Over the centuries and over the decades the festive spirit of holi slowly deteriorated; it has been hugely corrupted and misused by people. I greatly feel this has been due to an excessively bad influence of bolloywood movies of the 1960s and the 1970s. The Bachan era (Don) bought in a lot of celebrity status to this festival and corrupted it with open indulgence in consumption of narcotics, alcohol and objectionable sexual opportunism and exhibitionism.
Bhang is a very intoxicating drink and is the official drink of Holi. Bhang escalates the spirit of holi - and believed to be a festival which does not recognise any restrictions. Typically buds and leaves of Indian Hemp plant called Cannabis Sativa(Charas/Grass/Hashish) are squashed and ground into a green paste. This is then added to milk, ghee (reduced butter), and spices to create a drink. The drink is accompanied with pakoras, barfi, jalebis, lassi, and kulfi all combined to be called as a Holi Lunch. Cultivation of Cannabis is illegal in many parts of the world including India where its abundantly grown, and there is only a mild social stigma attached to it compared to smoking marijuana outright. The psycho-active component of cannabis preparations is delta 9-TetraHydroCannabinol and not DeHydroCrotinin. Delta 9-THC as it is referred to is prepared from the Indian hemp plant cannabis sativa, a hardy, aromatic annual herb. cannabis is probably the most commonly used illicit drug in the world. The cannabis herb contains other psychoactive components too, but Delta 9-THC is most abundant. The most potent forms of cannabis come from the flowering tops of the plants or from the dried, black-brown, resinous exudate from the leaves referred to as hashish or charas. The stem and leaves of the plant when cut, dried and chopped are then smoked in cigarettes commonly called as "Joints" "Grass" or mixed with milk, sweetmeats and cakes to make "Bhang".
As far as health effects go, Cannabis smoke is a potential cause of Cancer because of presence of similar if not more carcinogenic substances as cigarette smoke. It can also lead to bronchitis. Far more significant are the psychological effects of cannabis. Chronic Cannabis use may precipitate Psychosis in vulnerable individuals and long-term cannabis use may exert subtle effects on memory, attention and the integration of complex information leading to insanity.
It is important that our youth are sensitised to the message that be it "Bhang" or "Charas" or "Grass", they all contain Delta 9-THC in different potencies. And as with all poisons, there is no such thing as too little of it. People might ignore it for a day; people might ignore these facts for pleasure; people might overlook these facts for forgetting pain and displeasure; but in all it hits back some time in life.
I also want to remind that in this festive mood, it is easy for everyone to forget that there is something known as the Narcotic Drugs and Psychotropic Substances (NDPS) Act in India. Few Indians realise how powerful this act is, with potential for abuse. For example, someone arrested under this act is presumed guilty until proven innocent, which is against normal jurisprudence. Bail can be granted only after a court hearing. Given the Indian judicial system, this can take a few months to many years. Its in all good that one stays away and discourage usage of Bhang or Joints or to that extent alcohol to the fullest extent.
But though Bhang is derived from Cannabis, and is listed under Narcotic substance source; Bhang does not come under Narcotic Drugs and Psychotropic Substances (NDPS) Act. Potency scale of products(2% to 20%) from Cannabis Bhang
Sources - Web and Paper on Potency of Cannibies