Threat from occupational exposure to pollutants, especially to young children and pregnant women, is growing rapidly. There is no time for complacency, note scientists
to highlight the health hazards posed by environmental and occupational exposure to pollutants, the Lucknow- based Industrial Toxicology Research Centre ( itrc ) recently organised a five-day 'International Conference on Environmental and Occupational Respiratory Diseases ( iceord )' in Lucknow, Uttar Pradesh. Some 175 scientists from 21 countries, took part in the conference, the main purpose of which was to stress upon the threat posed by environmental and occupational respiratory diseases in developing countries.
Besides, the mandate of the conference included identifying principal scientific conclusions and uncertainties of current research on these diseases; facilitate a dialogue between the scientific and policymaking communities on ways to reduce uncertainties and motivate interventions and bring out a set of recommendations for the government and policymakers.
Environmental and occupational respiratory diseases account for a significant portion of preventable illness and premature death the worldwide. Unfortunately, all such diseases -- pneumonia, chronic obstructive lung disease, tuberculosis, asthma, and lung cancer -- are caused due to common exposure in households, workplaces and outdoor environments. The burden is greatest in developing countries such as India. Experts believe that since there are no effective cures for most of these diseases, only preventive measures can help. The experts covered three areas of exposure -- workplace/ occupational, indoor/households and outdoors.
Important occupational diseases highlighted during the conference were:
• occupational lung diseases such as asbestosis, silicosis, asthma, pneumoconiosis (dust disease);
• chronic occupational pulmonary diseases ( copd ) characterised by progressive development of airflow limitation that is not fully reversible;
• occupational respiratory diseases.
"Occupational chronic respiratory diseases are believed to constitute one third of all occupational illnesses. As many as 50 million cases occur each year worldwide," said S K Saxena, director, Directorate General Factory Advice Service and Labour Institutes, ministry of labour, Mumbai. In Columbia 1.8 million workers, in India 1.6 million and in usa 1.7 million are at risk due to occupational lung diseases like silicosis and asbestosis, he further added. However, scientists noted that in developed countries it is not severe and deaths due to such exposure are low when compared to developing countries.
To combat occupational exposure to pollutants, scientists stressed on the need to develop systems to monitor and prevent the occurrence of these diseases; surveillance and prevention to protect millions of workers in quarries, for instance; and need to list extremely polluted conditions in many small industrial units.
In India, the most important source of indoor air pollution ( iap ) is combustion of domestic fuels (such as cow dung, wood and crop residues) for cooking, on which 80 per cent (1991 census) of the population relies. "A pollutant released indoor is a thousand times more likely to reach the lungs than a pollutant released outdoors," cautioned Dietrich Schwela, air pollution scientist, department of protection of the human environment, World Health Organisation, Geneva.
"Globally three million people die every year due to air pollution. Out of that 1.8 million die due to iap in developing countries," said N K Ganguly, director general, Indian Council of Medical Research ( icmr ), New Delhi. In India, 589,000 people die due to iap -- 496,000 in rural areas and 93,000 in urban areas, he added. It is generally women and young children who face the brunt of iap . In poor households, there is no such thing as a separate kitchen. Thus people who stay indoors are continuously exposed to iap . It is worst for young children whose lungs are still developing.
According to Kirk Smith, professor of environmental health sciences at University of California, usa , there is strong evidence to link iap with acute respiratory infections and chronic obstructive lung disease in children below five years of age.
Cross-country analysis by Anita Zaidi of Agha Khan Hospital in Islamabad, Pakistan, also shows a strong link between traditional biomass fuel use and infant mortality. The experts concluded that traditional fuels emit large quantities of dangerous pollutants and are often burned in poorly ventilated conditions. Hence, they are responsible for substantial ill health in the country.
