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PubMed1995

Drinking water quality and monitoring in north Africa: the Moroccan experience.

In Morocco, the water quality standards have been derived from World Health Organization guidelines for all that concerns bacteriological and toxicological parameters; for the rest of the parameters, several other sources have been used especially EEC, US and Canadian standards. Local considerations have dictated, however, the value of the maximum acceptable level adopted for the total dissolved solids (2000 mg/l), instead of the 1500 mg/l generally considered to be the maximum acceptable level. The National Office of Potable Water (ONEP) developed quite an extensive network for water quality monitoring, comprised of a central laboratory conducting all sorts of analytical determinations ranging from parasitological, planktonic and bacteriological examinations, to the determination of trace metals, pesticides, global radioactivity and toxicity tests. The work of the central laboratory is seconded by 34 small branch laboratories spread all over the country. The preparation of reference analytical methodologies has been a subject on the agenda of the next phase of the work of the commission in charge of the preparation of standards dealing with drinking water. A first approach of the Moroccan water quality standards implementation have been made by ONEP. The evaluation of the costs necessary to be in conformity with these standards and the dispensation requests to be presented, where appropriate, to health authorities are on the way.

Fresh Water↗
PubMed1997

Current and potential doses from Arctic seafood consumption.

Current collective and individual dose rates to humans are estimated from the consumption of seafood harvested in the Arctic Seas. Statistical data on catches are used for the dose assessment, as well as observed data (1991-1994) on the radioactivity of marine biota. The actual collective dose rates to the world population are estimated to be: 2.7-4.5 manSv/year due to consumption of seafood from the Barents Sea, and 0.03 manSv/year-due to seafood from the Kara Sea. The contribution of 137Cs to the collective dose rate is about 90%. Current individual dose rates to high-rate consumers are estimated to be: 2.6 x 10(-6) Sv/year due to seafood from the Barents Sea; and 4.2 x 10(-6) Sv/year-due to seafood from the Kara Sea. The future radiological impact of the radioactive waste (RW) disposals in the Kara Sea is simulated for the period over 1000 years, using the regional box model of the Arctic Seas. The model predictions are made for three hypothetical scenarios of long-term radionuclide releases, prepared within the framework of the International Arctic Seas Assessment Project. The potential collective dose to world population truncated to 3000 AD is shown to be not higher than 0.13 manSv. The maximum individual dose rates from Arctic seafood consumption are estimated to be about 1.2 x 10(-7) Sv/year. The predicted doses are much smaller than the actual doses due to the current radioactive contamination of the Arctic Seas.

Animals↗
PubMed2004

Effects of long-term exposure to Cu2+ and Cd2+ on the pentose phosphate pathway dehydrogenase activities in the ovary of adult Bufo arenarum: possible role as biomarker for Cu2+ toxicity.

The effects of copper and cadmium on metabolism through the pentose phosphate pathway were evaluated in Bufo arenarum toad ovary. The effects of the two metals on dehydrogenases from this pathway were evaluated by three experiments: (1) in samples obtained from control females with addition of the metals to the reaction mixture (in vitro), (2) in samples obtained from control females and after long-term exposure of females to 4 and 100 microg/L of Cu or Cd in the incubation media (in vitro after exposure to the metals in vivo), and (3) 14CO2 production through the pentose phosphate pathway was evaluated after [U-14C]glucose microinjection on ovulated oocytes (in vivo after microinjection of the metals). Results from (1) evidenced inhibition of both enzyme activities but only above 1.5 mM Cu and Cd added to the reaction mixture. In (2) both glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities decreased in samples from the ovaries of females exposed in vivo to Cu, in a concentration-dependent manner (up to 90% in females exposed to 100 microg/L Cu: 2.12 +/- 1.57 NADPH micromol/min microg protein x 10(-5) vs 19.97 +/- 8.54 in control females). Cd treatment of the toads only rendered an inhibitory effect on 6-phosphogluconate dehydrogenase activity after exposure to 4 microg/L of the bivalent cation. (3) In vivo 14CO2 evolution significantly decreased in oocytes coinjected with 6.3 x 10(-3) mM Cu (calculated intracellular final concentration of the metal injected) and radioactive glucose. Cu and Cd concentration in samples from exposed females were always under detection limit by particle-induced X-ray emission. The results presented here are in agreement with a role for both glucose 6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase activities determination as biomarkers of effect and exposure for Cu but not for Cd toxicity.

Animals↗
PubMed1998

Role of placental metallothionein in maternal to fetal transfer of cadmium in genetically altered mice.

