In the spring of 2008, the Tobacco Institute of Japan together with the associations of tobacco retailers and vending machine manufacturers introduced Taspo, "tobacco passport." At the time, the system seemed a reasonable enough solution to one of Japan's perennial problems — underage smoking. However, Taspo now is reported to have found a new use — helping investigators track down the movements of criminal suspects.

The Tobacco Institute of Japan, which oversees the Taspo system, revealed recently that personal data and records of specific tobacco purchases at Taspo-required vending machines were handed over to public prosecutors. That may seem no different from using credit card purchases as evidence or using cell phone records to trace criminal activity, but smokers still have a right to privacy.

Smokers should be made more fully aware that their data could be handed over to third parties. One wonders just how many tobacco purchases are being recorded, compiled and turned over to investigative authorities. One hopes that the personal record of tobacco purchases will not be given to employers, insurance companies or one's own family. It would probably be easier to track the smokers down in the increasingly few places left allowed for smoking.

The problem is that once data is collected, it rarely disappears. Of course, Taspo is still a voluntary system in which cardholders are told that their information may be accessed by third parties. Many smokers no doubt are unconcerned. However, the idea of having every cigarette purchase recorded on a central database should make more people than the dwindling number of smokers uncomfortable.

The purchase of tobacco, no matter how deleterious to one's health, is still legal, and individuals should still maintain the ultimate control over their own personal data. One has to wonder whether the accumulation of data by businesses is for marketing research or for other purposes. When even the purchase of a pack of cigarettes becomes part of an information database, the surveillance of people's private lives by technological means has gone too far.