German DUI Study


 

A great deal of manipulation of the data, and even ignoring a HUGE portion of the data which would have made the complete study worthless had the ignored data contained even a small percentage of drinking drivers, the very best science from government produces the following REMARKABLE ADMISSION:

<<< For all BAC classes above 0%, we found 330 drivers in the accident study. Of those accidents, 213 were attributable to the effects of alcohol. By dividing those two numbers, we obtain an AR for exposed persons of 213/330=0.65 or 65%. That means, 65% of all accidents involving an intoxicated driver can be attributed to the effects of alcohol. However, in only 16.8% of all accidents (or 330 accidents) was the driver intoxicated. To determine which proportion of all accidents are attributable to the effects of alcohol, the population AR should be computed. This is done by dividing the excess accidents by the total number of all accidents, that is, 213/1968=0.108. Thus, 10.8% of all accidents may be attributed to the effects of alcohol. >>>

In other words, the most expert government weasel wording proved that 89.2% of the fatal accidents in this study were NOT caused by alcohol, but were caused by OTHER factors. In other words, the average driver in this study was 8.3 TIMES more likely to be killed in an accident where alcohol was NOT a factor than he was to be killed in an accident where alcohol WAS a factor?

WHAT are these other factors? Why is it assumed that these other factors which are responsible for 89.2% of the accidents are not the IDENTICAL factors involved in the fatal accidents which “may be attributed to the effects of alcohol“?

 

http://fathersmanifesto.net/duigerman.htm

 

Grand Rapids Effects Revisited: Accidents, Alcohol and Risk

H.-P. Krüger, J. Kazenwadel and M. Vollrath

Center for Traffic Sciences, University of Wuerzburg, Röntgenring 11, D-97070 Würzburg, Germany

ABSTRACT

Risk analysis is based on information collected about both exposure to danger and the dangerous event itself. In the case of alcohol-related accident risk, information is needed about the prevalence of driving under the influence of alcohol (DUI) and the frequency with which DUI drivers are involved in accidents. These requirements were met in Borkenstein et al.’s Grand Rapids Study. However, one shortcoming of that study was the risk of causing an accident (rather than just being involved in an accident) had to be estimated because the authors did not know whether the driver was responsible for the accident. Our 1993 Accident Study collected information about BAC, responsibility for causing the accident, and driver characteristics for all drivers involved in 4,615 accidents. The information about exposure was taken from the German Roadside Survey, which sampled 13,149 drivers in 1993. Using those data, the well-known risk function of Borkenstein et al. was replicated. However, the BAC distribution for drivers involved in an accident but not responsible for it was markedly different from that for the drivers in the Roadside Survey. In calculating risk function, Borkenstein et al. assumed identical distributions for these two samples. It can be shown that the problematic “dip” in the risk function was at least in part caused by this assumption.

INTRODUCTION

Risk analysis is based on information collected about both exposure to danger and the dangerous event itself. In the case of alcohol-related accident risk, information is needed about the prevalence of driving under the influence of alcohol (DUI) and the frequency with which DUI drivers are involved in accidents. Although these requirements were met in Borkenstein et al.’s Grand Rapids Study the study has one shortcoming: The risk of causing an accident (rather than just being involved in one) had to be estimated because the authors did not have information on whether the driver was responsible for the accident. In our Accident Study, which took place in Germany in 1994, we obtained this information directly from the police. All the analyses described below include only those drivers who were responsible for causing the accident. Information about DUI prevalence was obtained from the German Roadside Survey (see Krüger et al., 1995, in this volume). The risk function resulting from our 1994 study is, in general, comparable to that resulting from the Grand Rapids Study. However, important differences were found concerning the steepness of the risk functions. In addition, it is demonstrated that the global risk function has to be differentiated for subgroups of drinking drivers. The impact of measures directed against these drivers is estimated by means of the attributable risk.

METHOD

The German Roadside Survey was conducted in the northern part of Bavaria (Unterfranken, part of the former West Germany), which has approximately 3 million inhabitants. Three components were done from the end of 1992 to the spring of 1994. Drivers were stopped and selected by the police who followed a random sampling plan. At a separate checkpoint, these drivers were interviewed and asked to supply a breath sample. Of those asked for a breath sample, 9128 (94.8%) agreed. The roadside survey oversampled weekends at night to obtain a large proportion of DUI drivers. For a representative picture of the DUI prevalence in Germany, the observations were adjusted using information from a representative study of driving in Germany (KONTIV; see Emnid, 1991).

The Accident Study was also conducted in Unterfranken. We equipped a selected sample of police cars with breath testing devices, under the condition that officers try to obtain breath samples from all accident drivers, whether or not they were suspected of DUI. In 1993 in Unterfranken, data were obtained from 1.968 drivers who were responsible for causing an accident.

The Roadside Survey and the Accident Study differed very much with regard to time of day (night: 20 p.m. to 4 a.m.; day: 4 a.m. to 20 p.m.) and day of week (weekend: Friday night to Monday morning; workday: Monday morning to Friday evening). These differences are reflective of such risk factors as, for example, the higher accident risk during the night. As we were mainly interested in alcohol-related accident risk, we controlled for these variables by applying a second weighting procedure to the data from the Roadside Survey. This two-dimensional weighting (by time of day and day of week) produced identical subject distributions in the two studies with respect to the combination of those two factors.

The alcohol-related accident risk is estimated by computing odds ratios. An odds ratio gives a good estimation of the relative accident risk for drivers in a certain BAC class compared to sober drivers (their risk is set to 1). A value larger than 1 indicates an increase in accident risk due to alcohol.

RESULTS

Risk Functions in 1964 and 1994

In 1964, Borkenstein et al. presented the well-known risk function for drivers responsible for causing an accident, which was one basic argument for setting BAC limits in different countries (for example, Germany). Figure 1 shows this risk function compared with the function computed from the Accident Study (both functions were smoothed). The shape as well as the magnitude of the functions are very similar. For drivers with blood alcohol concentrations (BAC) up to 0.04%, the alcohol-related accident risk is nearly identical to or even less than that for sober drivers. Both studies found that, for drivers at BACs ranging from 0.14% to 0.16%, the accident risk is about 25 times as high as it is for sober drivers. However, for nearly all BACs, the 1994 alcohol-related accident risk in Germany was greater than in 1964, a finding that may be a function of today’s more complex traffic situations, which in combination with alcohol cannot be handled adequately anymore. At BACs greater than 0.14%, the deteriorating effects of the intoxication may be so great as to make the differences in traffic conditions irrelevant.

Figure 1
Accident risk functions from Borkenstein et al. (gray line) and from our study (black line). At the abscissa, BAC is given in percent, at the ordinate, the odds ratios are given.


Analysis of factors modifying the alcohol-related accident risk showed driver age to be the strongest mediator (see Vollrath, Krüger & Kazenwadel, 1994; Krüger, Kazenwadel & Vollrath, 1995). The global accident risk for drivers between 18 and 24 years is much greater than that for older drivers. In addition, the alcohol-related accident risk for those young drivers increases much faster than it does for older drivers. In light of these findings, we strongly recommend lowering the BAC limit for younger drivers.

