A google search of "low-tar cigarettes" results in numerous matches, the majority of which appear to be negative on their usefulness, saying that they are no less hazardous than regular-tar cigarettes. In fact, some of the matching articles suggest that switching to low-tar cigarettes halves the chance of quitting smoking. However, this conclusion is contradicted by some other studies such as this one which states the following:
Smoking and health experts have been concerned that reducing the nicotine content of cigarettes would lead to smoking a greater number of cigarettes and therefore increased exposure to other tobacco smoke toxins, as is seen in smokers of the currently marketed low-nicotine yield cigarettes, Benowitz said. The new research on reduced-nicotine content cigarettes strongly counters that prediction.
Another article, titled "Could FDA reduce nicotine levels in cigarettes?", states the following:
Another strategy might be to reduce the harm from tobacco by lowering the nicotine content/delivery of cigarettes down to the level at which they are no longer addictive. A form of this strategy was proposed in the 1990’s by leading tobacco researchers Professor Neal Benowitz, and Professor Jack Henningfield. The FDA legislation singles out nicotine as the only chemical that cannot be reduced to zero, but this allows FDA the right to reduce the nicotine delivery of tobacco products down to a level just above zero at which they would no longer be addictive.
Hence, there does seem to be some disagreement on the subject. This disagreement may have played some role in the FTC ceasing to release reports on the tar and nicotine content of cigarettes. This Boston Globe article describes this as follows:
The Federal Trade Commission for three decades regularly released reports on the nicotine and tar content of cigarettes -- reports that frequently came under criticism for failing to adequately reflect the amount of nicotine smokers inhale in actual use.
The reports showed that nicotine levels on average had remained stable since 1980, after falling in the preceding decade. The last of those studies was released in September 1999, commission spokeswoman Claudia B. Farrell said yesterday.
The Federal Trade Commission has continued collecting data on nicotine, but she did not know why they have not published reports on the findings.
This brings up the question of whether the FTC should have continued to release this data to the public, even if the data was less than perfect. In any event, this is now the responsibility of the FDA (Food and Drug Administration). Section 915 of the recently passed Family Smoking Prevention and Tobacco Control Act states the following:
(2) may require that tobacco product manufacturers, packagers, or importers make disclosures relating to the results of the testing of tar and nicotine through labels or advertising or other appropriate means, and make disclosures regarding the results of the testing of other constituents, including smoke constituents, ingredients, or additives, that the Secretary determines should be disclosed to the public to protect the public health and will not mislead consumers about the risk of tobacco-related disease.
From the above excerpt, the law appears to give the Secretary of Health and Human Services the power to require tar and nicotine content to be included in advertisements and on package labels but does not mandate that this will occur. Likewise, it does not appear to mandate the disclosure of tar, nicotine, and other ingredients to the public but leaves this to the discretion of the Secretary. Hence, it is unclear as to if or when updated tar and nicotine figures will be released to the public.