Tissue distribution and temperature-dependence of Anguilla anguilla L. EROD activity following exposure to model inducers and relationship with plasma cortisol, lactate and glucose levels

Anguilla anguilla L. ethoxyresorufin-O-deethylase (EROD) elevation by 2.7 microM beta-naphthoflavone (BNF) 3 days water exposure, or 4 mg/kg ip exposure, was studied in four different organs--liver, kidney, gills, and intestine. The results demonstrated a significant increase in liver EROD activity for the two previous conditions, whereas kidney EROD activity only increased during the intraperitoneal exposure. A. anguilla was also exposed during 8, 16, and 24 h to water contaminated with 2.7 microM BNF or benzo[a]pyrene (BaP) at 20 degrees C and 25 degrees C. Both compounds significantly increased liver EROD activity from 8 up to 24 h. There was no significant difference in liver EROD activity elevation by both compounds, either at 20 degrees C or 25 degrees C. Liver EROD activity was demonstrated to be one of the first warning systems concerning the presence of polycyclic aromatic hydrocarbons (PAHs) in water. A. anguilla 3 h exposure to diesel oil water-soluble fraction (DWSF) significantly increased plasma cortisol and significantly decreased plasma lactate. A prolonged exposure beyond 3 h, i.e. 4 h, 2, 3, 4, and 6 days to the previous conditions demonstrated a significant liver EROD activity elevation from Day 2 up to 6, and a significant increase in erythrocytic nuclear abnormalities (ENA) at Day 6.     

Endocrine and metabolic changes in Anguilla anguilla L. following exposure to beta-naphthoflavone--a microsomal enzyme inducer

Anguilla anguilla L. were exposed during 24 and 48 h to 2.7 muM beta-naphthoflavone (BNF), a known microsomal enzyme inducer. The BNF effects on thyroid-stimulating hormone (TSH), free triiodothyronine (T3), free thyroxine (T4) and cortisol plasma levels were investigated. Alterations on plasma glucose and lactate levels were also measured as an indication of energy-mobilizing hormones alterations. BNF showed to be able to decrease significantly A. anguilla plasma T4 levels, whereas TSH, T3 and cortisol plasma remained constant. However, plasma glucose levels were significantly increased, demonstrating that intermediary metabolism has been affected. These results demonstrate that BNF a PAH-like compound alters the normal functioning of the hypothalamo-pituitary-thyroid (HPT) axis in A. anguilla.     

Naphthalene and beta-naphthoflavone effects on Anguilla anguilla L. hepatic metabolism and erythrocytic nuclear abnormalities

The effects of a polycyclic aromatic hydrocarbon (PAH) such as naphthalene (NAP)--an environmental contaminant--and beta-naphthoflavone (BNF)--a model substance (PAH-like compound)--were investigated in European eel (Anguilla anguilla L.) over 3-, 6-, and 9-day exposure (0.1-2.7 microM). Both xenobiotics revealed to be strong biotransformation (phase I) inducers. After 3-day exposure, liver ethoxyresorufin O-deethylase (EROD) activity was significantly increased by all NAP and BNF tested concentrations. At 6 and 9 days, liver EROD activity was significantly induced mainly by the highest NAP and BNF concentrations. Liver cytochrome P450 content was significantly induced after 3-day exposure to 0.9 and 2.7 microM BNF and 9-day exposure to 0.1, 0.3 and 0.9 microM NAP. Liver alanine transaminase (ALT) activity was measured as an indicator of hepatic health condition, revealing a significant decrease after 6-day exposure to 0.9 microM BNF. Genotoxicity measured as erythrocytic nuclear abnormalities (ENA) was detected in all BNF treated fish on day 6, whereas on day 9, ENA frequencies returned to control levels, significantly decreasing at 0.9 microM BNF exposure. Immature erythrocytes (IE) frequency demonstrated a decreasing tendency along the BNF experiment and concomitantly with the above ENA response. The present experimental results elect EROD activity in A. anguilla as a useful short- to medium-term biomarker of exposure to both PAH and PAH-like compounds. However, some problems can emerge in the presence of high xenobiotic concentrations. Concerning genotoxicity, it is hypothesized that ENA response depends on different factors such as the exhaustion of the detoxification process, the balance erythropoiesis/erythrocytic catabolism and the DNA repairing capacity.     

