Early effects of low benzene exposure on blood cell counts in Bulgarian petrochemical workers.

OBJECTIVES: Only few studies have examined early hematological effects in human populations exposed to low benzene levels and their findings are controversial. We evaluated hematological outcomes (WBC, neutrophils, lymphocytes, monocytes, eosinophils, basophils, RBC, Hb, HCT MCV, platelets and MPV) in a population of 153 Bulgarian petrochemical workers exposed to benzene (range 0.01-23.9 ppm) and 50 unexposed subjects. METHODS: Written informed consent was obtained and a self-administered questionnaire used to collect information on current smoking habits, lifestyle, and occupational activities. Exposure assessment was based on personal monitoring sampling the day before phlebotomy. Urinary trans-trans-muconic acid (t,t-MA) was determined at the beginning and end of the work shift. Based on individual airborne benzene measurements, study subjects were categorized in three exposure categories (referents, <1 and > or =1 ppm). Mean values of each hematologic outcomes in each exposure category were compared with the referent group using a multiple linear regression model adjusted for age, gender, current smoking habits and environmental toluene level. The influence of the CYP2E1 (RsaI and DraI) and NQO1 609C>T genetic polymorphisms on differential hematological parameters was also investigated. RESULTS: No dose-response effect was observed for most of the examined hematological outcomes (WBC, lymphocytes, neutrophils, monocytes, RBC, Hb, HCT, MCV, platelets and MPV). The eosinophil count was inversely related to benzene exposure only among smokers. Conversely, basophils increased with increasing exposure. No effect on benzene hematotoxicity was found for any of the investigated polymorphisms. CONCLUSION: In our study we did not find a decline in WBC and lymphocytes related to benzene exposure. A myeloproliferative effect of benzene is highly unlikely to explain the observed reduction in eosinophils and increase in basophils as it would lead to a concordant depression in all granulocyte subpopulations. Whether benzene effects at low doses are present in Caucasian populations remains uncertain, thus warranting further investigations.

Study of erythrocytes, hemoglobin levels, and menstrual cycle characteristics of women exposed to aromatic hydrocarbons.

OBJECTIVES: The impact of occupational hazards on erythrocyte and hemoglobin levels and menstrual cycle characteristics in women exposed to aromatic hydrocarbons was studied. The investigated cohort consisted of 110 women exposed to benzene, toluene, xylene and styrene while working in the transport and storage of petrochemical products (TSPP), the laboratory for the control of aromatic hydrocarbons (LCAH), and rubber and latex (RL) production at the biggest petrochemical plant in Bulgaria, Neftochim. Controls consisted of 45 women from the administrative personnel in the same plant. METHODS: Questionnaires were administrated to all participants to obtain self-reported demographic data, data on characteristics of the menstrual cycle, and psychosomatic symptoms. Erythrocyte counts (RBC) and hemoglobin (HGB) levels were determined by the semiautomatic hematology analyzer Serono System 190, USA. All subjects had signed an informed consent. RESULTS: The mean RBC counts and HGB levels of the women from the LCAH and TSPP departments were statistically significantly lower than those of the control group. We found statistically significant differences in all exposed groups in comparison with controls when the dose-response relationship was investigated. No statistically significant differences were found in menstrual cycle characteristics (duration of the menstrual cycle, days and quantity of bleeding) between the subjects exposed and the controls in all age groups investigated, but the numbers were too small to allow definite conclusions. CONCLUSIONS: The lowering of HGB levels and RBC counts in the investigated women were mainly due to the direct influence of aromatic hydrocarbons in the working environment on hematopoiesis. The studied group was too small to enable us to determine the impact of aromatic hydrocarbons on menstrual cycle characteristics, and the possible combination of these effects.

An assessment of the exposure of technicians working in a chemical laboratory for aromatic hydrocarbons at Neftochim, Burgas.

