Rick Simpson and his cannabis extract, known as Rick Simpson Oil or by the abbreviation RSO, are household names wherever there is awareness of cancer and the need to cure it.  Rick’s movie “Run from the Cure” has been distributed around the world and has contributed enormously to the awareness of the efficacy of the substances contained within cannabis extracts in fighting cancer and promoting the general well-being of cancer sufferers – as well as those who find themselves dealing with many other diseases and conditions.
Solvent extraction and the “Rick Simpson oil for sale” phenomenon
While Rick should most definitely be commended for his efforts, which have resulted in bringing the healing properties of the cannabis plant to the attention of the public at large, it should be well understood that there are some serious problems with what Rick puts out there as information. 
First off you will find that he recommends making your own oil at home. And he recommends using naphtha as a solvent to do it with . . . yet a quick Wikipedia search will inform you that naphtha is not an accurate description of any one substance, but rather a general term that describes a variety of substances that are mostly derived from petrochemical sources, and are all highly toxic and carcinogenic in themselves.  Rick is on record as having stated that the toxicity of the residues of naphtha left behind in the extract is negated by the positive properties of the oil itself.  (the “light naptha” that Rick advises is the “correct one” to use is also known as benzene, which is classed as an A1 Carcinogen).