Biotransformation, stress and genotoxic effects of 17beta-estradiol in juvenile sea bass (Dicentrarchus labrax L.)

The effects of 17beta-estradiol (E(2)) on fish became a matter of concern, since significant levels of this hormone were detected in the aquatic environment released mainly by domestic sewage treatment plants. In this perspective, the current study was focused on E(2) effects upon biotransformation, stress and genotoxic responses of juvenile Dicentrarchus labrax L. (sea bass). Fish were exposed to E(2) during 10 days in two different ways: water diluted (200 ng/L or 2,000 ng/L) and i.p. injected (0.5 mg/kg or 5 mg/kg). A battery of biological responses was evaluated: liver ethoxyresorufin-O-deethylase (EROD) and alanine transaminase (ALT) activities, liver somatic index (LSI), plasma cortisol, glucose and lactate concentrations, as well as erythrocytic nuclear abnormalities (ENA). All the exposure conditions induced endocrine disruption, measured as plasma cortisol decrease, and genotoxicity, measured as ENA increase. Thus, no differences were detected either between different exposure routes or tested concentrations. Concerning liver EROD and ALT activities, as well as plasma glucose and lactate concentrations no differences were found between treated and control groups. LSI was the only parameter to respond differently in the two exposure routes, as only E(2) water diluted induced a significant increase in this hepatic indicator.     

Elimination of chloramphenicol, sulphamethoxazole and oxytetracycline in shrimp, Penaeus chinensis following medicated-feed treatment

Muscle residue depletion of chloramphenicol (CAP), sulphamethoxazole (SMZ) and oxytetracycline (OTC) following oral administration was evaluated in shrimp, Penaeus chinensis under field conditions. Three groups of shrimps were cultured in tanks filled with seawater and fed a commercial medicated diet containing 2000 mg kg(-1) CAP, SMZ and OTC, respectively, twice daily for 3 days. Sampling was conducted at different intervals (0, 0.5, 1, 1.5, 2, 3, 4, 8, 10, 12, 16, 24, 36, 48, 72, 96, 120, 144, 168 h) after the cessation of medication. Drug analysis was carried out by HPLC. The elimination half-life (t(1/2)) of CAP was 10.04 h, the elimination half-life (t(1/2)) of SMZ was 5.68 h and that of OTC was 16.12 h. If the EU MRPL value of 0.3 ng/g for CAP and MRL value of 0.1 microg/g for SMZ and OTC quoted for muscle from finfish is extended to shrimp muscle, extrapolation of the data indicates that it would be passed after a 139.7 h (95% CI=132.0-144.4 h), 30.6 h (95% CI=27.2-33.1 h), 90.3 h (95% CI=87.9-92.5 h) withdrawal period for CAP, SMZ and OTC in shrimp muscle, respectively.     

Methylmercury genotoxicity: a novel effect in human cell lines of the central nervous system

Methylmercury is an important source of environmental contamination and the central nervous system (CNS) is one of the main target organs. Methylmercury genotoxicity was already demonstrated in peripherical tissues but was never detected in the brain. Thus, the objective of this work was to verify its genotoxic effect using brain cell lines. Glioblastoma (U373) and neuroblastoma (B103) human cell lines were exposed to methylmercury (0-10 microM). By measuring cellular viability, concentrations inducing <20% of cellular death (P<0.05) were selected: 1 and 0.1 microM. To detect micronuclei, 200,000 cells were treated with methylmercury for 24 h, and then incubated with cytochalasin B (2 microg/ml) for 72 h (U373) or 48 h (B103). The binucleation index, frequency of micronucleated cells, micronucleation index, metaphasic index and index of nucleoplasmic bridges were determined. Statistical analysis showed indices and percentages significantly higher (P<0.05) in methylmercury-treated cells. Each cell line was shown to be differently sensitive to each biomarker of genotoxic damage, which seems to indicate the existence of different mechanisms of toxicity. This work demonstrates, for the first time, MeHg ability to provoke genotoxicity in cells of brain origin with relatively low levels of exposure.     

