toluene dose absorbed during the workshift only in the case of constant exposure. Otherwise, this measurement refers to the rate of toluene absorption, mainly in the last 2 hours of daily exposure.

This paper indicates some immunological aspects of asbestos-related diseases and especially concerns the activity of macrophages--cells of immunological surveillance. Macrophages establish a very important population of cells which initiate or suppress specific immune response; they are responsible for effective T-cell activation, express antitumour activity. The process of lung fibrosis generated by the inhalation and deposition of asbestos fibres is also closely related to macrophage activity. An open question which is still to be resolved concerns asbestos-induced fibrosis; it may arise as a consequence of tissue injury and repair or change collagen synthesis. Another question is, to what extent macrophages may be protective cells and when they become undesirable? Since their overstimulation or damage in the case of chronic exposure to asbestos dust may be the reason of the increased release of inflammatory mediators, reactive oxygen intermediates which may in turn cause tissue injury, fibrosis or, in final effect, cancer. If so, we could then say that lung response (expressed by e.g. alveolar macrophage activity) to chemical insult may cause further damage to this tissue.