The role of placental metallothionein (MT) as a barrier for maternal to fetal transfer of cadmium (Cd) was investigated using mice which overexpressed the MT-1 isoform (MT-1*), mice which did not express the MT-1 and 2 isoforms (MT-null) and control mice (C57BL/6). In addition, immunohistochemical localization of MT in the placenta was determined in these mice. Two days prior to parturition, the mice were injected with radioactive 109Cd chloride (4 microCi, 0.6 ng Cd/mouse) and killed 24 h later. Organs and fetuses were collected and radioactivity, MT and metal levels were measured. Cd accumulated mainly in the liver and kidney (80% of administered dose) with very low levels (0.1-0.3%) detected in fetuses. When analyzed on a per organ or per gram basis, MT-null fetuses accumulated significantly more Cd (3-10-fold) than the control fetuses and there was no significant difference in fetal Cd accumulation in the MT-1* and control fetuses. As expected, MT and zinc levels were higher in MT-1* than C57BL/6 mice and no MT was detected in MT-null mice. Most striking was the high hepatic MT levels in MT-1* dams (4 mg/g). Immunohistochemical analysis showed MT staining in spongiotrophoblasts, glycogen cells, visceral yolk sac, trophoblast giant cells and maternal decidual cells with the MT-1* placenta staining much more intensely as compared to control placenta. The results suggest that placental MT reduces maternal to fetal Cd transfer, however the low doses of Cd administered in the present experiment resulted in high levels of Cd accumulation in liver and kidney in all groups of mice with a low concentration of Cd reaching the placenta. Thus, the role of placental MT as a barrier for Cd is inconclusive.

Animals↗
PubMed2002

Synthesis, in vitro receptor binding, and in vivo evaluation of fluorescein and carbocyanine peptide-based optical contrast agents.

Site-specific delivery of drugs and contrast agents to tumors protects normal tissues from the cytotoxic effects of drugs and enhances the contrast between normal and pathologic tissues. One approach to achieve selectivity is to target overexpressed receptors on the membranes of tumor cells and to visualize the tumors by a noninvasive optical imaging method. Accordingly, we conjugated fluorescein and carbocyanine dyes to somatostatin and bombesin receptor-avid peptides and examined their receptor binding affinities. We also prepared potential dual imaging probes consisting of a bioactive peptide for tumor targeting, a biocompatible dye for optical imaging, and a radioactive or paramagnetic metal chelator for scintigraphic or magnetic resonance imaging of tumors. Using these approaches, the resulting carbocyanine derivatives of somatostatin and bombesin analogues retained high binding for their respective receptors. Further evaluation of representative molecules in rats bearing somatostatin- and bombesin-positive tumors showed selective uptake of the agents by the tumor cells. Unlike carbocyanine derivatives, the receptor binding of fluorescein-somatostatin peptide conjugates was highly sensitive to the type of linker and the site of fluorescein attachment on the nonreceptor binding region of the peptide. In general, the presence of flexible linkers disrupted binding affinity, possibly due to the interaction of the linker's thiourea group with the peptide's cyclic disulfide bond. While the receptor binding affinity of the dual probes was not dependent on the type of chelating group examined, it was affected by the relative positions of fluorescein and chelator on the lysine linker. For somatostatin compounds, best results were obtained when the chelator was on the alpha-amino lysine linker and fluorescein was on the epsilon-amino group. In contrast, conjugation of the chelator to epsilon- and fluorescein to the alpha-amino lysine linker of bombesin peptides resulted in high receptor binding. These findings indicate that despite their small size, conjugation of dyes to truncated somatostatin and bombesin peptide analogues results in promising diagnostic agents that retain high receptor binding activity in vitro. The results further show that these contrast agents can selectively and specifically localize in receptor-positive tumors in rat models.

Animals↗
PubMed1980

Radio-gas chromatography of chromium (III) hexafluoroacetylacetonate.

A method has been developed for the determination of trace levels of chromium by radio-gas chromatography. The technique involves conversion of radioactive 51Cr to a metal chelate compound, using C2H5I131 as an internal standard, and detection of radioactivity of 51Cr in the chelate by a flow system surrounding a Nal(TI) scintillation detector. The detection limit is found to be as low as 10(-12) g. From the observed radio-chromatogram it can be shown that the method is selective and free from interference.

Animals↗
PubMed1987

The synthesis of protected 5'-mercapto-2',5'-dideoxyribonucleoside-3'-O-phosphoramidites; uses of 5'-mercapto-oligodeoxyribonucleotides.

