Use of the illegal drug named Ecstasy MDMA () has increased alarmingly in Britain over the last few years, and in 1992 the British Medical Journal claimed that at least seven deaths and many severe adverse reactions have followed its use as a dance drug. 14 deaths have so far been attributed to the drug in Britain although it is possible that other drugs contributed to some of those deaths. While it is true that all drugs by their very nature change the way in which the body reacts to its environment and are therefore potentially erous, it is still unclear whether casual use of Ecstasy is as erous as authorities believe. What is certain is that the drug causes distinct changes to the body which, unless understood, may lead to fatal complications (并发症) in certain circumstances. In almost all cases of MDMA related deaths in Britain, overheating of the body and inadequate replacement of fluids have been noted as the primary causes of death. Perhaps the most ing (确凿的) evidence urging against the use of Ecstasy is that it is undoubtedly an addictive (成瘾的) substance, but one that quickly loses its ability to affect the mind, while it increases its effect upon the body. Yet, unlike the classic addictive drugs, Ecstasy does not produce physical withdrawal symptoms. In fact, because one becomes quickly tolerant of its effect on the mind, it is necessary to give up its use for a while in order to experience again its full effect. Any substance which produces such a strong effect on the user should be treated with appropriate respect and care. 1. What is the main topic of this passage?