For some, college wouldn’t be worth attending were it not for the weekend alcohol benders: Week-long bouts of studiousness bookended by weekends of debauchery and heavy drinking. Provided you lay off the sauce more often than not, letting loose a couple of days per week never hurt anyone, right? Wrong. According to a new study,  even sporadic instances of heavy drinking can damage DNA.

Coming out of Mexico, the study worked with university students to analyze the effect of weekend alcohol consumption on the lipids comprising cell membrane and its genetic material, i.e. DNA. This is the first study of its kind to examine the effect of alcohol on DNA during the early stages of alcohol abuse. Earlier studies ignored it, likely because they focused on subjects who had consumed alcohol in an addictive manner for some time.

Oddly enough, researcher Adela Rendón was prompted to launch the study when she observed college students acting like college students. While lecturing Clinical Biochemistry on a Monday morning, she noticed that students who had drank over the weekend were inattentive and out of sorts. She suspected that this was due to alcohol consumption and not because “Clinical Biochemistry” sounds like the most boring subject on Earth. She involved the students and went ahead with gathering experts and completing necessary administrative documents.

The eventual aim of the study? Oxidative damage caused by the consumption of alcohol beverages in young people.

The activity of the alcohol enzyme dehydrogenase, responsible for metabolizing ethanol into acetaldehyde, acetoacetate and acetone was measured. Oxidative damage is evaluated by a TBARS biochemical test (types that react to barbituric acid), and reflects the lipid peroxidation that affects the membrane due to the impact not only of the ethanol in the blood but also of the acetaldehyde produced by the action of the enzyme on the ethanol. That means there are at least two means by which free radicals are formed and which can damage cell membrane integrity.

Researchers were surprised not because they found results, but by the volume of those results.

“We saw that the ones who drank sustained twice as much oxidative damage compared with the group that did not consume alcohol,” Rendón said. Further examining cells via the “comet test” (used to measure damage to cell DNA), they found that students who drank had 5.3 times the number of damaged cells as those who abstained.

Scientists expect to observe that kind of damage in chronic alcohol abusers, but were surprised to see any damage at all stemming from a comparatively isolated instance of drinking.

“When we talk about youth alcohol abuse, we are referring to youngsters who drink alcohol without having become addicted. Addiction involves a more complex issue socially and psychologically speaking. This is social alcohol abuse,” said Rendón, “but which causes damage in the long term and you have to be aware of that.”

The harmful consumption of alcoholic beverages is a global issue and constitutes a significant health, social and economic problem. According to World Health Organisation data, alcohol is responsible for 2.5 million deaths a year worldwide and drinkers between the ages of 19 and 25 account for 320,000 of them.

Advance apologies to college students, who will likely receive the news in an email forward from their mothers, who will then follow up with a phone call to “talk about your drinking.”