The Attributable Risk

Although drivers under the influence of alcohol are obviously at a greater relative risk than unintoxicated drivers, the magnitude of the risk to the larger community attributable to the presence of intoxicated drivers remains an unanswered question. In the German Roadside Survey, only 5.5% of all drivers were found to have BACs greater than 0. Thus, drivers in Germany are exposed to the increased accident risk due to DUI in only 5.5% of their trips (this statement is valid because of the representative weighting procedure described above). By combining the information about the distribution of exposure (DUI) with the estimate of alcohol-related accident risk, one can determine the degree to which accidents can be explained by DUI. This question is adressed by the measure of the attributable risk (for an overview, see Breslow & Day, 1980; Kahn & Sempos, 1989). The basic idea of attributable risk is that some of the accidents involving intoxicated drivers are not due to the effects of alcohol but are the result of the global accident risk also present for sober drivers. This means that the number of accidents involving intoxicated drivers is adjusted to allow for this global accident risk, yielding an excess number of accidents which are attributable to the effects of alcohol.

There are two definitions of attributable risk (AR), addressing two different aspects: (1) The attributable risk for exposed persons (Cole & MacMahon, 1971) renders an estimate of the proportion of all accidents with intoxicated drivers that is attributable to the effects of alcohol. (2) The attributable risk for the population (first described by Levin, 1953) renders an estimate of the proportion of all accidents (including those with sober drivers) that is due to the effects of alcohol.

To compute these ARs, we chose the BAC classes given in Table 1. The first column shows the number of drivers from the German Roadside Survey according to BAC class, and the second column the number of drivers from the accident study. The first step in computing the number of accident-involved drivers within each BAC class attributable to the effects of alcohol (excess) is to compute a factor k of accident involvement for sober drivers. This factor is calculated as:

k = 1638 / 8438 = 0.1941

Using this factor, the number of drivers that would be expected to be responsible for causing an accident is estimated for each BAC class. For example, for a BAC greater than 0.20%, 10 drivers were found in the Roadside Survey. Multiplying this number by k results in 10 * 0.1941 = 2. Thus, we would expect 2 drivers to be found in the Accident Study in this BAC class (not due to alcohol). However, 64 were found yielding an excess number of 62 accidents which may be attributed to the effect of alcohol. Those excess numbers are given in the third column of Table 1. Of course, there are large difference among the BAC classes. At lower BACs, we even find negative numbers indicating the “dip” in the risk function for lower BACs first described by Borkenstein et al. (1964).

Table 1
Number of drivers in the Roadside Survey and the Accident Study in the different BAC classes. For the computation of the excess number of accidents, see text.

BAC classes

Roadside

Accident

Excess

0

8438

1638

0

< 0.02

284

53

-2

< 0.04

155

21

-9

< 0.06

64

13

1

< 0.08

40

27

19

< 0.10

12

23

21

< 0.12

16

18

15

< 0.14

9

23

21

< 0.16

4

31

30

< 0.18

6

29

28

< 0.20

5

28

27

>= 0.20

10

64

62

Sum

9043

1968

213

For all BAC classes above 0%, we found 330 drivers in the accident study. Of those accidents, 213 were attributable to the effects of alcohol. By dividing those two numbers, we obtain an AR for exposed persons of 213/330=0.65 or 65%. That means, 65% of all accidents involving an intoxicated driver can be attributed to the effects of alcohol. However, in only 16.8% of all accidents (or 330 accidents) was the driver intoxicated. To determine which proportion of all accidents are attributable to the effects of alcohol, the population AR should be computed. This is done by dividing the excess accidents by the total number of all accidents, that is, 213/1968=0.108. Thus, 10.8% of all accidents may be attributed to the effects of alcohol.

Figure 2 gives both ARs computed for different BAC classes. The AR of exposed drivers indicates for each BAC class the percentage of accidents attributable to alcohol. For BACs less than 0.06%, the AR is small, even negative. Hardly any accidents involving drivers with those BACs can be attributed to intoxication. This changes dramatically for BACs greater than 0.06%. At BACs less than 0.08% but greater than 0.06%, about 70% of all accidents are due to alcohol. For all BAC classes greater than 0.08%, the ARs are greater than 80%. For drivers in this latter BAC categories, nearly all the accidents may be attributed to the effects of alcohol.

Figure 2
Attributable risk for the exposed drivers (left ordinate, gray line) and the population (right ordinate, black line) in each BAC class. Both risks are given in percentages.


The AR of the population indicates the magnitude of those alcohol effects in relationship to the total number of accidents occuring. The population ARs can be interpreted as follows: If no drivers with BACs greater than 0.20% were present in traffic, 3% of all accidents would not happen. Adding these percentages for all BAC classes gives the 10.8% of all accidents which are due to alcohol. About a third of these accidents can be attributed to drivers with BACs greater than 0.2%.

As Figure 3 shows, this population AR gives a good indication of the effectiveness of measures directed against DUI. In this Figure, the 10.8% accidents were set to 100%. Had no DUI drivers been present in traffic, none of these accidents would have occured, which would have resulted in a 100% reduction. If no one with a BAC greater than 0.08% drove, a reduction of 96% would result. Thus, if the legal limit for DUI in Germany (0.08%) was an effective deterrant against driving with a higher BAC, this would mean that nearly everything that could be done to prevent alcohol-related accidents would have been accomplished. Thus, countermeasures directed at those persons driving at BACs higher than 0.08% can be expected to be most effective in reducing the number of accidents attributable to the effects of alcohol. In contrast, measures directed at drivers with BACs less than 0.08% cannot be very effective. At most, 4% of all accidents attributable to the effects of alcohol may be prevented.

Figure 3
Risk functions for our Accident Study (circles, black line), for the Grand Rapids Study (squares,gray line) of Borkenstein et al. (1964), and for a study by Perrine et al (1971; triangles, thin line)


Sub-Groups Included in the Risk Function

The question remains how to indentify the characteristics of the these drivers with BACs greater than 0.08%. Is driving with high BACs done very seldom by nearly all drivers or is it done quite often by a small subgroup of drivers? We can begin to answer this question be analyzing the risk functions in Figure 1 in detail. These smoothed functions give the impression that alcohol-related accident risk increases monotonically. However, if smaller BAC classes are selected and BAC is truncated at 0.18%, the picture changes. In Figure 4, odds ratios were computed for BAC classes of 0.02%. The risk functions are shown from our Accident study, from the Grand Rapids Study (drivers responsible for the accident), and from a study by Perrine, Waller & Harris (1971) of fatally injured drivers.

Figure 4
Percentage reduction in alcohol-caused accidents if no drivers at BACs higher than the ones given were present in traffic


Although the studies were done at different times in different countries, the similarities in the structures are striking. In none of the three risk functions is there a monotone increase in risk, but different peaks are found. In our Accident study, the first (small) peak is present between 0.08% and 0.10%, a second peak at 0.14% to 0.16% and a third peak at BACs greater than 0.20%. In the Grand Rapids Study, similar peaks are found but are shifted towards higher BACs. This reflects the finding shown in Figure 1 that, in our Accident Study, the alcohol-related accident risk is higher than that found by Borkenstein et al. (1964). In contrast, in Perrine et al.’s study, the peaks are shifted towards lower BACs, which makes sense as only fatally injured drivers (very serious accidents yielding a larger alcohol-related accident risk) were examined.

