SPIs on Alcohol and Drugs

Introduction

Three SPIs on alcohol and drugs are proposed:

1. The number and percentage of severe and fatal injuries resulting from road accidents involving at least one active road user impaired by psychoactive substance (concentration above a predetermined impairment threshold)
2. The percentage of fatalities resulting from accidents involving at least one driver impaired by alcohol
3. The percentage of fatalities resulting form accidents involving at least one driver impaired by drugs other than alcohol

The first indicator is not yet possible to realise. The indicators 2 and 3 are realisable for some countries at present.

The SPI Manual discusses several measurement issues (see below for some issues).

Measurement methods

There are no specific sampling issues for the SPI on alcohol and drugs, since all drivers or all active road users involved in fatal or serious crashes are tested. In order to calculate the drug concentration at the time of crash, data are needed on:

• Time of crash
• Time of sample collection

For alcohol, blood testing may be used or evidential breath testing for surviving road users involved in fatal crashes. The results of breath alcohol concentrations and blood alcohol concentrations are very well comparable. Fixed factors can be used for the transformation from one concentration to the other. In Europe different transformation rules are used: e.g. the Netherlands and the United Kingdom use a factor of 2300 between the blood and breath alcohol concentration, whereas most other European countries use a factor of 2100. In order to avoid problems with comparability, the blood alcohol concentration (BAC) should at least be reported above or below a predetermined impairment threshold. This is in order to make international comparisons for certain levels, as legal limits vary from 0.0 to 0.8 in Europe. A level of 0.5 grams per litre blood should be used.

For drugs, a saliva specimen or a blood specimen may be used. All illicit drugs and relevant psychoactive medicinal drugs should be tested for. A country that uses saliva specimens for collection for drugs may have an under registration, compared to countries that use blood specimens. This is because saliva samples are sensitive for the detection of benzodiazepines and THC. The technique of analysing saliva is developed further, and in the near future a transformation factor from saliva to blood will be developed.

For drugs neither the types of drugs nor concentration limits are established so far. International agreements need to be achieved as to for which drugs to test and categories of test results.

Core substances may include: alcohol, cannabis, cocaine, opiates, XTC, amphetamines and benzodiazepines. In addition to these core substances the drug panel could be expanded to include other drugs that are nationally frequently used.

Recommendations

• Routines for registration of impaired active road users should be part of the existing road accident data registration.
• It is very important that samples should be collected as soon as possible after a crash occurs