Martín-Cantera et al. BMC Public Health 2010, 10:136 http://www.biomedcentral.com/1471-2458/10/136 not being the main implicated factors, are related to some cases [3-5]. Usually, when we talk about impli- cated factors in RTI, four groups can be considered: human factors, aspects related to the vehicle, aspects related to the collision environment (traffic, lane, etc) and socio-economic aspects [6,7]. The alcohol consumption factor on its own is the big- gest contributor to the production of serious RTIs. The use of certain types of medication and psychoactive sub- stances may alter the driving capacity as well [8]. In our field, between 5% and 15% of drivers killed in an acci- dent show significant blood levels of other psychoactive substances (including or not including alcohol) [9]. There have also been international studies which have proven the existence of a relationship between psy- choactive substances like benzodiazepines [10,11], can- nabis and cocaine [12,13]. As for health problems, the previous morbidity of the driver is considered to be a possible accident inducing factor, and some chronic health problems like diabetes mellitus, epilepsy, hearing or visual impairments, cogni- tive deteriorations and some psychiatric disorders have been associated with RTI. Despite this, the illness-acci- dent relationship is not easy to consider objectively due to methodological difficulties [14]. Drugs and psychoactive substances According to the 2006 Catalan Health Survey (ESCA’06), 21.7% of the Catalan population take some kind of medication, 69.5% of which is prescribed by a doctor, 5.5% prescribed by a pharmacist and 25% is self- medicated. Table 1 shows the available data on the con- sumption of certain medication which can affect driving capacities in the general population of Catalonia [2]. In a study carried out on the Spanish driving popula- tion killed in a traffic accident in 1992, 45% had been taking some kind of medication during the previous year, 17% of which were taken regularly [15]. On the other hand, a study which included 8,000 Spanish drivers showed that an estimated 10% of those killed or injured in a traffic collision had taken some Table 1 Consumption of certain drugs in the general population of Catalonia Pharmacological Group Anxyolitics Antidepressants Antihistamines Hypnotics Antiepileptic drugs Antiparkinsonian agents (>65 yrs) ESCA’06 General population (%) 9,1 6,8 3,18 7,32 0,3 0,76 Men (%) 5,72 3,73 2,44 4,02 0,28 0,6 Women (%) 12,38 9,77 3,89 10,62 0,30 0,8 Page 2 of 9 kind of psychoactive substance. Moreover, an analysis by the National Toxicology Institute (Instituto Nacional de Toxicología) during the period between 1991 and 1999 showed that in 4.382 drivers killed on the road, 54% had taken some kind of psychoactive substance and 5% had been on medication [16,17]. Finally, a recent study, performed in Catalonia, which assessed subjects who had been injured in a traffic accident, observed a high prevalence of consumption of psychoactive sub- stances, especially alcohol, cannabis and cocaine, which was relevant in all age groups [18]. Several review papers underline the effect of certain drugs on driving capacity such as narcoleptics or anti- psychotics, anxyolitics, sedatives and hypnotics, tricycle antidepressants, lithium, (narcotic and non narcotic) analgesics and anti-migraine agents, anaesthetics, antie- pileptic drugs, non steroid anti-inflammatory drugs, mio-relaxing agents, anti-Parkinson drugs, H1-antihista- mines, anticolinergics and some cardiovascular drugs [19,20]. A recently published review paper suggests the need for research on the role of medication in road safety (other than the use of benzodiazepines, which has already been widely studied) [21], and the need to inves- tigate more on the side effects of different drugs when driving [22]. In Spain, the cautionary information about the effect of drugs on driving capacities is ruled by Royal Law (Real Decreto) 1345/2007 [23], which newly includes a picto- gram for any medication that can alter driving ability or the ability to use dangerous machinery. This information is currently being reviewed and classified according to the ICADTS (International Council on Alcohol, Drugs and Traffic Safety) categories, shown in Table 2. These take into consideration 3 groups according to the alcohol intake amounts considered safe, risky or not recom- mended. Currently, 424 active principles have been reviewed, which will lead to a change in 2,633 medicine labels by 2011, as in other eleven EU countries [24]. The European Union has also dealt with problems related to medication and driving, particularly in an international project named “The Integrated Project DRUID (Driving Under the Influence of Drugs, Alcohol and Medicines)”, which analyses the effect that the intake of medicines, medicinal herbs and psychoactive substances can have on road safety [25]. Chronic health conditions Until the 1960’s, the correlation between chronic health problems and road traffic injuries was very controversial. Different groups of researchers started to observe a cor- relation between collisions and injuries suffered by dri- vers with diabetes, epilepsy, cardiovascular illnesses, alcoholism and mental disorders [26].