They recommended that efforts to promote cleaner fuels, improved stoves and better ventilation should be given priority wherever they can be effectively introduced. Lessons learned in one country can also be effectively applied in others. Coordinated multi-site research efforts are also needed to specify and quantify the health effects of iap . Although other diseases are also thought to be associated with these exposures, the priority should be given to children and pregnant women.
Ambient air pollution is gaining significance as a major cause of respiratory diseases today. But most of these studies come from developed countries, where a pollutant such as pm 10 (particulate matter less than 10 microns in size) record 60-70 microgramme per cubic metre (g/m 3 ) on average, if not lower. In contrast, in a developing country such as India, the levels are sometimes 10 times higher.
According to N Vichita-Vadakan of the College of Public Health, Chulalongkorn University, Bangkok, Thailand, pm 10 is the primary air pollutant of concern. At levels exceeding just 200 g/m 3 , there are as many as 4,000 to 5,000 premature deaths in Bangkok every year due to short-term exposure to pm 10. For an increase of every 30 g/m 3 there is an increase of 26 per cent in the incidence of respiratory ailments.
Here, too, the risk to children and pregnant women was emphasised. Isabelle Romieu of the Pan-American Health Organisation, Mexico, pointed out that air pollution affects children the most and results in low birth weight due to long-term exposure of pregnant women to particulates and sulphur dioxide. These children are then more susceptible to develop respiratory problems, which aggravate when exposed to diesel exhaust.
Studies conducted in usa show children between eight and nine years of age with four-year exposure to particulates (20-65 g/m 3 ) had decreased lung function. The worst sufferers are children from the poorer sections of society as malnutrition and vitamin deficiency makes them more vulnerable.
John Samet, from the us -based John Hopkins University who has conducted epidemiological studies in 88 cities across usa , says: "Scientific evidence on the link between particulate pollution and mortality and morbidity (diseases and deaths) is strong enough." But whereas in a country like usa a process like setting air quality standards has a very well worked out mechanism, it is yet to develop in India. This is clearly a challenge for India.
According to S R Kamath, retired professor of medicine, Mumbai's kem hospital, studies in Mumbai show that cough, common colds, eye irritation, headache and dermatitis show strong correlation with the ambient levels of sulphur dioxide, nitrogen oxides and total suspended particulate matter. He also added that recent studies reveal that deaths due to nitrogen dioxide and pm 10 are also increasing. A study conducted by J N Pande, head of department (medicine), All India Institute of Medical Sciences, New Delhi, in 1997 and 1998 in the capital also showed that emergency room visits due to asthma, coad and acute coronary events shoot up whenever the ambient air pollution levels go up.
The department of paediatrics and clinical epidemiology unit of the King George's Medical College, Lucknow, reported similar results after studying 664 slum children between one month and four and five years of age.
Scientists also discussed other issues such as malnutrition and exposure to environmental tobacco smoke, asbestos fibres and respiratory illnesses among children. Active and passive smoking is the most important cause of respiratory diseases in the world today, they noted. The draft recommendation also emphasises that no conceivable economic benefit from its production and sale justifies the heavy burden tobacco smoking imposes.
The experts ended the five-day conference with suggestions to improve the future of millions of people, especially children. Some of their recommendations are:
• Although more research needs to be carried especially in developing countries, there is enough evidence from studies elsewhere to warrant immediate action to reduce exposures to many specific pollutants.
• Scientific research should focus on exposure to vulnerable groups such as children, pregnant women and those malnourished. Further health assessment efforts should be undertaken stress on the fact that environment and occupational health interventions can be cost-effective ways to improve health and advance economic growth.
• Agencies responsible for public and workers' health need to develop coordinated activities to effectively deal with polluted environs.
• Effective and sustainable interventions for cleaning up a polluted environment will be best achieved by engaging community and labour groups and the media as well as government agencies and scientific organisations.
• Indian and other developing countries should consider creating national centres of excellence to assess these problems and develop solutions. Such centres should include behavioural scientists and policy analysts so that effective interventions can be designed and implemented.
