The Drug Awareness Warning Network Annual Report, published by the US federal government contains a statistical compilation of all drug deaths which occur in the United States. According to this report, there has never been a death recorded from the use of marijuana by natural causes. Unlike opiates, barbiturates or amphetamines, there seems to be little risk from the use of large amounts of marijuana. When a person smokes too much they feel very tired and lie down. When people swallow large amounts of hashish, occasionally they get sick to their stomach.
http://www.drug-overdose.com/marijuana.htm
The info is also readily verfiable through many many other sources. Have yourself a field day.