Llobet Jm

Acute toxicity of uranium in rats and mice

The enormous expansion in the mining, processing, use and operations involving uranium that has occurred over the last forty years has led to the dispersion of concentrated uranium at many sites over almost the entire world. While the dangers due to nuclear reactions are given wide play in the public press, the toxicological hazards of increased levels of uranium are less widely appreciated. On the other hand, during uranium processing there is a possibility that workers will inhale or ingest some uranium, giving rise to internal contamination. This contamination will result in radiation doses to the organs of the body, and if the intake of uranium is large enough, chemical toxic effects. Under some circumstances the toxic chemical effects of uranium may be more important than the radiation dose received. The interest of this question has increased following the accident at Chernobyl on 26 April 1986. Many details are still unknown concerning the exact nature of the Chernobyl accident. However, it is known that Chernobyl reactor was fueled with about 200 tons of uranium dioxide packaged in 1661 fuel assemblies.

PCDDs and PCDFs in food samples from Catalonia, Spain. An assessment of dietary intake

Food samples from local markets and supermarkets of Tarragona (Catalonia, Spain) were analyzed for PCDD/F concentrations. On lipid basis, PCDD/F levels in meat, fish, eggs, and fats and oils were similar or lower than those found in other countries. By contrast, in general terms PCDD/F levels in milk, vegetables, and cereals showed higher levels than those previously reported. The total dietary PCDD/F intake by the population of Tarragona was estimated to be 210 pg I-TEQ/day. This value is higher than the dietary intake of PCDD/Fs found in a number of surveys from other countries. However, when total dietary intake of PCDD/Fs was calculated including only fish and seafood, meat, milk and dairy products, eggs, and fats and oils, a dietary intake of PCDD/Fs of 117 pg I-TEQ/day was obtained. This intake is in the same range than that reported for different regions and countries. The results of the present study show that food groups such as vegetables, fruits, and cereals should not be excluded to estimate the total dietary intake of PCDD/Fs by general populations, especially in those countries and/or regions in which their consumptions are notable.

Oral vanadium administration to streptozotocin-diabetic rats has marked negative side-effects which are independent of the form of vanadium used.

In the present investigation, the effects of oral administration of sodium metavanadate, sodium orthovanadate and vanadyl sulphate to alleviate some signs of diabetes in streptozotocin-treated rats have been evaluated. Streptozotocin-induced diabetic rats drank aqueous solutions (NaCl, 80 mM) containing sodium metavanadate (0.15 mg/ml), sodium orthovanadate (0.23 mg/ml), or vanadyl sulphate pentahydrate (0.31 mg/ml) for 28 days. The vanadium-treated animals were compared to controls, either diabetic or nondiabetic, receiving drinking water containing NaCl (80 mM) only. Daily food and fluid intake were significantly decreased in the vanadium-treated animals relative to diabetic controls. Also, vanadium treatment reduced the level of hyperglycemia in diabetic rats, with sodium metavanadate being the most effective of the vanadium compounds tested. However, daily vanadium intake was significantly lower in the animals receiving sodium metavanadate. Signs of toxicity were observed in all vanadium-treated animals as evidenced by some deaths, decreased weight gain, and increased serum concentrations of urea and creatinine. Moreover, vanadium was detected in all tissues analyzed. Although some signs of diabetes were improved by vanadium treatment, because of the severe toxic side effects noted in all of the vanadium-treated animals, it seems evident that oral vanadium administration is not a suitable therapy of diabetes mellitus in streptozotocin-diabetic rats.

Assessment of baseline levels of PCDD/F in soils in the neighbourhood of a new hazardous waste incinerator in Catalonia, Spain

In order to determine the baseline contamination by polychlorinated dibenzo-p-dioxins (PCDD) and polychlorinated dibenzofurans (PCDF) in an area from Catalonia (Spain), which will be under the influence of a new hazardous waste incinerator, PCDD/F concentrations were measured in 40 soil samples collected in the vicinity of the facility now under construction. Thirty samples represented rural soils and 10 samples urban soils. PCDD/F concentrations ranged between 0.08-8.4 ng I-TEQ/kg for rural soils and 0.63-24.2 ng I-TEQ/kg for urban soils. The mean value for the 40 samples was 1.64 ng I-TEQ/kg (dry matter). The current PCDD/F levels and profiles are comparable to those found in soils from other countries. The PCDD/F concentrations found in this study show that at present the contamination by PCDD/F in soils of the examined area is rather low.

Lead in children's hair, as related to exposure in Tarragona province, Spain

Concentrations of lead were determined in the hair of 478 school children living in an industrial and an agricultural area of Tarragona Province, Spain. The influence of age, sex, hair colour and family occupation on the childrens hair lead concentration was also evaluated. Girls had more lead in their hair than boys (10.54 vs 6.55 micrograms g-1), and the lead levels decreased with age. Lead concentrations in hair with respect to hair colour decreased in the order red, blond, brown, black. Family occupation was one of the most significant factors influencing the lead content of childrens hair. Although the average lead content was higher in the industrial area (9.38 micrograms g-1) than in the agricultural area (7.80 micrograms g-1), this difference was not statistically significant.

Evaluating the environmental impact of an old municipal waste incinerator: PCDD/F levels in soil and vegetation samples.

