Biomass smoke exposure as a serious health hazard for women

Materyal ve Metod: Eylül 2008-Mart 2009 tarihleri arasında Süreyyapaşa Göğüs Hastalıkları ve Göğüs Cerrahisi Eğitim ve Araştırma Hastanesinde yatırılarak tedavi edilen kronik obstrüktif akciğer hastalığı (KOAH), astım, bronşektazi, tüberküloz veya interstisyel akciğer hastalığı olan toplam 100 kadın (ortalama yaş 55.13 ± 17.65 yıl) hasta çalışmaya dahil edildi. Biomass maruziyeti konusunda veri toplanması, hastanede meslek, eğitim seviyesi, doğum yeri, ısıtma ve pişirme sırasında biomass dumanına maruz kalma (tezek, odun, kömür, kuru bitkiler) ve maruziyet yılı değerlendirildi.


INTRODUCTION
Indoor air pollution (IAP) is a major environmental and public health hazard for many of the world's poorest most vulnerable people.There has been an increasing scientific interest in indoor pollution since the second half of 1980 (1). IAP resulting from combustion of biomass fuels has now been recognised as a relevant risk factor for respiratory disorders especially in developing countries in relation to the shift from use of biofuel to petroleum products (kerosene, LPG) and electricity in developed countries (2).
Biomass fuel, or biofuel, refers to any plant or animal based material deliberately burned by humans as their primary source of domestic energy for cooking, home heating and lightening.While the wood is the most common biofuel, use of animal dung and crop residues is also widespread (2).Typically burnt in open fires or poorly functioning stoves, the use of these fuels leads to very high levels of IAP.Smoke exposure affects mainly women and also young children accompanying their mothers during cooking and other household activities (2).Around 50% of the world's population uses biomass fuels ranging from near zero in industrialized countries to more than 80% in countries like China, India and sub-Saharan Africa.In Latin America, approximately 50-75% of households were reported to use biomass fuels for cooking, especially in rural areas (1).In Turkey, use of biomass fuels was documented to be 30% in urbanized areas; 30% in rural areas and 90% in Central Anatolia, East Anatolia and Southeastern Anatolia regions (3).
Biomass smoke contains thousands of substances, many of which have a significant potential to damage human health.The most damaging substances are carbon monoxide, nitrous dioxides, sulphur oxides (more with coal), formaldehyde and polycyclic organic matter which includes carcinogens such as benzo(a)pyrene (1,2).
There is now consistent evidence that biomass smoke exposure increases respiratory and non-respiratory diseases.A significant relation of smoke exposures to the risk of childhood acute respiratory infections, pneumonia in particular and respiratory diseases seen in women including chronic bronchitis and chronic obstructive pulmonary disease, asthma, lung cancer and lung fibrosis was demonstrated.Besides, evidence of an inc-reased risk of tuberculosis was also shown by a number of studies (1,2).
The present study was designed to investigate the effects of biomass exposure in hospitalized women suffering from lung disease.

MATERIALS and METHODS
A total of 100 women [mean (SD) age: 55. 13  Being ≥ 18 years of age and to be hospitalized for a respiratory disease including asthma, bronchiectasis, tuberculosis and interstitial lung disease were the inclusion criteria.Patients lacking a definite clinical diagnosis or cooperation to answer questionnaire were excluded from the study.Data collection on biomass exposure was based on application of hospital-based survey questionnaire to the study sample selected through random sampling.Questionnaire included items on occupation, level of education, place of birth (location, region), exposure to biomass fuel fumes for heating and cooking purposes (animal dung, wood, charcoal, dried plant) and years of exposure with animal dung, wood, charcoal, dried plant.Besides use of flueless systems such as floor furnace, barbecue, fireplace or bottled gas for heating was considered to be risky exposure and years of exposure was also recorded for the heating methods.
Data on symptoms, respiratory function tests, findings of spirometry, physical examination, high resolution of computerized tomography, chest X-ray, bacteriological investigation (sputum smear and culture results) were collected from medical records.
COPD diagnosis was made via spirometry and clinical assessment and patients who had spirometric measurement FEV 1 /FVC < 0.70 and characteristic symptoms of COPD such as chronic and progressive dyspnea, cough and sputum production were considered to have COPD according to GOLD guidelines (4).
Patients who had symptoms of recurrent episodes of wheezing, breathlessness, chest tightness and coughing at night or early morning and who were under asthma treatment were considered to have asthma in accordance with GINA guidelines (5).
Diagnosis of tuberculosis was based on smear or culture positivity of bacteriological sputum or histopathological confirmation.Diagnosis of interstitial lung disease and bronchiectasis was performed radiologically via high resolution of computerized tomography.

Statistical Analysis
Descriptive statistics were used.Continuous variables will be summarized using mean and standard deviation (for normally distributed variables) and median and quartiles (for non-normally distributed variables).Categorical variables will be summarized with percent in each category.

RESULTS
Mean (SD) age of the study population composed of 100 women was 55.13 (17.65) years.
Migration was evident in 12 (12%) patients in the first decade of their lives while 37 (37%) patients identified that they migrated in the second decade and 60 (60%) patients in the third decade of their lives.