The average exposure to aromatic hydrocarbons per working shift of laboratory assistants at a chemical laboratory were measured. The laboratory is one of the service departments for four different production departments at Neftochim, Burgas--the largest oil refinery in Bulgaria. Long-term sampling of the air from different workplaces in the laboratory was performed by sampling charcoal sorbent tubes (type CT-CN-2), manufactured by Higitest (type NIOSH). The concentration of benzene, toluene, ethyl benzene, xylene and isopropyl benzene in the air at the laboratory was determined by gas chromatography using the Varian MEGA 1 with a flame ionisation detector and Inowax capillary column. The measured exposure levels of toxic substances in the aromatic hydrocarbons analysis laboratory were as follows: Benzene, 0.15-1.3 mg/m3, in single samples its concentration was 4.06-8.63 mg/m3; toluene, 0.15-0.46 mg/m3, in single samples its concentration was 5.5-15.62 mg/m3; ethyl benzene in most samples was 0.02 mg/ m3, in single samples its concentration was 20.68 mg/m3; xylene in most samples was 0.4 mg/m3, in single samples its concentration was 0.51-1.68 mg/m3; isopropyl benzene in most samples was 0.1 mg/m3, in single samples its concentration was 0.20-1.12 mg/m3. The results, obtained by measuring the average work-shift exposure of laboratory assistants to aromatic hydrocarbons in the air at the analytical laboratories, show that the measured concentrations are smaller than the respective threshold limit values. Bearing in mind, however, that some of these substances have an effect on the human organism, exposure to them is excessively hazardous for laboratory technicians.

[Occupational sensitization to methylene diphenyl diisocyanate during the manufacture of polyurethane products]. / Profesionalna senzibilizatsiia s metilen-difenil-diizotsianat v proizvodstvoto na poliuretanovi izdeliia.

A complex occupational hygienic and clinical allergologic investigation in a methylene-diphenyl diizocyanate (MDI)-based polyurethane products manufacture was carried out for the first time in this country. The average MDI concentrations for a shift are within the limits of TWA, but during short operations exceed STEL and reach 0.072-0.181 mg/m3. By clinical and immuno-allergologic methods, applied on 46 MDI-exposed workers and 42 controls, the sensibilizing effect on the respiratory system, skin and eyes was detected. The allergic reactions take the course of bronchial asthma (6.5%), rhinitis and rhinopharyngitis (37%), rhinosinusitis (13%), conjunctivitis (13%), and urticaria and dermatitis (17.4%), as in 12 cases (12%) the allergic illnesses are combined. The specific occupational sensibilization, proved by positive dermal allergy tests with MDI in 24 (52%) exposed workers, and increased MDI-IgE antibodies in 4 workers, is of high statistical reliability in comparison with the control group and supposes immune reactions of quick type (IgE) and mainly retarded type--cell mediated. Various prophylactic measures against the proven occupational sensibilization risk are proposed.

Occupational exposure to Cr(VI): comparison between chromium levels in lymphocytes, erythrocytes, and urine.

The relationships between chromium (Cr) levels in lymphocytes, erythrocytes, urine, and ambient air were compared among 14 chrome-platers from a metallurgic plant in Bulgaria and two groups of local controls, one from the same heavily polluted industrial town as the chrome-platers (n = 11) and one from a seaside resort town 100 km away (n = 6). Among the chrome-platers, the Cr concentration in peripheral lymphocytes was positively correlated with total Cr and Cr(VI) levels in ambient air and with Cr excretion in urine. As compared to the controls, the chrome-platers had mean Cr levels in lymphocytes twice as high, in erythrocytes ninefold higher, and in urine fourfold to eightfold higher. Although Cr levels in urine and lymphocytes were similar between the two control groups, levels in erythrocytes were 3 times higher among subjects from the industrial area than among those from the seaside town. The study suggests that lymphocyte Cr could be a good indicator of the Cr body burden caused by high exposures to Cr(VI), such as in electroplating operations. In these conditions, erythrocyte Cr may be less useful, possibly owing to increased toxicity due to the high affinity of erythrocytes for Cr. However, when exposure is lower, such as in most environmental situations, erythrocyte Cr should provide a better and more sensitive index than lymphocyte Cr. By contrast, urinary Cr, which provides information on total Cr exposure, including Cr(III) from dietary and environmental sources, does not seem to be of value for studying occupational exposure to Cr(VI).

Industrial evaluation of "Hygitest" detector tubes for ethyl acetate.

"Hygitest" detector tubes for ethyl acetate based on a silica gel carrier treated with an indicator reagent--chromium-sulphuric acid were developed. Their quality parameters were compared with the characteristics of the detector tubes for ethyl acetate produced by other companies. An evaluation of the developed detector tubes in industrial atmosphere was carried out. The results obtained are discussed in view of the non-specificity of the detector tubes proposed.

