Examination of Firearms Review: 2007 to 2010 - Interpol

quantitation of common drugs of abuse in oral fluid, collected with Quantasil
oral fluid collection kits, was reported with LODs/LOQs being 2-10 ng/mL [41].
A confirmational analysis of drugs, including morphine, cocaine,
benzoylecgonine, and amphetamines in oral fluid by LC-MS was also reported.
300 µL of oral fluid is required for the testing, with LODs of 0.5 – 1 ng/mL [33].
That the window of detection of drugs in oral fluid reflects the corresponding
window in blood suggests that oral fluid is a specimen of choice for roadside
testing. However, oral fluid/blood ratios vary from drug to drug, from person to
person, and even intra-individually, posing challenges in interpretation of the
results for oral fluid. Blood (B) and oral fluid (OF) samples collected from
drivers suspected of DUID in Belgium, Germany, Finland, and Norway for the
ROSITA-2 project were used to study the relationship between the oral fluid
and the blood concentrations of drugs of abuse [42]. The ratios found in this
study were comparable with those that were published previously, but the
range was wider. The median of the OF:B ratios of basic drugs such as
amphetamines, cocaine, and opiates were 4-13, 22, and 2-10 respectively.
The ratios for benzodiazepines were very low (median OF:B ratio: 0.02-0.1)
while that for THC was 15. Several methods for estimating the prevalence of
high blood concentrations of THC and amphetamine in a population of drug
users by analysing their OF suggested that dividing the drug concentration in
OF by the OF/B regression coefficient gives an acceptable estimation of high
blood drug concentrations, which may give valuable additional information on
possible drug impairment [43]. The presence of THC in blood is usually
interpreted as an indicator for recent drug use. However, a study of chronic
cannabis users over 7 days of continuous monitored abstinence showed that
substantial whole blood THC concentrations (0.3 ± 0.7 ng/mL) persisted
multiple days after drug discontinuation in heavy chronic cannabis users [44]. A
comparison of the impairment of driving-relevant skills by alcohol or cannabis
suggested that a THC concentration in serum of 7-10 ng/mL is correlated with
an impairment comparable to that caused by BAC of 0.05%. The per se limits
for THC in blood appear to be the most effective approach to differentiating
drivers who are impaired by cannabis use from those who are no longer under
the influence [45]. The relationship between blood zopiclone and zolpidem
concentrations and driving impairment was assessed by a clinical test, and the
impairment was compared in that with a group of drivers with suspected
alcohol-related impairment [46]. It is concluded that the percentage of impaired
drivers with blood zopiclone concentrations above 130 µg/L roughly
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