| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Arnica montana | Flower | -- | -- | * | |
| Matricaria recutita | Plant | -- | -- | Kameoka, H. and Nakai, K. 1987. Components of essential oil from the root of Glycyrrhiza-glabra. Nippon Gogeikagaku Kaishi 61(9): 1119-1122. | |
| Spinacia oleracea | Leaf | -- | -- | * |