Men who use spit (either snuff or chewing) tobacco have a higher risk of death from heart disease, stroke, and all causes combined compared to non-users, two large prospective studies from the American Cancer Society find.

A prospective study follows a group of healthy people over time to gauge consequences of certain behaviors.

The studies are the largest to date on the subject and challenge the claim that smokeless tobacco might be an acceptable alternative to smoking.

Surveys show more than 7.7 million Americans used spit tobacco in 2003, with about four percent of middle school students and seven percent of high school students reporting spit tobacco use.

According to the Centers for Disease Control, one in seven male high school students use spit tobacco as a direct result of marketing to gets kids hooked via "starter" packs with less nicotine and flavorings like mint and cherry.

"These studies point to a significant potential danger of spit tobacco," said Dr. Michael J. Thun, the society's head of epidemiology and co-author of the report.

For the studies, S. Jane Henley and colleagues from the society's department of epidemiology and surveillance research used two large prospective cohorts to investigate patterns of disease and death among men who reported current use of smokeless tobacco at the time they were enrolled in the study.

Together, both cohorts comprised nearly 1 million men, nearly 10,000 of them smokeless tobacco users.

Men who reported spit tobacco use at the time they enrolled had higher death rates from all causes combined and from cardiovascular diseases compared to men who reported never using any tobacco product.

Associations with other diseases were less clear.

"The higher risk of cardiovascular disease that we found among spit tobacco users could reflect a toxic effect of tobacco, or may represent confounding from other factors, like the lower socioeconomic status of men who used chewing tobacco or snuff," said Henley.

"Regardless, the tobacco industry should not be allowed to promote these products as a cessation aid. The appropriate comparison is between smokeless products and nicotine replacement therapy, not between these products and smoking."