Table 2 Toxicant animal carcinogenicity and non-cancer response indices* per mg nicotine of constituents in smoke generated by the modified intense regime based on Counts et al11 2005 smoke constituent level data
ConstituentMean level in smoke, μg/mg nicotine90th percentile in smoke, μg/mg nicotineMax level in smoke, μg/mg nicotineT25†mg/kg bw/dayPotency/mg/kg bw/dayToxicant animal carcinogenicity index‡Tolerable level μg/m3Toxicant non-cancer response index§
Mean90th percentileMaximumMean90th percentileMaximum
Acetone359446501NDNo TL
1-Aminonaphthalene16.2¶19.0¶24.8¶×10–30.57×10–30.74×10–3No TL
2-Aminonaphthalene10.1¶11.6¶14.3¶×10–30.93×10–31.1×10–3No TL
3-Aminobiphenyl2.9¶3.4¶4.1¶NDNo TL
4-Aminobiphenyl2.2¶2.7¶3.2¶ND**No TL
Benzo[a]pyrene9.0¶11.2¶13.8¶1.1††0.918.2×10–310.2×10–312.6×10–3No TL
Butyraldehyde43.052.463.6NDNo TL
Carbon monoxide15.2‡‡17.9‡‡27.3‡‡ND10 0001.51.82.7
Catechol48.861.665.41040.010.490.620.65No TL
Crotonaldehyde28.836.641.3INo TL
Hydrogen cyanide204277390ND922.730.843.3
Hydroquinone56.676. TL
Isoprene45955174694.8†† TL
Lead23.5¶27.7¶48.6¶39.3††† TL
Methyl ethyl ketone93.2116124ND10000.090.120.12
NAB13.4¶21.0¶23.9¶LNo TL
NAT99.7¶148¶183¶INo TL
Nitric oxide180280349NDNo TL
Nitrogen oxides199313390ND40‡‡‡
NNK70.1¶102¶111¶0.015§§§674.76.87.4No TL
NNN110¶175¶189¶ TL
Propionaldehyde60.374.088.4NDNo TL
Pyridine21.425.428.1LNo TL
Quinoline0.330.420.46NDNo TL
Resorcinol1.01.41.6INo TL
  • *Toxicant animal carcinogenicity and non-cancer indices. A cancer hazard index (CHI) is the numerical value of the amount of an individual component in cigarette smoke, normalised per mg nicotine and multiplied with its cancer potency factor (1/T25). A non-cancer hazard index (NCHI) is the numerical value of the amount of an individual component in cigarette smoke, normalised per mg nicotine and multiplied with its non-cancer potency factor (or divided by its TL).

  • †Values are from oral administration unless otherwise stated.

  • ‡Animal carcinogenicity potency factors. The T25 cancer potency estimation method of Dybing et al16 was used. The T25 value is the chronic daily dose, which will give tumours in 25% of the animals above background at a specific tissue site. The T25 is determined by linear extrapolation from the lowest dose giving a statistically significant increase in tumours (Dybing et al).16 The pertinent data from the individual cancer bioassay studies underlying the calculation of the T25 values are presented in the Annex of the full report. For the present calculations, the T25 values were converted to cancer potency factors per unit mg (1/T25).

  • §Non-cancer potency factors. Chronic reference exposure levels (REL) published by the Office of Environmental Health Hazard Assessment, California Environmental Protection Agency in February 2005 were used ( A chronic REL is an airborne level of a chemical at or below which no adverse health effects are anticipated in individuals indefinitely exposed to that level. RELs are developed both from human and animal toxicological data and presented referring to the target system for each substance. A REL is for the present calculations viewed as the inverse of the respective constituent’s non-cancer potency factor. In the present report, the term “tolerable level (TL)” was used instead of “REL”.

  • ¶ng/mg nicotine.

  • **No data for T25 calculation.

  • ††Inhalation administration.

  • ‡‡mg/mg nicotine.

  • §§Hexavalent chromium.

  • ¶¶Cresol mixture.

  • ***Highly non-linear dose–response.

  • †††Lead subacetate.

  • ‡‡‡WHO guideline for nitrogen dioxide, not listed by Cal/EPA in 2005.

  • §§§Subcutaneous administration.

  • Bw, body weight; E, evidence of non-carcinogenicity; I, insufficient evidence of carcinogenicity; L, limited evidence of carcinogenicity; NAB, N'-nitrosoanabasine; NAT, N'- nitrosoanatabine; ND, no data; NQ, not quantifiable; NNK, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone; NNN, N′-nitrosonornicotine.