Elevated atmospheric CO2 might increase the health risk of long-term ingestion of leafy vegetables cultivated in residual DDT polluted soil

Abstract

Residual dichlorodiphenyltrichloroethane (DDT) in the environment and a continuously increasing atmospheric carbon dioxide (CO₂) concentration are two issues that have received a lot of attention. This study was conducted using a pot experiment to investigate the interactive effects of elevated CO₂ and DDT on the uptake of DDT, the physiological responses and the resulting health risks in three vegetables. These vegetables included Brassica juncea var. foliosa Bailey (B. Bailey), Brassica campestris L. var. communis Tsen et Lee Suzhou Qing (B. Lee) and Brassica campestris L. ssp. pekinensis (Lour.) Olsson Chun Dawang (B. Olsson). Two levels of CO₂ and four DDT treatment levels were set up. Results showed 5 mg kg^-1 DDT significantly reduced the shoot biomass of B. Bailey when compared to 0 mg kg^-1 DDT treatment under ambient CO₂ condition. Elevated CO₂ concentration stimulated the growth of B. Bailey and B. Lee, increased the DDT uptake in the shoots of both vegetables and the values of some photosynthesis indices, and triggered the activity of peroxidase and catalase in the shoots when compared to the related ambient CO₂ treatment. Elevated CO₂ concentration increased the values of hazard indexes for non-carcinogenic and cancer risks of all vegetables when compared to the individual ambient CO₂ treatment (each of vegetable has an ambient CO₂ treatment), especially for B. Bailey (increase amplitude of 123.81%-127.78% at 5 mg kg^-1 DDT). Long-term ingestion with these DDT-polluted vegetables might result in an elevated carcinogenic risk and elevated atmospheric CO₂ may enhance the non-carcinogenic and carcinogenic risks.

Keywords: Antioxidants; Dichlorodiphenyltrichloroethane; Health risk; Leaf vegetable; Photosynthesis.