Heavy Metal and Microbial Contamination of Valerian (Valeriana officinalis L.) Roots Grown in Soil Treated with Sewage Sludge.

Contamination with heavy metals and microbes of roots of Valerian (Valeriana officinalis L.) grown in either unamended soil (US) or sewage sludge-amended soil (SSAS) were studied in two seasons in the UK. The concentrations of heavy metals found in the washed roots from SSAS were greater than the concentrations found in roots from the US plots by 480, 2800, 215, 1900, and 82% (in 2002) and 234,446, 187,426, and 450% (in 2004) for cadmium, chromium, copper, lead, and zinc, respectively. Drying reduced the levels of coliforms, and washing treatments also tended to reduce the levels of microorganisms (Clostridia, molds, Bacillus sp.) detected on dried roots. [ABSTRACT FROM AUTHOR]