The occurence of those peaks in three different studies from different countries and different years suggests that the overlay of risk functions of different sub-populations produces the typical shape of the overall risk function. Extended studies on drinking behavior indicate that three different groups of drinkers may be responsible for the peaks. These hypothesis is supported by studies on hardcore drinking drivers (for example, Simpson & Mayhew, 1993). The assumption of three sub-groups of drinkers is indicated in Figure 5 (the risk function here was computed from our data for BAC classes of 0.01%). The first group consists of moderate drinkers who will never exceed a maximum BAC of around 0.10% (consumption limit). At higher BACs, this group cannot compensate the effects of alcohol very well, which yields the first peak of the risk funktion. Two groups of heavy drinkers are responsible for the other peaks. Both groups have probably developed a certain amount of alcohol tolerance, enabling them to compensate for the effects of alcohol at higher BACs.

Figure 5
Hypothetical sub-populations of drinkers responsible for the peaks in the alcohol-related accident risk function (thick lines). The thin line represents the empirical risk function.


DISCUSSSION

Our Accident Study replicated the well-known risk function of Borkenstein et al. (1964). The comparison indicates that driving under the influence of alcohol resulted in a greater accident risk in 1994 compared to 1964. Considering the incidence of DUI, it was argued that effective countermeasures that substantially reduce the number of accidents attributable to the effects of alcohol should be directed towards drivers with BACs greater than 0.08%. This also implies that simply changing the legal DUI limit from 0.08% to 0.05% is insufficient with respect to alcohol-induced accidents as the potential reduction would be only about 4%. Further inspection of the risk function indicates that certain subgroups of drinking drivers are responsible for the alcohol-related accident risk in the higher BAC range. Measures capable of deterring drinking drivers in this range were expected to have a substantial impact on traffic safety, namely, result in a decrease in accident rates.

REFERENCES

Borkenstein, R.F., Crowther, F.R., Shumate, R.P., Ziel, W.B. & Zylman, R. (1964). The role of the drinking driver in traffic accidents. Department of Police Administration, Indiana University.

Borkenstein, R.F., Crowther, F.R., Shumate, R.P., Ziel, W.B. & Zylman, R. (1974). The role of the drinking driver in traffic accidents (The Grand Rapids Study). Blutalkohol, 11, Supplement 1.

Breslow, N.E. & Day, N.E. (1980). Statistical methods in cancer Research. Volume 1 – The analysis of case-control studies. Lyon: International Agency for Research on Cancer.

Cole, P. & MacMahon, B. (1971). Attributable risk percent in case-control studies. British Journal of of Prevention and Social Medicine, 25, 242-244.

Emnid (1991). KONTIV 89. Bericht zur Methode, Anlagenband und Tabellenteil. Bielfeld: Emnid.

Kahn, H.A. & Sempos, C.T. (1989). Statistical methods in epidemiology. New York: Oxford University Press.

Krüger, H.-P., Kazenwadel, J. & Vollrath, M. (1995). Das Unfallrisiko unter Alkohol unter besonderer Berücksichtigung risikoerhöhender Faktoren. In H.-P. Krüger (Hrsg.), Das Unfallrisiko unter Alkohol. Stuttgart: Fischer Verlag (in preparation).

Levin, M.L. (1953). The occurrence of lung cancer in man. Acta Unio Internationale Contra Cancrum, 9, 531-541.

Simpson, H.M. & Mayhew, D.R. (1993). The hard core drinking driver. In H.-D. Utzelmann, G. Berghaus & G. Kroj (Eds.), Alcohol, Drugs and Traffic Safety – T92 (pp. 847 – 853). Cologne: TÐV Rheinland.

Vollrath, M., Krüger, H.-P. & Kazenwadel, J. (1994). Modifying risks: Youthful drivers, drinking drivers and driving conditions. 1994 Annual Scientific Meeting of the Research Society on Alcoholism (RSA), Maui.

NTSB: James E. Hall


Alcohol and Other Drug Use in Commercial Transportation

James E. Hall

Chairman, National Transportation Safety Board, Washington, D.C. 20594 USA

ABSTRACT

Quite a bit of progress has been made in the United States in reducing the use of alcohol and drugs by commercial vehicle operators in all modes of transportation over the past few years. Drug use prevention and testing programs have been required by the Federal Government since the mid to late 1980’s. More than 7,000,000 employees in safety-sensitive jobs are covered by the required programs.

Random drug testing of rail workers in 1993 continued to show a reduction in the number of those testing positive for the fourth consecutive year. The positive rate was again less than 1.00 percent. This percentage is down from 6 percent in 1988. The U.S. Federal Aviation Administration reported that 1993, was the fourth year in a row that aviation workers tested positive at a rate less than one percent. Because of these low rates, new regulations that became effective in 1995, will permit the random testing rates for those industries to be reduced from 50 percent to 25 percent. In the trucking industry, one survey conducted by the American Trucking Associations, compiled drug testing data from its member companies for the year 1990. A positive rate from random tests was 2.5 percent. As in the other industries, marijuana was the drug of choice followed by cocaine. More recently, the Federal Highway Administration conducted a four State roadside random pilot drug and alcohol testing program. Through the end of 1993, the positive rate for drugs was 3.8 percent and for alcohol the positive rate was 0.18 percent. Earlier studies in the trucking industry had found considerably higher positive testing rates.

This paper will discuss the progress that has been made and review current developments in the field and discuss new testing requirements.

INTRODUCTION

Much has changed in the United States since we reported to you at T-92. Indeed, there have been significant changes in alcohol-related crashes in both commercial and non-commercial areas of highway safety and in transportation safety in general. There have been similar significant changes in employee drug and alcohol testing programs and in the rate of positive drug tests in commercial transportation over a long period of time. Until recently, very little was known about the use of impairing drugs (including alcohol) by the operators of railroad trains, airplanes, ships and heavy trucks. In the United States, the data indicated that a significant problem existed and that strong action was required to control it.

I have the honor to chair the National Transportation Safety Board (NTSB). The Board is an independent accident investigation agency chartered by Congress to investigate transportation accidents, determine their probable causes, and make recommendations to prevent their recurrence. We have no regulatory authority and no financial incentives to promote our recommendations. Keep that in mind as I address alcohol and other drugs in the commercial transportation system and as a context in which progress has been achieved.

We have already reported to you that the Safety Board began documenting the abuse of alcohol and other drugs in transportation accidents in the 1970’s. By the early 1980’s, it became clear that a problem existed in all modes of transportation and that not much was being done about it. In 1983, the Safety Board recommended that the Department of Transportation (DOT) issue rules to prohibit the use of alcohol or other drugs while on duty or for a specified period before duty and to require toxicological tests on all employees responsible for train operation. In 1985, the Federal Railroad Administration (FRA) of the DOT issued a final rule on “Control of Alcohol and Drug Use in Railroad Operations.” The rule required alcohol/drug testing after accidents, for reasonable cause, and for those applying for employment. Following additional recommendations by the NTSB, the DOT in 1988, issued drug testing rules for more than 4,000,000 persons working in safety sensitive occupations in all areas of commercial transportation (Sweedler, 1992).

As you may know, the U.S. testing rules apply to Federal transportation employees and to private sector transportation employees in safety-sensitive positions. The original rules specified urine tests for the presence of marijuana, opiates, cocaine, amphetamines, and phencyclidine (PCP). In addition to the pre-employment, post-accident, and reasonable cause tests required for railroad workers, the rules added random testing to all modes, including railroad. The random test rate was 25 percent of covered employees in the first year and 50 percent in subsequent years. There were many differences in the rules among the various transportation modes including a lack of test result reporting in all modes except aviation and rail and omission of alcohol tests in all modes except rail. Further, the rules do not separate post-accident testing for more comprehensive blood testing as requested by the NTSB. However, as a result of landmark legislation, many of the rules changed.