Hormonal response to conspecific chemical signals as an indicator of seasonal reproduction dynamics in the desert hamster, Phodopus roborovskii

Changes in male blood plasma testosterone and cortisol in response to exposure to scent marks (urine and midventral gland secretion, MVGS) of conspecific males and diestrous females in different seasons have been studied in the desert hamster (Phodopus roborovskii), a species whose ecological features are poorly known. The results show that a significant increase in the plasma testosterone level is observed in winter (only to female MVGS), spring (to female MVGS and urine), and summer (to female urine), but not in autumn. The level of plasma cortisol significantly increases only in response to female urine in spring and male MVGS in summer.     

Endocrine and immunological parameters in individuals involved in Prestige spill cleanup tasks seven years after the exposure

In November 2002 the oil tanker Prestige spilled 63,000 tonnes of heavy oil off the northwest coast of Spain, impacting more than 1000 km of coastline. A general concern led to a huge mobilization of human and technical resources, and more than 300,000 people participated in cleanup activities, which lasted up to 10 months. Some endocrine and immunological alterations were reported in Prestige oil exposed subjects for several months. Therefore, the objective of this study was to evaluate if these alterations are still present seven years after the exposure. Fifty-four individuals exposed for at least 2 months were compared to 50 matched referents. Prolactin and cortisol plasma concentrations, percentages of lymphocyte subsets (CD3⁺, CD4⁺, CD8⁺, CD19⁺, and CD56⁺16⁺), plasma levels of circulating cytokines (interleukin (IL) 2, IL4, IL6, IL10, tumour necrosis factor α, and interferon γ), and serum concentrations of neopterin, tryptophan and kynurenine were determined in peripheral blood samples. Results showed significant differences in exposed individuals vs. referents only in cortisol (increase), kynurenine and %CD16⁺56⁺ lymphocytes (both decrease). Time of exposure to the oil or using protective clothes did not influence the results, but effect of using protective mask was observed on neopterin, %CD8⁺, CD4⁺/CD8⁺ ratio and IL4. Surveillance of the exposed individuals for early detection of possible health problems related to the endocrine or immunological systems is recommended.     

Alteration of DNA,RNA and collagen synthesis in lung organ cultures exposed to mercury ions

We have examined the effect of Hg²⁺ ions on DNA, RNA and collagen synthesis in organ cultures of neo-natal rat lungs. These cultures exhibit many biochemical characteristics of lung in vivo and they continue to synthesize macromolecules at increasing rates up to 6 days. When these cultures were exposed to 1.0μM HgC1₂, the synthesis of DNA was stimulated nearly 3-fold after 72 hr of exposure followed by a decline at 120 hr reflecting cumulative cytotoxicity. Higher concentrations were inhibitory at all times. A nearly 3-fold increase in RNA synthesis occurred after 24 hr exposure to 1.0 μM HgC1₂ and at 72 hr the cultures continued to synthesize RNA at rates comparable to control. There was a decrease in RNA synthesis at 120 hr. Increased collagen synthesis was observed at concentrations up to 10 μM and at all times. The maximal increase, 2–3 fold, occurred at 120 hr in cultures exposed to 0.1 M. These studies suggest that Hg²⁺-induced cell injury in lung organ cultures elicits a reparative response characterized by increased collagen synthesis. This is similar to chemically induced tissue-injury in lungs in vivo. The relevance of these data to the mechanism of induced pulmonary fibrosis is discussed. These studies also point to the usefulness of organ cultures for studying pulmonary toxicity of environmental agents.     

