Systemic inflammatory changes and increased oxidative stress in rural Indian women cooking with biomass fuels
Highlights
► Effect of chronic biomass smoke exposure on cardiovascular health was investigated. ► Serum markers of systemic inflammation and oxidative stress were studied. ► Biomass using women had increased systemic inflammation and oxidative stress. ► Indoor air pollution and observed changes were positively associated.
Introduction
Unprocessed solid biomass such as dried cow dung cake, wood and crop residues is still used for cooking and room heating in a majority of rural households in India and neighboring countries. For example, 72% households in India, 88% in Bangladesh, 80% in Nepal, 72% in Pakistan and 67% in Sri Lanka use biomass for daily household cooking (WHO, 2006). Poverty is the main reason behind the use of biomass as most of the rural people can't afford cleaner fuel with their modest income. Besides, cleaner fuels such as compressed natural gas or liquefied petroleum gas (LPG) are not readily available in the remote villages. Cooking in the Indian villages is generally done by the womenfolk in traditional earthen ovens in poorly ventilated kitchen. Since biomass is not combustion efficient, it emits high level of smoke that causes severe indoor air pollution (IAP).
Biomass smoke contains a wide spectrum of potentially health-damaging pollutants that include coarse, fine and ultrafine particles, carbon monoxide (CO), oxides of nitrogen and sulfur, transitional metals, polycyclic aromatic hydrocarbons, volatile organic compounds and bioaerosols (Morawska and Zhang, 2002, Smith, 2000). The level of particulate matter of less than 10 μm in diameter (PM10) in biomass-using households in India especially during cooking time far exceeds traffic-generated PM10 level in the cities (Balakrishnan et al., 2002, Ezzati and Kammen, 2002, Smith, 1993). Ultrafine particles (UFPs) having a diameter of less than 0.1 μm represent a substantial proportion of particulate pollutants in biomass smoke (Naeher et al., 2005). Inhaled UFPs can readily cross the alveolar-capillary barrier reaching the blood stream (Elder and Oberdörster, 2006, Nemmar et al., 2002). In circulation, UFPs adsorb onto the surface of erythrocytes and can travel to all vital organs of the body including the brain (Oberdörster et al., 2004). Therefore, exposure to biomass smoke can mediate systemic alterations besides its adverse effects on the lung and the airways. In conformity with this, we have recently reported greater prevalence of hypertension among relatively young, never-smoking housewives of rural India who cooked exclusively with biomass than their age- and sex-matched neighbors who cooked with LPG (Dutta et al., 2011).
The mechanism of hypertension among biomass users, however, is currently unknown. An intimate relationship exists between inflammation, endothelial dysfunction and hypertension (Tycinska et al., 2011). Subtle or overt activation of inflammatory mediators is frequent among hypertensives (Laffer and Elijovich, 2010). In fact, hypertension has been considered in part as an inflammatory disorder (Gupta et al., 2011, Montecucco et al., 2011). Inflammation may lead to oxidative stress and up-regulated production of blood coagulation proteins that increase the risk of cardiovascular diseases (Knol et al., 2009) primarily by potentiating blood pressure (Ibald-Mulli et al., 2001, Touyz and Briones, 2011, Urch et al., 2005). Oxidative stress and endothelial dysfunction are consistently observed in hypertensive subjects, and accumulating evidence suggests that they also have a causal role in the molecular processes leading to hypertension (Touyz and Briones, 2011).
