R.C. Gouvea

Accumulation of 210Po in foodstuffs cultivated in farms around the Brazilian mining and milling facilities on Poços de Caldas plateau

Abstract Several sample types from the environment of the uranium mining and milling facilities of Pocos de Caldas plateau (CIPC) in Minas Gerais state, Brazil have been assayed for their concentrations of uranium and its daughters. This paper presents the data for 210 Po in food, soils and fertilizers in the CIPC region and, for comparison, the corresponding results from a vegetable garden in a control region in Joinville, in the state of Santa Catarina. The results show that vegetables from two gardens near the CIPC region have no significant differences in Po content, despite the closeness of one of the sites to a uranium mine. For some species of vegetables, however, nearsite values were twice those in the control region. Superphosphate fertilizers influence the accumulation of 210 Po by plants, as well as the concentrations in soils, and their contribution is more evident than that of local deposition. The major concentration in the leaf and stem suggests that the accumulation of 210 Po in vegetables is due chiefly to its deposition on and absorption by their leaves.

Human occupational radioactive contamination from the use of phosphated fertilizers.

210Po and 210Pb concentrations in urine, hair and skin smear samples from individuals using phosphated fertilizers have been compared with a control group of occupationally unexposed individuals. Urine and hair samples of the test group showed slightly higher concentrations of 210Po and 210Pb than those observed for the control group. These concentrations remained, however, lower than those for uranium mine workers. Skin smear values indicated contamination by direct contact with dust from fertilizers and this may contribute to skin cancer induction in this risk population.

Lead-210 in vegetables and soils from an area of high natural radioactivity in Brazil

Contamination of vegetables and associates soils by 210Pb, originating either by natural fallout from uranium or by the processing mills of Poços de Caldas (CIPC), State of Minas Gerais, Brazil is estimated by comparison with similar control samples collected from areas distant from the mining and milling operations. For lichens and bryophytes, the mean values of 210Pb concentrations were significantly higher than those of the control region. Similarly, vegetables and soils from kitchen-gardens located near the mill contained much higher concentrations of 210Pb than those observed for other regions.

Concentrations of 210Pb and 210Po in hair and urine of workers, of the uranium mine at Poços de Caldas (Brazil)

210Po and 210Pb concentrations in urine and hair samples from individuals working in different areas of the uranium industrial complex of Poços de Caldas (Brazil) have been determined and compared with a control group of occupationally unexposed individuals. In the control group, smokers showed higher urinary excretion of these radionuclides. Such difference could not be detected in the workers group, which showed an increase in urinary excretion of 210Po for the group working in the chemical laboratory. Accumulation of 210Po and 210Pb in hair showed the same trends as for urinary excretion. The workers group, with the exception of the office employees, showed a 210Po/210Pb ratio > 1 in hair.

Lead-210 and polonium-210 concentrations in some species of marine molluscs

Data are presented for 210Pb and 210Po concentrations in three species of molluscs collected in the intertidal region of the coast of Rio de Janeiro, Brazil. Lead-210 activity in the soft tissue of the edible mussel Perna perna was 20 times higher than that found in its shell. The visceral mass contained the largest activity for both radionuclides, which is attributed to the feeding habits of the molluscs. Animals collected from Ponta Negra beach (open sea) showed higher concentrations of isotopes than those collected from Boa Viagem beach (within Guanabara Bay).

Levels of 210Po and 210Pb in cigars

Abstract210Po and 210Pb concentrations have been determined in 58 cigar brands manufactured in 11 countries. Cuban and American cigars showed the lowest 210Po content. The mean levels of 210Po in Brazilian, European and Dominican cigars were almost identical and somewhat lower than the levels observed for cigars from other Latin American countries. Cuban, American and European cigars contained low levels of 210Pb. Cigars from the remaining countries contained twice as much 210Pb. The mean 210Po/210Pb ratio showed an excess of polonium. In the case of a one cigar-a-day smoker, the calculated annual absorbed dose due to 210Po is -16 mGy.

Increase of 210Po levels in human semen fluid after mussel ingestion

Polonium-210 ((210)Po) radioactive concentrations were determined in human semen fluid of vasectomized non-smoker volunteers. The (210)Po levels ranged from 0.10 to 0.39 mBq g(-1) (mean: 0.23 ± 0.08 mBq g(-1)). This value decreased to 0.10 ± 0.02 mBq g(-1) (range from 0.07 to 0.13 mBq g(-1)) after two weeks of a controlled diet, excluding fish and seafood. Then, volunteers ate during a single meal 200 g of the cooked mussel Perna perna L., and (210)Po levels were determined again, during ten days, in semen fluid samples collected every morning. Volunteers continued with the controlled diet and maintained sexual abstinence through the period of the experiment. A 300% increase of (210)Po level was observed the day following mussel consumption, with a later reduction, such that the level returned to near baseline by day 4.

A multidisciplinary approach to the study of the fluminense vegetation

The fluminense vegetation, more specifically the flora from the Jurubatiba restinga has been investigated by a multidisciplinary team of botanists, chemist, radiobiologist, insect physiologists and geneticist. Vouchers of 564 specimens have been collected, identified, organized in an herbarium, and a database is being build up containing, in addition to classical botanical data, chemical data and information on the potential economic use either for landscape gardening, alternative foods or as medicinal plants. Phytochemical studies of the Guttiferae, Clusia hilariana, yielded oleanolic acid and nemorosone. Their biological activities against the haematophagous insect Rhodnius prolixus vector of Chagas disease have been investigated. Finally, it has been observed that aquatic plants possessed high levels of the natural radionuclide polonium-210, which seems to be originated mainly from soil rather than from atmospheric supply.

Uptake of 210Pb and 210Po by Brazillian Bunodosoma caissarum corrêa, 1964 (Cnidaria, actinidae)

Bunodosoma caissarum, a carnivorous marine species exclusive to the Brazilian southern coast, recognized as a sensitive bioindicator of artificial radioactive pollution, also shows a great capacity for concentrating natural alpha-emitters. The authors have measured the alpha-emitters 210Po and its precursor 210Pb in this animal. The average concentrations found are greater (by a factor of 4.6) for 210Po measured in samples gathered on Ponta Negra Beach (protected outer coast) than the values obtained in specimens collected on Boa Viagem Beach (closed bay) along the Rio de Janeiro coast, Brazil. The same was also found for 210Pb (a factor of 2.5).

Teores elevados de Polônio-210 em plantas aquáticas da restinga de Carapebus, RJ

210Po concentrations have been determined in one green alga and in five freshwater plants grown in a pond of the Carapebus restinga (State of Rio de Janeiro). The alga Chara sp showed elevated concentration of 210Po, similar to that observed for marine algae. All the other plants had the lowest concentration of 210Po in the stems and the highest in the roots. Intermediate values were observed in the leaves. The unexpected high concentration of 210Po in the roots, even superior to reported values for roots of plants from high radioactive background areas, must be due to the elevated levels of this radionuclide in associated soils that are known to be rich in humic organic material. There seem to have been no translocation of this radionuclide from the roots to the other parts of the plants.