Anguilla anguilla L. antioxidants responses to in situ bleached kraft pulp mill effluent outlet exposure

This study assesses the antioxidant enzymes activities viz., catalase, glutathione peroxidase, glutathione S-transferase and nonenzymatic antioxidant molecule such as glutathione in Anguilla anguilla L. gill, kidney and liver in response to 8- and 48-h exposure to bleached kraft pulp mill effluent (BKPME). A. anguilla were caged and plunged at three different sites-50 (Site 1), 100 (Site 2) and 2000 m (Site 3) away from the closed BKPME outlet. A significant gill (8 and 48 h) and kidney (48 h) catalase activity decrease was observed at site 2 exposure whereas liver showed a significant increase in catalase activity after 8 and 48 h to site 1 exposure. Glutathione peroxidase (GPX) activity was significantly decreased in gill after 8-h exposure to site 1 and 48-h exposures to sites 1 and 2, respectively. Concerning gill, kidney and liver glutathione S-transferase (GST) activity, a significant gill GST activity decrease after 8 h at site 2 and 48 h at sites 1 and 2 was observed; in kidney, a significant decrease in its activity was observed after 48 h at sites 1 and 2, respectively, whereas in liver, the decrease was significant only at site 2 after 48-h exposure. The in situ BKPME exposure caused a significant total gill and kidney reduced glutathione (GSH) decrease after 8 h at site 2 exposure and after 48 h at site 1 and 2 exposures, respectively. However, a biphasic response was observed in liver, i.e. initial significant increase after 8 h at site 2 followed by a significant decrease after 48 h to the same site exposure. The enzymatic and nonenzymatic antioxidants pattern in gill and kidney, as observed in this study, was different than liver, demonstrating that the liver was more resistant to oxidative damage than gill and kidney. In addition, A. anguilla gill, kidney and liver antioxidants adaptation potentials may serve as a surrogate biomarker to BKPME exposure.     

Induction of EROD activity in European eel (Anguilla anguilla) experimentally exposed to benzo[a]pyrene and beta-naphthoflavone

The induction of liver ethoxyresorufin O-deethylase (EROD) activity was investigated in the European eel, Anguilla anguilla, collected from a Mediterranean brackish environment and experimentally exposed to benzo[a]pyrene (B[a]P) and beta-naphthoflavone (BNF). Eels were injected intraperitoneally at increasing doses (0.1, 1, 10, and 50 mg/kg wet body weight) using corn oil as a carrier and sacrificed after 7 days. The main objectives of the present study are: (1). to assess of the sensitivity of EROD induction as a biomarker to polycyclic aromatic hydrocarbon (PAH) exposure; (2). to determine an EROD dose-response relationship of the contaminants used; and (3). to compare the efficiency of B[a]P and BNF as inducers of EROD activity. Results showed that both chemicals resulted in a dose-dependent EROD induction, but increases were not linear. EROD activity seemed to reach a plateau at the exposure of 10 mg/kg in both treatment groups; B[a]P was a more potent inducer than BNF was at the higher doses (10 and 50 mg/kg), while the opposite result was observed at the lower ones (0.1 and 1 mg/kg). The greatest induction occurred in eels treated with 10 mg/kg B[a]P, in which a 261-fold increase in EROD activity was observed. Results showed that EROD activity in A. anguilla is significantly induced by B[a]P and BNF exposure, responding to a wide range of concentrations of these contaminants. We infer that this tool may be suited as a diagnostic biomarker for biomonitoring PAHs pollution in Mediterranean brackish environments and further field research is suggested.     

Genotoxic and biochemical responses in caged eel (Anguilla anguilla L.) after short-term exposure to harbour waters

European eel (Anguilla anguilla L.) were caged and exposed in situ for 8 and 48 h to the Aveiro offward fishing harbour water (HW) and to clean seawater under laboratory conditions (Control). Eel liver biotransformation (Phase I) was measured as ethoxyresorufin-O-deethylase (EROD) activity, cytochrome P450 (P450) and glutathione S-transferase (GST) activity (Phase II). Genotoxic responses were determined as blood, liver and kidney DNA strand breaks as well as erythrocytic nuclear abnormalities (ENAs). HW failed to significant increase liver EROD, GST activities and ENA frequency. Nevertheless, P450 content was significantly increased after 8 and 48 h exposure. Genotoxicity measured as DNA integrity decrease was found in blood after 8 and 48 h exposure to HW, whereas in liver and kidney, it was observed after 48 h exposure to HW. Blood, kidney and liver genotoxicity may be due to the presence of polycyclic aromatic hydrocarbons (PAHs) which are genotoxic compounds and the main HW organic contaminants.     

