| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| 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. | |
| Euphorbia hirta | Plant | -- | -- | * | |
| Sophora japonica | Plant | -- | -- | * | |
| Eucalyptus globulus | Leaf | -- | -- | Leung, A.Y., Encyclopedia of Common Natural Ingredients Used in Food, Drugs, and Cosmetics, John Wiley & Sons, New York, 1980. | |
| Chamaemelum nobile | Plant | -- | -- | * |