Accumulation of Cu, Zn, Pb, and Cd in edible parts of four commonly grown crops in two contaminated soils.

Soil heavy metal pollution resulting from human activities is causing major concern due to its potential risk. In this study, four crop species with different cultivars were planted in 2 levels (heavily and slightly) of heavy metal contaminated soils, and the accumulation of Cu, Zn, Pb, and Cd in the edible parts of the crops were investigated. Metal concentrations in sesame seeds grown in both soils exceeded both the Chinese Food Hygiene Standard (CFHS) and Codex Alimentarius Commission Standard (CACS), while the metal concentrations in all pepper cultivars in the slightly contaminated soil were below the CFHS and CACS. Other crops were generally in between in both soils. Among the tested crops, the order of soil-plant transfer factor (TF) was: sesame > green soybean > cowpea > pepper. Additionally, old fruit of cowpea contained larger amounts of metals than young fruit. It suggests that sesame should not be planted in the metal contaminated area, while pepper cultivar "Chaobianjiao No.1" may be an alternative to be grown in the slightly contaminated soil. There were differences in individual human susceptibilities to metals. Therefore, a comprehensive risk assessment should consider the frequency, amount and species consumed by human besides metal concentrations in crops.