| Plant | Low PPM | High PPM | StdDev | *Reference | |
|---|---|---|---|---|---|
| Cimicifuga dahurica | Rhizome | -- | 8.0 | -0.6 | * |
| Cinnamomum sieboldii | Root Bark | -- | 9.0 | -0.2 | * |
| Cinnamomum aromaticum | Bark | 2.0 | 10.0 | 1.9 | * |
| Cinnamomum verum | Leaf | -- | 10.9 | -0.5 | * |
| Cinnamomum sieboldii | Bark | -- | 7.0 | 0.1 | * |
| Cinnamomum verum | Bark | 4.9 | 9.0 | 1.3 | * |
| Cinnamomum burmannii | Bark | -- | 5.0 | -1.1 | * |
| Cistanche salsa | Plant | -- | 8.0 | -0.7 | * |
| Citrullus lanatus | Fruit | -- | 4.0 | -0.7 | Leung, A. Y. and Foster, S. 1995. Encyclopedia of Common Natural Ingredients 2nd Ed. John Wiley & Sons, New York. 649 pp. |
| Citrus paradisi | Fruit | -- | 7.7 | -0.4 | * |
| Citrus medica | Fruit | -- | 9.0 | -0.3 | * |
| Citrus aurantium | Fruit | 4.0 | 10.0 | -0.2 | Suziki, A., Morimoto, I., and Okitzu, T., Elution of Metals from Crude Drugs, Shoykugaku Zasshi 36(3):190-195. |
| Citrus sinensis | Fruit | 0.44 | 5.5 | -0.6 | * |
| Citrus aurantiifolia | Fruit | 1.0 | 6.0 | -0.5 | USDA's Ag Handbook 8 and sequelae) |
| Citrus reticulata | Fruit | -- | 4.8 | -0.6 | * |
| Cnidium officinale | Rhizome | -- | 9.0 | -0.3 | * |
| Cocos nucifera | Seed | 3.2 | 33.0 | 1.6 | * |
| Coix lacryma-jobi | Seed | -- | 5.0 | -0.9 | Suziki, A., Morimoto, I., and Okitzu, T., Elution of Metals from Crude Drugs, Shoykugaku Zasshi 36(3):190-195. |
| Colocasia esculenta | Root | 1.6 | 8.0 | -0.4 | * |
| Colocasia esculenta | Leaf | -- | 1.5 | -0.7 | * |