of MRTPs. The same range of research methods employed to establish a causal relationship between tobacco and disease will be needed to provide evidence on the health effects of MRTPs on both individual and public health. This chapter discusses that evidence and provides guidance on how the Food and Drug Administration (FDA) should consider different types of that evidence in its decision-making process. The chapter begins with a discussion of the composition of modified tobacco products. The committee then discusses biomarkers of MRTPs, including biomarkers of exposure and biomarkers of effects. Next, it discusses preclinical and clinical studies, including the advantages and disadvantages of those studies, and what evidence the various study types can provide to inform the FDA’s decisions on MRTPs.
Smokeless tobacco products, such as oral snuff, and combusted tobacco products, such as cigarettes, are the main types of tobacco products used in the United States (SAMHSA, 2007). The composition of tobacco and tobacco smoke has been the subject of intense study for at least the past 60 years, and studies have identified more than 8,000 constituents of tobacco and tobacco smoke (Rodgman and Perfetti, 2009). Validated methods are available to quantify many constituents of tobacco and tobacco smoke (Borgerding and Klus, 2005; Rodgman and Perfetti, 2009), and the chemical composition can have a large effect on the potential health risks of a given product. Product composition, including how the constituents compare to other products, therefore, is an important aspect of any new product. Although different tobacco products continue to be introduced, this section discusses the types of tobacco products currently available, the methods for analyzing them, and the commonly reported constituents. Smokeless products are discussed first, followed by a discussion of combusted products.
Smokeless Tobacco Products
Types of Smokeless Products
Smokeless tobacco products used in the United States include moist snuff and chewing tobacco (for oral use), and dry snuff (for nasal use). Types of chewing tobacco include plug, twist, and loose leaf varieties. The use of chewing tobacco and dry snuff has declined over time. Oral moist snuff is by far the most popular kind of smokeless tobacco in the United States (Federal Trade Commission, 2007). Oral moist snuff is used by placing the tobacco—either loose or packaged in a tea bag-like sachet—