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PubMed1981

[Effect of mercury on the sexual cycle and prenatal and postnatal development of progeny].

Extensive use of mercury in various economic branches and its toxic properties as well as increasing number of exposed population make it necessary to elaborate the data on the relatively little known aspects of hazardous effects of this compound. Basing on the data from literature and our own studies we analysed the effects of mercury on the sex cycle in humans and animals, penetration of mercury from mother's blood to fetus, embryotoxic and teratogenic effects of mercury and influence of prenatal intoxication on postnatal development of progeny. Toxic effects of organic and inorganic effects of mercuric compounds, especially mercury vapours, were compared. A need was pointed out to decrease the value of the maximum allowable concentration of mercury vapour to 0.01 mg/m3 in case of women's occupational exposure to that element.

Abortion, Spontaneous↗
PubMed1982

[Human allergic hypersensitivity and chemical residues in food].

Chemical and immunological basis of hypersensitivity reactions to low molecular weight substances are recalled. Then the authors give examples of directly reactive chemicals as penicillins and some antineoplastic drugs. The possible role of reactive impurities as penicillins and aspirin is also reminded. It is emphazised that some substances induce allergic reactions through their metabolites: such reactions are mostly unforeseeable. The second part of the paper recalls the main clinical manifestations of these allergic hypersensitivity reactions to chemical residues in food. It is finally emphazised that the datas from animal experiments and epidemiological studies could allow a classification of chemical substances according to their potential risk. This would be of great importance to determine which substances may be authorized in food stuffs and/or to specify the maximum allowable concentrations.

Anti-Bacterial Agents↗
PubMed1981

[Heavy metal content in the soils in the area of the Damianov Copper-Extraction Plant in the city of Srednogorie].

A study was carried out on soils for heavy metals content in the region of one of the largest scale enterprises in the country - Copper Extraction Plant "G. Damjanov", Srednogorie town. A sensitive method was used with atom absorption spectrophotometer Perkin Elmer, Model 272, for the determination of the heavy metals investigated: manganese, nickel, zinc, copper, lead and cadmium. The authors investigated soil samples from two horizones: from 0.30 and from 30-60, comparing the results obtained with those in control "pure" soils and with the existing maximum allowable concentration (MAC). Elevation of the quantity of heavy metals in the soils was established, being best manifested with copper and lead, 90% of the samples containing copper over MAC, and with lead-over 33%.

Bulgaria↗
PubMed1994

[Effects of exposure to TNT on sex hormones in male workers].

Field investigation on labour hygiene in two plants producing trinitrotoluene (TNT) in Henan Province showed most air TNT levels in the workplace exceeded national maximum allowable concentration (MAC 1 mg/m3) and the skin of the workers exposed to TNT was severely contaminated. Determinations of serum levels of sex hormones showed those of testosterone were lower, but those of interstitial cell-stimulating hormone (ICSH or LH) and follicle stimulating hormone (FSH) were higher in workers exposed to TNT than that in controls with statistical significance (P < 0.01).

Adult↗
PubMed1993

[An experimental study of the atherogenic effect of the vanadium and nickel contained in drinking water when combined].

During an annual toxicological experiment on white male rats, receiving orally vanadium (V) and nickel (Ni) in doses, equivalent to the accepted in Bulgaria, maximum allowable norms for ist category surface waters (respectively 0.005 mg/kg and 0.0025 mg/kg), 2 and 6 times and 20 and 60 times higher, is studied the atherogenic effect of the latter after the indices: total cholesterol, beta-lipoproteins, phospholipids, lecithin, total lipids, total protein and hexoses of glycoproteins in the serum; oxyproline, hexauranium acids and hexoses, hexosamines, connected with the proteins in the aorta. It is established that V and Ni in chronic combined effect in doses, equivalent to those accepted in Bulgaria, in maximum allowable concentrations for Ist category waters and surpassing them 2 and 6 time respectively, lead to no changes in the biochemical composition of the connective tissue of the aorta and to disorders in the lipidic and protein metabolism, while in higher doses is registered an increase of the glucoproteins and decrease in the glucosaminglycans in the aorta and decrease of the total lipids in the serum. The results point out, that V and Ni in the conditions of the experiment don't accelerate the processes of the natural ageing of the vessels and have no atherogenic effect. Juxtaposing the data for V and Ni concentrations in drinking waters in Bulgaria with our results give grounds to reckon, that their raised content in drinking waters in some regions do not represent a risk factor for the development of atherosclerosis.

