Comparative measurement of metal contents in raw and cooked rice samples prepared in different rice cookers using SR-XRF and health risk assessment

Abstract

Rice is full of nutrients that are essential to humans, however, exposure to the high metal contents in rice could also pose potential health risks to consumers. This work aimed to investigate this safety concern using the synchrotron radiation X-ray fluorescence spectrometry (SR-XRF), which is considered one of the most advanced and accurate elemental analysis techniques, to quantify metal contents, namely Fe, Zn, Cu, Ca, and Mn, in raw and cooked rice samples in order to assess the potential health risks associated with rice consumption. The results indicated that cooked rice samples had lower Fe and Ca but higher Zn, Cu, and Mn contents than raw rice samples (p < 0.05). The highest changes in metal contents were the decrease in the Ca content, which was reduced up to 8.5 times in rice samples cooked with running water and was lower than the detection limit (< 2.0 mg kg−1) in rice samples cooked with de-ionized water. When comparing the average estimated weekly intake with the available provisional tolerable weekly intake (PTWI) issued by the World Health Organization (WHO), the results showed that Fe, Zn, and Cu had lower average estimated weekly intake values than the PTWI levels. In terms of chronic, non-carcinogenic health risk assessment, the individual hazard quotient (HQ) of each metal of interest was less than the limit (1.0). However, the hazard index (HI), which combined all HQ values, was 1.15, indicating possible chronic health risks from rice consumption. The results obtained from this work suggest that further investigation is needed to fully understand and to promote awareness of the health risks caused by rice consumption.