Assessment of transfer factor of potential toxic elements (PTEs) in aloe vera plant

Abstract

Aloe Vera plants are widely used for cosmetic, health and Medicinal purposes. Various studies have highlighted the nutritional and health benefits of Aloe Vera plants, but few studies have investigated their bioconcentration of pollutants. The main aim of our study was to estimate transfer factor (TF) of potential toxic elements (PTEs) in aloe vera gel. We estimated of PTEs including arsenic (As), cadmium (Cd), iron (Fe), nickel (Ni), lead (Pb), and zinc (Zn), in 5 groups of aloe vera plants. After 6 weeks we sampled the aloe vera gel and soil and detected the concentration of PTEs using inductively coupled plasma optical emission spectrometry (ICP-OES). We then estimated the concentration of PTEs in aloe vera gel in Iran using the results of a meta-analysis of PTEs in agricultural soil in Iran and a Monte Carlo Simulation (MCS) model. The mean (± SD) TF for Fe, Pb, As, Cd, Zn, and Ni were equal to 0.558 ± 2.487%, 0.555 ± 1.225%, 0.163 ± 0.372%, 0.122 ± 1.123%, 0.069 ± 0.415% and 0.032 ± 0.748%, respectively. The rank order of PTEs, based on their TF, was Fe > Pb > As > Cd > Zn > Ni. Moreover, the rank order of PTEs, based on the 95th percentile of concentrations in Aloe vera gel in Iran, was Pb (0.7828 mg/kg) > As (0.2800 mg/kg) > Zn (0.1601 mg/kg) > Cd (0.0444 mg/kg). TF of PTEs in Aloe vera gel were less than 1, which shows natural levels of metals in plant tissues. On the other hand, the 95th percentile concentration of PTEs in aloe vera gel was lower than the standard limits. Hence, aloe vera gel cannot threaten the health of consumers due to PTEs.