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Driving under the influence of drugs. Correlation between clinical signs and type of intoxication.
S. Z a n ca n er , R. G io r g e tti , C . D al P o z z o , G . M o lin a r i, R . S n en g h i and S .D .
Ferrara
Centre o f Behavioural and Forensic T oxicology, U niversity o f Padova, V ia F alloppio 50 ,
35121 Padova, ITA LY
IN T R O D U C T IO N
W ith the aim o f highlighting the ro le played by psychotropic substances (alcohol, d ru g s o f
abuse, psychoactive drugs) in causing road accidents, a survey based on clinical and chem ico-
toxicological analyses w as carried out on car drivers in the V eneto region during the w eekends
o f the three-m onth periods June-A ugust 1994 and 1995, and in January 1995 and January
1996.
The aim o f the p resen t study w as to focus on the correlation betw een clinical signs found on
objective exam ination and alcohol and psychoactive substances in drivers' b iological fluids.
M A T E R IA L S A N D M E T H O D S
A scertainm ents w ere carried out in collaboration w ith H ighw ay Police personnel from 1.00
a.m . to 7 .00 a.m . on w eekend nights. Seven team s w orked contem poraneously th roughout the
Veneto R egion, each team com posed o f one doctor w ith experience in ascertaining fitness to
drive within the toxicologico-forensic am bit, one doctor specializing in em ergency treatm ent,
and tw o Italian R ed C ross volunteers.
The m edical personnel w orked inside a R ed C ross am bulance equipped w ith instrum entation for
em ergency treatm ent, m obile on-site exam ination, and chem ical toilet.
P r o c e d u r e
Each toxicologico-forensic ascertainm ent w as preceded by a p relim inary phase for:
- driver identification;
- analysis o f expired air (breathalyser);
- request for inform ed consent to m edical exam ination (verbally o r in writing).
D rivers w ho w ere stopped by the police w ere taken to the am bulance w here, in conditions o f
clinical safety, rapid toxicological and sem eiotic (ocular and neurological) screening w as carried
out. I f this screening revealed one o r m ore signs indicating intake o f psychoactive substances,
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drivers w ere subm itted to com plete toxicologico-forensic ascertainm ent, by m eans o f a
standardized procedure, as follow s:
- drivers w ere asked to give their inform ed consen t to clinical exam ination and sam pling o f
biological fluids;
- any refusals were docum ented and a report m ade to the H ighw ay Police;
- general and m edical details w ere collected;
- drivers w ere subjected to an objective physical exam ination aim ed a t finding signs o f intake
o f psychoactive substances (recent o r p revious in take, in toxication , w ithdraw al
sym ptom s, correlated pathologies); in particular, the fo llow ing param eters w ere all
recorded: m ydriasis and m iosis; presence o f conjunctival congestion , nystagm us; m otor
coordination (finger-to-nose, speech, gait); arterial blood pressure; heart rate;
- blood and urine sam ples w ere taken (double collection fo r "A nalysis" and possib le
"C ounter-analysis");
- a proper chain o f custody w as guaranteed by using special form s fo r recording all
operations involving biological sam ples (sam pling , transport, receipt at laboratory ,
preservation).
T o x ic o lo g ic a l in v e s t ig a t io n
The analytical procedure described in Tedeschi et al. (1992) w as used. C hem ico-toxicological
screening w as carried out using im m unochem ical and chrom atographic techniques, with
confirm ation o f positive results by G C-M S.
R E S U L T S
Rapid clinical screening w as carried out on 2779 drivers. Inform ed consen t to carry out
com plete ascertainm ents w as requested in 532 cases: 52 drivers d id not consen t to medical
exam ination o r d id not supply even a biological sam ple, and w ere charged w ith driv ing under
the influence o f drugs. O f the rem aining 480 drivers, 413 supplied b lood and 372 urine
sam ples. The analysis o f the sam ples gave the fo llow ing results: - BA C > 10m g/100m l 52 .1%
(n=250); - B A C >80 mg/lOOml 31.7% (n=152); - drivers under the influence o f d rugs 11.7%
(n=56).
The general characteristics o f the sam ple population, types o f psychoactive substances identified
and the phenom enon o f m ultiple intake are show n respectively in Table 1 and F igures 1 and 2.
F igures 3-11 show positive clinical findings according to type o f psychoactive substance taken
and in the contro l groups o f unim paired drivers (B A C <50).
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D IS C U S S IO N A N D C O N C L U S IO N S
T he procedure used here covered a special population sam ple, characterized principally by a
high percentage o f m ale drivers under 30, unm arried , em ployed, o f m edium to low degree o f
schooling , and com ing from discos.