灭螺药氯硝柳胺急性暴露对斑马鱼胚胎/幼鱼代谢能力的影响

氯硝柳胺（Niclosamide, NIC）是我国目前使用最久,也是使用量最多的化学灭螺药物,其带来的环境问题和生物安全问题逐渐引起人们重视。我们前期研究证实,NIC急性暴露会干扰斑马鱼幼鱼脂代谢途径,该研究在此基础上,进一步深入研究环境相关浓度NIC急性暴露对胚胎/幼鱼代谢水平的干扰效应。将受精2 h内的健康斑马鱼胚胎暴露于环境相关浓度的NIC（浓度依次为0,5,10,20和40 μg/L）至120 h。结果表明,和对照组相比,40 μg/L NIC暴露会显著改变幼鱼体内代谢产物,如葡萄糖和乳酸含量（P < 0.05 和P < 0.05）;另外,NIC暴露还会显著抑制幼鱼体内柠檬酸合成酶（CS）活力,而乳酸脱氢酶（LDH）活力被显著增强（P < 0.05 和P < 0.05）。代谢相关过氧化物酶体增值剂激活受体（PPAR）家族中的两个基因,pparα和pparγ,在NIC暴露组中其mRNA的相对表达水平都被显著上调（P < 0.05 和P < 0.05）。上述结果说明,环境相关浓度的NIC急性暴露会对早期胚胎的发育及幼鱼体内代谢水平造成干扰,表现为改变体内代谢相关基因的表达水平,并对代谢相关酶的活力和代谢产物的含量造成影响。     

Effect of temperature on blood parameters of the salamander <Emphasis Type="Italic">Batrachupems tibetanus</Emphasis> (Schmidt, 1925) (Amphibia: Hynobiidae)

To better understand how Batrachupems tibetanus responds to different temperature regimes in the blood parameters and to estimate the change in plasma cortisol level in this species exposed to different temperatures, the animals were stochastically divided into three groups and exposed respectively to 4.6°C, 14.6°C and 19.6°C for 12 days. The concentrations of glucose, total protein, albumin, triacylglycerol, Ca²⁺, K⁺, Na⁺, Cl⁻, and plasma cortisol level were measured respectively. There was no significant difference between the plasma cortisol level of the control group and the experiment groups. Glucose level at 4.6°C and 19.6°C was significantly lower than glucose level at 14.6°C. The plasma triacylglycerol level was significantly influenced by acclimation temperature. The concentration of total protein, albumin, globulin and the ratio between albumin and globulin were not significantly influenced by temperature when compared with control group. There was no significant change in concentration of Ca²⁺ at different temperatures. The concentration of K⁺ was significantly influenced by temperature. Plasma K⁺ level significantly increased at 19.6°C. The plasma Na⁺ level and Cl⁻ were significantly influenced by temperature. Na⁺: Cl⁻ ratio was significantly influenced by temperature. Therefore, glucose, triacylglycerol, Na⁺ and Cl⁻ levels could be considered as indicators of thermal stress in B. tibetanus; plasma cortisol, albumin, globulin levels, and albumin/globulin ratio are not influenced by temperature.     

Comparison of the sensitivity of different toxicity test endpoints in a microalga exposed to the herbicide paraquat

The use of herbicides constitutes the principal method of weed control but the introduction of these compounds into the aquatic environment can provoke severe consequences for non-target organisms such as microalgae. Toxic effects of these pollutants on microalgae are generally evaluated using phytotoxicity tests based on growth inhibition, a population-based parameter. However, physiological cellular endpoints could allow early detection of cell stress and elucidate underlying toxicity mechanisms. Effects of the herbicide paraquat on the freshwater microalga Chlamydomonas moewusii were studied to evaluate growth rate and cellular parameters such as cellular viability and metabolic activity assayed by flow cytometry and DNA damage assayed by the comet assay. Sensitivity of growth and parameters assayed by flow cytometry were similar, showing a significant effect in cultures exposed to a paraquat concentration of 0.1 microM or higher, although in cultures exposed during 48 h to 0.05 microM, a significant stimulation of cellular fluorescein fluorescence was observed, related to cellular metabolic activity. After only 24 h of herbicide exposure significant DNA damage was observed in microalgal cells exposed to all paraquat concentrations assayed, with a 23.67% of comets in cultures exposed to 0.05 microM, revealing the genotoxicity of this herbicide. Taking into account the results obtained, comet assay provides a sensitive and rapid system for measuring primary DNA damage in Chlamydomonas moewusii, which could be an important aspect of environmental genotoxicity monitoring in surface waters.     