The Omnibus Transportation Employee Testing Act of 1991 was sparked by the derailment of a New York City subway train. The train operator had a BAC of 0.21 percent more than 13 hours after the crash. The Omnibus Testing Act is the legislation that changed the face of alcohol and other drug testing in the United States. The legislation required the DOT to issue regulations to include testing for alcohol, the most commonly used and abused substance in the United States. It expanded the drugs for which tests would be conducted from a maximum of five to a minimum of five and allowed for expansion to a greater number based on analysis by the Departments of Transportation and Health and Human Services. Mass transportation was specifically included in the drug testing programs to override a court decision that the Federal Transit Administration lacked specific regulatory authority in this area. It did not include the commercial maritime industry as regulated by the United States Coast Guard. Nearly 8 million transportation personnel in safety sensitive positions are now included in the alcohol and other drug testing program. Notably, every holder of a commercial drivers license (CDL) is included. That means every driver of a bus and large truck is now subject to testing regardless of whether the driver operates in intra or interstate commerce (Federal Register, 1994).

During the regulatory process of implementing the legislation, a number of key changes were made in the commercial transportation alcohol and drug testing system. The drug test rules now allow the random drug test rate to be reduced from 50 percent to 25 percent of covered employees if the industry-wide drug test positive rate on random tests is below 1 percent for 2 consecutive years. When an industry qualifies for the 25 percent testing rate, it must maintain the positive rate below 1 percent. If it doesn’t, the random test rate will increase to 50 percent of covered employees. All transportation industries are now required to report test results.

Alcohol testing is the major change required by the Omnibus Testing Act. In general, the rules implementing the act prohibit covered employees from performing safety sensitive functions: 1) when test results indicate an alcohol concentration of 0.04 or greater; 2) within 4 hours after using alcohol (8 in aviation); 3) while using alcohol on the job; 4) during the 8 hours following an accident if their involvement has not been discounted as a contributing factor or until they are tested; and 5) if they refuse to submit to required alcohol tests. Employers must remove an employee from the safety-sensitive function if they violate any of these prohibitions and keep them off duty until they have met the conditions. If an employee has an alcohol concentration of 0.02 or greater, but less than 0.04, or is otherwise impaired by behavior, speech, and performance indicators, that person is removed from duty for 8 hours or until a test result below 0.02 is obtained. The rules require employers to conduct pre-employment, reasonable suspicion, post-accident, return-to-duty, and follow-up alcohol testing. The random alcohol test rate for covered employees was set at 25 percent. However, this rate could be reduced to 10 percent if the industry-wide random test positive rate is below 1 percent for 2 consecutive years. I hasten to point out that there are differences in each mode of transportation that are specific to that mode. For additional detail, the rules were published in the Federal Register on February 15, 1994.

In general, the rules require implementation on January 1, 1995 for large employers (generally 50 or more covered employees) and January 1, 1996 for all other employers. All other existing drug testing rules and alcohol testing in rail remain in effect until the new rules are implemented. Certain transportation industries have filed suit regarding certain aspects of the rules. For example, some trucking industry organizations objected to pre-employment alcohol tests as “an intelligence test.” The Secretary of Transportation has supported elimination of pre-employment alcohol tests as an unnecessary burden on the industry.

I am able to report on some exciting results in two industries where drug test results have been reported for several years and on a special program in the trucking industry.

AVIATION

At T-92, we reported that the felony conviction of three former Northwest Airlines pilots of flying a passenger jetliner while intoxicated brought new focus to the problem of flying under the influence of alcohol. (ICADTS Reporter, 1991). In 1990, the FAA issued new rules designed to identify and ground pilots involved in alcohol or drug-related motor vehicle offenses that result in convictions or administrative actions. Pilots applying for a medical certificate must consent to the release of information from the National Driver Register (NDR) to enable the FAA to obtain and review motor vehicle offense information pertaining to the applicant. The FAA can deny or take action to suspend a certificate of a pilot who receives two or more alcohol or drug-related convictions or administrative actions within a 3-year period (ICADTS Reporter, 1990). To date, over 1,000 cases have been referred to the FAA’s chief counsel for administrative action (FAA, 1994).

From 1983 to 1988, no pilot in a fatal commuter crash tested positive for alcohol. However, the pilot of one of these fatal crashes did test positive for a metabolite of cocaine. In 1988, a Trans-Colorado Airlines, Fairchild Metro III, operating as Continental Express, with two crew members and 15 passengers on board, crashed short of the runway at Durango, Colorado, killing the two crew members and seven passengers. The NTSB found that the captain’s use of cocaine degraded his performance and contributed to the accident (NTSB, 1989). For on-demand (unscheduled) air taxi fatal accidents, the percentage of those pilots tested that were positive for alcohol declined from 7.4 in the 1975 to 1981 period to 1.8 in the 1983 to 1988 period (NTSB, 1984 and NTSB, 1992).

An aviation success story in the United States is the effectiveness of the drug testing program. Testing program results have shown a low rate of positive drug tests in aviation from the beginning of the testing program, especially among flight crews. In 1991, FAA statistics from drug tests conducted on 279,881 aviation employees and job applicants in safety and security-related positions showed that 0.96 percent of the tests were positive for drugs of abuse. In 1992, 275,176 tests were conducted and 2,605 were positive, a rate of .95 percent. These results include repair facilities workers, contractors, and airline personnel and applicants. The positive rate for airline employees and applicants remained about the same in 1991 (0.46 percent) as 1990 (0.40 percent).

Pre-employment tests accounted for 49 percent of the positive total in 1991 and 44 percent in 1992. Random tests of current employees accounted for the 46 percent of the positives in 1991 and 50 percent in 1992. Return to duty, reasonable cause, and periodic tests, in that order, accounted for the remaining positive tests in 1992. There were no positive post-accident tests in 1992 and four in 1991. Positive results from random tests remained below 1 percent for the third consecutive year. Flight crew accounted for 42 positive tests in 1991 and 32 in 1992. By far the largest number of positive tests come from maintenance personnel (1,586 in 1991 and 1,598 in 1992). Positive tests for both years indicated that marijuana was most prevalent (52 percent in 1991 and 57 percent in 1992), followed by cocaine (42 percent in 1991 and 33 percent in 1992), amphetamines (4 percent in 1991 and 4.7 percent in 1992), opiates (5 percent in 1991 and 4 percent in 1992), and PCP (1 percent in 1991 and 0.7 percent in 1992). Some persons tested positive for more than one drug (DOT, 1992,1994). Clearly, progress has been made and the aviation industry has now been permitted to reduce the random drug test rate to 25 percent of covered employees.

RAILROAD

In 1972, the Safety Board recommended that the FRA, “…prohibit the use of narcotics and intoxicants by employees for a specific period prior to their reporting for duty and while they are on duty.” Accidents in which alcohol and other drugs were involved continued to occur. In 1987, the Safety Board investigated a total of 156 selected accidents in which toxicological tests for alcohol and/or drug use were available in 103 cases (88 under the FRA rule, 14 transit, and 1 other). In 29 of these accidents, 1 or more railroad or rail/rapid transit employees used alcohol and/or drugs (including prescription drugs) (NTSB, 1988a).