The immediate priority for these centres should be to foster development of high-quality training programmes needed to bolster the ranks of scientists and others required to address the widespread problems posed by polluted environment in developing countries. Such institutions should develop collaborative relations with similar institutions throughout the world. Advanced techniques of research including genetic sequencing, biomarkers and sophisticated toxicological methods show promise to help better understand some of the worst problems created by high environmental exposures.
“Lung cancer can also be due to occupational exposure”
gregory r wagner , director, division of respiratory disease studies, National Institute for Occupational Safety and Health, Morgantown, USA, speaks to Down To Earth on the complex problems posed by exposure to pollutants
What are the various occupational lung diseases?
Various occupational lung diseases depend on the type of exposure. Most important are silicosis, due to exposure to silica; asbestosis, due to exposure to asbestos; asthma, which in many cases gets worse due to exposure to environmental pollutants; chronic obstructive pulmonary disease ( copd ) and other respiratory infections. Lung cancers can also be occupational and are of great concern.
Are these diseases due to the exposure to environment only or is the genetic make-up also responsible?
The primary issue is environmental exposure. But there are variations among people. “If a child’s lungs are exposed to pollutants, they may never reach their full potential”
It is a matter of degree. Even if you are constitutionally strong but are exposed to higher pollution levels, you are going to suffer. Despite the awareness, why have we not been able to control them?
Incidence of certain diseases is on the rise, while others are declining. The us has been able to reduce silicosis because of stringent standards and increasing awareness levels. But incidence of other diseases, such as asthma, is on the rise because there are about 300 agents that have been confirmed through epidemiological studies and linked with asthma. How does one know whether it is occupational or something else?
Suppose there is an adult who develops asthma later in life, then the workplace is one area that needs to be looked into. Occurrence of asthma also has some genetic component in it. Is it true that occupational lung diseases are more hazardous for children than adults?
Certainly. It is a fact that people’s lungs keep growing until the age of 25 years. If a child’s lungs are exposed to certain pollutants, there is a possibility that they will never grow to their full potential. Thus their lung function goes down. I think this is an area of major concern. Exposing children and even young adults to pollutants hampers the growth of their lungs and exposes them to future infections.
Out of all these occupational lung diseases, which is the most dangerous?
This is very difficult to pinpoint. We have not even talked about whole range of lung cancers. Cancers due to occupational exposure are extremely dangerous. It also depends, among other things, on the kind and extent of exposure and the number of people getting exposed. For instance, among asthma and lung cancer, even if we have less incidence of lung cancer than asthma, we still know that in 90 per cent of the cases lung cancer is fatal.
Do occupational diseases differ in developing and developed countries?
There are differences in degree. For instance, in usa , it is now rare to find silicosis deaths. In India, there are cases where people are exposed to pollutants, develop a disease and die within five years of exposure. So here the extent of unprotected exposure is high. Also the chances of getting silicosis are high in a population that has high incidence of tuberculosis.
Does this mean that factors like socioeconomic and financial status are also responsible? Don’t you think this is like getting trapped in a vicious cycle especially in developing countries India?
I would not call it vicious cycle but a complex system. There cannot be a single answer. For instance, it does not matter if you only control automobile emissions in urban areas, when one has high levels of asbestos exposure at the workplace. I think there is a need for a comprehensive multiple strategy that recognises these problems that are very resistant to simple solutions. We need to recognise factors from the personal, occupational, political and economic environment and then tackle the problem from all fronts. It is a complex problem that does not respond to simplistic solutions.
How do you think globalisation will affect occupational lung diseases?
Being in the area of public health, it is important that we have some optimism that things will move towards better. I hope that there will be exportation of knowledge, exportation of successful experiments in prevention, information that will help developing countries jump over the steps of learning and can gain experience from other countries and adapt control measures.
There are some fears as well. In many developed countries, the problems have been eliminated but the hazardous technology has been exported to the developing countries where restrictions are not very strict.