Personal tools

Document Actions

The filtering effects of various household fabrics on the pollen content of hash oil (cannabis extract)

by admin last modified 2008-03-25 01:40 PM

Horrocks M, Bedford KR, Morgan-Smith RK. 1997. Journal of Forensic Sciences 42, 256-259.


Hash oil samples were analyzed for pollen before and after filtration through 12 different household fabrics, to determine to what extent such samples can be shown to have come from the same source despite having undergone these different treatments. Unfiltered hash oil samples extracted from the same batch of cannabis leaf material showed similar pollen values. An unstirred portion of the extraction solution showed differences in some pollen values to those of stirred samples, suggesting differential rates of pollen settling. However, the presence of some of the same uncommon pollen types in unstirred and stirred samples suggests a common source. Of 12 filter fabrics, ten (a bath towel, two tea towels, a bedsheet, two pillowcases, three stockings and a t-shirt) had a minor effect on the pollen content of the hash oil by slightly reducing the frequencies of some of the larger sized pollen types. Only two of the fabrics had a major effect on the pollen content of the hash oil. The nappy markedly reduced the proportion of the larger sized pollen types resulting in a marked increase in the proportion of some smaller pollen types whereas the calico filtered out virtually all pollen.

Illicit hash oil samples recovered from different people or places may therefore in many cases be compared to determine a common source despite samples from the same batch having undergone different filtration treatments and despite differential settling rates of pollen. Also, hash oil samples may be compared to samples of untreated cannabis leaf material to establish a common source.


Forensic science, pollen analysis, palynology, substance abuse, cannabis, hash oil.

Copyright © 2004 Microfossil Research Ltd
Website designed by Enterprise Web Services NZ Ltd
Website hosted and maintained by Winterhouse Consulting Ltd

Powered by Plone