I know that this is probably old news, seeing as it was reported in March 2009 but according to Iranian Scientists, drinking large quantities of hot tea could be linked to an increased risk of oesophageal cancer. Notably, this is concerning tea which is drunk at 70c or higher and the risk is lessened when milk is added to tea, thus cooling the overall temperature. The article said,
"Drinking a cup of tea in under two minutes straight after it was poured was associated with a five-fold higher risk of cancer compared with drinking tea four or more minutes after being poured..."
Furthermore, a doctor commenting on this issue suggested that tea drinkers simply wait until their tea goes from 'scalding' to 'tolerable' before drinking it. In addition, it was said that in Iranian cultures, there is more of a tradition of drinking tea at such a high temperature and that in the UK, as 'we' tend to add milk to our tea, this cools the tea enough for it not to be risky.