DISCUSSION
COPD, asthma, lung fibrosis, interstitial lung diseases, pulmonary tuberculosis and lung cancer are considered among the respiratory diseases associated with exposure of IAP.Women and children seem to be at greater risk of adverse health effects resulting from the IAP since they spend more time indoors compared to rest of the population (1).Accordingly in our study population composed primarily of housewives (86%) who were spending majority of their time indoors with household activities, the significant exposure to biomass fumes from the heating and cooking was evident.Indeed, all of the women included this study was identified to have biomass fuels exposure in the past, especially early years of their li-   ves with almost more than 40 years of average exposure to animal dung, dry plant and charcoal.
People from lower socioeconomic status have been considered to be more susceptible to tuberculosis which is a significant socioeconomic public health issue (6).In this line, indicating higher use of biomass fuels in rural areas of Turkey including people from lower socioeconomic level, Central Anatolia (29%) and Eastern Anatolia (23%) were the most commonly identified geographical regions of place of birth and to be born in a village (67%) predominated in our population.Besides, in correlation to their low socioeconomic level, half of our patients were identified to be illiterate.
While wood has been considered as the most commonly used biofuel, use of animal dung and crop residues was also documented to be widespread (7).Accordingly wood usage was very common (93%) in our population.
The evaluation of the medical records showed that out of 100 female patients, tuberculosis was evident in 26%, COPD in 22%, bronchiectasis in 15%, interstitial diseases in 17%, and asthma in %12.
IAP has been considered a risk factor for COPD by the Global Strategy for the Diagnosis Management, and Prevention of Chronic Obstructive Lung Disease (4).
Albeit not consistent, the association between IAP exposure and increased risk of chronic bronchitis with possible progression to COPD, emphysema and cor pulmonale was reported in majority of studies.Accordingly, the association between exposure to biomass smoke and chronic bronchitis or COPD was documented in some cross-sectional, case control and cohort studies.Exposure was usually estimated via questionnaires based on hours by the wood stove, or hours multiplied by years of exposure.The evidence for chronic bronchitis has generally been defined by questionnaire symptoms.Spirometrical evaluation was done.Additionally, women exposed to biomass fumes were reported to be more likely to suffer from chronic bronchitis and COPD compared with urban women even though the prevalence of smoking was higher among the latter group (8)(9)(10)(11)(12)(13)(14)(15).
In Turkey and Iran, women exposed to biomass for cooking/heating showed significantly higher prevalence of chronic bronchitis and COPD while recent studies showed contribution of wood smoke and poverty to reduced lung function as an important risk factor for development of COPD among non-smoking women (16)(17)(18).
First large epidemiological study conducted in Turkey showed that biomass exposure, as a sole reason for COPD, was significantly common among female patients living in rural areas (54.5%) (19).In a systematic review and meta-analysis of 25 studies concerning respiratory diseases associated with solid biomass fuel exposure in rural women and children, the overall pooled ORs indicated significant associations with chronic bronchitis in women (OR 2.52, 95% CI 1.88 to 3.38) and COPD in women (OR 2.40, 95% CI 1.47 to 3.93) (20).
There are still relatively few published studies from developing countries about the relation between asthma and IAP while exposure is not measured and confounding is not dealt with in some of these studies.Although evidence from developing countries suggests that IAP may increase risk of developing asthma for children, a number of studies reported no effect for children (8,(21)(22)(23)(24)(25).
Evidence in adults comes from in rural China which reported adjusted OR for wheezing and asthma for the group with occupational exposure to wood smoke to be 1.36 (1.14-1.61)and 1.27 (1.02-1.58),respectively (20,24).In a systematic review and meta-analysis of 25 studies concerning respiratory diseases associated with solid biomass fuel exposure in rural women and children, no significant association with asthma in children or women was noted (20).
A few studies have found an increased risk of tuberculosis from exposure biomass fuels, although none of them measured the level of exposure specifically and confounding not fully accounted for in one (26)(27)(28).In these studies, adjusted OR for socio-economic factors OR were 2.58 (1.98-3.37),2.4 (1.04-5.6)(26)(27)(28).Association between use of biofuel and tuberculosis was found similar with adjustment only for age (27).An increase in risk of tuberculosis may result from reduced resistance to infection, as exposure to smoke interferes with mucociliary defenses and decreases antibacterial properties of lung macrophages (29).Biomass smoke exposure may be an additional factor in the well-established relationship between poverty and tuberculosis and may be explained by factors including malnutrition, overcrowding and limited access to health care.
There is some evidence also that wood smoke exposure may be associated with interstitial lung disease (inflammation of the lung structure leading to fibrosis) in developed countries (30)(31)(32).In a small case control study, patients with cryptogenic fibrosing alveolitis were determined to be more likely to live in a house heated by a wood fire (33).Several studies have described lung fibrosis which resembles pneumoconiosis including cases with progressive massive fibrosis among subjects exposed to wood smoke.Exposure to inorganic or organic dusts may coexist in these patients.Nonoccupational silicosis has also been reported in developing countries, and attributed to sand storms, but these subjects have often also exposed to biomass smoke (34)(35)(36).
The existing studies on the relationship between biomass usage and respiratory diseases in developing countries, provide important evidence of associations with a range of serious and common health problems but suffer from a number of methodological limitations, namely: a.The lack of detailed and systematic pollution exposure determination, b.The fact that all studies to date have been observational and, c.That many have dealt inadequately with confounding (1).
In conclusion, poverty is one of the main barriers to the adoption of cleaner fuels and slow pace of development in many countries implies that biofuels will continue to be used by the poor for many decades.The available data indicate the significant impact of biomass fuels usage on the respiratory health worldwide and that protective public health measures should be implemented (1).Our findings indicating significant impact of biomass exposure in women seem to emphasize the need for the detailed analytic epidemiologic studies concerning assessment biomass exposure to be able develop practical, robust and valid methods for measuring the exposure levels and patterns-particularly for women and young children.

Table 1 . Demographic and basic clinical features of patients (n= 100).
COPD: Chronic obstructive pulmonary disease.