New Delhi, Sept. 14: A recent study by US scientists warns that mosquito coils emit smoke that could cause cancer among people exposed to the fumes for a long period.

The research, conducted by the University of California and published in the journal of environmental health perspectives, was based on a study of 50 samples of coils. The samples contained S-2 or Octachlorodipropyl, banned for sale in the US.

“It is possible the coils are exposing the users to Bischloromethyl Ether, also known as BCME, a potent lung carcinogen. The exposure could be high if the coils are used overnight, as they often are,” the study underlines.

“We do not know if mosquito coils cause cancer but we do know they can cause a lot of health hazards, the most primary being breathing difficulty, particularly for people with asthma,” said Dr B.K. Sharma, a general physician in Delhi.

In India, two million people are afflicted by malaria every year. Apart from malaria, mosquitoes are carriers of killer diseases like encephalitis and dengue.

Scores of people died of Japanese Encephalitis in Andhra Pradesh recently.

It is, therefore, virtually impossible for people not to use one or another mosquito repellent. More so, because the surroundings often have stagnant water or open drains that are breeding grounds for mosquitoes.

What is of concern is that it is not mosquito coils alone that are harmful to health — researches both in India and abroad have shown that almost all mosquito repellents have hazardous side-effects.

A study by the Indian Academy of Sciences, a part of the Indian Council for Medical Research, shows that almost all repellents use synthetic pyrethroids, that is, Diethyl Toluimide. The market for mosquito repellents — coils, mats, lotions and vaporisers — growing annually at 7 to 10 per cent, is about Rs 500-600 crore.

Earlier, the Malaria Research Centre had carried out a survey in nine states and revealed that “ mosquito repellents widely used in the country are harmful to health”.

The result of the survey revealed that 11.8 per cent users of Diethyl Toluimide, cutting across all age groups, complained of toxic effects.

The most common complaint was breathing difficulty, followed by irritation in the eye, headache and skin reaction. Two persons said they developed asthma after using mosquito repellents.

Researchers said the side-effects might not appear immediately, but do surface over time. Doctors recommend safe alternatives like mosquito nets, neem cream made of neem oil and coconut or mustard oil.

Kochi in Kerala, where the problem is endemic, has carried out an experiment to kill mosquitoes when they are at the larvae stage.

The Kochi corporation increased the salinity of water in canals and stagnant pools — major breeding grounds. The experiment was successful as it killed the larvae in the breeding ground itself.