| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Marrubium vulgare | Plant | -- | -- | Williamson, E. M. and Evans, F. J., Potter's New Cyclopaedia of Botanical Drugs and Preparations, Revised Ed., Saffron Walden, the C. W. Daniel Co., Ltd., Essex UK, 362 pp, 1988, reprint 1989. | |
| Myristica fragrans | Seed | -- | -- | Leung, A.Y., Encyclopedia of Common Natural Ingredients Used in Food, Drugs, and Cosmetics, John Wiley & Sons, New York, 1980. | |
| Salvia sclarea | Plant | -- | -- | CRC Handbook of Medicinal Herbs and/or CRC Handbook of Proximate Analyses | |
| Thymus vulgaris | Essential Oil | -- | -- | * |