Metaphase analysis, micronuclei assay, and urinary mutagenicity assay of mice exposed to diesel emissions

Female Swiss mice were exposed 8 h/day to diesel exhaust for 1, 3, and 7 weeks. Urine was collected overnight for 4 days prior to sacrifice while the mice continued to be exposed for eight hours during the day. The presence of mutagens was determined by the Ames Salmonella test. One hour prior to sacrifice each mouse received 1 mg/kg colcemide. After sacrifice, the marrow from each femur was obtained. The marrow from one femur was used to prepare slides for metaphase analysis and the other for micronuclei assay. Other mice received IP 50 mg/kg cyclophosphamide 24 h prior to sacrifice or 1 μmole/kg benzo(a)pyrene in each of four daily doses prior to sacrifice and served as positive controls. The Ames Salmonella assay of the unconcentrated urine after 1, 3, and 7 weeks and concentrated urine after 7 weeks exposure to diesel exhaust did not significantly vary from clean air controls. In the micronucleus test, and metaphase analysis, cyclophosphamide produced a strong positive response and the 7 week diesel exposure was not different from clean air controls.     

Anguilla anguilla L. Genotoxic responses after in situ exposure to freshwater wetland (Pateira de Fermentelos, Portugal)

Pateira de Fermentelos is a Cértima River enlargement, close to its river mouth (by the Agueda River), where the introduction of agricultural chemicals such as fertilisers and pesticides, domestic sewage, as well as heavy metals from electroplating industries, results in increased water pollution. The present research work concerns a 48 h in situ exposure of caged eels (Anguilla anguilla L.) at the Pateira de Fermentelos. Five exposure sites were selected, i.e., site A, site B, site C, site D and site E in order to study its water genotoxicity potential, measured in gill, blood, liver and kidney as DNA strand breaks. Eels were also exposed at a reference site by the Cértima River spring. Bottom water samples were collected for further physical-chemical analysis. Site A exposure, significantly decreased gill, blood and liver DNA integrity. Gill and liver DNA integrity was also significantly decreased at site B. At site C only blood DNA integrity was significantly decreased. The present field in situ study demonstrated that the three exposure sites close to the Pateira initial part, such as A, B and C are polluted by pro and/or genotoxic compounds. The genotoxic effects induced in A. anguilla L. suggest a different contamination of the exposure sites A, B and C, in genotoxic chemicals. Thus, according to its genotoxic potential the exposure sites A, B and C, may be ordered as follows site A>site B>site C. No genotoxic effects on A. anguilla L. were observed at site E as DNA strand breaks increase.     

Organic compounds in tire particle induce reactive oxygen species and heat-shock proteins in the human alveolar cell line A549

Debris produced from the attrition of tires of motor vehicles constitutes 5-7% of the atmospheric particulate matter (PM10). Debris particles are indeed small enough to enter human lung and thus morphological and chemical characterization has been performed. We demonstrated that the organic fraction of tire debris induces a dose-dependent increase in cell mortality, DNA damage, as well as a significant modification of cell morphology at the dose of 60 microg/ml, which may correspond to the quantity present in the air humans inhale daily. The present research aims at investigating if reactive oxygen species (ROS) production and Hsp70 expression are involved in the cascade of toxic effects produced on the A549 cell line, as it has been suggested for the ultrafine atmospheric particles and diesel exhaust. To this end, cells were exposed at the doses of 10, 50, 60, 75 microg/ml of TD organic extract (TDOE) and analyzed at different exposure time. ROS were detected by the oxidation of 2'7'-dichlorodihydrofluorescein diacetate to dichlorofluorescein, and fluorescence was measured by flow cytometry. Hsp70 protein expression was determined by immunochemical analysis, and protein expression quantification performed by optical densitometry. ROS production was analysed after 2 h of treatment. A statistically significant increase in fluorescence was observed and the intensity of the stress response was parallel to the increasing concentrations used. An evident increase of Hsp70 expression at lower doses (10, 50 microg/ml) and at longer exposure times (72 h) was observed, during the time that our previous studies showed that cell viability, plasma membrane integrity, and DNA molecules were not affected. Thus it can be deduced that the increase in Hsp70 expression protected the cells from those damages, which became evident at the higher doses, and that this parameter might be used as a sensitive indicator of exposure. These data suggest that ROS production may be the first event caused by A549 exposure to TDOE and this result is in line with other evidences provided for the role of ROS generation in ultrafine PM toxicity. It can be suggested that this event induces an overexpression of Hsp70 only at the lower doses and longer exposure time, when cells still appear unaffected. Subsequently when ROS generation reaches high levels, a general inhibition of protein synthesis probably occurs, culminating in cell toxicity.     

