History and uses of hemp - The Hempcrete Topic: Designing and Building with Hemp-lime - page 8

the period from the late eighteenth to late nineteenth centuries. This, combined with the
relatively slow growth and development of the town since the beginning of the twentieth
century, means that the history of the British hemp industry is preserved in the buildings
of Bridport and West Bay today.
Another of the main uses of the plant throughout history has been in religious ceremonies,
and more recently as a recreational drug, due to its relaxing and mildly psychoactive effect.
This use of cannabis, or marijuana, as a narcotic eventually led to the growing and posses-
sion of the hemp plant being outlawed in most Western countries in the early decades of the
twentieth century. The prohibition of cannabis remains in force widely today, in the West at
least, with some notable exceptions, such as the Netherlands, which was the first Western
country to introduce an official policy of tolerating the possession of small amounts of the
drug without prosecution. Other countries, including Spain, Portugal, the Czech Republic
and Switzerland, have followed its example in recent years by decriminalizing the posses-
sion and use of small amounts of the drug. In November 2012 the US states of Washington
and Colorado voted to legalize cannabis, although it is still unclear how this will work in
practice, since the drug continues to be illegal under US Federal law, which of course has
jurisdiction in both of these states.
Rediscovering hemp
The unfortunate side-effect of the prohibition of the drug cannabis has of course been the
blanket banning of cultivation of all forms of the hemp plant, and its consequent unavailab-
ility to Western societies for its many non-drug-related uses. The cultivation of hemp in the
UK was outlawed in 1928. Since the 1930s, much effort has gone into developing cultivars
of the plant which contain very little THC. The success of this endeavour means that, for
some decades now, an industrial hemp plant with little or no THC content has been widely
available.
The term 'industrial hemp' refers to cultivars of Cannabis sativa which have been bred
to have a THC content of 0.2 per cent or less. These cultivars have been legal to grow in
the UK since 1993, and in Canada since 1995. The THC content in a drug-producing plant
would be 10-15 per cent or higher, depending on the strain and method of cultivation. Be-
cause the industrial hemp plant looks identical to the drug-producing strains, however, the
growing of industrial hemp in the UK requires a special licence from the government.