[The toxic hygiene problems of workers in the Dinamik automobile tire plant in Sofia].

Toxic hygienic investigations were carried out involving a representative group of 131 workers (50 females and 81 males) distributed into three main workshops--preparatory, confection, and vulcanization--at "Dynamic" automobile tire plant in Sofia. The majority of male and female workers were in the age range beyond 40 years, having a general occupational experience in excess of 10 years and specialized occupational experience from 10 to 20 years or more. The chemical hazard was among the leading ones in the occupational environment, differing in nature according to the technologies used.

[The assessment of the occupational risk to workers in electric steel production].

These studies, centering on occupational environmental factors, biologic monitoring, and toxicodynamic investigations, involved a total of 105 workers distributed into eight job groups, who were 45 years, of age on the average and had from 5 to 10 years of special occupational experience at "Electrosteel" Works. Evidence was obtained for presence of unfavorable microclimate conditions, elevated equivalent levels of noise, excess of general and local vibrations, exposure to manganese aerosols, carbon monoxide, and nitrogen oxides; some of the subjects and deviations in hepatic status and connective tissue. Job groups found to be at risk were those of steel founders, crane workers, and pourers.

[Granulocyte alkaline phosphatase--a biomarker of chronic benzene exposure].

In tracing the cellular population status in the peripheral blood of workers, exposed to benzene, was included and cytochemical determination of the alkaline phosphatase activity in leucocytes. This enzyme is accepted as marker of the neutrophilic granulocytes, as maturation of the cells and their antibacterial activity are parallel to the cytochemical activity of the enzyme. 78 workers from the coke-chemical production from state firm "Kremikovtsi" and 41 workers from the production "Benzene" and "Isopropylbenzene"--Oil Chemical Plant, Burgas are included.

[Changes in the blood system under chronic toxic exposure].

On the basis of accumulated experience from the numerous investigations of the elements of the peripheral blood in workers of different areas in industry and agriculture a classification is made of the injuries of the blood system under chronic toxic effects. Results from the peripheral blood state of 200 workers with chronic exposure to benzol and other aromatic hydrocarbons are given, as well as for 155 agricultural workers in contact with pesticides for many years and 308 children of the region with polluted by heavy metals (mainly lead) environment. Attention is drawn, that both the acute intoxications and chronic toxic effects have provoking role for the manifestation of concealed congenital, not rarely genetically stimulated insufficiency of Gl-6-PHD, which is manifested clinically as haemolytic anemia and secretly proceeding hemoglobinopathies, which clinically develop as thalassemia at entering of toxic doses of drugs, heavy metals, pesticides in the organism.

[The hematological and biochemical changes in workers exposed to benzol].

The study embraces 122 workers from two productions, where the leading chemical noxious in the working environment is benzol. The workers are distributed in groups according to the calculated index of exposure in view of looking for dependence dose-effect. Routine indices of peripheral blood are examined as well as the activity of myeloperoxidase and alkaline phosphatase in leucocytes.

[The acute toxicity of the microbial preparation bulmoscide].

The acute toxicity of a new Bulgarian microbial preparation bulmoscid on the basis of Bacillus thuringiensis H-14 in the conditions of oral, dermal, inhalation and intraperitoneal introduction in experimental animals is determined. The assessment of toxicity is made by using toxicometric, integral, hematologic, histologic and microbiologic methods in accordance with Bulgarian and international criteria and standards. It is established, that the preparation bulmoscid introduced orally in dose 5500 mg.

[The level of mercapturic acids in the urine of workers in the petroleum refining industry].

Examination are carried out on 236 workers from three productions of oil-processing industry, who are exposed to the effect of hydrocarbons--saturated from the ethylene order, saturated (benzine), aromatic and sulphuric compounds--sulphur-containing organic, hydrogen sulphide, sulphur dioxide. The purpose of the study is to establish the risk of exposure to alkylating agents, which are potentially cancerogenic and mutagenic. Leading noxa in the production of high-octane aviation benzine (production "sulfur acidic alkylation", are the sulphur containing organic compounds, hydrogen sulphide, and in some working places--hydrocarbons (benzine and aromatic); in the production of "Ethylene" and "Polypropylene" leading noxae are the saturated hydrocarbons, and the sulphur-containing organic compounds as well as the unsaturated hydrocarbons (ethylene and propylene).

[Epidemiological studies on the manufacture of cross-linked polyethylene].

In the production of cross-linked polyethylene in the air of the working environment above the norm concentrations of acetophenon, dicumyl peroxide and antioxidant are established, which create unfavourable working conditions. During clinical and laboratory examinations of 55 workers, engaged in the production of cross-linked polyethylene, are registered subjective complaints from the irritating effect of the chemical noxae on the mucous membranes and skin. Methaemoglobinaemia is found in 4 workers.

