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Kolkata has the highest number of lung cancer cases worldwide

By Rashme Sehgal

Seventy per cent of Kolkata's citizens suffer some form of respiratory disease. Delhi is not far behind at 68%, reports a new study on air pollution by the Chittaranjan National Cancer Institute, West Bengal's department of environment and the Central Pollution Board, Delhi

 Kolkata has the highest number of people suffering from lung cancer in the world. This is because it is one of the most polluted cities in the world.

Lung cancer cases, as also other air pollution-related health problems including haematological abnormalities, impaired liver function, genetic changes and neurobehavioural problems, were found to be most prevalent amongst those categories of workers exposed to high levels of vehicular emission. These include roadside hawkers, traffic policemen and taxi and auto drivers.

These are some of the startling findings of a comprehensive study on the respiratory and systemic effects of air pollution on residents of Kolkata and Delhi, conducted by the Chittaranjan National Cancer Institute in Kolkata.

Dr Twisha Lahiri who conducted the survey with financial support from West Bengal's department of environment and the Central Pollution Board, Delhi, believes the situation in Delhi is only marginally better than it is in Kolkata. Lahiri says: "Seventy per cent of the public in Kolkata suffer from respiratory symptoms including cough, sinus, wheezing breath, upper and lower respiratory symptoms. In Delhi, the figure is 68%, which is pretty close."

Lahiri blames the problem on the huge increase in vehicular traffic. The situation is further compounded in Kolkata with its narrow streets, poorly maintained vehicles and the use of adulterated fuel. Similarly, in Delhi, 50% of pollution levels affecting the national ambient air quality standard in the capital is caused by vehicular emissions.

The survey sampled around 2,000 respondents from different occupational and socio-economic backgrounds in both Delhi and Kolkata. All the respondents were non-smokers. The team of researchers also sampled 300 people from the Sunderban islands in the Gangetic delta of West Bengal where air pollution levels are extremely low. Needless to say, respiratory illnesses are the lowest in the Sunderbans.

Both adults and children were examined separately in the study. Respiratory symptoms and illness data were collected through a questionnaire, a survey and clinical examinations.

The survey also studied the impact of air pollution on 3,500 school children in the age-group 8-16 years in Delhi, 3,200 children in Kolkata and another 12,000 children from different districts in rural West Bengal who are not exposed to high levels of air pollution.

According to Lahiri, the difference in respiratory disorders in the cities and in the Sunderbans is 60:24.

The study found that the lung function of 46% of adults in Delhi, 56% in Kolkata and 21% in the Sunderbans were impaired. In rural areas, the use of bio-fuel causes respiratory problems.

Amongst kids, the figures for respiratory ailments are equally high. Sixty-four per cent of children in Delhi and 65% in Kolkata suffer from different respiratory ailments, against 24% in rural West Bengal.

The sputum of people from Kolkata and Delhi saw an increase in inflammatory cells like neutrophils, eosinophils and lymphocytes. The number of alvelar macrophages (AM) had also risen. These are the lungs' first line of defence against inhaled pollutants. Lahiri points out: "Compared to rural India, which has 3.4 AM in rural West Bengal, Kolkatans and Delhites have a mean of 20.6 and 15 AM respectively."

What is worse, doctors maintain, is that enhanced cellular activity produces tissue-damaging enzymes which trigger lung inflammation and lung damage. An increase in iron-laden macrophages in the sputum also increases covert haemorrhaging within the lungs.

These views are shared by experts across the globe. Japanese researchers also point out a marked co-relation between increasing use of diesel and adulterated fuel and cases of lung cancer. Hitomi Suzuki, a chemist at Kyoto University who led the study, that discovered that diesel exhaust could be carcinogenic. He went on to warn that it was responsible for the increasing number of lung cancer cases in cities.

Suzuki, who recently attended a seminar in the Indian capital called 'The Leapfrog Factor -- Towards Clean Air in Asian Cities', organised by the Centre for Science and Environment (CSE), warns: "I personally believe that the recent increase in the number of lung cancer patients in vehicle congested areas is closely linked with respirable carcinogens being emitted by truck engines and other diesel exhaust vehicles."

American Michael Walsh, international vehicle technology and fuel quality expert, points out that both regulators and civil society groups in Asia need to do a 'technological leapfrog' in order to improve the quality of air in the region.

Having a responsive government helps. When air pollution levels in Hong Kong reached the highest-ever levels on March 29, 2000, there was a huge public outcry. The government responded swiftly by instituting a task force to implement measures to control vehicular emissions, to monitor the effectiveness of these measures and to take further action based on the impact. The task force set a target of reducing particulate emissions by 80% and nitrogen oxide emissions by 30% by the end of 2005.

Kong Ha, senior officer, motor vehicle emissions, Hong Kong environment protection department, stated at the seminar that Hong Kong was the first city in the world to introduce ultra-low-sulphur diesel with a sulphur content of 50 parts per million, from 2000. In addition, new petrol cars were asked to meet Euro 3 standards from 2001. India is planning to introduce these from 2005.

Sunita Narain, director, CSE, quotes a recent study to show how small particulate emissions go deep into an individual. Schools located in high-traffic zones where there are frequent traffic jams and poorly-maintained vehicles have accelerated breathing disorders among children.

Lahiri wants a similar study to be extended to all the major cities in the country. Describing air pollution as "slow murder" she maintains that the setting up of stringent emission standards and the establishment of a credible inspection and maintenance programme are necessary steps to improve air pollution levels.

The findings of the Chittaranjan National Cancer Institute study were quoted by the Supreme Court when it gave its landmark judgement in favour of CNG.

(Rashme Sehgal is a Delhi-based independent journalist)

InfoChange News & Features, May 2004