Heavy metals in commonly consumed rice grains in Bangladesh and associated probabilistic human health risks

Abstract

Food contamination by heavy metals is a concerning issue worldwide. The presence of elevated levels of heavy metals in commonly consumed rice has emerged as a critical issue in ensuring food safety. This research encompassed the collection of 44 rice samples, representing seven distinct varieties, through a randomized sampling approach across various retail markets within Dhaka city. The investigation of heavy metal content (including Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, Hg, and Pb) within the rice samples was carried out employing Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The findings disclosed substantial disparities in heavy metal concentrations among the different rice varieties. Notably, the concentrations of Cr (0.99 mg/kg), Fe (8.35 mg/kg), Pb (0.49 mg/kg), and Co (0.02 mg/kg) were observed to exceed the established maximum permissible limits. This contamination of the rice varieties may stem from either natural processes or human activities. Utilizing these metal concentrations, this study employed Monte-Carlo simulation to calculate health risk and probabilistic health risk. The Target Hazard Quotients (THQs) for Cr, Fe, and As exceeded the threshold of 1 in each rice variety, particularly in Amon and Lal Biroi in Mymensingh, Najirshail in Bogra, 28 in Sherpur and Kushtia, Miniket in Bogra and Rajshahi, and lastly, paijam in Rangpur and Tangail. Furthermore, the Hazard Index (HI) exceeded 1 in all rice varieties, implying that the consumption of these selected rice grains may have a substantial impact on overall food quality and its potential health consequences. Both carcinogenic risk and probabilistic risk for As, Ni, Cd, Cr, and Pb were found to surpass the threshold levels and safe limits, respectively. This suggests that individuals who have regularly consumed these rice varieties may face a heightened probability of developing cancer in the future, as predicted. According to sensitivity analysis, metal concentration and food ingestion rate (FIR) are the most relevant components that contribute to the significant impact of carcinogenic health hazards. Finally, the study concluded that heavy metal intake from food poses a risk to human health, necessitating the effective monitoring based on each geographic location and identify the source of this heavy metal to limit its exposure.

Keywords: Daily metal intake (DMI); Human health risk; ICP-MS; Monte Carlo simulation.

Fig. 1

Sample Collection locations in the study area of Dhaka City.

Fig. 2

Heavy metal concentration of (a) Cr (b) Pb (c) Fe (d) Co (e) Ni (f) Mn (g) As (h)Cu (i) Zn (j) Cd (k) Hg.

Fig. 3a

Target Hazard Quotient (THQ) for metals along with rice variety and Origin (a) Amon Rice (b) Lal Biroi Rice (c) Najirshail Rice (d) Chinigura Rice.

Fig. 3b

Target Hazard Quotient (THQ) for metals along with rice variety and Origin (e) Miniket Rice (f) BR-28 Rice (g) Paijam Rice.

Fig. 4

Hazard Index of rice varieties considering multiple metals addressing Adult and Children groups.

Fig. 5

Carcinogenic health risk between Adult and Children group.

Fig. 6a

Predicted probability results of the target carcinogenic risk (CR) for As & Pb for adult and Children Group.

Fig. 6b

Predicted probability results of the target carcinogenic risk (CR) for NI, Cd, and Cr for adult and Children Group.

Fig. 7

Sensitivity analysis on the Target Carcinogenic Risk for As, Pb, Ni, Cd, and Cr.

Fig. 8

Overall findings of the study.