Administration, Oral↗
PubMed1994

[An assessment of the air pollution in the area of the Maritsa-Iztok Economic Union].

The heating-electric plant "Maritsa Iztok" is situated in the area of Stara Zagora, on arable agricultural land, in close vicinity to settlements. It includes three heating plants, working with low caloric coals, of high ashen and sulphuric content and briquet fabric. Two stations for observation and evaluation of the atmospheric air in the district of plant "Maritsa Iztok", the meteorological conditions and geographic situation are chosen according to the Bulgarian State Standards 17, 2, 5, 01-81: station 1-"Gŭlŭbovo" and station 2-"Mednikarovo" for indices--dust, sulphur dioxide, hydrogen sulphide, ammonia, nitrogen peroxide. In order to determine the content of the already mentioned pollutants in the atmospheric air are used Bulgarian State Standards and the results are compared with the corresponding maximum allowable concentrations, according to Regulation No 2 of the Ministry of Health.

Air Pollutants↗
PubMed1994

[The information value of biotesting and chemiluminescence methods in evaluating drinking water quality].

The article studies the informative value of test objects for the evaluation of potable water which contains toxic substances. A number of test objects is proposed by the authors to estimate the chemical harmlessness of water: tetrachimens, Daphnia and peroxide ferment system. The data obtained with the help of test-objects possess a sufficient selective sensibility as far as maximum allowable concentration of various toxic substances is concerned. The authors stress that these methods of biological testing may complement or precede the traditional methods of water evaluation.

Animals↗
PubMed1996

External ocular hyperemia: a quantifiable indicator of spacecraft air quality.

BACKGROUND: Eye irritation consistently ranks as a top astronaut complaint but is difficult to measure. Exposure to internal air pollution hypothetically disrupts the eye's tear film, thereby exposing the crewmembers' conjunctivae to the irritating effects of the recirculated, contaminant-laden atmosphere of the space vehicle. Causes elude engineers and toxicologists, who report that measured irritants remain below established Spacecraft Maximum Allowable Concentrations. Lack of objective ocular endpoints stymies efforts to identify etiologies. HYPOTHESIS: Computers offer a practical means of analyzing ocular hyperemia in space. METHODS: We use computer analysis to quantify redness and blood vessels of digitized images of bulbar conjunctivae in near real time. Custom software masks artifacts, lids and lashes for each photographic or telemedicine ocular image, Algorithms then generate semi-independent measurements of hyperemia. Computed difference scores between 34 pairs of images were compared with subjective difference scores as voted on by a panel of ophthalmology residents. RESULTS: Objective data were reliably extracted from ocular images and significantly correlated (r = 0.583, p < 0.05) with subjective scores. CONCLUSIONS: This ground-based methodology generates accurate and reliable ocular endpoint data without mass, volume, or power penalty. To assist in identifying and eliminating onboard ocular irritants, these objective data can be regressed against independent variables such as mission elapsed time, subjective astronaut complaints, levels of chemical and electromagnetic contaminants, nephthelometric and barothermal data. As missions lengthen, sensitive tools such as hyperemia quantification will become increasingly important for assessing and optimizing spacecraft environments.

Adult↗
PubMedDate not supplied

Natural fluoride and trace metal levels of ground and surface waters in the greater Accra region of Ghana.

In a study of levels of fluoride and trace metals in ten different stations of both surface and groundwaters in the Greater Accra Region, Ghana, groundwaters were found to have lower pH than surface water, resulting in groundwaters having higher concentrations of dissolved ions. Groundwaters had higher fluoride levels than surface waters. The correlation coefficient for fluoride on total alkalinity and for fluoride on sodium were 0.56 and 0.27 respectively which implied that rock weathering played a minor role in the recorded fluoride enrichment of the underground waters. A likely mechanism for the higher underground fluoride levels could be bacterial decay of plant materials resulting in the release of fluoride to the underground waters. The levels of Cu, Cd, Pb and Zn fell within the expected background ranges. 90% of the sites had Mn levels above the detection limits in both underground and surface waters. 70% of boreholes in Accra plains had Fe levels higher than the WHO recommended limits of 0.3 mg/l for drinking water. Generally, underground waters had higher concentration of fluoride and trace metals than surface waters.