Perhaps the most serious railroad accident involving drugs or alcohol took place at Chase, Maryland in January, 1987. A freight train improperly passed a stop signal and entered a main line track and stopped. A passenger train travelling at 120 miles per hour crashed into the freight train killing 15 passengers, the engineer and injured 174 others. Both the freight train engineer and brakeman were found to be heavy or frequent users of marijuana and were impaired by marijuana at the time of the crash (NTSB, 1988b).

The results of the FRA’s employee testing program showed significant reductions when we last reported the 1991 results to you. I am pleased to report that the trend of lower positive test rates has continued in 1992 and 1993. In mandatory tests conducted on rail workers after accidents, 1.5 percent tested positive for alcohol or other prohibited drugs in 1991, 2.1 percent in 1992 and 2.0 percent in 1993. This is a substantial decrease from the 6.0 percent level in 1988. In the reasonable cause tests, 2.1 percent were positive in 1991 and 1.9 percent were positive in 1992 and 1993. This, too, is a substantial decrease from 5.4 percent in 1988. In 1990, random testing was introduced. In 1991, 0.9 percent were found positive for drugs and by 1993 the random drug test positive rate decreased to 0.7 percent (FRA, 1994). The railroad industry has also been permitted to reduce its random drug test rate to 25 percent of covered employees.

COMMERCIAL TRUCKING

At T-92, we reported that drivers of heavy and medium trucks with positive BACs are involved in about 750 fatal crashes each year, 7,700 injury crashes, and 4,750 property damage-only crashes (TRB, 1987). We also reported on the Insurance Institute for Highway Safety roadside voluntary survey of truck drivers in which 29 percent had evidence of drugs in their blood or urine. Cannabinoids were found in 15 percent, nonprescription stimulants in 12 percent, prescription stimulants in 5 percent, cocaine metabolites in 2 percent, and alcohol in less than 1 percent. In 1992, we reported on a 1989 FHWA audit of more than 143,000 truck driver drug tests. The overall positive test result rate was 2.1 percent. By category of tests, 2.8 percent were positive on pre-employment test, 0.8 percent positive on biennial tests and 14.2 percent positive for reasonable cause tests. However, these results were not consistent with the IIHS or the Safety Board’s study.

In the Safety Board’s study of fatally-injured truck drivers, we found that 33 percent of the drivers tested positive for one or more drugs of abuse. The most prevalent drugs found were alcohol and marijuana (13 percent each), followed by cocaine (9 percent), methamphetamines/amphetamines (7 percent), other stimulants (8 percent), and other drugs at less than 1 percent. Forty one percent of those drivers tested positive for drugs of abuse were found to be multiple drug users. Almost 11 percent were positive for three or more drugs of abuse (NTSB, 1990b). In that study, we recommended that the Federal Highway Administration conduct a study of roadside drug and alcohol testing. The Omnibus Testing Act I referred to earlier included a provision requiring that study and results are now available.

A 1-year pilot study was conducted on interstate and major State roads in Nebraska, Utah, Minnesota, and New Jersey. Only Nebraska and Utah could conduct random, suspicionless drug and alcohol tests. Minnesota and New Jersey conducted probable-cause based testing supplemented by voluntary tests. The study found an overall positive test rate of 4.6 percent for drugs and 0.20 percent for alcohol. The positive drug test rate was substantially lower than the 29 percent found in the IIHS study. Both the IIHS and FHWA studies found an alcohol positive test rate of less than 1 percent. The test refusal rate was 4.2 percent for drugs and 1.0 percent for alcohol. The refusal rate in this study was much lower than the 12 percent refusal rate in the IIHS roadside testing study.

Marijuana was the most frequently identified drug, followed by cocaine, amphetamines, opiates, and PCP. Rates varied markedly among the States with amphetamine usage higher in Utah and cocaine usage highest in New Jersey. Study data may be subject to interpretation because the reporting procedures included both a medical review officer and a drug hierarchy in which some drugs were not counted, for example in multiple drug cases. Further, the type of roadway and truck included in the sample led the authors to believe that “the results presented, understate the actual level of alcohol and drug use.” (FHWA, 1995) Nevertheless, this random roadside study provides the best data currently available on the prevalence of alcohol and drug use by commercial truck drivers in these States.

Approximately 7 million holders of a commercial drivers license are now subject to alcohol and other drug testing and the regulations now require test result reporting. Therefore, I have great confidence that we will soon have even more comprehensive data to report to you and that we can, as in aviation and rail, report reductions in positive drug and alcohol test rates.

OTHER MODES OF TRANSPORTATION

The maritime industry was not included in the Omnibus Testing Act. We remain concerned that the U.S. Coast Guard does not include uninspected fishing vessels in its post-accident testing program. We note, however, that all merchant mariners are now required to be tested for drug use when applying for new or renewed licenses, certificates of registry, or other credentials. (Federal Register, 1995) We look forward to better data reporting as well.

As I noted earlier, the crash of a subway train at Union Station in New York sparked Congressional passage of the Omnibus Testing Act and granted specific safety and testing authority to the Federal Transit Administration. Most of the rail rapid transit systems in the U.S. have had some sort of alcohol/ drug testing programs. A study of substance abuse in the transit industry showed that drug and alcohol use was highest at transit agencies with limited or no testing programs. We believe that the Omnibus Testing Act will help standardize and improve the testing and prevention programs used by the industry.

CONCLUSIONS

I believe that the U.S. Federal Government has been exceptionally successful in its drug testing programs and that at least one agency with a history of alcohol testing has been very successful in reducing positive test rates. I have every expectation that other transportation industries will achieve similar success and that we will be able to document that success as fully as the rail and aviation industries have done. Any attempts to further weaken our currently successful programs should be very carefully considered.

I would like to note that the transportation workforce has a very low positive drug test rate compared to the total workforce in the United States. A large independent testing lab reported that less than 3 percent of transportation workers in safety-sensitive positions tested positive for drugs in 1992 and 1993 while about 10 percent of the general workforce tested positive in these years. (SKB, 1994) That said, there must be no tolerance, absolutely zero, for alcohol and drug use in transportation. We have had great success, but we are only half-way there. Obviously, testing alone will not solve this problem. Testing does have a deterrent effect, but effective programs must also include strategies to identify and treat abusers before it is too late.

REFERENCES

Department of Transportation. 1992. Press Release No. FAA 42-92, August 26, 1992. Washington, D.C.

Department of Transportation. 1994. Press Release No. DOT-164-94, November 23, 1994. Washington, D.C.

Federal Aviation Administration. 1991. Press Release, No. FAA 32-91, July 25, 1991. Washington, D.C.

Federal Aviation Administration. 1991. Data from Civil Aeronautical Medical Institute. Oklahoma City, OK

Federal Highway Administration. 1991. Report on the FHWA’s controlled substances testing project. FHWA-MC-91-010, Washington, D.C.

Federal Highway Administration. 1995. Random drug and alcohol pilot program final report. FHWA-MC-95-, Washington, D.C.

Federal Railroad Administration. 1992. Press release FRA 03-92. Washington, D.C.

Federal Railroad Administration. 1994. Press release FRA 24-94. Washington, D.C.

Impact 1991.Traffic Injury Research Foundation of Canada. Ottawa, Canada, Vol. 2, No. 3.