The syntheses of the four novel, base protected 5'-(S-triphenylmethyl)mercapto-2',5'-dideoxyribonucleoside-3 '-O-(2-cyanoethyl N,N-diisopropylphosphoramidites) are described. These compounds have been used to prepare 5'-(S-triphenylmethyl) mercapto-oligodeoxyribonucleotides, which are readily purified by reversed phase h.p.l.c., owing to the highly lipophilic trityl group. After cleavage of the S-trityl group by silver or mercuric ions, the free thiol moiety can be coupled to a wide variety of reagents, generating very useful probes. Fluorescent labelled 5'-mercapto-oligodeoxyribonucleotides are being used for automated DNA sequencing without radioactivity, and heavy metal labelled 5'-mercapto-oligonucleotides will be used in X-ray crystallography.

Base Sequence↗
PubMed2002

Estimates of radiological risk from depleted uranium weapons in war scenarios.

Several weapons used during the recent conflict in Yugoslavia contain depleted uranium, including missiles and armor-piercing incendiary rounds. Health concern is related to the use of these weapons, because of the heavy-metal toxicity and radioactivity of uranium. Although chemical toxicity is considered the more important source of health risk related to uranium, radiation exposure has been allegedly related to cancers among veterans of the Balkan conflict, and uranium munitions are a possible source of contamination in the environment. Actual measurements of radioactive contamination are needed to assess the risk. In this paper, a computer simulation is proposed to estimate radiological risk related to different exposure scenarios. Dose caused by inhalation of radioactive aerosols and ground contamination induced by Tomahawk missile impact are simulated using a Gaussian plume model (HOTSPOT code). Environmental contamination and committed dose to the population resident in contaminated areas are predicted by a food-web model (RESRAD code). Small values of committed effective dose equivalent appear to be associated with missile impacts (50-y CEDE < 5 mSv), or population exposure by water-independent pathways (50-y CEDE < 80 mSv). The greatest hazard is related to the water contamination in conditions of effective leaching of uranium in the groundwater (50-y CEDE < 400 mSv). Even in this worst case scenario, the chemical toxicity largely predominates over radiological risk. These computer simulations suggest that little radiological risk is associated to the use of depleted uranium weapons.

Computer Simulation↗
PubMed2002

Methods and techniques for the selective extraction and recovery of oxoanions.

An important goal in environmental chemistry is the extraction of metals that are toxic or radioactive from soils and waters. For many such metals, the problem is solved by designing compounds with coordination sites that are specific for that particular metal. For cases such as oxoanions, however, where the inorganic center is already fully coordinated by oxygens, different strategies need to be used. Chromate, phosphate, selenate, pertechnetate, and aluminate are such anions. These species are problematic contaminants in soils and waters because they are either toxic, environmentally undesirable, or radioactive. Furthermore, under both acidic and basic conditions, the coordination positions of these oxoanions are occupied by oxygens. Chromium(VI) as either chromate or dichromate presents a particular problem because it is a strong oxidizing agent. In this review the different methods of extracting this group of pseudotetrahedral oxoanions are discussed, along with the individual advantages and limitations of each strategy.

Animals↗
PubMed2005

Actinide and metal toxicity to prospective bioremediation bacteria.

Bacteria may be beneficial for alleviating actinide contaminant migration through processes such as bioaccumulation or metal reduction. However, sites with radioactive contamination often contain multiple additional contaminants, including metals and organic chelators. Bacteria-based bioremediation requires that the microorganism functions in the presence of the target contaminant, as well as other contaminants. Here, we evaluate the toxicity of actinides, metals and chelators to two different bacteria proposed for use in radionuclide bioremediation, Deinococcus radiodurans and Pseudomonas putida, and the toxicity of Pu(VI) to Shewanella putrefaciens. Growth of D. radiodurans was inhibited at metal concentrations ranging from 1.8 microM Cd(II) to 32 mM Fe(III). Growth of P. putida was inhibited at metal concentrations ranging from 50 microM Ni(II) to 240 mM Fe(III). Actinides inhibited growth at mM concentrations: chelated Pu(IV), U(VI) and Np(V) inhibit D. radiodurans growth at 5.2, 2.5 and 2.1 mM respectively. Chelated U(VI) inhibits P. putida growth at 1.7 mM, while 3.6 mM chelated Pu(IV) inhibits growth only slightly. Pu(VI) inhibits S. putrefaciens growth at 6 mM. These results indicate that actinide toxicity is primarily chemical (not radiological), and that radiation resistance does not ensure radionuclide tolerance. This study also shows that Pu is less toxic than U and that actinides are less toxic than other types of metals, which suggests that actinide toxicity will not impede bioremediation using naturally occurring bacteria.

