Table 4.
Reported findings of relevant studies for evaluating the potential of nicotine to act as a complete carcinogen.
| Route/adequacy scoring | Number of (sub-)studies | Positive* | Negative* | Labs† |
|---|---|---|---|---|
| Inhalation | ||||
| Total | 1 | 0 | 1 | 1 |
| High score | 1 | 0 | 1 | 1 |
| Low score | 0 | 0 | 0 | 0 |
| Oral | ||||
| Total | 7 | 0 | 7 | 5 |
| High score | 5 | 0 | 5 | 5 |
| Low score | 2 | 0 | 2 | 2 |
| Dermal | ||||
| Total | 1 | 0 | 1 | 1 |
| High score | 0 | 0 | 0 | 0 |
| Low score | 1 | 0 | 1 | 1 |
| Other‡ | ||||
| Total | 14 | 2 | 3 | 12 |
| High score | 1 | 0 | 1 | 1 |
| Low score | 13 | 2 | 2 | 11 |
To facilitate comparisons, the (sub-)studies were grouped into high and low-adequacy scoring studies with overall scores subjectively set to >2 and ≤2, respectively.
*As judged by the authors of the respective studies, where “positive” indicates stimulating carcinogenesis and “negative” indicates a lack of carcinogenic effect.
†Number of different laboratories contributing studies.
‡The two positive studies (both s.c.) were those with the longest exposure period. Many shorter but still chronic studies in this category were not planned as carcinogenicity studies and were, therefore, often not judged by the respective authors as positive or negative for carcinogenesis. This resulted in a total number of studies that was higher than the sum of studies reported as positive or negative by the authors.