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Selenium is an important micronutrient that plays key functions in antioxidant defense, immune function, and thyroid health. However, its benefits and risks are closely linked to selenium methylation, a process that significantly influences its biological activity and potential toxicity. This review critically analyse the role of selenium methylation in modulating selenium’s effects on health, highlighting its impact on both protective and adverse outcomes. it also discusses the current understanding of selenium’s essential functions and toxicity risks, emphasizing the complexities of Se methylation. The review addresses notable research gaps and controversies, including inconsistent findings on selenium’s cancer-preventive properties, the diverse biological activities of different selenium species, and the challenges in determining optimal selenium intake levels. By synthesizing existing knowledge and identifying key areas for further investigation, this review aims to advance readers’ understanding of selenium’s multifaceted roles that guide future research and public health strategies.

This study evaluated the effectiveness of coke and lemonade extraction methods compared to the standard 1 % v/v HNO3 method for determining inorganic arsenic (iAs) concentrations in rice bran samples using a field-deployable method (Arsenator field kit). The limit of detection (LOD) for the methods was 45 μg kg−1, comparable to existing literature. The extraction efficiencies were assessed by comparing iAs recovery rates, with coke extraction yielding the highest recovery of 127.4 %, followed by lemonade at 116.2 %, and HNO3 at 100 %. Statistical analysis indicated strong correlations between the extraction methods, particularly between HNO3 and coke (Pearson correlation coefficient, 0.990), suggesting that coke extraction is a reliable alternative to the traditional HNO3 method. However, lemonade extraction showed a lower correlation (0.940) and higher false negative rates, indicating potential limitations for regulatory compliance. Notably, at the maximum contaminant limit (MCL) of 0.100 mg kg−1, coke extraction produced an 8 % false positive rate with no false negatives, while lemonade extraction had an 8 % false positive rate and a 17 % false negative rate. This study underscores the potential of coke extraction as a cost-effective and efficient alternative for assessing iAs levels in rice products, especially in resource-limited settings. Recommendations include the standardization of coke extraction protocols and the development of robust monitoring programs to ensure food safety and public health protection against arsenic contamination. Overall, the findings contribute valuable insights for improving arsenic detection methods and regulatory compliance in food safety practices.

This study aimed to assess the potential health risks associated with consuming three commonly consumed medicinal herbs in Malawi: Azadirachta indica, Mondia whitei, and Moringa oleifera. The concentrations of five metal(loids) (As, Cd, Pb, Cr, and Co) were determined using inductively coupled plasma mass spectrometry, while their safety was assessed by comparing the measured values with the legislated maximum contaminant levels (MCL)and reported metal(loids) concentrations in other countries. The results indicated significant variations of metal(loids) concentrations amongst the studied medicinal herbs, with Azadirachta indica containing the highest mean As (0.078 ± 0.010 mg kg−1) and Cd (0.049 ± 0.05 mg kg−1) concentrations and Mondia whitei and Moringa oleifera contained the highest mean Co (1.01 ± 0.05 mg kg−1) and Cr (1.42 ± 1.18 mg kg−1) concentrations, respectively. However, the mean concentrations of As, Cd, Pb, Cr, and Co fell below the MCL set by World Health Organization (WHO), Alimentarius Commissions, and European Commission. The estimated daily intake (EDI) for each metal(loid) was less than 1, indicating that the studied medicinal herbs do not pose serious health risks to non-regular consumers. The study also emphasizes the importance of assessing the potential risks associated with consuming medicinal herbs contaminated with heavy metals or metalloids, as it can seriously threaten human health.

This review aimed to investigate the reported concentrations of arsenic (As), cadmium (Cd), and lead (Pb) in rice cultivated in Africa and African rice paddies compared to other regions. It also aimed to explore the factors influencing these concentrations and evaluate the associated health risks of elevated As, Cd, and Pb exposure. Relevant data were obtained from electronic databases such as PubMed, Scopus, and Google Scholar using specific keywords related to arsenic, cadmium, lead, rice, Africa, paddy, and grain. While the number of studies reporting the concentrations of As, Cd, and Pb in rice and rice paddies in Africa is relatively low compared to other regions, this review revealed that most of the African rice and paddy soils have low concentrations of these metals. However, some studies have reported elevated concentrations of As, Cd, and Pb in paddy fields, which is concerning due to the increased use of agrochemicals containing heavy metals in rice production.Nonetheless, agronomical interventions such as implementing alternate wetting and drying water management, cultivating cultivars with low accumulation of As, Cd, and Pb, amending rice fields with sorbents, and screening irrigation water can limit the bioaccumulation of these carcinogens in paddy fields using phytoremediation techniques. Therefore, we strongly urge African governments and organizations operating in Africa to enhance the capacity of rice farmers and extension officers in adopting approaches and practices that reduce the accumulation of these carcinogenic metals in rice. This is essential to achieve the sustainable development goal of providing safe food for all.