Preliminary survey of the cadmium content of phosphate fertilizer samples used for tobacco (Nicotiana tabacum L.) production
Cadmium (Cd) is classified as a known human carcinogen (Class 1) by the International Agency for Research on Cancer. It is one of the potential carcinogenic substances in tobacco products. Tobacco (Nicotiana tabacum L.) leaves may accumulate relatively high levels of Cd. The presence of this carcinogenic heavy metal in soils originates from both natural and anthropogenic sources. Anthropogenic inputs of Cd to agricultural soils may occur by the application of Cd-contaminated phosphate fertilizers and sewage sludges. In particular, phosphate fertilizers can contain high Cd levels due to the presence of the metal in the phosphate rocks used for their manufacturing. In order to investigate the Cd concentration in P-fertilizers used for tobacco production, a few P-fertilizer samples were obtained from various countries and analyzed for their Cd and P content. A >100-fold difference was found between the extreme Cd concentrations. Although the bioavailability of the Cd added through these sources to the tobacco plants in the field is not known, the use of fertilizers containing high Cd concentrations should be avoided to protect the soil from gradually accumulating this contaminant and to avoid possible additional Cd contamination of crops. Therefore, while several strategies may be followed to reduce the Cd concentration in tobacco leaves, the implementation of new agricultural practices such as the screening of fertilizers' sources may also contribute to avoid further Cd soil contamination.