Other Trace Contaminants in Smokeless Tobacco

Research has shown trace concentrations of other contaminants in SLT products, such as cadmium, polonium-20, formaldehyde, benzo(a)pyrene and lead. Organizations with anti-tobacco agendas, like the National Cancer Institute and the Mayo Clinic, have published disparaging, factually incorrect references to these agents, variously labeling them as “used in car batteries”, “poison”, “nuclear waste” and “embalming fluid.” Rodu notes that, “While these allegations provide maximum shock value for anti-tobacco propaganda, we have documented that a smokeless tobacco user’s exposure to these compounds is similar to levels present in one’s daily diet.”

Here is a primer on some of these agents.

Cadmium

Cadmium is found in low concentrations in most soils, and it has the most widespread distribution of all heavy metals in foods. Cadmium is present in the general diet. Cereals and grains provide the highest percentage of total intake, but cadmium is also present in shellfish and some vegetables such as spinach. A typical general diet supplies about 25 micrograms (1/1000 of a gram) of cadmium daily, and the World Health Organization set a maximum recommended intake of 52 micrograms per day. A smokeless tobacco user consuming 10 grams of moist snuff per day may be exposed to approximately 4 to 8 micrograms of cadmium (All research estimates for smokeless tobacco are from 1987).

Polonium-210

Polonium-210 is a radiodecay product of Radium-226, which is itself a product of Uranium-238 decay. Although Radium-226 is located primarily in uranium-bearing ores and associated soils, Polonium-210 is disbursed widely in the environment by rain and other weather events because an intermediate decay product, Radon-222, is an extremely mobile gas. The dominant mechanism of plant deposition is from surface absorption and transfer to edible foliage and seeds, berries or fruits. Food ingestion is the major source of polonium-210; the diet supplies from one to ten pico Curies per day. Polonium-210 in tobacco is derived both from fertilizers and from airborne particles that are trapped by leaves. Consumption of 10 grams of moist snuff per day gave an exposure of about one to seven pico curies daily from polonium-210. In 1989, research showed that Swedish moist snuff users were estimated to have a polonium-210 exposure consistent with three dental radiographs, and it was concluded that the risk to snus users was so small that no special measures or other actions were necessary.

Formaldehyde

Formaldehyde is primarily produced as an industrial chemical and has widespread use in manufacturing. Formaldehyde is also present as a natural product in the environment and in most plants and animals. For example, formaldehyde is present in human blood in concentrations of 2 to 3 milligrams per liter. It is present in varying concentrations in a wide variety of foods such as meat and poultry, fish, and fruits and vegetables. The concentration of formaldehyde in moist snuff is about 5 to 7 micrograms/gram.

Benzo(a)pyrene

Polycyclic aromatic hydrocarbons (PAHs) have been present in the environment since the advent of fire. More specifically, they have been present in human diets since man began cooking meat. One of the most common, and intensely studied, PAHs is benzo(a)pyrene (BaP). The major dietary source of BaP is charbroiled meats, but plants also contain measurable amounts of BaP due to direct surface contamination of plants from environmental sources. Thus, in addition to charcoal-broiled steaks, dietary sources include leafy vegetables, tea and cereals. Some moist snuff brands contain low levels of BaP (<0.1 to 4 nanograms per gram)(a nanogram is one millionth of a gram), while others contained concentrations up to 63 nanograms per gram. The concentration of BaP in any brand of moist snuff probably reflects the proportion of fire-cured tobacco used in that blend.

Cadmium

Throughout much of the 20th century the major source of lead in the environment was from combustion of lead-containing fuels. Absorption from dietary sources is limited, because lead in the soil is not readily taken up by most plants. In addition, lead in livestock is largely deposited in bone tissue, which limits its transfer to meat consumers. Fruits and vegetables remain the largest sources of dietary lead, and the average diet supplies about 50 micrograms per day, with a maximum daily intake of 150 micrograms set by the World Health Organization. A person consuming 10 grams of moist snuff per day is exposed to about 3 to 16 micrograms of lead.

Here is a summary table of these agents in tobacco products and common foods:

This research was supported by the Tobacco Research Fund (UAB).