|"To summarise there are a number of explanations which may account for the identification of cocaine, THC and nicotine in Egyptian mummies. The identification of THC is not considered unusual due to the local prevalence of C. sativa in the Middle East. In addition we know that the Egyptians utilised hemp to make ropes and THC can also be produced by reactions that occur when burning incense.
The presence of nicotine can be accounted for, as nicotine is present in small amounts in many plants commonly used as food. It is therefore fairly common for human remains to contain residual amounts of nicotine. The use of tobacco based insecticide sprays during the nineteenth century may account for the discovery of tobacco leaves in the mummy of Ramses II as well as for the identification of higher levels of nicotine in mummies that have been kept in museums over long periods of time. Amongst the resins and plant oils used by Ancient Egyptian embalmers there may have been plants, which contained significant amounts of nicotine. This contention is supported by Balabanova's discovery that the proportion of cotinine to nicotine in artificially mummified Egyptian remains is significantly less (3.4% vs 40.3%) than in naturally mummified remains. 
The discovery of cocaine in Egyptian mummies is however not so easy to account for as no direct evidence unequivocally supports any particular contention. Although it is possible that experimental error or modern fake mummies could account for these results both of these explanations are highly unlikely. The authenticity of the mummies has been confirmed by independent experts, the methods employed by Balabanova are reliable and are also used by forensic departments around the world. In addition Balabanova's results were confirmed by GC/MS at four different laboratories.
However, there is no reason to suppose that the cocaine identified by Balabanova in Egyptian mummies originated in South America because there are cocaine producing Erythroxylum species, which are indigenous to regions of Africa, India and Asia. The hypothesis that trade routes existed between Egypt and South America simply cannot be substantiated with any corroborative evidence and it would be incredibly unlikely that if links had existed that trade would have been restricted to plants that could be used as drugs. Furthermore, the use of such drugs by indigenous cultures is often associated with their religious beliefs and drugs are often revered as gifts from the gods. It would therefore be unusual for a culture to use particular drugs and to not make reference to their effects in their texts and legends.
Although Thor Heyerdahl established it is theoretically possible that Egyptian reed boats could survive a single trans-Atlantic journey, it beggars belief that such an exhaustive journey would be repeated over thousands of years without mention in any surviving Egyptian texts. Additionally, Mesoamerican scholars have thoroughly refuted pre-Columbian African "influences" on New World cultures. 
It is certainly feasible that plants containing cocaine were present in Ancient Egypt as there are examples of flora known to have grown there which subsequently became extinct, although some have been reintroduced. These include: both the blue and white water lilies, the "Ished" Tree (modern persea); a sacred tree on whose leaves the name of Pharaoh was inscribed to guarantee him a long life, the carob (Ceratonia siliqua), the Christ's Thorn (Ziziphus spina) and the Stone Pine (Pinus pinea). If the heraldic flower of the South was a real plant (and some believe that it was invented), the most likely candidate is the so-called Madonna lily (Lilium candidum).
Cocaine containing plants, such as E. monogynum, which is present in India, could have been acquired by the ancient Egyptians or in neighbouring areas which the Egyptians traded with.