LETTERS

Can THC occur in hemp seed oil ?

To the editors,

     We have been approached by a firm which exports hemp seed oil from Hungary, who told us that foreign police or customs officials using dogs had stopped one of their consignments as it was suspected of containing THC.  They sent us a small sample of the consignment, with the request that we investigate the validity of the suspicion, since literature data indicate that hemp seed oil should not contain THC.  Our working hypothesis was that the THC content could only be due to contamination of the oil with the seed tunic [bract].

1)  The cannabinoid content of our own samples of 2 year old hemp seed oil was determined.
2)  The THC content of 99 % pure Kompolti oil samples containing leaf and tunic debris and, as a control, that of oil from a hemp variety with a high THC content (of the hashish type) were also determined.
3)  Determinations were made of the THC content of hemp seed oil from the Kompolti and high THC control varieties, purified to 99.9 % and further cleaned manually.
4)  Finally, the THC content of the sample sent by the firm was determined.

     Our own hemp seed oil had a THC content of 0.025 %, which even we did not know.  Neither the Kompolti hemp seed oil purified mechanically to 99 %, nor the manually purified oil of Kompolti or of the control variety with high hashish content had a THC content which could be demonstrated chromatographically.  The THC content of oil pressed by ourselves mechanically from the variety with high hashish content was 0.375 %.
     It should be noted here that, due its extremely low THC content, the THC content of the oil sent by the firm can only be determined by thin-layer chromatography or gas chromatography after special preparation.
     Since hemp seed oil and oils prepared from seeds not cleaned of leaf debris and tunics were found to have a cannabinoid content demonstrable by thin layer chromatography and gas chromatography (CBD was also identified), while oil prepared from seeds purified from the tepal (tunic) had none, it can be concluded that this cannabinoid content entered the oil in the course of the technological process of oil manufacturing.  It can only originate from tunic and leaf debris.  Consequently, hemp seed oil should only be pressed from seeds of eating quality, i.e. of at least 99.9 % purity, in which case there can be no possible occurrence of THC in the oil.  It should be noted that even the 0.375 % THC content found in the variety with the highest THC content is completely innocuous, while that of oil pressed from purified and unpurified seeds of the other varieties was entirely negligible.