Safe utilization of polluted soil by arsenic, cadmium and lead through an integrated sericultural measure

Effective remediation technologies to remediate multiple heavy metal contaminated farmlands are lacking. To make full use of farmlands and control its consequent health risks, we planted mulberry trees in arsenic (As)-cadmium (Cd)-lead (Pb) co-contaminated soils at four different sites; then reared silkworms on leaves harvested from these mulberry trees; and finally used the silkworm excrement to in situ remediate the As, Cd, and Pb polluted paddy soil. Mulberry leaves and stalks showed weak abilities to accumulate As, Cd, and Pb. As and Pb tended to accumulate in silkworm pupae and silkworm excrement, respectively, posing a potential health risk when they were used as pharmaceutical materials or foods. However, using the leaves of mulberry trees planted in Cd-contaminated soils to rear silkworms had a low health risk. Silkworm excrement significantly reduced the As, Cd and Pb concentrations in rice grains, with As and Cd concentration being lower but for Pb being higher their respective national limit standards. In conclusion, based on the rational utilization of resources such as silkworm excrement, pupae, and cocoons, the integrated measure in this study could effectively reduce the environmental health risks resulting from multiple As, Cd, and Pb contamination.