§ Mr. FlynnTo ask the Secretary of State for the Home Department (1) if tests on prisoners to check for illegal drug use will include checks simultaneously for cannabis, heroin and cocaine; [32749]
390W(2) what evidence he has of prisoners changing from cannabis use to heroin use to avoid detection in present drugs surveillance tests; [32750]
(3) what is his calculation of the length of time residues of (a) alcohol, (b) cannabis, (c) heroin and (d) cocaine can be detected in the human body. [32751]
§ Miss WiddecombeResponsibility for these matters has been delegated to the Director General of the Prison Service, who has been asked to arrange for a reply to be given.
Letter from Derek Lewis to Mr. Paul Flynn, dated 10 July 1995:
The Home Secretary has asked me to reply to your recent Questions about the drug testing programme in prisons.All mandatory drug tests include simultaneous checks for cannabis, heroin and cocaine.There is no evidence from the initial phase of implementation of mandatory drug testing that prisoners are changing from cannabis to heroin use to avoid detection. We are aware that heavy users of cannabis may retain the drug in their bodies for longer than light users of cannabis or users of harder drugs such as heroin. This has been taken into account in the development of the drug testing policy and we are taking a number of precautions to ensure that prisoners are not encouraged to move from cannabis to harder drugs in the mistaken belief that they are more likely to escape detection.The period over which residues of different drugs remain detectable within the body depends not only on the drug type, but also on the metabolism and physical make-up of the individual and the frequency of and amount of drug taken. The detection period will also depend on the detection threshold set for the particular test.The attached table provides estimates on drug retention. The figures are based on the period of time that a drug remains detectable when a urine sample is used as the basis for the drug test.
Drug type Typical maximun detection period Alcohol1 12 to 24 hours Cocaine 2 to 4 days Cannabis2 Single use (once a week) 1 to 4 days Moderate use (2 to 4 times a week) 2 to 7 days Heavy use (daily use) 7 to 14 days Chronic use (extreme daily use) up to 30 days Opiates (including heroin) 2 to 4 days 1 Tests for alcohol are not part of the Prison Service mandatory drug testing programme which covers controlled drugs only. 2 The retention of cannabis in the body is highly dependent on the amount of the drug taken and the frequency of use; far more so than for other drug-types. For this reason a number of different "typical" scenarios have been provided in the table.