A comment in the article suggests the need to determine a relationship between the number of cigarettes smoked daily and the extent of disease that results. There is no safe use for any tobacco product. Tobacco use will result in either disease, disability or death.
To parse the degree of damage by number of tobacco units may seem to imply that there might actually be a "safe" level. Such is not now and never will be the case.
Raymond J. Melrose
The writer, a dentist, is past president of the American Cancer Society.