In order to determine the temporal variation in the levels of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in the vicinity of an old municipal solid waste incinerator (MSWI) (S. Adrià del Besòs, Barcelona, Spain), 24 soil and vegetation samples were collected at the same sampling points in which samples had been taken 1 year before. Each sample was analyzed for PCDDs and PCDFs by high-resolution gas chromatography/high-resolution mass spectrometry. While in the previous study PCDD/F concentrations in soil ranged from 1.22 to 34. 28 ng I-TEQ/kg (median and mean values: 9.06 and 12.24 ng I-TEQ/kg), in the present study, PCDD/F levels ranged from 1.33 to 54.23 ng I-TEQ/kg (median and mean values: 11.85 and 14.41 ng I-TEQ/kg). On the other hand, in the previous study, PCDD/F levels in vegetation ranged from 0.33 to 1.98 ng I-TEQ/kg (median and mean values: 0.58 and 0.70 ng I-TEQ/kg), whereas in the present study, PCDD/F levels ranged from 0.32 to 2.52 ng I-TEQ/kg (median and mean values: 0.82 and 0.97 ng I-TEQ/kg). During the last 12 months, PCDD/F levels increased in 16 of the 24 soil samples and in 17 of the 24 vegetation samples analyzed. However, no significant differences in the median I-TEQ concentrations of both studies were found either in soil or vegetation samples.

CONCENTRATIONS OF LEAD AND CADMIUM IN EDIBLE VEGETABLES FROM TARRAGONA PROVINCE, SPAIN

The lead and cadmium content of 20 species of edible vegetable collected in Tarragona Province (Spain) was investigated. Samples consisting of bulbs, and leaves and soft stalks (chard, parsley, spinach and lettuce) contained the highest levels of both metals. In contrast, fruits and similar garden produce (tomato, green pepper, cucumber, artichoke, green bean and broad bean) contained the lowest concentrations of lead and cadmium in both the northern and southern area of the province. Most species analyzed did not show any significant differences between the two study areas. The mean daily intakes of lead and cadmium by man have been estimated to be: 47.5 micrograms Pb and 15.3 micrograms Cd (north), and 37.5 micrograms Pb and 32.5 micrograms Cd (south). These values do not pose a health risk for consumers, according to the levels proposed by FAO/WHO.

Embryotoxicity and teratogenicity of uranium in mice following subcutaneous administration of uranyl acetate

The effects of multiple maternal subcutaneous injections of uranyl acetate dihydrate (0.5, 1, and 2 mg/kg/d) from d 6 to d 15 of gestation were evaluated in Swiss mice. External, internal soft-tissue and skeletal examinations of fetuses were performed on gestation d 18. Maternal toxicity occurred in all uranium-treated groups as evidenced primarily by deaths as well as significant decreases in weight gain and in body weight at termination. Although it was not dose-related, embryotoxicity also occurred in all uranium-treated groups (significant increases in the number of nonviable implantations and in the percentage of postimplantation loss). Fetal body weight was significantly decreased at 1 and 2 mg/kg/d, whereas the number of total internal and total skeletal defects showed dose-dependent increases at 0.5, 1, and 2 mg/kg/d. Most morphological defects were developmental variations, whereas malformations were only detected at 1 and 2 mg/kg/d. On the basis of these data, both the maternal no-observable-adverse-effect level (NOAEL) and the NOAEL for embryotoxicity of uranyl acetate dihydrate were below 0.5 mg/kg/d, whereas the NOAEL for teratogenicity was 0.5 mg/kg/d.

Effectiveness of chelation therapy with time after acute uranium intoxication

The effect of increasing the time interval between acute uranium exposure and chelation therapy was studied in male Swiss mice. Gallic acid, 4,5-dihydroxy-1,3- benzenedisulfonic acid (Tiron), diethylenetriaminepentaacetic acid (DTPA), and 5-aminosalicylic acid (5-AS) were administered ip at 0, 0.25, 1, 4, and 24 hr after sc injection of 10 mg/kg of uranyl acetate dihydrate. Chelating agents were given at doses equal to one-fourth of their respective LD50 values. Daily elimination of uranium into urine and feces was determined for 4 days after which time the mice were killed, and the concentration of uranium was measured in kidney, spleen, and bone. The excretion of uranium was especially rapid in the first 24 hr. Treatment with Tiron or gallic acid at 0, 0.25, or 1 hr after uranium exposure significantly increased the total excretion of the metal. In kidney and bone, only administration of Tiron at 0, 0.25, or 1 hr after uranium injection, or gallic acid at 1 hr after uranium exposure significantly reduced tissue uranium concentrations. Treatment at later times (4 to 24 hr) did not increase the total excretion of the metal and did not decrease the tissue uranium concentrations 4 days after uranyl acetate administration. The results show that the length of time before initiating chelation therapy for acute uranium intoxication greatly influences the effectiveness of this therapy.

Evaluation of the oral toxicity of uranium in a 4-week drinking-water study in rats

Uranium is an ubiquitous constituent of mans natural environment. Most exposure to uranium bas occurred during the mininz, processin~, and transformation of the metal into fuel elements for nuclear reactors (Cothern and Lappenbusch 1983; Tasat and De Rey 1987), The enormous expansion in the operations involving uranium that bas occurred over the last forty years bas led to the dispersion of concentrated uranium at many sites over almost the entire world, While the dangers due to nuclear reactions are ~iven wide play in the public press, the toxicolo~ical hazards of increased levels of uranium are less widely appreciated.