DRUGS AND HIGHWAY CRASHES

THREE QUESTIONS ARE CONSIDERED: (1) THE EXTENT TO WHICH MIND-ALTERING DRUGS OTHER THAN ALCOHOL ARE A FACTOR IN TRAFFIC ACCIDENTS; (2) THE TYPE OF DRUG USER MOST LIKELY TO GET INTO TROUBLE ON THE ROAD; AND (3) THE OVERLAP BETWEEN DRUG USERS AND ALCOHOL USERS. THE EXISTING LITERATURE BASED ON LABORATORY DATA IS NOT CONSISTENT BUT SUGGESTS THAT MANY PSYCHOACTIVE DRUGS CAN BE EXPECTED AT LEAST THEORETICALLY TO IMPAIR DRIVING ABILITY. THE VARIOUS STUDY METHODS TO DETERMINE THE ROLE OF ALCOHOL IN ACTUAL HIGHWAY CRASHES ALL SUFFER CERTAIN DEFICIENCIES: (1) CASE HISTORIES CAN SUGGEST RELATIONSHIPS AND MECHANISMS BUT GIVE NO INSIGHT INTO THE REQUENCY OF SUCH RELATIONSHIPS. (2) ANALYSIS OF BLOOD OR OTHER BIOLOGICAL SAMPLES INVOLVED IN CRASHES WILL MISS SOME DRUGS, BUT MORE IMPORTANT IS THAT IT PROVIDES NO CLUE AS TO THE FREQUENCY OF CONTRIBUTION TO CRASHES. (3) SAMPLING OF DRUG CONCENTRATIONS IN PERSONS WHO HAVE CRASHED, USING A CONTROL GROUP OF PERSONS WHO HAVE USED THE ROADS UNDER SIMILAR CONDITIONS AND NOT CRASHED, HAS BEEN USED ONLY ONCE AND SUGGESTS THAT DRUGS OTHER THAN ALCOHOL WERE ONLY A MINOR FACTOR IN CRASH OCCURENCE. (A FINDING WAS THAT 10--20% OF THE POPULATION ON THE ROAD AT A GIVEN TIME IS TAKING PRESCRIBED MEDICATION.) (4) COMPARING CRASH RATES OF KNOWN USERS AND NONUSERS FAILS TO ACCOUNT FOR THE POSSIBILITY THAT OTHER FACTORS ARE INVOLVED IN CRASHES. DRUG USERS HAVE MUCH HIGHER CITATION RATES THAN NONUSERS, BUT THIS MAY BE RELATED NOT TO USE BUT TO THE BASIC REASON FOR USING DRUGS. A TENTATIVE CONCLUSION IS THAT MARIHUANA, DEPRESSANTS, AND TRANQUILIZERS MAY NOT BE ASSOCIATED WITH A SUBSTANTIAL INCREASE IN CRASH RISK WHILE AMPHETAMINES MAY. THREE TYPES OF DRUG USERS--- SOCIOPATHS, TEENAGE AND COLLEGE AGE USERS OF MARIHUANA ONLY, AND ALCOHOLICS MAKING PRESCRIBED OR UNPRESCRIBED USE OF PSYCHOACTIVE DRUGS--- ARE DISTINGUISHED WITH RESPECT TO CRASH RISK. IT IS CONCLUDED THAT THE FIRST AND THIRD GROUPS REQUIRE TAILOR-MADE CONTROL MEASURES.