The impact of increasing pollution on cancer: An interview with Dr. Krishnatreya – Part I

A recent report by United Nations predicts that in India, by 2020 there will be a 500% increase in e-waste generation compared to 2007.

Dr. Manigreeva Krishnatreya is the first HealthTrooper from the state of Assam and he deliberates at length on various topics ranging from pollution to cancer epidemiology in India. 

In the first of a 4-part series, Dr. Krishnatreya shares his thoughts on the impact of pollution on population health in India. In this insightful interview, Dr. Krishnatreya presents the toxic effects of industrial pollutants and also discusses another much ignored pollutant – e-waste. He also raises an alarm on the impending health crisis and asks that urgent action be taken to curb the crisis.

Otolaryngologist by training, Dr. Krishnatreya is affiliated with Dr. Bhubaneswar Borooah Cancer Institute in Guwahati, Assam as a cancer epidemiologist. Dr. Krishnatreya is also General Secretary of the Cancer Research Foundation, a not for profit organization that addresses the entire gamut from cancer awareness to diagnosis and treatment, specially in the north east of India where the incidence of cancer is highest in the country.   He is also an avid columnist, cancer researcher and former cricketer. 

In your recent article titled “Cancer Trends and Burden in India, published in The Lancet Oncology in December 2018, you discuss two main types of environmental pollutants that are linked to increased burden of cancer seen in India – effluent waste and air pollution:      The following questions are centered around these two pollutants.

a. What are the sources of effluents that are causing increased toxicity in our rivers and tributaries?

The major source of effluents polluting our rivers and tributaries are industries manufacturing chemicals, bulk drugs and pharmaceuticals, dye and dye intermediates, and textiles. Lack of stringent regulatory environment, poor effluent treatment infrastructure and insufficient financial incentives to adopt water-saving technologies for industries have contributed to water pollution in the country.

b. What are the kinds of contamination that are seen in these effluents?

There is a wide range of chemicals and toxins in polluted water, form organic to in-organic compounds. However, arsenic and other heavy metals, disinfection byproducts, and nitrate compounds accentuate cancer risk in vulnerable population. Chlorine interacts with organic materials in water to form a mixture of disinfection byproducts such as trihalomethanes like chloroforms and nitrate contamination of water is seen from agricultural products like pesticides. Nitrates when ingested can lead to the endogenous formation of N-nitroso compounds, which are potent carcinogens.

c. What are the steps taken by the government to reduce these wastes?

In the year 1992, Central Pollution Control Board (CPCB) of India launched water pollution control program for industries. Further in the year 2015, CPCB laid guidelines for implementing liabilities and penalties for environmental damages due to handling and disposal of hazardous waste. Compensations that are envisaged in the guidelines were loss of life, property, yield, crop, and treatment costs towards human health impacts. The CPCB imposes immediate response one-time liability of around 12,000 € for non-compliance by industries. Recent initiatives by the National Green Tribunal has stopped the farmers to cultivate vegetables on the land along the Yamuna bank because soil contained heavy metals and farmers are allowed to grow only non-edible crops.

Apart from Industrial waste, you discuss e-waste – e-waste is a new entry into our ecosystem. Do we have adequate agencies and measures to dispose e-waste?

Presently, the usage of electrical and electronic equipment (EEE) like computers, cell phones, televisions, refrigerators, air conditioners, DVDs, iPods, copiers, and fax machines is very common and usage of electronic products is rising exponentially, and hence, the amount of electrical and electronic waste (e-waste) produced each day is equally growing enormously around the world and in our country as well. A recent report by United Nations predicts that in India, by 2020 there will be a 500% increase in e-waste generation compared to 2007. However, primitive recycling techniques such as burning cables may result in direct contact with harmful materials such as lead, cadmium, chromium, brominated flame retardants or polychlorinated biphenyls (PCBs). Around 80% of old electronic items are dumped in storage because of the uncertainty of how to manage these materials. In India, Ministry of Environment and Forests is the apex body concerning e-waste pollution. The correct techniques of e-waste disposal are incineration and deep land filling in non-human inhabited areas.