International Committee on Alcohol, Drugs and Traffic Safety. ICADTS Reporter. 1990. Sweedler, B.M., Stewart, K., Ed. Vol. 1, No. 4. Potomac Press, Bethesda, MD.

International Committee on Alcohol, Drugs and Traffic Safety. ICADTS Reporter. 1991. Sweedler, B.M., Stewart, K., Ed. Vol. 2, No. 1. Potomac Press, Bethesda, MD.

Lund, A.K.; Preusser, D.F.; Blomberg, R.D.; Williams, A.F. 1988. Drug use by tractor-trailer drivers. Journal of Forensic Sciences, JFSCA, Vol. 33, No. 3. St. Mary’s City, MD.

Mandello, T.A.; Seaman, F.J. 1979. Prevalence, cost and handling of drinking problems on seven railroads. DOT-TSC-1375. Washington, D.C.

National Highway Traffic Safety Administration. 1989. Data tapes from the Fatal Accident Reporting System. Washington, D.C.

National Transportation Safety Board. 1992. Safety Study: A review of alcohol and other drugs involved aviation accidents 1983 to 1988. Washington, D.C.

National Transportation Safety Board. 1990b. Safety Study: Fatigue, Alcohol, Other Drugs, and Medical Factors in Fatal-To-The-Driver Heavy Truck Crashes. Vol. 1, NTSB/SS-90/01. Washington, D.C.

National Transportation Safety Board. 1989. Aircraft accident report: Trans-Colorado Airlines, Inc., flight 2286 Fairchild Metro III, SA 227AC, N68TC, Bayfield, Colorado, January 19, 1988. NTSB/AAR-89/01. Washington, D.C.

National Transportation Safety Board. 1988a. Safety Study: Alcohol/Drug Use and Its Impact on Railroad Safety. NTSB/SS-88/04, Washington, D.C.

National Transportation Safety Board. 1988b. Railroad accident report: Rear-end collision of Amtrak passenger train 94, the Colonial, and Consolidated Rail Corporation Freight Train ENS-121, on the Northeast Corridor, Chase, Maryland, January 4, 1987. NTSB/RAR-88/01. Washington, D.C.

Schneck, D., Amodei, R., and Kernish, R. 1991. Substance abuse in the transit industry. Department of Transportation. Report No. DC-90-7021, Washington, D.C.

SmithKline Beecham Clinical Laboratories. 1994. Press release. Februrary 17, 1994. Collegeville, PA.

Sweedler, Barry M. 1992. Alcohol and other drug use in the railroad, aviation, marine and trucking industries-progress has been made. In proceedings of Alcohol, drugs and traffic Safety, T-92, Cologne, Germany.

Transportation Research Board. 1987. Zero alcohol and other options-limits for truck and bus drivers. Special Report 216. Washington, D.C.

Drugged Driving



http://druggeddriving.org/ddp.html

 

a. Drugged driving is on the scale of drunk driving

b. Drugged driving is not just an American problem

c. Which drugs do drugged drivers use?

d. How do we know that drug use causes crashes and impacts highway traffic safety?

e. The impairment conundrum

a. Drugged driving is on the scale of drunk driving

On the nation’s highways, drugged driving now poses a danger on the scale of the better-known problem of drunk driving. In a national survey, drugs were present more than 7 times as frequently as alcohol among weekend nighttime drivers in the U.S., with 16% testing positive for drugs, compared to 2% testing at or above the legal limit for alcohol.i In addition, a recent study of seriously injured drivers at the Maryland Shock Trauma Center showed that 5l% of the sample tested positive for illegal drugs, compared to 34% who tested positive for alcohol.ii In 2007, nearly 10 million people drove under the influence of drugs.iii

 

         Young drivers are particularly at risk for being impacted by drugged driving as supported by data on youth behaviors. Monitoring the Future showed that 30% of high school seniors had driven impaired or had been a passenger of an impaired driver in the two weeks prior to being surveyed.iv Nearly one quarter (23.2%) of high school seniors said they drove or rode with a driver after he or she used marijuana while 15.8% said they drove or rode with someone after having five or more drinks.

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b. Drugged driving is not just an American problem

Countries throughout the world are recognizing that their efforts to curb drunk driving are having good but still limited success pushing rates of drunk driving down while drugged driving continues to increase. In some samples drugged driving is passing alcohol-impaired driving as a highway safety threat.

Many countries are ahead of the U.S. in terms of dealing with drugged driving, especially Australia, New Zealand, Canada and Western Europe. For example, in a roadside study of drivers in British Columbia, over 10% tested positive for drug use compared to only 8% who tested positive for alcohol.v While alcohol-impaired drivers tended to be younger in age, with more positive test results occurring during weekends and later nighttime hours, drug-impaired drivers were more evenly distributed across all age groups and survey times.

The following data is from high school seniors in Texas which demonstrates the increase and stability of drugged driving while drunk driving has decreased since 1988. This data, like many studies from Europe and Australia show that the trend for drunk driving is down but the trend for drugged driving is up. Note that in the most recent year, the rate of drugged driving nearly equaled that of drunk driving among Texas teens.     

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c. Which drugs do drugged drivers use?

In a study of seriously injured drivers, 26.9% tested positive for marijuana while 11.6% tested positive for cocaine, and 5.6% tested positive for either methamphetamine or amphetamine.vi These percentages are far higher than those detected among drivers in the 2007 NHTSA National Roadside Survey (NRS) which found 8.6% of weekend nighttime drivers positive for marijuana, 3.9% positive for cocaine, and 1.3% positive for methamphetamine.vii The higher statistics from the crash study compared to the NRS random driver sample are clear evidence that drugged driving is a serious threat to highway safety.

Additionally, in a recent British Columbia roadside study of drivers, 10.4% of drivers who provided an oral fluid sample tested positive for at least one drug other than alcohol.viii Cannabis and cocaine were the most commonly detected illegal substances, with 4.6% of drivers testing positive for each. 0.9% of drivers tested positive for opiates. Amphetamines, methamphetamine and benzodiazepines were detected in less than 1% of drivers.

Of the total number of positive drug tests, cannabis accounted for 49.4%. Cocaine was detected in 29.3% of positive cases while opiates were detected in 14.8%. Cannabis and cocaine was the most common polydrug combination, and accounted for 8.3% of all positive drug cases.

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d. How do we know that drug use causes crashes and impacts highway traffic safety?

The Institute for Behavior and Health, Inc. has concluded that the costs of drugged driving each year include:

20% of motor vehicle accidents are attributable to Drugged Driving ix

8,600 People died in 2005 as a result of Drugged Driving x

580,000 People were injured in car crashes as a result of Drugged Driving xi

$33,000,000,000 in damages every year xii

 

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e. The impairment conundrum

Unlike drugged driving, drunk driving is easily detectable through Blood Alcohol Concentration (BAC). Modern technology can measure the BAC in a portable breath test that can be used at the roadside. State laws on drunk driving are very specific with BAC cut-off levels of 0.08%. For commercial drivers, the limit is 0.04%. The cutoff levels of 0.08% and 0.04% work reasonably well with alcohol because there is a correlation between the level of impairment and the blood alcohol level (as the alcohol level increases, the behavior becomes more impaired and as the BAC falls, impairment lessens). Nevertheless, drunk driving depends on a per se determination rather than measurement of impairment. What is measured and what is illegal for a driver is the BAC. That is what the per se level means.