The influence of the cigarette smoke pollution and ventilation rate on alpha-activities per unit volume due to radon and its progeny

Alpha and beta activities per unit volume air due to radon, thoron and their decay products were evaluated in the air of various cafe rooms polluted by cigarette smoke. Both CR-39 and LR-115 type II solid state nuclear track detectors (SSNTD) were used. Equilibrium factors between radon and its progeny and thoron and its daughters have been evaluated in the air of the studied cafe rooms. The committed equivalent doses due to short-lived radon decay products were determined in different regions of the respiratory tract of non-smoker members of the public. The influence of cigarette smoke pollution, ventilation rate and exposure time on committed equivalent dose in the respiratory systems of non-smokers was investigated. Committed equivalent doses ranged from 1.15 x 10(-11)-2.7 x 10(-7) Sv.y(-1)/h of exposure in the extrathoracic region and from 0.8 x 10(-12)-1.7 x 10(-8) Sv.y(-1)/h of exposure in the thoracic region of the respiratory tract of non-smokers.     

Contamination of terrestrial gastropods, Helix aspersa maxima, with 137Cs, 85Sr, 133Ba and 123mTe by direct, trophic and combined pathways

(137)Cs, (85)Sr, (133)Ba and (123m)Te contaminations of terrestrial gastropods, Helix aspersa maxima, by direct deposition, labelled food ingestion or combined (trophic and direct pathways) exposure were carried out under laboratory conditions. The aim of this study was to compare the three contamination pathways: direct, trophic and combined, in terms of individual mortality, radionuclide uptake, depuration and distribution in the tissues. An initial group of 30 snails (2 years old) was exposed to radioactive aerosols during a 20-h period. These aerosols were assumed to be representative of those that would be released during a nuclear accident occurring in a PWR. A second group of 50 snails (same age) was submitted to an ingestion of commercial food contaminated by the same aerosols, twice a week for 21 days (flour at a feeding rate of about 0.2g). A third group of 40 snails was submitted to a combined exposure: exposure to radioactive aerosols (20h), followed by ingestion of flour contaminated by the same aerosols, twice a week for 21 days. No significant difference between the three groups and a reference group of 10 snails was observed, neither in growth nor in mortality. Concerning the direct pathway, at the end of direct deposition (about 1 day after the beginning), cesium was the most bioavailable element, distributed rather homogeneously throughout the whole body (13% of the total Cs in all organs excepting the digestive system and 28% in the muscle). Strontium was measured in the shell (about 70%). Barium was found in the muscle (20%) and in the shell (65%). Tellurium was mainly present in the shell (70%) and in the digestive system (20%). After 21 days of depuration, the faeces eliminated 42% of the Te. As for contamination by ingestion, Te mainly accumulated in the digestive system (72% of Te present in the total body), Ba accumulated in the muscle (75%) and Sr in the shell (70%). Concerning contamination by combined pathways, at the end of the 21-day exposure, the 4 radionuclides had the same tendency as direct deposition. However, the effect of the trophic pathway was significant: it causes an 18% increase of Sr in the shell and an 7% increase of Cs in the digestive system in comparison to direct deposition, resulting in a final 86% in the shell and 27% in the digestive system.