Young people in the United States are smoking less but they're using more smokeless tobacco products, according to data by the National Institute of Drug Abuse and published Dec. 14 in their yearly study Monitoring the Future, which tracks the smoking habits of US adolescents in grades 8, 10 and 12.

According to the survey, 10th -12th graders are using smokeless tobacco more than before, most likely because of the proliferation of new smokeless tobacco products and increased marketing of those products. While 8th, and 12th graders were smoking less, 10th graders were smoking more than in previous years (5.9 percent in 2008 comparted to 6.3 percent in 2009) the study found. Among that same group, however, smokeless tobacco use rose 6.5 percent in 2009 from 4.9 percent in 2004, and rose 8.4 percent in 2009 compared to 6.1 in 2006 among 12th graders.

Tobacco giants Philip Morris and RJ Reynolds' entry into the smokeless tobacco market with the purchase of existing smokeless tobacco companies as well as the introduction of new smokeless tobacco products are largely to blame for the trend, the report said.

Smokeless tobacco includes snuff, plug, dipping tobacco, chewing tobacco and more recently "snus," or moist tobacco in a sachet, and they often link the names of their companies best-selling cigarette brands on their products. They come in both "fresh" and "mellow" flavors as well as a wide variety of youth-friendly candy-like forms and fruit flavors.

Another trend uncovered by the survey was that teens are not aware of the risks of using smokeless products, which have been found to increase risk of oral cancer, gum disease and cardiovascular disease. Chewing tobacco has also been shown to cause cracking and bleeding lips, bleeding and receding gums as well as  irregular heart rates and high blood pressure. Constant exposure to tobacco juice is also linked to cancer of the esophagus, pharynx, larynx, stomach and pancreas.