Fluorides↗
PubMed2004

Human health risk assessment of 2-mercaptobenzothiazole in drinking water.

2-Mercaptobenzothiazole (MBT) is used as a vulcanization accelerator in rubber products that come into contact with potable drinking water. When such products are evaluated for contact with potable water and submitted for ANSI/NSF Standard 61 certification, any chemical extracting from these products must be below an appropriate action level of exposure. As defined by Standard 61, a total allowable concentration (TAC) is the maximum concentration of a nonregulated contaminant allowed in a public drinking water supply, and the single product allowable concentration (SPAC) is 10% of the TAC. Currently, MBT has a TAC of 40 microg/L and a SPAC of 4 microg/L. A comprehensive health effects evaluation of MBT was performed to determine whether these action levels should be revised. Epidemiological investigations indicate that workers occupationally exposed to MBT have an increased risk of death from bladder cancer. Genotoxicity investigations in bacterial and mammalian test systems provide some evidence indicating that MBT has the potential to induce mutations and chromosomal aberrations. Toxicity studies in rats and mice chronically exposed to MBT identified increases in various tumours, such as adrenal gland tumours, pituitary gland tumours, liver tumours and renal pelvis tumours. The biological significance of most of these tumours is questionable due to a variety of factors, such as a lack of dose-response between tumour incidence and dose, and the effect of test article vehicle (corn oil) upon tumour rates. Potential human health effects of exposure to MBT can be predicted from an NTP 2-year cancer study in rats, as well as epidemiological investigations in occupationally exposed workers. A comprehensive review of the epidemiological and toxicological dataset for MBT indicates that the induction of renal pelvis transitional cell tumours is the most sensitive and relevant health effects endpoint upon which to base a revised TAC and SPAC. A multistage model was used to extrapolate to low-dose MBT exposures due to the genotoxicity and clastogenicity of MBT. A TAC of 600 microg/L was derived for MBT, and was based upon an LED10 of 157.681 mg/kg per day. A SPAC of 60 microg/L was derived by multiplying the revised TAC by 0.10, and rounding to one significant figure. These revised action levels are based upon the most sensitive health effects endpoint, as well as current cancer risk assessment methodology.

Animals↗
PubMed1992

Serum fluoride as an indicator of occupational hydrofluoric acid exposure.

To define the relationship between ionic fluoride concentration in the serum of workers and the amount of hydrofluoric acid (HF) in the work environment, pre-and postshift serum and urine samples of 142 HF workers and 270 unexposed workers were examined. The maximum and minimum concentrations of HF in the air in each workshop varied from the mean by less than 30%. The preexposure levels of serum and urinary fluoride in HF workers were higher (P < 0.001) than the control values. This suggests that fluoride excretion from the body continues for at least 12h. The postshift serum and urinary fluoride concentrations of these workers were significantly higher (P < 0.001) than the preshift concentrations. A good correlation (r = 0.64) was obtained between postshift serum fluoride and postshift urine fluoride. There was a linear relationship between mean serum fluoride concentration and HF concentration in the workshop. A mean fluoride concentration of 82.3 micrograms/l with a lower fiducial limit (95%, P = 0.05) of 57.9 micrograms/l was estimated to correspond to an atmospheric HF concentration of 3 ppm. This is the maximum allowable environmental concentration recommended by the Japanese Association of Industrial Health, and it is also the threshold limit value suggested by the American Conference of Governmental Industrial Hygienists. The results demonstrate that exposure to HF can be monitored by determining the serum fluoride concentration.

Adolescent↗
PubMed1999

Steady-state oxidation model by horseradish peroxidase for the estimation of the non-inactivation zone in the enzymatic removal of pentachlorophenol.