What can we as citizens do to reduce e-waste?

Many of these electronic items can be reused, refurbished, or recycled but unfortunately they are not, thus making the electronic discards as one of the fastest growing segments of world’s waste stream. Presently cell phones and computers are causing the biggest problem because they are replaced most often. As a citizen we can reduce, recycle, and safely remove these electronic items from our ecosystem.

Do we have enough awareness programs to discuss the toxicities associated with e-waste?

Unfortunately, we do not have enough awareness programs to discuss e-waste and its associated toxicities. The Government must immediately create the necessary awareness about e-waste among the public as it is done for tobacco and other health related programs.

Air pollution is the second environmental pollutant that can cause cancer as discussed in your article (Lancet 2018). Again what are the sources of air pollution and what are the main carcinogens?

The Air (Prevention and Control of Pollution) Act was enacted in 1981 and amended in 1987 to provide for the prevention, control and abatement of air pollution in India. The revised guideline (2009) for the annual safety concentration level of ambient particulate matter (PM) of less than 2.5 microns set by ministry of Environment, Forests and Climate in industrial, rural, and ecologically sensitive regions is 40 µg/m3. Now, it is a matter of grave concern that 11 cities of India out of 12 cities globally have the worst air pollution levels, as per the World Health Organization’s World Global Ambient Air Quality Database. The average ambient air pollution in Indian cities is two to three times higher than safety level. So, it is just a matter of time that India’s cities are set to become the lung cancer capitals of the World. The main sources of air pollution in the country are industrial and vehicular emissions. Other than these, household air pollution due to cooking and heating households using solid fuels (i.e., wood, charcoal, coal, dung, crop wastes) on open fires or traditional stoves result in exposure to carcinogens. The carcinogens include PM 2.5, nitrous oxide, Sulphur dioxide, and carbon particles. Now there is enough epidemiologic and experimental evidence of the genotoxic and mutagenic effects of air pollution on human DNA, which is key cancer driver.

What are the factors that affect the most polluted cities – is it geographical location, type of industry or socio-political reasons?

The key factors for air pollution in the country is geographical where the pace of development is rapid in nature. For example, most of the top polluted cities are economically developing faster compared to economically lesser developed areas like Arunachal Pradesh in the North East India, which is less polluted. Another could be social behavior and densely populated areas which are most likely to affected more by air pollution.

What are the initiatives taken by the government to reduce air pollution? Is it working?

Air pollution is a ticking time bomb. The government needs to develop an action plan (such as monitoring rising air pollution levels) to meet clean air targets on an urgent scale. Ongoing initiatives by the Government to curb air pollution is not working. India needs to step up its efforts to avert an impending public health crisis.

What kind of epidemiological studies are being conducted to shed light on environmental pollutants and cancer?

So far in India, there are no large scale ecological studies to shed light on environmental pollution and growing cancer risk. We, at the Dr B. Borooah Cancer Institute, Guwahati along with the Center for Cancer Epidemiology, Tata Memorial Center in Mumbai and the Public Health Foundation of India have begun this process.

What type of cancers are typically caused by industrial effluents and by air pollution?

Potentially, almost all types of cancers can be attributed to air and water pollution considering the genotoxic and mutagenic effect of pollutants. But, direct and sustained exposure like that occurs in skin, urinary bladder, gall bladder, lungs, and stomach are most commonly affected due to air and water pollution.

Follow Dr. Manigreeva on twitter @manigreeva


Krishnatreya, M, “Cancer trends and burden in India” The Lancet Oncology Volume 19 (2018), Volume:19, Page: e660

Thanks Dr. Manigreeva for sharing your thoughts. 

Disclaimer: Interviews are published unedited or with minimal changes.

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