The possib ility o f revealing the intake o f d rugs o f abuse by rapid clinical screening has been
reported several tim es (e .g ., T ennant, 1988). The alm ost constant ocular changes caused by
such intake and the ease and rapidity w hich w ith non-invasive clinical tests can be carried out
mean that ocular signs probab ly represent the best m eans o f identifying users o f psychoactive
substances (M cL ane and C arro ll, 1986; C one, 1990; U rey, 1991).
Clinical ocular tests m ust be integrated w ith sem eiological m ethods exploring m otor
coordination (finger-to-nose, w alk-and-turn) and o ther param eters such as heart rate, blood
pressure , signs o f needle m arks, w ithdraw al syndrom es, e tc.) if further details on the type o f
substance taken and the categories o f substances in w hich eye effects are negligible (e .g .,
alcohol, phencyclid ine) are to be identified (K ulberg, 1986).
A nalysis o f resu lts in term s o f correlation betw een clinical ascertainm ent and the presence o f
psychoactive substances in biological fluids allow s the fo llow ing considerations to be m ade:
- clinical eye param eters are far m ore sensitive than others in identifying subjects w ho have
taken psychoactive subtances; in particu lar, m ydriasis (Fig. 3) is found in a very high
percentage o f D U I drivers and in tw o-th irds o f those w ho have taken stim ulants
(am phetam ines and cocaine);
- the m oderate frequency o f m ydriasis in subjects w ho have not taken psychoactive
substances m ay be due to the particular circum stances in w hich they w ere stopped by the
police: the sam ple population w as exam ined at night and had been exposed to excessive
levels o f light and noise in discos;
- conjunctival congestion (Fig. 5) w as very high in those taking cannabinoids and
stim ulants, and w as also considerable in d runk d rivers , consisten t w ith data from the
literature. T he absence o f nystagm us (Fig. 6) w as closely correlated w ith non-D U I
drivers;
- o f the clin ical signs o f lack o f m otor coordination (Figs. 7, 8 and 9), finger-to -nose appears
to be the m ost sensitive, being im paired in a high percentage o f D U I drivers (B A C > 80
m g/100 m L) and those taking opiates (Fig. 9);
- in take o f stim ulants does not cause signs o f im paired m otor coordination , w hich are found
to a lesser exten t than in the control group;
- high heart rate (>100) w as frequently found in those taking stim ulants and cannabinoids
(F ig . 11).
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Interpretation o f resu lts from on-site clinical screening is som etim es d ifficult, due to the
frequent finding o f m ultiple intake o f psychoactive substances. In these cases, observed clinical
effects often depend on unpredictable interactions bew teen substances w hich have opposite
effects on the sam e organ or apparatus. H ow ever, the fact that these drivers m anifestly show
clinical alterations is extrem ely important, since interpretative difficulties on the clinical level can
be resolved by chem ico-toxicological analyses.
The results o f our epidem iological trial indicate the follow ing.
1. In the d river population exam ined, there is a definite problem o f driv ing under the influence
o f alcohol and psychoactive substances.
2. M ost drivers exam ined had taken cannabis or stim ulants.
3. The high num ber o f drivers under the influence o f cannabinoids is an em erging p roblem ,
particularly in view o f the serious im pairing effect w hich cannabis derivates have on driving
ability (Ferrara e t al, 1994). The phenom enon is probably due to the greater ease o f access and
use o f these drugs, w hich m ay now be taken for personal use (depenalized in Italy in 1993).
4. The pharm acological effects o f disinhibition and im paired perception o f risk , confirm ed in
studies on am phetam ines and cocaine (Schm edtje et al, 1988; B urns,1993; F errara et al, 1995),
probably explain the dangerous driving behaviour w hich leads to the greater num bers o f
"Saturday night accidents".
5. R apid clinical screening, m ainly o f ocular and neurological signs, to identify those taking
psychoactive substances is useful in cases in w hich sam ple num bers are high and the expected
frequency o f positive results is quite low (e.g ., w ork environm ent, general driving population ,
drivers requesting renew al o f driv ing licences).
R E F E R E N C E S .
B urns M (1993), Cocaine effects on perform ance. In U tzelm ann H D , B erghaus G , K roj G
(Eds), A lcohol, D rugs and T raffic Safety -T92, V erlag TU V R heinland, K oln, p. 612-619.
C one EJ (1990), T esting hum an hair fo r drugs o f abuse. 1. Indiv idual dose and time profiles o f
m orphine and codeine in p lasm a, saliva, urine, and beard com pared to drug-induced effects on
pup ils and behavior. J A nal T oxicol 14, 1-7.
F errara SD, G iorgetti R, Z ancaner S (1994), Psychoactive substances and driving: state o f the
art and m ethodology. A lcohol D rugs D riving 10, 1-55.