A theoretical model for the rate of oxidation of pentachlorophenol (PCP) catalyzed by horseradish peroxidase (HRP), was investigated to account for the influence of hydrogen peroxide (H2O2) concentration on the catalytic activity. To evaluate the maximum allowable H2O2 concentration, a relatively simple steady-state model was developed based on the Ping-Pong Bi-Bi mechanism considering the effect of excess H2O2. Several sets of experimental data obtained from batch reactions using an equimolar concentration of H2O2 and PCP were used to estimate the kinetic parameters by a nonlinear regression method. The model profiles acquired using the estimated parameters were in good agreement with experimental data at different initial enzyme and substrate concentrations. The best-fitted parameters were used to predict the initial rate of the enzyme reaction. The model prediction was coincident with the experimental results of other studies, indicating that the proposed model could be used for the optimization of reaction conditions. The maximum allowable H2O2 concentration to prevent H2O2 inhibition was calculated from the proposed model equation: [H2O2](0,max) = (square root)KmH2O2Ki[PCP]0/KmPCP+[PCP]0. Using this equation, a curve depicting the non-inactivation zone for the two substrates (hydrogen peroxide and PCP) was plotted and it could be used for experimental design and optimal process operation. To minimize enzyme inactivation by H2O2, it was determined that the concentration of H2O2 should be lower than 2.78 mM, regardless of the stoichiometric ratio.

Journal Article↗
PubMed2002

Distribution and mobility of metals in contaminated sites. chemometric investigation of pollutant profiles.

The distribution and mobility of heavy metals in the soils of two contaminated sites in Piedmont (Italy) was investigated, evaluating the horizontal and vertical profiles of 15 metals, namely Al, Cd, Cu, Cr, Fe. La, Mn, Ni, Pb, Sc, Ti, V, Y, Zn and Zr. The concentrations in the most polluted areas of the sites were higher than the acceptable limits reported in Italian and Dutch legislations for soil reclamation. Chemometric elaboration of the results by pattern recognition techniques allowed us to identify groups of samples with similar characteristics and to find correlations among the variables. The pollutant mobility was studied by extraction with water, dilute acetic acid and EDTA and by applying Tessier's procedure. The fraction of mobile species, which potentially is the most harmful for the environment, was found to be higher than the one normally present in unpolluted soils, where heavy metals are, to a higher extent, strongly bound to the matrix.

Environmental Monitoring↗
PubMed2003

Release of heavy metals from Tunisian traditional earthenware.

Lead and other heavy metals are found to leach from the glazes of some Tunisian glazed earthenware in concentrations high enough to constitute a serious health hazard. When yellow/green and white/green colored mugs available on the Tunisian market were filled with acetic acid solutions, concentrations of up to 51 microg lead per ml of leachate were measured. The values greatly exceed the limit allowed by the US Food and Drug Administration (FDA) regulations for a 24-h leaching test. The use of a traditional milk derivative (leben) widely consumed as a beverage in Tunisia as a leaching agent shows that amounts as high as 1407 microg of lead is ingested per mug of milk derivative consumed. The use of such utensils may constitute a serious health hazard to the Tunisian consumer. Stringent regulations and controls are therefore required to protect the consumer against lead and other heavy metals of non-occupational origin.

Acetic Acid↗
PubMed2001

Degradation of the insecticide azinphos methyl in orange and peach juices during storage at different temperatures.

The degradation of azinphos methyl in orange and peach juice was studied. The insecticide was aseptically added to packed orange and peach juices and stored at 40, 20 and 0 degrees C. Samples were removed at regular intervals and were analysed for residues of azinphos methyl. Residues were determined with a simple gas-chromatographic method using a 30 m glass capillary column and an NP detector. The recoveries of azinphos methyl were 87-110% for orange juice and 92-108% for peach juice, and the limit of determination was 0.004 mg/kg for both juices. From the experimental data, rate constants, half-lives, and times needed to reach legal limits for the decomposition of azinphos methyl in orange and peach juices were evaluated. Half lives for orange and peach juices were 6.5 and 7.8 days at 40 degrees C, 86.6, and 92.4 days at 20 degrees C, and 407.7 and 495.1 days at 0 degrees C, respectively.

Azinphosmethyl↗
PubMed1992

Potential lead exposures from lead crystal decanters.

We measured the concentrations of lead leached into 4% acetic acid, white port, and a synthetic alcoholic beverage that were stored in lead crystal decanters for 1-, 2-, and 10-day periods at room temperature. In decanters from 14 different manufacturers, measured lead concentrations ranged from 100 to 1800 micrograms/L. The pH of the leaching medium is probably the dominant factor determining the extent of lead leached, with greater leaching occurring at lower pH values. The consumption of alcoholic beverages stored in lead crystal decanters is judged to pose a hazard.

Acetates↗