Possible cancer risks associated with eating food cooked over a flame

Is it risky to eat phulkas or rotis that are cooked on the open flame of a gas or charcoal stove? Is this made worse by the chemicals present in gas flames? I started reading up about this because published literature shows a link between cooking food by grilling and the incidence of cancer. Possibly cancer causing substances such as Heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs) are formed when meat, including beef, pork, fish, or poultry, is cooked using high-temperature methods, such as pan frying or grilling directly over an open flame.

http://www.cancer.gov/cancertopics/causes-prevention/risk/diet/cooked-meats-fact-sheet

A research paper reports a finding that those with higher consumption of hamburgers were 79% more likely to get prostate cancer. 

Meat consumption, cooking practices, meat mutagens, and risk of prostate cancer

Are there similar risks to vegetarians? A substance named acrylamide has been found to cause cancer in rats, and could therefore be possibly harmful to humans as well. High-temperature cooking such as frying, baking, or broiling produces acrylamide. Boiling and microwaving are less likely to do so:

http://www.cancer.gov/cancertopics/causes-prevention/risk/diet/acrylamide-fact-sheet

The document linked to the URL below quotes Dr Paul Brent, the chief scientist of Food Standards Australia and New Zealand (FSANZ) on the topic of acrylamide and cancer. It also says that acrylamide is found in burnt toast.

http://www.abc.net.au/health/talkinghealth/factbuster/stories/2011/01/25/3093063.htm

I could not find any peer-reviewed publication reporting on possible links between cooking flat bread such as phulkas, rotis and naans in contact with a flame. If you wish to investigate the existence of any such link, there seem to be at least two different projects that are attractive. One is to use the Ames test to verify if the burnt spots in flame-cooked foods contain any mutagenic chemicals, possibly followed by carcinogen assays on mice and rats. The other project would be to do a questionnaire based survey of cancer patients from India, or in some other country in South Asia, to look for statistical evidence of a link between fairly frequent consumption of flame-cooked food and the occurrence of specific types of cancer. It would be significant if the test is conducted over a population of cancer patients having different types of cancer and if the statistics point to a link with a specific type of cancer, say cancer of the digestive system. 

Questionnaire based surveys do not usually establish any causative link, but provide significant information that may lead to further research. An investigation covering both the projects mentioned above could lead to very significant conclusions.

Only a fraction of Indians smoke cigarettes or its local version, beedies, while a much larger fraction probably consumes flame-cooked food. The number of deaths due to smoking in India is said to have been estimated by the World Health Organization to be 900,000/year in 2009.
Crisis in India: Smoking Expected to Kill 1 Million People Annually by 2010
Information presented above gives us a clue that the scientific investigations proposed could be of considerable value to Indians as a whole. I hope that epidemiologists would look into this question soon.

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