Two independent studies raise new health concerns about consumption of alcohol and use of smokeless tobacco products. Both suggest a link between the products and cancer.
Presenting the study at the meeting of the American Chemical Society, researcher Silvia Balbo explained how popular alcoholic beverages may be carcinogenic and hold special risk for people of Asian descent.
Balbo says the human body breaks down, or metabolizes, the alcohol in beer, wine and hard liquor. One of the substances formed in that breakdown is acetaldehyde, a substance with a chemical backbone that resembles formaldehyde.
Formaldehyde is a known human carcinogen. Scientists also have known from laboratory experiments that acetaldehyde can cause DNA damage, trigger chromosomal abnormalities in cell cultures and act as an animal carcinogen.
"We now have the first evidence from living human volunteers that acetaldehyde, formed after alcohol consumption, damages DNA dramatically," Balbo said.
Balbo says moderate drinkers have much less risk because a natural enzyme in the body converts the acetaldehyde to a relatively harmless substance. However, she says about 30 percent of people of Asian descent -- almost 1.6 billion people -- are unable to metabolize alcohol to the harmless substance. That genetic variant results in an elevated risk of esophageal cancer from alcohol drinking. Native Americans and native Alaskans have a deficiency in the production of that same enzyme, she said.
Also at the meeting of the American Chemical Society, researcher Stephen Hecht presented findings suggesting smokeless tobacco products contain a substance that is a strong oral carcinogen, posing a risk for the nine million consumers who use the products.
Strong oral cavity carcinogen
"This is the first example of a strong oral cavity carcinogen that's in smokeless tobacco," Hecht said. "Our results are very important in regard to the growing use of smokeless tobacco in the world, especially among younger people who think it is a safer form of tobacco than cigarettes. We now have the identity of the only known strong oral carcinogen in these products."
Hecht's team identified the carcinogen as (S)-NNN, one of a family of hundreds of compounds called nitrosamines, most of which are capable of causing cancer. Nitrosamines occur in a variety of foods, ranging from beer to bacon, and also form naturally in the stomach when people eat foods containing high levels of nitrite.
The problem, says Hecht, is that nitrosamine levels in smokeless tobacco are far higher than in food.
Hecht said evidence has been accumulating for years that people who use smokeless tobacco have an increased risk of cancer of the mouth, esophagus and pancreas. He says these findings should prompt the federal government to ban or regulate the products.