[Assessment of risk due to the intake of uranium isotopes in mineral spring waters].
OBJECTIVE
To complement the data of a previous research concerning the evaluation of the lifetime risk of radiation-induced cancer due to the ingestion of 226Ra, 228Ra and 222Rn in mineral spring waters from a natural highly radioactive region of Brazil. The study was performed to evaluate the lifetime risk of radiation-induced cancer due to the ingestion of 238U and 234U in the same spring waters.


METHODS
It is assumed that the risk coefficient for natural U isotopes is the same as for the 226Ra-induced bone sarcomas and that the equilibrium for skeletal content is 25 times the daily ingestion of 226Ra, but 11 times the daily ingestion of long-lived uranium isotopes. Waters samples were collected seasonally over a period of one year at all the spring sites used by the local population of Aguas da Prata, S. Paulo State (Brazil).


RESULTS
Concentrations ranging from 2.0 to 28.4 mBq/L and from 4.7 to 143 mBq/L were observed for 238U and 234U, respectively. Based upon the measured concentrations the lifetime risk due to the ingestion of uranium isotopes was estimated. A total of 0.3 uranium-induced cancers per 10(6) exposed persons was predicted, suggesting that chronic ingestion of uranium at the levels observed at these springs will result in an incremental increase of fatal cancers of 0.1%.


CONCLUSIONS
By taking into account the uncertainties in evaluating the carcinogenic effects, it can be concluded that virtually no cancer would be expected from the ingestion of uranium in the mineral spring waters analyzed.
Camargo
I M
IM
Departamento de Radioproteção Ambiental, Universidade de São Paulo, Brasil.
Mazzilli
B
B
D001859:Bone Neoplasms / Q000139:chemically induced*; D001938:Brazil; D004326:Drinking; D006801:Humans; D007554:Isotopes / Q000032:analysis; D008900:Mineral Waters / Q000009:adverse effects* / Q000032:analysis*; D018570:Risk Assessment; D012509:Sarcoma / Q000139:chemically induced*; D014501:Uranium / Q000009:adverse effects* / Q000032:analysis*
D007554:Isotopes; D008900:Mineral Waters; D014501:Uranium
Estimativa de risco devido à ingestão de isótopos de urânio em fontes de águas minerais.