The relationship between illegal drug use and impairment is even more complex than for alcohol with no linear relationship between blood levels of a drug (or drug metabolities) and impairment. There are loops of impairment related to blood levels. The size and shape of these curves vary considerably depending on the drug. In most cases blood concentrations rise and fall after illegal drug use but there are different levels of impairment at the same blood levels for any person. The legal issues are different for illegal drug use than from alcohol use by drivers over the age of 21 because the use of these drugs is illegal, as underage drinking is illegal.

In recognition of the serious problem of drugged driving for commercial drivers and for others involved in safety-sensitive jobs such as airline pilots and train engineers, in 1988 the U.S. Department of Transportation established the per se standard for illegal drug use: any evidence of recent illegal drug use was considered a violation of the law. The per se standard is not a measure of impairment but a marker of illegal driving behavior. This is exactly the standard now needed for all drivers on the U.S. roads. It is the standard widely used in most of the developed world including Western Europe. While this is controversial to some people, IBH asks if this is not a reasonable standard, why is it used for pilots and truck drivers? And if it is reasonable for commercial drivers and others, then why is it not a reasonable standard for all drivers? IBH believes this standard is not only reasonable but that widespread adoption of the per se standard for illegal drug use is important to improve highway safety.

For drivers under the age of 21, for whom alcohol is illegal, there is no legally acceptable alcohol level; any evidence of drinking is a violation. This fits with the Department of Transportation’s standard for illegal drug use: when the substance use is illegal, there is no expectation of a “safe” level. This includes use of all of illegal drugs including the nonmedical use of prescription drugs. Effective public education and law enforcement using the per se standard is the way forward not only to improve highway safety for all Americans but also to reduce illegal drug use. As a bonus an effective drugged driving program will provide a new path into treatment and long-term recovery for millions of Americans.

Click here to learn more about the per se standard.

 

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________________________________________

iRichard Compton, & Amy Berning, Results of the 2007 National Survey of Alcohol and Drug Use By Drivers. National Highway Traffic Safety Facts. Washington, DC: NHTSA’s National Center for Statistics and Analysis (July 2009) DOT HS 811 175

iiJ. Michael Walsh, Ron Flegel, Randolph Atkins, Leo A. Cangianelli, Carnell Cooper, Christopher Welsh and Timothy J. Kerns, Drug and Alcohol Use Among Drivers Admitted to a Level-1 Trauma Center, Accident Analysis and Prevention, Volume 37, Issue 5, Pages 894-901 (September 2005)

iiiSubstance Abuse and Mental Health Services Administration. (2007). Results from the 2006 National Survey on Drug Use and Health: National Findings (Office of Applied Studies, NSDUH Series H-32, DHHS Publication No. SMA 07-4293). Rockville, MD.

iv O’Malley, P.M. and Johnston, L. D. Drugs and Driving by American High School Seniors, 2001-2006, Journal of Studies on Alcohol and Drugs68(6):834-842.

v Beirness, D.J., & Beasley, E.E. (2009). Alcohol and Drug Use Among Drivers: British Columbia Roadside Survey 2008. Ottawa, ON: Canadian Centre on Substance Abuse.

viJ. Michael Walsh, Ron Flegel, Randolph Atkins, Leo A. Cangianelli, Carnell Cooper, Christopher Welsh and Timothy J. Kerns, Drug and Alcohol Use Among Drivers Admitted to a Level-1 Trauma Center, Accident Analysis and Prevention, Volume 37, Issue 5, Pages 894-901 (September 2005)

viiRichard Compton, & Amy Berning, Results of the 2007 National Survey of Alcohol and Drug Use By Drivers. National Highway Traffic Safety Facts. Washington, DC: NHTSA’s National Center for Statistics and Analysis (July 2009) DOT HS 811 175

viiiBeirness, D.J., & Beasley, E.E. (2009). Alcohol and Drug Use Among Drivers: British Columbia Roadside Survey 2008. Ottawa, ON: Canadian Centre on Substance Abuse.

ix20% is a conservative estimate based on:

• J.M. Walsh’s finding that 50% of seriously injured drivers tested positive for drugs OTA (Walsh JM, Flegel R, et al Acc Anal Prev 37, 2005)

• Barry Logan’s study showing 35% of fatally-injured drivers test positive for drugs (Schwilke, dos Santos, Logan, J For Sci, 2006)

• Barry Logan’s trucker drug-testing study which found 21% of truckers test positive for drugs (Couper, Logan. J For Sci, 2001)

• CDC estimates that 18% of traffic accidents are drug-related (http://www.cdc.gov/ncipc/factsheets/drving.htm)

• NIDA estimates that drugs are used by 10% to 22% of drivers in collisions (http://www.nida.nih.gov/infofacts/driving.html)

• NHTSA notes that, for fatally injured drivers, cannabis is detected in 7% to 37% with a mean of 14%. Each of five other drugs can be found in about 5% or less (http://www.nhtsa.dot.gov/)

x Figure based on IBH’s conservative estimate that 20% of vehicle crashes are attributable to drugged driving, and recent data from the Fatality Analysis Reporting System

xi Figure based on IBH’s conservative estimate that 20% of vehicle crashes are attributable to drugged driving, and the most recent data from the NHTSA

xii Figure based on IBH’s conservative estimate that 20% of vehicle crashes are attributable to drugged driving, and recent data from AAA’s estimate that the cost of car accidents costs $164.2 billion dollars annually

 

 


 

a. Drugged driving is on the scale of drunk driving

On the nation’s highways, drugged driving now poses a danger on the scale of the better-known problem of drunk driving. In a national survey, drugs were present more than 7 times as frequently as alcohol among weekend nighttime drivers in the U.S., with 16% testing positive for drugs, compared to 2% testing at or above the legal limit for alcohol.i In addition, a recent study of seriously injured drivers at the Maryland Shock Trauma Center showed that 5l% of the sample tested positive for illegal drugs, compared to 34% who tested positive for alcohol.ii In 2007, nearly 10 million people drove under the influence of drugs.iii

 

Young drivers are particularly at risk for being impacted by drugged driving as supported by data on youth behaviors. Monitoring the Future showed that 30% of high school seniors had driven impaired or had been a passenger of an impaired driver in the two weeks prior to being surveyed.iv Nearly one quarter (23.2%) of high school seniors said they drove or rode with a driver after he or she used marijuana while 15.8% said they drove or rode with someone after having five or more drinks.

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b. Drugged driving is not just an American problem

Countries throughout the world are recognizing that their efforts to curb drunk driving are having good but still limited success pushing rates of drunk driving down while drugged driving continues to increase. In some samples drugged driving is passing alcohol-impaired driving as a highway safety threat.

Many countries are ahead of the U.S. in terms of dealing with drugged driving, especially Australia, New Zealand, Canada and Western Europe. For example, in a roadside study of drivers in British Columbia, over 10% tested positive for drug use compared to only 8% who tested positive for alcohol.v While alcohol-impaired drivers tended to be younger in age, with more positive test results occurring during weekends and later nighttime hours, drug-impaired drivers were more evenly distributed across all age groups and survey times.

The following data is from high school seniors in Texas which demonstrates the increase and stability of drugged driving while drunk driving has decreased since 1988. This data, like many studies from Europe and Australia show that the trend for drunk driving is down but the trend for drugged driving is up. Note that in the most recent year, the rate of drugged driving nearly equaled that of drunk driving among Texas teens.