PM10, PM2.5 (particulate matter of less than 2.5 μm in diameter) and UFPs present in biomass smoke are able to mediate oxidative stress and to produce pro-inflammatory mediators that may lead to pulmonary as well as systemic inflammation (Donaldson et al., 2001, Donaldson et al., 2005, Pope et al., 2004). PMs induce liver to produce pro-inflammatory mediators interleukin-6 (IL-6) and C-reactive protein (CRP; Delfino et al., 2009, Hertel et al., 2010), and blood coagulation proteins (Metassan et al., 2010). Elevation of CRP in human blood accompanies inflammation and cardiovascular diseases (CVDs; Kusche-Vihrog et al., 2011). CRP causes stiffness of vascular endothelium and consequent development of hypertension (Kusche-Vihrog et al., 2011). Inflammation may lead to oxidative stress. Oxidative stress is tightly regulated by a balance between production of reactive oxygen species (ROS) such as superoxides and hydrogen peroxides and their removal by antioxidant enzymes including superoxide dismutases (SODs), heme oxygenase-1, NAD(P)H quinone oxidoreductase-1, catalase and thioredoxin. ROS are natural byproducts of metabolism and these molecules play important roles in cell signaling. However, excessive levels of ROS due to up-regulated production and/or decreased removal by antioxidants can be toxic to the cells (Gao and Mann, 2009, Lee et al., 2005, Mann et al., 2007, Motohashi and Yamamoto, 2004). Collectively, these reports suggest that chronic inhalation of biomass smoke may lead to inflammation and oxidative stress which, in turn, can raise arterial blood pressure.
Though there have been numerous studies from the western world, there have been very few reports on this aspect from this part of the world, especially from India. We found it utterly necessary to undertake such a study in India as conditions in the developing countries like India vary greatly from the conditions of the developed countries of the western world. We aimed to study if biomass smoke aggravated systemic inflammation and oxidative stress in a group of never-smoking, poor rural women in eastern India who cooked exclusively with biomass for the past five years or more compared to their neighbors those who cooked with liquefied petroleum gas (LPG), a relatively cleaner fuel. For this, we examined the biomarkers of inflammation and oxidative stress that are well-established by renowned scientists of the western world. We also examined if there was any possible impact on their arterial blood pressure.
Section snippets
Participant recruitment and sample size
This cross-sectional study was conducted in 6 villages in Hooghly, Howrah, Burdwan and Birbhum districts of West Bengal, a state in eastern India. The villages were selected on the basis of the following criteria: i. the location should be at least 5 km away from the national or state highways to minimize the impact of vehicular pollution, ii. no air-polluting industry like coal-based thermal power plant, brick kiln, sponge iron factory and rice mill within 5 km radius in order to control the
Demographic characteristics of the participants
Demographic and socio-economic characteristics of biomass- and LPG-using women are compared in Table 1. It is apparent that the two groups were well-matched with respect to age, body mass index (BMI), years and hours of cooking, passive smoking due to presence of smokers in the family, food habit, and number of family members. However, they differed significantly (p < 0.05) with respect to education, family income and presence of separate kitchen. Compared with controls, biomass users were less
Discussion
This study has shown that chronic inhalation of smoke during daily household cooking with biomass aggravates oxidative stress and systemic inflammation, and increases the prevalence of hypertension and tachycardia among women in rural India. Like the present finding, a Guatemalan study has earlier shown higher prevalence of hypertension in women who cooked exclusively with biomass (McCracken et al., 2007). Since hypertension and tachycardia are known risk factors for CVD (Whitworth, 2005),
Conflict of interest
The authors declare that there are no conflicts of interest.
Acknowledgments
The study was funded by Council of Scientific and Industrial Research, India and Central Pollution Control Board, Delhi under Ministry of Environment and Forests, Government of India.
References (63)
- et al.
NAD(P)H oxidases in coronary artery disease
Adv. Clin. Chem.
(2010) - et al.
ACC/AHA/ESC guidelines for the management of patients with supraventricular arrhythmias—executive summary. A report of the American College of Cardiology/American Heart association Task Force on practice guidelines and the European Society of Cardiology Committee for practice guidelines (writing committee to develop guidelines for the management of patients with supraventricular arrhythmias) developed in collaboration with NASPE-Heart Rhythm Society
J. Am. Coll. Cardiol.
(2003) - et al.
