Two to three drinks significantly tarnishes the performance of mariners who are adamant that they are not impaired, according to a new study of low-dose alcohol.
The findings support current federal policy on the hazards of low alcohol levels for commercial shippers, said the study's authors. At a minimum, safety training for mariners should include education about the effects of small doses of alcohol, they said.
The current blood alcohol concentration (BAC) limit of 0.04 percent is set for commercial ship personnel by the U. S. Department of Transportation. The amount of alcohol consumed in the study was between 0.04 and 0.05 percent.
"It took only 18 participants to produce a statistically large effect from this relatively small amount of alcohol," said co-author Damaris Rohsenow. "This makes us think that at .03 or .02 percent BAC, mariners may not be OK. In fact, the strength of the findings suggest that the current limit of 0.04 percent may need to be lowered, but this will require the results of further research.
"The tricky thing about low dose is that participants believed they weren't impaired," Rohsenow continued. "They couldn't tell and neither could the observers. This tells us that people are not good judges of their own impairment at low doses, or of the impairment of others."
The study appears in the current issue of the journal Addiction. Rohsenow is a professor at the Center for Alcohol and Addiction Studies in the Brown University School of Medicine. The study's lead author is Jonathan Howland, a professor in the Social and Behavioral Science Department in the Boston University School of Public Health.
The researchers investigated the effects of low doses of alcohol on the simulated operation of a commercial ship's power plant. The study was conducted at the Massachusetts Maritime Academy. Participants were 18 volunteer engineering students in their senior year, at least 21 years of age, with previous experience on the simulator.
After consuming alcohol or a placebo, participants were randomized to one of four simulator scenarios, each replicating a system failure in a power plant subsystem such as main propulsion or electrical engineering. For those under the influence, the time trying to correct the problem was almost twice as long as those under the placebo condition, 351 seconds versus 186 seconds, respectively.
"If it takes twice as long to get a ship started back up, that is a significant problem," Rohsenow said. "When the engine stalls in a large ship, the vessel cannot be steered or slowed. It is imperative to restart a commercial ship as soon as possible. That vessel may leave a channel, run aground or collide with a bridge, pier or ship."
Problems related to low doses of alcohol are most likely to occur for mariners who come directly from shore to ship for watch duty after having had a quick drink or two, Rohsenow said. Over-the-counter drugs, such as antihistamines and painkillers, may cause the same effects in terms of slower reaction times, she said.
"One thing the maritime industry and federal regulators may want to consider is the use of Breathalyzer or behavioral tests for commercial seafarers going on watch," Rohsenow said.
The research was funded by a grant from the Alcoholic Beverage Medical Research Foundation and by a Career Research Scientist Award from the Office of Research and Development, Medical Research Service, Department of Veteran Affairs.
The National Institute on Alcohol Abuse and Alcoholism recently presented the findings to Congress in a report on alcohol and health.
Rohsenow and colleagues are currently studying the effect of hangover on mariners.
Journal
Addiction