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Drugs and
driving – just how big is the problem?
10 years ago almost nobody talked about drugs and driving
- it was not considered to be a significant issue or problem. But
this is no longer the case.
In
October 2002, PACTS hosted a major conference, ‘Fit to Drive?
Impairment through drink and drugs’. In this feature we look
at the presentation of Dr Rob Tunbridge, head of impairment studies
at the Transport Research Laboratory (TRL).
And
we examine just how big the problem of drugs and driving is, where
we are in terms of being able to detect impaired motorists and the
impact cannabis has on an individual’s ability to drive.
The extent of the problem
Unlike alcohol, there are no routine statistics about the part drugs
play in levels of road accidents/driving offences - because drugs
are far less evident and far harder to detect than alcohol.
So while there are some 75,000 convictions annually for driving
above the legal alcohol limit in England and Wales there are fewer
than 2,000 convictions for the offence of driving while unfit through
drink or drugs. And it is not even clear what proportion of that
number is for drug use.
While the problem of drugs remains overshadowed by alcohol, studies
by TRL into the incidence of drugs in road fatalities point to a
significant increase over the past 10 – 20 years.
The first study, in the mid 1980s, was prompted by Government concerns
about the possible involvement of medicinal drugs in road accidents.
The study showed an incidence of around 6 per cent - not a major
cause for concern compared to the 25 per cent of fatally injured
drivers that were over the drink-drive limit. The incidence of illicit
drugs- just 3 per cent at that time - gave even less cause for concern.
In response to rising concern about an increase in illicit drug
taking, the Department of Transport (now DfT) commissioned TRL to
repeat the study in 1995. "The interim results in 1997 caused
quit a stir and have continued to prompt interest in the subject
ever since," Dr Tunbridge told conference delegates. "We
published the final results this year and they confirm an increase
in illicit drug incidence from 3 per cent to 18 per cent over the
previous decade."
Dr Tunbridge went on to point out that just because 18 per cent
of road fatalities contained evidence of illicit drugs, this does
not mean that drugs necessarily caused the accidents. However, the
increase is clearly of concern.
Detecting drugs
If assessing the extent of the problem is tough, then proving an
offence is even more challenging.
In 1997, the Home Office sent two police officers to the US to look
at the Drug Recognition Expert (DRE) system, which has subsequently
been adopted by UK police forces. The system has two principal components,
Drug Recognition Training (DRT) and the Field Impairment Test (FIT).
DRT is a system to identify the signs and symptoms of a person under
the influence of drugs. The system classifies the drugs into six
main groups similar to those used for chemical analysis.
FIT is a standardised method of examination comprising five separate
tests; pupillary examination, the Romberg test, walk and turn, one
leg stand and finger to nose. It is designed for use at the roadside
or a police station.
However, FIT is voluntary - drivers cannot be compelled to take
the test and it cannot be universally applied. For example, older
drivers and the disabled are exempt - which excludes some 20 per
cent of the population.
Combined with other observations made on a driver, FIT provides
a strong indication as to whether or not he or she is impaired.
The system from which it is derived has been used in the US for
over 20 years and is a widely accepted method for assessing drug-impaired
drivers. In trials conducted by TRL, 92 per cent of drivers who
failed a FIT test subsequently proved positive for drugs. This is
very similar to routine US findings.
However, FIT is not an easy test to administer and the results are
not easy to determine – because some people will struggle to
pass the test even if they have not taken any drugs.
In 1998 the Department for Transport, asked TRL to get actively
involved in addressing the issue of detecting drug drivers. Roadside
trials were carried out using two drug screening devices - one using
an individual’s sweat (Drugwipe) and the other using saliva
(Cozart). Both devices were tested for practicality, not accuracy,
and received a positive response from drivers and the police. "The
vast majority of drivers supported the principle of roadside testing
and the police found both methods generally acceptable," says
Dr Tunbridge.
As a result the DfT and the Home Office have developed a draft protocol
for a screening device. As well as accuracy and reliability, the
device should be non-invasive, relatively cheap, robust and easy
to use. "While there has been progress in developing such a
device there is still some way to go," according to Dr Tunbridge.
The
effect of cannabis
In 1999 the DfT asked TRL to conduct research on the effects of
cannabis - and a combination of cannabis and alcohol - on drivers.
The research was carried out using the TRL driving simulator.
A number of measures were used including DRT and FIT tests and a
physiological examination carried out by police surgeons. Participants
also provided samples of urine and saliva prior to smoking and a
further saliva sample at 30 and 60 minutes post dosing. They also
performed an adaptive tracking task - a computerised test known
to be sensitive to impairment.
The tests showed that under the influence of cannabis – with
or without alcohol – a drivers’ average speed reduced
by 5 mph. This confirmed findings from previous studies that - under
the influence of cannabis - drivers are aware of their impairment,
attempt to compensate by driving more cautiously, but are unable
to compensate for the loss of capability in some psychomotor skills.
For example, the study confirmed previous observations that cannabis
adversely affects a driver’s tracking ability - and that tracking
performance deteriorated as the dose level increased. It was also
clear that general medical examination and standardised impairment
testing by police surgeons were effective in determining impairment.
Both the cannabis and cannabis/alcohol study reports are available
to download from the TRL website on www.trl.co.uk/publications/DfT.
Making progress
The Government sees the drugs issue as one best tackled through
a partnership approach. There are many more uncertainties about
drugs and driving than about alcohol, and the Government’s
objective is to pull together many strands of research and try to
crystallise them into advice for drug users, or for people who have
contact with drug users.
It does not belive that large-scale publicity campaigns of the kind
used for drink driving are the answer. Rather, it belives the key
is that the messages conveyed should reach their targets and have
the desired effect on them.
Acknowledgement:
We are grateful to PACTS for supplying copies of the papers presented
at its conference, ‘Fit to Drive? Impairment through drink
& drugs’ held in London on 22 October 2002. A copy of the
conference papers can be purchased for £15 from:
Sally Verkaik
Administrator
Parliamentary Advisory Council for Transport Safety (PACTS)
St Thomas' Hospital South Wing
Block 5 Governors Hall
Lambeth Palace Road
London
SE1 7EH
Tel: +44 (0)207 922 8112.
Fax: +44 (0)207 401 8740.
Email: sally.verkaik@pacts.org.uk
Website: www.pacts.org.uk
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