Abstracts

The Espírito Santo State, Brazil, has areas of high natural radioactivity, especially on the beaches of Guarapari, where it is comparable to the locations with the highest natural radioactivity on the planet ¹1. Franca EP, Almeida JC, Becker J, Emmerich M, Roser FX, Kegel G, et al. Status of investigations in the brazilian areas of high natural radioactivity. Health Phys 1965; 11:699-712.^,22. Pfeiffer WC, Penna-Franca E, Ribeiro CC, Nogueira AR, Londres H, Oliveira AE. Measurements of environmental radiation exposure dose rates at selected sites in Brazil. An Acad Bras Ciênc 1981; 53:683-9.^,33. Veiga R, Sanchesa N, Anjosa RM, Macarioa K, Bastosa J, Iguatemya M, et al. Measurement of natural radioactivity in Brazilian beach sands. Radiat Meas 2006; 41:189-96.^,44. Costa Dantas R, Navoni JA, Alencar FLS, Xavier LAC, Amaral VS. Natural radioactivity in Brazil: a systematic review. Environ Sci Pollut Res 2020; 27:143-57.. Higher mortality rates for esophagus, stomach, lung, and prostate cancer were reported in Guarapari from 1996 to 2001 ⁵5. Veiga LHS, Koifman S. Pattern of cancer mortality in some Brazilian HBRAs. Int Congr Ser 2005; 1276:110-13.. To verify whether this excessive cancer mortality still exists in Guarapari, we studied the mortality rates for all causes, all cancers, and the most prevalent cancers (esophagus, stomach, larynx, lung, prostate, breast, and leukemias) from 2000 to 2018, and compared them with rates observed in the Espírito Santo State.

Data from all-cause mortality (International Classification of Diseases - ICD-10: A00-Z99), all-cancer mortality (ICD10: C00-C97), and mortality from cancer of the esophagus (ICD10: C15), stomach (ICD10: C16), larynx (ICD10: C32), trachea, bronchi and lung (ICD10: C33 and C34), prostate (ICD: C61), breast (IC10: C50), and leukemias (ICD10: C91-C95) were collected from the Brazilian Health Informatics Department (DATASUS) ⁶6. Departamento de Informática do SUS. Mortalidade - Espírito Santo. http://tabnet.datasus.gov.br/cgi/tabcgi.exe?sim/cnv/obt10ES.def (accessed on Dec/2020).
http://tabnet.datasus.gov.br/cgi/tabcgi.... from 2000 to 2018. Mortality rates were calculated using the direct method ⁷7. Gordis L. Measuring the occurrence of disease: II. Mortality. In: Gordis L, editor. Epidemiology. 3rd Ed. Philadelphia: Elsevier Saunders; 2004. p. 48-70., based on the state’s population during the period ⁸8. Departamento de Informática do SUS. População residente - Espírito Santo. http://tabnet.datasus.gov.br/cgi/deftohtm.exe?ibge/cnv/popes.def (accessed on Dec/2020).
http://tabnet.datasus.gov.br/cgi/deftoht... . Crude mortality rates and age-adjusted rates standardized by the World Health Organization (WHO) world population ⁹9. Ahmad OB, Boschi-Pinto C, Lopez AD, Murray CJL, Lozano R, Inoue M. Age standardization of rates: a new WHO standard. Geneva: World Health Organization; 2001. (GPE Discussion Paper Series, 31). were calculated. Crude mortality rates were calculated for each municipality, and standardized rates were calculated for the entire state and nine municipalities where natural radioactivity has known values. The comparison of mortality rates observed in Guarapari with that observed in the state was performed by: (a) comparison of crude mortality rates in Guarapari with the average of crude rates observed in the 78 municipalities of Espírito Santo; (b) comparison between the expected and observed values for deaths in Guarapari based on the standardized rate observed for the state; (c) comparison between the averages of the annual mortality rates observed in Guarapari with the rates observed in Espírito Santo. To verify a possible relationship between natural radioactivity and mortality rates, the Spearman’s correlation test was performed using data from the nine municipalities with natural radioactivity. Data on natural radioactivity in Espírito Santo were taken from Veiga et al. ³3. Veiga R, Sanchesa N, Anjosa RM, Macarioa K, Bastosa J, Iguatemya M, et al. Measurement of natural radioactivity in Brazilian beach sands. Radiat Meas 2006; 41:189-96., which evaluated the radioactivity of the beaches of Espírito Santo, from Marataízes to São Mateus. This study was approved by the Vila Velha University (UVV) Ethics Research Committee.

The results are summarized in Tables 1, 2 and 3. In Guarapari, all-cause mortality rates, all-cancer mortality, and mortality from the malignant neoplasms evaluated did not differ or were lower than expected (Table 1). The differences were significantly lower for all cancers, esophageal cancer, stomach cancer, and prostate cancer (Table 1). The average crude mortality rates from all cancers observed in Guarapari showed no significant difference from the average of the same rates in the 78 municipalities of Espírito Santo (respectively 93.98/100,000, 95%CI: 83.9-102.3 and 89.2/100,000, 95%CI: 85.1-93.3; Mann-Whitney test, p = 0.4676). Likewise, the means of standardized mortality rates observed in Guarapari showed no significant difference from those of the state, except for mortality from esophageal cancer, significantly lower in Guarapari (Table 2). There was no correlation between mortality rates and the level of natural radiation in the municipalities where radioactivity was evaluated (Table 3).