[The relationship of exposure to chemically harmful compounds and disorders of the health status in workers in ethylene production].

On the basis of job characteristics of workers from the production "ethylene", chronometric studies and measurement of concentration from chemical compounds are developed professional diagrams and risk diagrams, which give a possibility for more precise account of the exposure to chemical noxious compounds (by figures). According to the values of the estimated total index of exposure 156 workers are distributed in 5 groups. Besides, 48 workers with prolonged length of service in the production and 37 persons control group are examined.

[Dermal exposure to ethylenediamine in the petrochemical industry].

During an examination of 47 workers engaged in ethylenediamine production subjective complaints of the skin were registered in 39% of them. Professional contact allergic dermatitis (26%) prevail over the contact irritative (6.5%) and lead very often to a change of employment for the operators.

[Changes in the peripheral blood of workers engaged in ethylbenzene-styrene and synthetic rubber and latex manufacture].

A total of 67 workers were examined from the production of "Ethyl benzene-styrene" and 184 workers from the production of "Synthetic rubber and latex", as well as a control group of 59 employees. The workers from the first production are exposed to the effect of styrene, ethyl benzene and toluene. The concentrations of the substances surpass MAC, with several times, at the majority of the working places.

[New epidemiological study data on the manufacture of divinyl].

Complex labour-hygienic studies were carried out on the working environment in divinyl production as well as on the health state of the workers. The leading deleterious factor of the environment are the concentrations of divinyl, hydrocarbons and ammonia above the norms. The latter have been determined by stationary and personal sample collecting.

[Assessment of the occupational risk to workers engaged in the manufacture of divinyl-styrene rubber].

The production of synthetic rubber, one of the varieties of petro-chemical branch in our country, is new and very prospective. The Bulgarian synthetic rubber is synthesized from petroleum products divinyl and styrene. After the hygienic assessment of the technological processes, a complete characteristic of labour conditions was made and the character of the working process was studied of the main occupations of the workers, attending the installations of Synthetic Rubber Plant.

[Experimental assessment of the risk for offspring in lead exposure].

Multigenerational studies were carried out on albino rats obtained from parent progeny - female-intact and male-perorally exposed to lead acetate, in the drinking water - 0.2 mg/kg (group I) and 20 mg/kg (group II); the data were compared with a control group. Changes were found in each progeny as follows : in PI - reduced erythrocyte count, increased reticulocytes (group II); enhanced ATP activity in brain homogenates (group II), as will as increased disulphide groups in homogenates from brain, liver and testis (group II), highly reduced indices of fertility - 50% and of gestation - 62% (group II), in 100% level of the same indices in the control animals respectively.

[Industrial hygiene studies in the production of various fibers and plastics].

The results from the labour-hygienic and clinical laboratory studies on working environment and workers engaged in production of polyamide (PAS) and polyacrylnitrile fibres (PAN) are summed up as well as in the production and processing of polyvinylchloride resin, polyurethan, polysterene and glass fibre laminates. The main deleterious factors in those productions are the chemical ones: caprolactam, acrylonitrile,tolyl diisocyanate, vinylchloride, styrene, etc. Noise and microclimate are the other unfavourable on-the-job factors.

[Assessment of the potential risk for progeny in work with endodan (experimental studies)].

An experimental assessment was made on endodan (ETM) effect, dithiocarbamate preparation, on the reproductive function of the parent generation albino rats, perorally intoxicated (by a sound) with doses 1/10 and 1/100 LD50, daily in the course of 6 months (LD50 = 380 mg/kg). The postnatal development of the three successive generations (F1, F2, F3) was studied. For that purpose, a complex of integral toxicological methods was used: weight, neurobehavioural activity, nortality (by 1st, 5th, 21st day), with the calculation of the indices of survival and lactation, and fertility with calculation of the indices of fertility and gestation and biochemical and clinical laboratory methods for the assessment of the functional state of liver, brain and testes.

[Effect of dimethylformamide on the health status of workers].

Results are reported of the clinical examination and some laboratory tests performed in a group of workers, employed in the production of polyacrylnitryl fibers "Bulana" at the oil- processing and chemical works in Burgas, who have been exposed for 3 to 5 years to dimethylformamide (DMF). DMF concentrations in the air of the work environment were within the threshold ones, or exceeded them from 3 to 6 times. The most common constitutional symptoms were: fatigue, weakness, numbness of the extremities, eye and throat irritation.

[Experimental substantiation of the maximum permissible concentration (MAC) of polyvinyl chloride resin].

The acute and chronic oral, dermal and inhalatory toxicity of PVH resin is studied in white rats. It is established that in acute treatment, irrespective of the route of PVC resin penetration into the organism, its effect proves weakly toxic. During chronic oral and inhalatory experiments, a slight affection of peripheral blood elements only is noted.