Actinoid Series Elements↗
PubMed2002

Trace metal uptake by the Chinese mitten crab Eriocheir sinensis: the role of osmoregulation.

Changes in salinity affect the bioavailability and consequent uptake of trace metals by euryhaline invertebrates. In many cases, salinity-related effects on metal uptake can be explained by changes in chemical speciation but salinity may also influence uptake indirectly through its action on osmoregulatory mechanisms. Specifically, it can be hypothesised that trace metal uptake may be reduced at salinities approaching the isosmotic point of a species because, at this point, there is reduced activity of ionic exchange pumps. The present study tested this hypothesis using the Chinese mitten crab, Eriocheir sinensis, a hyper-hypoosmoregulator with an isosmotic point around 33 per thousand. Crabs were exposed to radio-labelled cadmium and zinc at 23, 33 and 43 per thousand for 4 days. To eradicate speciation effects, crabs were exposed to the same concentration of the radio-labelled free metal ion (estimated using MineQL computer software) at each salinity. Haemolymph samples were taken daily and radio-labelled metal concentrations were estimated from radioactivity counts and used to provide relative measures of metal uptake. Neither cadmium nor zinc uptake was lowest at the isosmotic point. The uptake of cadmium increased significantly with increase in salinity, while the uptake of zinc showed no significant change with increased salinity. Thus changes in trace metal uptake rates in E. sinensis do not appear to be controlled only by changes in free metal ion concentrations. The different effects of salinity change on the uptake of cadmium and zinc (in the absence of free metal ion change) also indicate that physiological responses to osmotic change alone do not control metal uptake rates for this species.

Animals↗
PubMed2002

Over the border--the problems of uncontrolled radioactive materials crossing national borders.

Cross-border movement of radioactive materials and contaminated items, in particular metallurgical scrap, has become a problem of increasing importance. Radioactive sources out of regulatory control, now often called 'orphan sources', have frequently caused serious, even deadly, radiation exposures and widespread contamination. The United States Nuclear Regulatory Commission reported over 2,300 incidents of radioactive materials found in recycled metal scrap and more than 50 accidental smeltings of radioactive sources. A further potentially serious problem is illicit trafficking in nuclear and other radioactive materials. In 1995 the International Atomic Energy Agency (IAEA) started a programme to combat illicit trafficking in nuclear and other radioactive materials, which includes an international database on incidents of illicit trafficking, receiving reports from some 80 member states. For the period 1993-2000 the IAEA database includes 345 confirmed incidents. While from 1994-1996 the frequency declined significantly, this trend has been reversed since 1997, largely due to radioactive sources rather than nuclear material. This paper compares monitoring techniques for radioactive materials in scrap applied at steel plants and scrap yards with monitoring at borders, a completely different situation. It discusses the results of the 'Illicit Trafficking Radiation Detection Assessment Program', a large international pilot study, conducted in cooperation between the IAEA, the Austrian Government and the Austrian Research Centre Seibersdorf. The aim of this exercise was to derive realistic and internationally agreed requirements for border monitoring instrumentation. Finally the present extent of border monitoring installations is discussed.

Crime↗
PubMed2003

Copper-binding proteins in human erythrocytes: searching for potential biomarkers of copper over-exposure.

The recognition that copper is essential but also potentially toxic to humans has prompted the search for biomarkers of copper excess. The experimental approach followed here involves the isolation and subsequent characterization of copper-binding molecules (CuBP) from human erythrocytes. Incubation (0-60 min) of freshly obtained erythrocytes in the presence of increasing concentrations of copper (10-50 microM; as 64Cu-histidine) led to time- and concentration-dependent uptake of the radioisotope. A near-maximal incorporation was attained after 20 min, with 45-55% of the radioactivity being recovered in 20,000 x g hemolysate supernatants (S-20). 64CuBP from S-20 were separated by size exclusion and metal-affinity chromatography. Most radioactivity loaded into a Sephadex G-75 column was recovered in association with molecules of MMr greater than 60 KDa (largely accounted for by hemoglobin; Hb). Only negligible amounts of radioactive Cu were associated with metallothionein. With further purification, the higher MMr 64Cu-binding fractions were resolved by Sephadex G-200 into two major peaks. The cpm/microg protein ratios of the first peak (high MMr) were proportional to the concentrations of copper presented to the erythrocytes. The second one contained mostly Hb molecules. Proteins from the first peak were concentrated in an affinity chromatography mini-column, suited to trap CuBP. The higher-affinity CuBP were eluted as a single peak which comprised around 60% of the load. An SDS-PAGE analysis of such peak reveals the presence of three bands, of which two are non-hemoglobin Cu-binding proteins. The latter, whose identity remains to be established, had MMr of approximately 30 and 40 KDa, respectively. Preliminary data indicate that the two bands bind 64Cu within a range of concentrations, relevant to those expected to occur during copper over-exposure conditions.