Ferrara SD , Snenghi R, G iorgetti R , Zancaner S, R ossi A, M ontisci F , Fenato F (1995),
Am fetam inici ed analoghi di sintesi: disabilita e crim ine. Bollettino delle Farm acodipendenze e
A lco lism o 18, 45-52.
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K ulberg A (1986), Substance abuse: clinical identification and m anagem ent. Pediatr Clin N orth
A m 33, 325-361.
M cLane N J, Carroll D M (1986), Ocular m anifestations o f drug abuse. S urv O phthalm ol 30 ,
298-313 .
Schm edtje JF, O m an CM , B aker E L (1988), E ffects o f scopolam ine and dex troam phetam ine on
hum an perform ance. A viat Space E nviron M ed 59, 407-410.
T ennant F (1988), T he rapid eye test to detect drug abuse, Postg rad M ed 84, 108-114.
T edeschi L , F rison G, C astagna F, F errara SD (1992). C om prehensive E IA /G C screening and
G C/M S confirm ation o f psychoactive substances in b lood and urine. In: Ferrara SD , G iorgetti
R (Eds). M ethodology in M an-M achine Interaction and Epidem iology on D rugs and Traffic
Safety, A ddiction R esearch F oundation o f Italy , Padova, pp. 147-166.
U rey JC (1991), Som e ocular m anifestations o f system ic drug abuse. J Am O ptom A ssoc 62 ,
832-842.
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T a b l e 1 : C h a r a c t e r i s t i c s o f p o p u la t i o n e x a m in e d .
S e x n° % A g e (y ea rs) 3 o
male 453 94.4 < 2 0 78 16.3
female 27 5.5 21-25 112 40.2
26-30 107 22.3
S ta tu s 31-35 51 10.6
unm arried 412 85.9 >35 51 10.6
married 51 10.6
legally separated 14 2.9 D riv in g e x p e r ie n c e (y ea rs)
divorced 2 0.4
not available 1 0.2 < 1 36 7.5
1-5 190 39.6
C o m in g from 5-10 133 27.7
disco 222 43.3 > 10 110 22.9
other public place 122 25.4 not available 11 2.3
private house 86 17.9
other 50 10.4 S c h o o l in g
none 1 0.2
E m p lo y m e n t prim ary school 29 6 .0
em ployed 420 87.5 m iddle school 255 53.1
unem ployed 34 7.1 high school 183 38.2
student 21 4.4 university degree 8 1.7
pensioner, o ther 5 1 not available 4 0.8
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Figure 1 Psychoactive substancesin biological fluids
cannabinoids cocaine amphetamines opiates benzodiazepines
n. = 56
Figure 2 Alcohol and psychoactive substances Frequency of multiple intake
n = 56%
alcohol and alcohol >80 and alcohol and 2 or 2 or more psychoactive psychoactive more psychoactive psychoactive substances substances substances substances
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F i g u r e s 3 -5 . P e r c e n t a g e s o f p o s i t i v e c l in ic a l s i g n s , a c c o r d i n g to ty p e o f
s u b s t a n c e i d e n t i f i e d b y to x ic o lo g ic a l e x a m i n a t i o n .
Figure 3 % Mydriasis
DUI Cannabinoids Stimulants Opiates Alcohol Negativecontrols
Figure 4 % M io s is20
0DUI Cannabinoids Stimulants Opiates Alcohol Negative
controls
Figure 5 % C o n ju n c tiv a l c o n g e s t io n
controls
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F i g u r e s 6 -8 . P e r c e n t a g e s o f p o s i t i v e c l in ic a l s i g n s , a c c o r d i n g to ty p e o f
s u b s t a n c e id e n t i f i e d b y to x ic o lo g ic a l e x a m i n a t i o n .
Figure 6 % Nystagmus
Stimulants Opiates Alcohol Negative controls
Cannabinoids
Figure 7 % Instab le ga it20
DUI Cannabinoids Stimulants Opiates Alcohol Negativecontrols
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Figure 8 % L ack o f c o o rd in a t io n
DUI Cannabinoids Stimulants Opiates Alcohol Negativecontrols
F ig u re s 9 -1 1 . P e r c e n ta g e s o f p o s it iv e c lin ic a l s ig n s , a c c o r d in g to ty p e o f
su b s ta n c e id e n tif ie d by to x ic o lo g ic a l e x a m in a tio n .
Figure 9 % P a th o lo g ic a l f in g e r - to -n o s e
DUI Cannabinoids Stimulants Opiates Alcohol Negativecontrols
Figure 10 % P s y c h o m o to r a g ita tio n
40
DUI Cannabinoids Stimulants Opiates Alcohol Negative controls
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