Origin | Low ng | High ng | Year | Sample |
---|---|---|---|---|
ND, not done. | ||||
ISO testing | ||||
Fischer | ND | 470 | 1990 | Global, multiple |
Gray | 54 | 326 | 1996 | Marlbro, 30 countries |
Australia | ND | 41 | 2001 | 15 brands |
Canada | 21 | 86 | 2002 | 27 brands |
Intense testing system | ||||
Australia | 38 | 94 | 2001 | Same 15 brands |
Canada | 58 | 138 | 2002 | Same 27 brands |