Biological Transport↗
PubMed2005

Biofilm formation in spent nuclear fuel pools and bioremediation of radioactive water.

Microbiological studies of spent nuclear fuel pools at the Cofrentes Nuclear Power Plant (Valencia, Spain) were initiated to determine the microbial populations in the pools' water. Biofilm formation at the nuclear power plant facilities and the potential use of those microbial populations in the bioremediation of radioactive water were also studied. Biofilm formation was analyzed by immersing different austenitic stainless steel coupons (UNS S30400, UNS S30466, UNS S31600), as well as balls of stainless steel (UNS S44200) and titanium (99.9%) in a spent nuclear fuel pool (under static and dynamic conditions) for 34 months. Epifluorescence microscopy and scanning electron microscopy revealed that biofilm formed on the samples, in spite of the radioactive and oligotrophic conditions of the water. Based on standard culture methods and sequencing of 16S rDNA fragments, 57 bacteria belonging to alpha-, beta-, and gamma-Proteobacteria, Firmicutes and Actinobacteridae were identified in the biofilms. The radioactivity of the biofilm was measured using gamma-ray spectrometry, which revealed that biofilms were able to retain radionuclides, especially (60)Co. Using metallic materials to decontaminate radioactive water could become a new approach for bioremediation.

Biodegradation, Environmental↗
PubMed2006

[Radioactivity monitoring of steel processing in Croatian steel mills and foundries].

The last twenty years have seen a number of cases of radioactive pollution in metallurgical industry. Therefore many metal producers have implemented systematic monitoring of radioactivity in their production processes, especially in steel processing, steel being the most applied construction material with the annual world output of over billion tonnes. Learning from the experience of the best known steel producers in Europe and the world Croatian steel mills have introduced radioactivity surveillance and control systems for radioactive elements in steel scrap, semi-finished and finished products. This paper argues in favour of radioactivity surveillance and control systems in steel and steel castings production in Croatia, and describes current systems and solutions available. Since we lack our own standards and regulations to control both domestic and imported steel scrap, semi-finished products (crude steel, hot and cold rolled strip) and finished products, we need to start implementing radioactivity surveillance and control systems in our steel and steel castings production applying the current international recommendations and guidelines, until we build up our own monitoring system and adopt legislation on the national level. This paper gives an overview of the basic types of radioactivity surveillance and control systems, the most frequent requirements to be met, as well as of the measurement and information flow in their application in steel and steel castings production.

Croatia↗
PubMed2001

Statistical data evaluation in mobile gamma spectrometry: an optimization of on-line search strategies in the scenario of lost point sources.

There is a potential risk that hazardous radioactive sources could enter the environment, e.g., via satellite debris, smuggled radioactive goods, or lost metal scrap. From a radiation protection point of view there is a need for rapid and reliable methods for locating and identifying sources. The methods could also be used to locate hot spots after radioactive fallout. Carborne and airborne gamma spectrometry systems are suitable for the task. This work focuses on a situation where the radionuclide to search for is known, which is not an unlikely scenario. The possibility that the source is located near a road can be high, and thus motivating a carborne spectrometer system. The main object is to optimize on-line statistical methods in order to achieve a high probability for locating the point source and still have reasonably few false alarms caused by variations in the natural background radiation. Data were obtained from a carborne 3-L NaI(Tl) detector and two point sources located at various distances from the road. The nuclides used were 137Cs and 131I. Spectra were measured stationary on the road. From these measurements we have reconstructed counts in spectral windows applicable to different speed and sampling times; the time 3 s and speeds 32 and 54 km h(-1) are used in this work. The maximum distance a source can be located from the road and still be detected is estimated with four different statistical analysis methods. This distance is called the critical distance, CD. The method is applied on gross counts in the full energy peak spectral window. For each method alarm levels have been calculated from background data obtained in Scania (Skåne), in the south of Sweden. The results show large differences in CD. With the best approach, the two sources could be detected from about 180 m (137Cs, 6 GBq) and 170 m (131I, 4.5 GBq).

Automobiles↗