References
- Allaway WH (1968): Agronomic controls over environmental cycling of trace elements. Adv Agron 20: 235–274.
- Bowen HJM (1966): Trace Elements in Biochemistry. New York, Academic Press, p. 241.
- Chizzola Rand, Franz C (1996): Metallic trace elements in medicinal and aromatic plants from Austria. J Appl Bot 70: 52–56.
- Kwapulinski J, Miroslawski J, Wiechula D, Rochel R et al. (1996): The use of ecotoxicological parameters for estima-tion of the quality of medicinal plant yielding areas. Bromatologia Chemia Toksykolo Giczna 29: 243–252.
- Parmar VS, Gupta AK, Jha HN, Verma PN et al. (1993): Metal content of the medicinal plants Agave americana, Sambu-cus nigra and Silybum marianum. Int J Pharmacog 31: 324–326.
- Piscator M (1985): Dietary exposure to Cd and health effects: Impact of environmental changes. Environ Health Prosp 63: 127–132.
- Schumacher M, Bosque MA, Domingo JL, Corbella J (1991): Dietary intake of lead and cadmium from foods in Tarrag-ona Province, Spain. Bull Environ Contam Toxicol 46: 320–328.
- Sherlock J, Smart GA, Walters B (1983): Dietary surveys on a population at Shipham, Somerset, United Kingdom. Sci Total Environ 29: 121–142.
- Somers E (1974): The toxic potential of trace metals in foods. A review. J Food Sci 39: 215–217.
- WHO (1992): Expert committee on specification for pharma-ceuticals preparations. 32 Report Geneva WHO. 44–52: 75–76 (WHO technical report series no 823).
- Wong MK, Tan P, Wee YC (1993): Heavy metals in some Chinese herbal plants. Biol Trace Element Research 36: 135–142.
- Zurera G, Estrada B, Rincon F, Pozo R (1987): Lead and cadmium contamination levels in edible vegetables. Bull Environ Contam Toxicol 38: 805–812.