Pattern of cancer mortality in some Brazilian HBRAs

doi:10.1016/j.ics.2004.11.046

International Congress Series

Volume 1276, February 2005, Pages 110-113

https://doi.org/10.1016/j.ics.2004.11.046 Get rights and content

Abstract

Among residents of Brazilian High Background radiation Areas, there is great concern about radiation-related health effects and there is also a common certitude that cancer incidence is higher in those areas than in other Brazilian areas with normal background radiation. This paper aims to present an overview of Brazilian High Background Radiation Areas and evaluate whether cancer mortality among residents from Poços de Caldas, Araxá, and Guarapari is higher than would be expected when applying mortality rate of their respective States. Results show that cancer mortality from the Brazilian HBRAs, Poços de Caldas, and Guarapari is higher than would be expected for their respective reference population. On the other hand, cancer mortality for the Araxá population is lower than would be expected.

Introduction

Some Brazilian locations have been globally recognized as High Background Radiation Areas (HBRAs); included among these are Poços de Caldas, Araxá, and Tapira, all located in Minas Gerais State and Guarapari, located in Espirito Santo State [1], [2]. As a consequence of this recognition, residents of those areas have great concern about radiation-related health effects. There is a common sense among these populations that cancer incidence is higher than in other Brazilian areas with normal background radiation. Nevertheless, no previous cancer statistics have been shown to support this hypothesis and, until the present time, no health effect study had been conducted in Brazilian HBRAs. Most of the data concerning natural radiation exposure in those areas were obtained during the late 1970s. Recently new assessments were performed at Poços de Caldas [3] and Guarapari [4]. Those results indicated that the great urbanization process in Guarapari changed the radiation exposure pattern; the external radiation exposure is at present lower than that in the past. The radiation level in Guarapari can be considered normal, except in the hot spots on the beaches and in the fishing village of Meaipe [4]. At Poços de Caldas, it was shown that only rural areas could be considered as high natural background radiation areas. The radiation dose in urban areas can be considered normal.

Therefore, this paper aims to assess whether there is an excess of cancer mortality among residents from Poços de Caldas, Araxá, and Guarapari in comparison with a reference population. The State of Minas Gerais was used as the standard population for Poços de Caldas and Araxá, and the Espirito Santo State for Guarapari.

Section snippets

Methodology

Mortality data on cancer and all other causes of death were examined for Poços de Caldas, Araxá, and Guarapari as well as for the States of Minas Gerais and Espirito Santo, which were used as reference areas. Mortality data from 1991 to 2000, obtained from the Brazilian National Mortality System, were evaluated for both sexes and for the following age intervals: <1, 1–4, 5–9, 10–14, 15–19, 20–29, 30–39, 40–49, 50–59, 60–69, 70–79, and 80 and over. Standardized mortality ratios (SMRs) for every

Results

Table 1 presents the observed and expected numbers of deaths for selected cancer and all causes of death for cities of Araxá and Poços de Caldas, respectively, using the specific general mortality for Minas Gerais State as the standard population. For the Araxá population, mortality for all causes of death was significantly higher than expected from the reference population (SMR=118, CI=115–121). Nevertheless, total cancer did not exceed the expectation and no statistically significant excess

Discussion

Studies of geographical variation need to be interpreted with caution because many factors other than environmental exposure can contribute to such variation in the recorded frequency of disease or death. Mortality data can be affected by varying qualities of cause of death certification and differences in survival among regions. The imprecision in the information produces a dilution effect and biases the results. Genetic and ethnic factors may confound geographical variations, and migration

Conclusion

This report represents the first time that cancer mortality has been assessed for Brazilian HBRAs. It was observed that cancer mortality for Poços de Caldas and Guarapari is higher than would be expected for their respective reference populations, Minas Gerais State and Espirito Santo State, respectively. On the other hand, cancer mortality for the Araxá population is lower than would be expected.

Nevertheless, natural radiation levels at those regions cannot be associated with this excess

References (4)

T.L. Cullen
Review of the Brazilian investigations in areas of high natural radioactivity. Part I: Radiometric and dosimetric studies
E. Penna Franca
Status of investigations in the Brazilian areas of high natural radioactivity
Health Physics
(1965)

There are more references available in the full text version of this article.

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