[An infrared spectrophotometric method for determining acetone in the air of a work area in the presence of other solvents]. / Infracherven spektrofotometrichen metod za opredeliane na atseton vuv vuzdukha na rabotnata sreda v prisustvieto na drugi raztvoriteli.

The acetone is used on a large scale in practice as solvent of nitro-cellulose and acetyl-cellulose paints and lacquer, rubber and resins. A spectrophotometric method in the infrared area for direct determination of gas phase of acetone is developed by means of 20 m.gas cuvette. The determination is performed in the specific for the acetone peaks at 1216 cm-1 and 1737 cm-1. With the method could be determined the acetone concentrations of 10 mg/m3 to 2000 mg/m3. For this purpose are worked out different standard scales of the acetone at various length of the gas cuvette. The method is specific in the presence of the most frequently used organic solvents--toluol, ethanol, butanol, mineral turpentine and cyclohexan. Ketones only stand in the way of determination.

[An infrared spectrophotometric method for determining nitrous oxide and halothane in the air of operating rooms]. / Infracherven spektrofotometrichen metod za opredeliane na dvuazoten okis i khalotan vuv vuzdukha na operatsionnite zali.

Nitrous oxide and halothane are one of the most widely used anesthetics in the surgical practice. A spectrophotometric method in the infrared area is worked out for direct determination in gas phase simultaneously on nitrous oxide at 2236 cm-1 and on halothane at 813 cm-1 by means of 20 m gas cuvette. The sensitivity of the method for nitrous oxide is 20 mg/m3 and for halothane 5 mg/m3. The reproducibility of the method expressed as coefficient of variation is +/- 1-6%. The method is specific in the presence of other anesthesiological means. The air samples are taken in bags of Tedlar and depending on the sampling velocity the method can be used for recording the moment and average shift concentrations of nitrous oxide and halothane.

[A comparative evaluation of the methods for determining nitrogen dioxide in an industrial environment]. / Sravnitelna otsenka na niakoi metodi za opredeliane na azoten dvuokis v usloviiata na proizvodstvenata sreda.

The present work has the purpose to make a comparative evaluation of the different types detector tubes--for analysis, long-term and passive for determination of NO2 and the results to be compared, with those received by the spectrophotometric method and the reagent of Zaltsman. Studies were performed in the hall of the garage for repair of diesel buses during one working shift. The results point out that the analysing tubes for NO2 give good results with the spectrophotometric method. The measured average-shift concentrations of NO2 by long-term and passive tubes are juxtaposed with the average-received values with the analytical tubes and with the analytical method.

[An evaluation of the toxic gas pollution in an open-pit mine]. / Otsenka na zamursiavaneto s toksichni gazove na otkrit rudnik.

The present work aims at giving a complete characteristic of the toxic chemical factor in the working environment of a pit "Kremikovtsi", for evaluating the occupational risk for the engaged workers. The basic pollution sources of the pit are the eliminating toxic gases during work from different types of machines and heavy-freight vans. The already measured concentrations of carbon monoxide, carbon dioxide, nitric oxides, hydrocarbons, aldehydes and lead, manganese, ferrous and mercury aerosols in all working places of the pit are under MAC. The calculated total index of toxicity for all working places surpasses up to 3 times the unit and is rated. 1st degree--unfavourable conditions of work concerning the toxic chemical factor.

[Hygienic evaluation and the effects of toxic factors in the work environment of copper-processing plants]. / Khigienna otsenka na toksichnite faktori na rabotnata sreda v osnovni uchast'tsi pri proizvodstovoto na med.

The study embraces the shops: metallurgic, electrolysis, production of sulfuric acid and shop 100. Tests are performed on the environmental pollution by dust, sulfur dioxide, chlorine, aerosols of sulfuric acid, carbon monoxide, nitric oxide and dioxide, hydrogen chloride, arsenic (II) oxide (III), selenium, tellurium and metal aerosols: lead, copper, cadmium and zinc. The total concentrations of chemical noxae, generating multicomponent mixtures with one-way effect on the work place, are reckon, and estimation in the Bulgarian Institute of Hygiene and Occupational Health and the Ministry of public health methods. In the same shop is comprised a representative group of workers with paraclinical tests: GOT and GPT activity, content of copper and zinc in blood. The assessment made on the work conditions and the changes already found in the workers lead to a discussion for optimizing the conditions in the new shops for copper production.