Chronic exposure to volcanic environments and chronic bronchitis incidence in the Azores, Portugal

doi:10.1016/j.envres.2006.06.016

Environmental Research

Volume 103, Issue 3, March 2007, Pages 419-423

https://doi.org/10.1016/j.envres.2006.06.016 Get rights and content

Abstract

The village of Furnas, like other active volcanic areas in the world, exhibits high levels of hazardous gases. We aimed to investigate the existence of a possible association between chronic exposure to volcanic sulfur gases and chronic bronchitis. To investigate this, we used two populations, one exposed to active manifestations of volcanism (Furnas) and another from an area where no volcanic activity took place for over three million years (Santa Maria), both in the Azores. We used data on the incidence of chronic bronchitis among both populations (1991–2001), obtained from the records of each local health center, and population denominators from censuses carried out in 1991 and 2001, using five age-groups. We also estimated relative risks and mean annual age-standardized rates of chronic bronchitis incidence. Incidence rates were extremely higher in the volcanically active area for both sexes, and especially in the youngest groups. Accordingly, the risk of chronic bronchitis for the people living in the volcanically active area was extremely higher (males RR=3.99; females RR=10.74) when compared to those living in the volcanically inactive area. Comparison of chronic bronchitis incidence rates between both populations suggests an association between this disease and the chronic exposure to the volcanically active environment, with all its hazardous gases like hydrogen sulfide and sulfur dioxide. These findings may help health officials to better advice people inhabiting volcanic areas, or others with high levels of sulfur gases, on how to prevent and minimize the risks of chronic bronchitis.

Introduction

Chronic bronchitis is a major public health problem worldwide defined as chronic or recurrent production of mucus in the lungs with the presence of persistent productive cough. These symptoms are present on most days for 3 months a year, for at least 2 successive years, with no other underlying pulmonary or cardiac disease (Siafakas et al., 1995; Heath and Mongia, 1998).

The main risk factors for chronic bronchitis are cigarette smoking, and chronic exposure to air-borne pollutants, such as occupational and environmental irritant dusts and gases (Haschek and Witschi, 1991; Fishwick et al., 1997). Many of these dusts and gases, in lethal and sub-lethal doses, may be of anthropogenic origin but may also be generated by volcanic eruptions and subsequent volcanic activity during hundreds of years. Volcanoes and volcanic manifestations, such as fumaroles and degassing soils, may release metals, and hazardous aerosols and gases such as the radioactive gas radon, carbon dioxide, hydrogen chloride, hydrogen fluoride, hydrogen sulfide (H₂S), sulfur dioxide (SO₂), and sulfuric acid (Haschek and Witschi, 1991; Delmelle and Stix, 2000; Durand et al., 2004).

Sulfur compounds may induce oxidative stress and changes in tissues of respiratory organs (Meng et al., 2003). For example, chronic exposure to H₂S, considered an extremely toxic gas, at concentrations as low as 50 ppm may cause pharyngitis and bronchitis while concentrations over 250 ppm may result in pulmonary edema (Williams-Jones and Rymer, 2000). Even at lower doses, chronic exposure to H₂S may be linked to noninfectious respiratory disease, as suggested by Bates et al. (2001) and Durand and Wilson (2006) in studies made in an urbanized geothermal field in Rotorua. A correlation between SO₂ and the prevalence of bronchitis in children has been found by Herbarth et al. (2001). On contact with moist membranes, SO₂ forms sulfuric acid, which is responsible for severe irritant effects on the eyes, mucous membranes, and skin. Sulfuric acid also depresses pulmonary particle clearance, the major protective mechanism in lungs (Williams-Jones and Rymer, 2000; Kikuchi, 2001; Komarnisky et al., 2003).

The present population-based retrospective cohort study tested the hypothesis that exposure to volcanic environment is associated to a higher risk in chronic bronchitis. In order to do this, we evaluated the differences in the incidence of chronic bronchitis, between 1991 and 2001, in two areas of the Azores (Portugal), one with active volcanic manifestations (Furnas) and the other with no type of volcanic activity (Santa Maria), by using medical data.

Section snippets

Methods

The Azores is a nine-island archipelago located in the North Atlantic Ocean at the triple junction of Eurasian, African and North American plates where seismic–volcanic events are common (Nunes et al., 1993; Lourenço et al., 1998). São Miguel, which is the largest island (757 km²), has its geology dominated by the three active volcanoes of Sete Cidades, Fogo, and Furnas. Presenting fumarolic fields and hydrothermal vents (Booth et al., 1978; Cruz, 2003), and the always present “rotten egg” odor,

Results

The number of cases of chronic bronchitis per year reported during the period between 1991 and 2001 in Furnas was approximately 1.5 males and 1.6 females, while in Santa Maria it was about 1.4 males and 0.5 females (Table 1).

In males, the incidence rate from 15 to 44 years old in Furnas was higher than the sum of the entire incidence rates for Santa Maria. Females presented similar behavior, with the incidence rate from 0 to 14 years old in Furnas being higher than the sum of the entire

Discussion

The present paper describes and analyses the differences in chronic bronchitis incidence rates in two populations of the Azores archipelago, one inhabiting an area with active volcanic manifestations (Furnas), such as SO₂ and H₂S emanations, and the other inhabiting an area with no type of active volcanism (Santa Maria). The present study suggests an association between volcanic environmental gases and chronic bronchitis. Despite the fact that it did not include individual exposure data, the

Acknowledgments

The authors wish to thank the staff of the Health Centers of Povoação and Vila do Porto. This study was financially supported by Centro de Investigação de Recursos Naturais (CIRN), and Direcção Regional da Ciência e Tecnologia (Government of the Azores). AFS Amaral was supported by a Ph.D. grant from Fundação para a Ciência e a Tecnologia (SFRH/BD/8186/2002).

Competing interests: Authors do not have competing financial interests.

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Chronic exposure to volcanic environments and chronic bronchitis incidence in the Azores, Portugal

Abstract

Introduction

Section snippets

Methods

Results

Discussion

Acknowledgments

Sci. Total Environ.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

Sci. Total Environ.

Environ. Res.

J. Volcanol. Geotherm. Res.

J. Volcanol. Geotherm. Res.

Nutrition

Environ. Res.

Trends in Chronic Bronchitis and Enphysema: Morbidity and Mortality

Investigation of health effects of hydrogen sulfide from a geothermal source

Arch. Environ. Health

A quantitative study of five thousand years of volcanism on São Miguel, Azores

Philos. Trans. R. Soc. London A

The Burden of Lung Disease: A Statistics Report from the British Thoracic Society

Groundwater and volcanoes: examples from the Azores archipelago

Environ. Geol.

Volcanic gases

Council Directive 1999/30/EC of 22 April 1999 relating to limit values for sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter and lead in ambient air

Official Journal L

New K–Ar ages, chemical analyses and magnetic data of rocks from the islands of Santa Maria (Azores), Porto Santo and Madeira (Madeira archipelago) and Gran Canaria (Canary islands) Arquipélago

Ciên. Nat.