C-reactive protein and cardiovascular diseases—is it ready for primetime?
Am. J. Med. Sci.
(2009) - et al.
Coronary artery diameter as a risk factor for acute coronary syndromes in Asian-Indians
Am. J. Cardiol.
(2005) - et al.
Combustion sources of particles. I. Health relevance and source signatures
Chemosphere
(2002) - et al.
Nrf2-Keap1 defines a physiologically important stress response mechanism
Trends Mol. Med.
(2004) - et al.
A sensitive spectrophotometric method for the determination of superoxide dismutase activity in tissue extracts
Anal. Biochem.
(1986) - et al.
Association between resting heart rate and arterial stiffness in Korean adults
Arch. Cardiovasc. Dis.
(2010) - et al.
Some thoughts on the vasculopathy of women with ischemic heart disease
J. Am. Coll. Cardiol.
(2006) Stroke in women
Nutr. Metab. Cardiovasc. Dis.
(2010)
Assessment of antioxidant enzyme activities in erythrocytes of pre-hypertensive and hypertensive women
J. Respir. Med. Sci.
Daily average exposures to respirable particulate matter from combustion of biomass fuels in rural households of southern India
Environ. Health Perspect.
C-reactive protein and coronary heart disease: a critical review
J. Intern. Med.
Comparison of real-time instruments used to monitor airborne particulate matter
J. Air Waste Manage. Assoc.
Air pollution exposures and circulating biomarkers of effect in a susceptible population: clues to potential causal component mixtures and mechanisms
Environ. Health Perspect.
Ambient particle inhalation and the cardiovascular system: potential mechanisms
Environ. Health Perspect.
Role of inflammation in cardiopulmonary health effects of PM
Toxicol. Appl. Pharmacol.
Hypertension with elevated levels of oxidized low-density lipoprotein and anticardiolipin antibody in the circulation of premenopausal Indian women chronically exposed to biomass smoke during cooking
Indoor Air
Translocation and effects of ultrafine particles outside of the lung
Clin. Occup. Environ. Med.
The health impacts of exposure to indoor air pollution from solid fuels in developing countries: knowledge, gaps and data needs
Environ. Health Perspect.
Vascular NAD(P)H oxidase activation in diabetes: a double-edged sword in redox signalling
Cardiovasc. Res.
Endothelial dysfunction and inflammation in different stages of essential hypertension
Saudi J. Kidney Dis. Transpl.
Inflammation, atherosclerosis, and coronary artery disease
N. Engl. J. Med.
Influence of short-term exposure to ultrafine and fine particles on systemic inflammation
Eur. J. Epidemiol.
Effects of air pollution on blood pressure: a population-based approach
Am. J. Public Health
Seventh Report of the Joint Committee on the Prevention, Detection, Evaluation and Treatment of High Blood Pressure. Bethesda, MD, National Heart, Lung, Blood Institute, National High Blood Pressure Education Program, May 2003
Prevalence, awareness, control, and associations of arterial hypertension in a rural central India population: the Central India Eye and Medical Study
Am. J. Hypertens.
Expert elicitation on ultrafine particles: likelihood of health effects and causal pathways
Part. Fibre Toxicol.
C-reactive protein makes human endothelium stiff and tight
Hypertension
Further evidence that smaller coronary artery diameter in Asian-Indians is a risk factor for development of coronary artery disease
Inflammation and therapy for hypertension
Curr. Hypertens. Rep.
Cited by (106)
Effects of PM<inf>2.5</inf> emissions from household fuel combustion on biomarkers and pulmonary function in rural areas of Fenwei Plain, China
2023, Atmospheric Pollution ResearchRisk analysis of air pollution correlates with socioeconomic and heart diseases
2023, Spatial Modeling of Environmental Pollution and Ecological RiskHousehold air pollution from wood-burning cookstoves and C-reactive protein among women in rural Honduras
2022, International Journal of Hygiene and Environmental Health