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A risk evaluation has been carried out under conditions of chronic three-month experiment in oral application of Gastrofenzin in doses 1/20, 1/100 and 1/200 LD50 for male and female white rats, respectively 33.2 and 43.8; 6.7 and 8.8; 3.4 and 4.4 mg.kg-1. There have been applied integral, behavioural, laboratory, biochemical (serum, liver, kidney, brain, brain mitochondria), histologic and electron microscopic methods. The highest doses cause functional and biochemical changes in the nerve system, liver and the kidneys without involving the structural elements of the respective tissues. Significant changes have not been observed in the doses 1/100 LD50 and 1/200 LD50. A dose-effect increase has been found out in the level of cytochrome-P-450 in the liver tissue, but the data are insufficient for determining the type of the caused induction. The results of the complex study show that in the three-month application in doses 1/20, 1/100 and 1/200 LD50 Gastrofenzin does not cause development of significant deviation in the organism of the mice from both sexes and its toxicological characteristic is comparatively favourable.

An evaluation of the gonadotropic effect of Gastrofenzin has been carried out in conditions of 45-day and 90-day oral application (daily, 5 times per week) in male white rats. The experiments are performed in doses 1/20, 1/100 and 1/200 LD50, respectively 33.8, 6.7 and 3.4 mg.kg-1. Functional and morphologic methods of investigation have been used-count, character and mobility, acid and osmotic resistance of the sperm cells, mean number of sperm cells in the sperm tube, spermatogenesis' indices, morphological characteristic of the testes as well as autoradiographic method for determining the proteolytic activity of the acrosome. Irrespective of the application term the highest dose (33.8 mg.kg-1) causes systemic deviations in the functional indicators and physiologic fluctuation of the morphologic parameters characterizing the spermatogenic epithelium at preserved proteolytic activity of the acrosome. The dose 1/20 LD50 (33.8 mg.kg-1) is considered to be effective on the gonads in conditions of three-month chronic oral application of Gastrofensin and the threshold of the gonadotoxic activity is about 1/100 LD50-6.7 mg.kg-1.

The dust professional exposition of the above ground workers in the mines "Obrochishte" at the village of Tsŭrkva, Varna Province has been evaluated as well as the dust pollution in the atmosphere of the village in respect to the hygienic standards for quartz-containing sand and manganic aerosol. The results show that the pollution with quartz-containing dust is in the normal ranges according to all hygienic parameters for fibrogenic dusts in working environment and the workers are not exposed to risk of silicosis. A greater than the standard exposition to manganic aerosol (from 1.1 to 5 PDK) has been found out in some groups of workers in the ore-dressing plant, in truck drivers of the intra-fabric transport, in fadromists and heavy scraper workers. The manganic aerosol is found to be a pollutant of the atmosphere also, and the cause of this is thought to be the mine storages in the open-air and the poor state of the intra-fabric roads.

Concentrations of adverse substances in air emissions of a copper manufacture have been determined. There have been found out dust, soot, copper, tin, lead. The generated emissions of these toxic elements from the investigated point generator are not above the admissible ranges and the established technologic conditions are not problematic. The concentrations of vinilchloride, carbon monoxide and carbon dioxide in the air of the working environment are below the respective admissible concentrations and the manufacture is not a source of pollution for the environment.

The method is a contribution in the evaluation of the exposition and the control of the standards for organic powders. The method concerns the sample-taking procedure and the analysis-making technique for determining of the concentration of the microbial pollution of the air. It is based on filtering of some amount of air through a membrane filter which is then processed for cultivating of microbial colonies on its surface. The results are obtained in number of microbial colonies per unit of air. The method presents opportunity to select and vary the filtered volume of air, to determine the respirable fraction, to determine the personal exposition, as well as for the simultaneous determining of the microbial pollution together with other important parameters of the particle pollutants of the air (metal, fibre and others).

The educational effects and living conditions' impact on the physical activity of boys with unequal social status have been investigated. Children from under school age to secondary school age, living in different towns and regions of the country have been studied. The indicators used for physical activity are 60 meters sprint, long jump, right and left hand small ball throw. A comprehensive analysis of the studied indicators is made. It has been found out that the boys from the asylums aged from 3 to 6 years living in town have significantly poorer results in the sprint events compared to the mean standards for the age.

At the Preparatory Workshop of the Plant for Automobile Tires (PAT), Sofia, complex investigations were undertaken to reveal possible genotoxic exposure. The studies included chemical analyses for levels of identifiable human carcinogens in the occupational ambient air (benz(a)pyrene, mineral oils, 2-naphthylamine); special techniques--questionnaire investigations and cytogenetic analysis by cytokinesis-block micronucleus method in peripheral lymphocyte cultures from 23 workers in occupational groups at risk; and urinalysis for contents of mercapturic acids. An out-of-house control group of 13 nonexposed subjects was concurrently investigated. For contents of benz(a)pyrene and mineral oils exceeding 2.5 to 3.5 times the respective occupational environment MACs, evidence from cytogenetic analysis showed substantial, 4-fold, increase in indexes of genotoxic impairment (frequency of micronucleated-binucleated lymphocytes, number of micronuclei per 1000 binucleated lymphocytes) in the workers investigated. These results are an indicator of genotoxic exposure and point to an increased potential risk of cancer development in the group of workers studied.

The arsenic exposure in the main departments and occupational groups of the copper smelter in Pirdop has been estimated in the present study. The contents of arsenic is measured in the air and in biological samples--urine and nails. At most of the workplaces the time-weighted average (TWA) concentrations do not exceed the threshold limit value (0.05 mg/m3). The maximum TWA level is about three times higher. The intake of arsenic is significantly increased in almost all observed occupational groups. However, the excretion of only 8% of the workers is higher than the maximum background level (100 micrograms/l). The estimated degree of exposure corresponds to a low health risk. Some of the most heavily exposed occupational groups may be expected to reach higher levels of intake and health risk.

To obtain reliable results from examination of air sampled onto adsorbents, it is necessary to define the latters' basic parameters: adsorption capacity under sampling conditions, and analytical recovery in separating substances from the sampling medium in view of the next step, analysis. Using a system specially developed for the purpose, the above parameters were tested with five types of activated carbon.

Correlative links between psychologic and psychologic indicators were studied in subjects occupied either in airline transportation or in the chemical industry. Investigations covered three groups of persons: managers of airline traffic (57 subjects); workers at "Vratsa" Chemical plant (14 subjects); and operators at "Vratsa" Chemical plant (14 subjects). The psychologic parameters measured included indicators of cardiac variance: mean--mean value of successive cardiac intervals, SD--standard deviation of mean value of cardiac intervals (R-R), AMo--amplitude of the mode, HI--homeostatic index, Pt--spectral power of R-R related to thermoregulation, Pp--spectral power of R-R related to respiration, IBO--index of centralization; psychologic parameters included: extrovertiveness, introvertiveness, neuroticism, psychoticism, interpersonality conflicts, self-control, social support, self-confidence, work satisfaction, psychosomatic complaints. There was evidence of significant and highly significant correlative links between indicators of cardiac variance and psychologic indicators. There thus appeared to exist certain relationships between the psychologic and psychologic levels during lengthy stressful occupational exposure.