Bioaccumulation of Arsenic by Cultivated Waterleaf Talinum triangulare from Soil Contaminated with Sodium Arsenate Pesticide and Health Risk Assessment

Abstract

Through a pot experiment, the as concentration in the Waterleaf T. Triangulare plant grown on As-pesticide contaminated soil was examined at two treatment doses of 50 mg/kg and 70 mg/kg. After being harvested, the plant's leaves and roots as well as the soil around them were pre-treated, acid-digested, and analyzed for as content using mass plasma atomic emission spectroscopy (MP-AES Model 42100). The results from this analysis were used to determine the health risk posed by ingesting the crop. The study revealed that in all treatment levels for frequency of harvest and time of harvest, the concentration of as in the plant grew continuously over the graded period of growth (between 3 and 9 weeks after planting). Additionally, the increase in as content seen in the plant (leaf) exceeded the permissible limit of 0.1 mg/kg or 0.5mg/kg in vegetables as set by FAO/WHO/USEPA and EC/CODEX, from the third week of growth through the ninth week. The results of this investigation have demonstrated that Waterleaf's edible portions can bioaccumulate as to a great extent. Health risks results depicted that the estimated daily intake of as (EDIM) averages were below 1.0mg/kg/day and the FAO/WHO-recommended permissible tolerated daily intake of 0.002 mg/kg/day for inorganic arsenic. Similarly, the target health quotient (THQ) was below unity (THQ < 1), indicating that there is no expectation of a health danger from ingesting the plant. However, HRI or HQ was greater than unity (HRI or HQ > 1) and target cancer risk (TCR) was within the permissible predicted lifetime risk of getting cancer (1×10-6 to 1 ×10-4), thus, suggesting the possibility of cancerous disease. In addition, the ratio of HRI to RFD indicates that consumption carries a very high health risk of cancer. The overall result indicates that a serious health issue for public health concern either now or in the future may arise from the consumption of waterleaf vegetable cultivated with high use of arsenate pesticides, based on the HRI and TCR which indicates the possibility of developing cancer during a lifetime.