The mortality rates observed in Espírito Santo are similar to those of Brazil and the Southeast Region ¹⁰10. Instituto Brasileiro de Geografia e Estatística. Taxa bruta de mortalidade por mil habitantes - Brasil - 2000 a 2015. https://brasilemsintese.ibge.gov.br/populacao/taxas-brutas-de-mortalidade.html (accessed on Apr/2021).
https://brasilemsintese.ibge.gov.br/popu... ^,1111. Instituto Nacional de Câncer José Alencar Gomes da Silva. Atlas de mortalidade por câncer. https://www.inca.gov.br/aplicativos/atlas-de-mortalidade-por-cancer (accessed on Apr/2021).
https://www.inca.gov.br/aplicativos/atla... . The results showed no excess mortality for cancer in Guarapari in the analyzed period; on the contrary, the number of deaths expected according to the mortality rates for the state was higher than those observed in Guarapari. Mortality rates from all cancers observed in Guarapari did not significantly differ from those observed in other municipalities of Espírito Santo. Although not significant, the mortality rate for all cancer was higher in Guarapari than that observed in the state. However, it was similar to cancer mortality rates observed in eight municipalities with more than 100,000 inhabitants (data not shown). It is known that cancer mortality is higher in the largest urban concentrations ¹²12. Pritchard C, Evans B. Population density and cancer mortality by gender and age in England and Wales and the Western World 1963-93. Public Health 1997; 111:215-20., and Guarapari belongs to the metropolitan area of Vitória, where 40% of the state’s population lives. Additionally, no correlation was observed between the levels of natural radioactivity and the mortality rates evaluated.

Altogether, these results do not confirm the findings of Veiga et al. ⁵5. Veiga LHS, Koifman S. Pattern of cancer mortality in some Brazilian HBRAs. Int Congr Ser 2005; 1276:110-13.. It is difficult to explain this discrepancy because comparing the results was impossible due to the standardization method used by Veiga et al. ⁵5. Veiga LHS, Koifman S. Pattern of cancer mortality in some Brazilian HBRAs. Int Congr Ser 2005; 1276:110-13., which was not clearly described in the paper.

Some studies showing a relationship between natural radioactivity and cancer conducted in different parts of the world, including Brazil, are criticized because they fail to consider many confounding variables ¹³13. Hendry JH, Simon SL, Wojcik A, Sohrabi M, Burkart W, Cardis E, et al. Human exposure to high natural background radiation: what can it teach us about radiation risks? J Radiol Prot 2009; 29:A29-42.. It is possible that the natural radioactivity on Espírito Santo beaches, particularly in Guarapari, may not be influencing the incidence of cancer. However, there have been reports of chromosomal anomalies in the resident population in Guarapari ¹⁴14. Barcinski MA, Céu-Abreu M, Almeida JC, Naya JM, Fonseca LG, Castro LE. Cytogenetic investigation in a Brazilian population living in an area of high natural radioactivity. Am J Hum Genet 1975; 27:802-6.1975., although these results were questioned due to the long reading time for cultures of lymphocytes ¹³13. Hendry JH, Simon SL, Wojcik A, Sohrabi M, Burkart W, Cardis E, et al. Human exposure to high natural background radiation: what can it teach us about radiation risks? J Radiol Prot 2009; 29:A29-42.. The gamma radiation emitted by radionuclides occurring on the beaches of Guarapari was at normal levels in homes and high in the sand of the beaches, but within tolerable limits for human exposure ¹⁵15. Vasconcelos D, Reis P, Pereira C, Oliveira A, Santos T, Rocha Z. Modelling natural radioactivity in sand beaches of Guarapari, Espírito Santo State, Brazil. World Journal of Nuclear Science and Technology 2001; 3:65-71.. It is also known that urbanization, with building modifications, reduces the population’s exposure to natural radiation in regions of high natural radioactivity ¹⁶16. Affonseca MS, Alves RN, Tolentino Junior J, Almeida EC. The influence of urbanization on natural radiation levels in anomalous areas. J Environ Radioact 2002; 63:65-75..

In conclusion, the results show that the natural radioactivity observed on the beaches of Guarapari is not related to higher mortality rates from malignant neoplasms in the local population. In contrast, the observed number of deaths from all cancers and cancer of the stomach, esophagus, and prostate was significantly lower than expected. Mortality rates for all cancers and stomach, esophagus, larynx, lungs, breast, and prostate cancers showed no difference from those observed in the state, except for esophageal cancer, which was significantly lower in Guarapari. Further investigations are necessary to verify factors involved in the lower mortality from esophageal cancer observed in this region.

References

Publication Dates

History