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c. Which drugs do drugged drivers use?

In a study of seriously injured drivers, 26.9% tested positive for marijuana while 11.6% tested positive for cocaine, and 5.6% tested positive for either methamphetamine or amphetamine.vi These percentages are far higher than those detected among drivers in the 2007 NHTSA National Roadside Survey (NRS) which found 8.6% of weekend nighttime drivers positive for marijuana, 3.9% positive for cocaine, and 1.3% positive for methamphetamine.vii The higher statistics from the crash study compared to the NRS random driver sample are clear evidence that drugged driving is a serious threat to highway safety.

Additionally, in a recent British Columbia roadside study of drivers, 10.4% of drivers who provided an oral fluid sample tested positive for at least one drug other than alcohol.viii Cannabis and cocaine were the most commonly detected illegal substances, with 4.6% of drivers testing positive for each. 0.9% of drivers tested positive for opiates. Amphetamines, methamphetamine and benzodiazepines were detected in less than 1% of drivers.

Of the total number of positive drug tests, cannabis accounted for 49.4%. Cocaine was detected in 29.3% of positive cases while opiates were detected in 14.8%. Cannabis and cocaine was the most common polydrug combination, and accounted for 8.3% of all positive drug cases.

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d. How do we know that drug use causes crashes and impacts highway traffic safety?

The Institute for Behavior and Health, Inc. has concluded that the costs of drugged driving each year include:

  • 20% of motor vehicle accidents are attributable to Drugged Driving ix
  • 8,600 People died in 2005 as a result of Drugged Driving x
  • 580,000 People were injured in car crashes as a result of Drugged Driving xi
  • $33,000,000,000 in damages every year xii

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e. The impairment conundrum

Unlike drugged driving, drunk driving is easily detectable through Blood Alcohol Concentration (BAC). Modern technology can measure the BAC in a portable breath test that can be used at the roadside. State laws on drunk driving are very specific with BAC cut-off levels of 0.08%. For commercial drivers, the limit is 0.04%. The cutoff levels of 0.08% and 0.04% work reasonably well with alcohol because there is a correlation between the level of impairment and the blood alcohol level (as the alcohol level increases, the behavior becomes more impaired and as the BAC falls, impairment lessens). Nevertheless, drunk driving depends on a per se determination rather than measurement of impairment. What is measured and what is illegal for a driver is the BAC. That is what the per se level means.

The relationship between illegal drug use and impairment is even more complex than for alcohol with no linear relationship between blood levels of a drug (or drug metabolities) and impairment. There are loops of impairment related to blood levels. The size and shape of these curves vary considerably depending on the drug. In most cases blood concentrations rise and fall after illegal drug use but there are different levels of impairment at the same blood levels for any person. The legal issues are different for illegal drug use than from alcohol use by drivers over the age of 21 because the use of these drugs is illegal, as underage drinking is illegal.

In recognition of the serious problem of drugged driving for commercial drivers and for others involved in safety-sensitive jobs such as airline pilots and train engineers, in 1988 the U.S. Department of Transportation established the per se standard for illegal drug use: any evidence of recent illegal drug use was considered a violation of the law. The per se standard is not a measure of impairment but a marker of illegal driving behavior. This is exactly the standard now needed for all drivers on the U.S. roads. It is the standard widely used in most of the developed world including Western Europe. While this is controversial to some people, IBH asks if this is not a reasonable standard, why is it used for pilots and truck drivers? And if it is reasonable for commercial drivers and others, then why is it not a reasonable standard for all drivers? IBH believes this standard is not only reasonable but that widespread adoption of the per se standard for illegal drug use is important to improve highway safety.

For drivers under the age of 21, for whom alcohol is illegal, there is no legally acceptable alcohol level; any evidence of drinking is a violation. This fits with the Department of Transportation’s standard for illegal drug use: when the substance use is illegal, there is no expectation of a “safe” level. This includes use of all of illegal drugs including the nonmedical use of prescription drugs. Effective public education and law enforcement using the per se standard is the way forward not only to improve highway safety for all Americans but also to reduce illegal drug use. As a bonus an effective drugged driving program will provide a new path into treatment and long-term recovery for millions of Americans.

Click here to learn more about the per se standard.

return to top

iRichard Compton, & Amy Berning, Results of the 2007 National Survey of Alcohol and Drug Use By Drivers. National Highway Traffic Safety Facts. Washington, DC: NHTSA’s National Center for Statistics and Analysis (July 2009) DOT HS 811 175
iiJ. Michael Walsh, Ron Flegel, Randolph Atkins, Leo A. Cangianelli, Carnell Cooper, Christopher Welsh and Timothy J. Kerns, Drug and Alcohol Use Among Drivers Admitted to a Level-1 Trauma Center, Accident Analysis and Prevention, Volume 37, Issue 5, Pages 894-901 (September 2005)
iiiSubstance Abuse and Mental Health Services Administration. (2007). Results from the 2006 National Survey on Drug Use and Health: National Findings (Office of Applied Studies, NSDUH Series H-32, DHHS Publication No. SMA 07-4293). Rockville, MD.
iv O’Malley, P.M. and Johnston, L. D. Drugs and Driving by American High School Seniors, 2001-2006, Journal of Studies on Alcohol and Drugs68(6):834-842.
v Beirness, D.J., & Beasley, E.E. (2009). Alcohol and Drug Use Among Drivers: British Columbia Roadside Survey 2008. Ottawa, ON: Canadian Centre on Substance Abuse.
viJ. Michael Walsh, Ron Flegel, Randolph Atkins, Leo A. Cangianelli, Carnell Cooper, Christopher Welsh and Timothy J. Kerns, Drug and Alcohol Use Among Drivers Admitted to a Level-1 Trauma Center, Accident Analysis and Prevention, Volume 37, Issue 5, Pages 894-901 (September 2005)
viiRichard Compton, & Amy Berning, Results of the 2007 National Survey of Alcohol and Drug Use By Drivers. National Highway Traffic Safety Facts. Washington, DC: NHTSA’s National Center for Statistics and Analysis (July 2009) DOT HS 811 175
viiiBeirness, D.J., & Beasley, E.E. (2009). Alcohol and Drug Use Among Drivers: British Columbia Roadside Survey 2008. Ottawa, ON: Canadian Centre on Substance Abuse.
ix20% is a conservative estimate based on:
• J.M. Walsh’s finding that 50% of seriously injured drivers tested positive for drugs OTA (Walsh JM, Flegel R, et al Acc Anal Prev 37, 2005)
• Barry Logan’s study showing 35% of fatally-injured drivers test positive for drugs (Schwilke, dos Santos, Logan, J For Sci, 2006)
• Barry Logan’s trucker drug-testing study which found 21% of truckers test positive for drugs (Couper, Logan. J For Sci, 2001)
• CDC estimates that 18% of traffic accidents are drug-related (
http://www.cdc.gov/ncipc/factsheets/drving.htm)
• NIDA estimates that drugs are used by 10% to 22% of drivers in collisions (http://www.nida.nih.gov/infofacts/driving.html)
• NHTSA notes that, for fatally injured drivers, cannabis is detected in 7% to 37% with a mean of 14%. Each of five other drugs can be found in about 5% or less (http://www.nhtsa.dot.gov/)