Potential Human Health Risk Assessment of Heavy Metals via Consumption of Root Tubers from Ogoniland, Rivers State, Nigeria

Engaging One Health in Heavy Metal Pollution in Some Selected Nigerian Niger Delta Cities. A Systematic Review of Pervasiveness, Bioaccumulation and Subduing Environmental Health Challenges

The Niger Delta environment is under serious threat due to heavy metal pollution. Many studies have been conducted on the heavy metal contamination in soils, water, seafood and plants in the Niger Delta ecosystem. However, there is a lack of clear understanding of the health consequences for people and strategies for attaining One Health, and a dispersion of information that is accessible. The study focused on investigating the contamination levels, distributions, risks, sources and impacts of heavy metals in selected regions of the Niger Delta. Prior studies revealed that the levels of certain heavy metals, including Cd, Pb, Cu, Cr, Mn, Fe and Ni, in water, sediment, fish and plants in most Niger Delta ecosystems were higher than the acceptable threshold attributed to various anthropogenic stressors. In the reviewed Niger Delta states, ecosystems in Rivers state showed the highest concentrations of heavy metals in most sampled sites. Groundwater quality was recorded at concentrations higher than 0.3 mg/L World Health Organization drinking water guideline. High concentrations of copper (147.915 mg/L) and zinc (10.878 mg/L) were found in Rivers State. The heavy metals concentrations were greater in bottom-dwelling organisms such as bivalves, gastropods and shrimp than in other fishery species. Heavy metal exposure in the region poses risks of communicable and non-communicable diseases. Diverse remediation methods are crucial to reduce contamination levels, but comprehensive strategies and international cooperation are essential to address the health hazards. Actively reducing heavy metals in the environment can achieve One Health objectives and mitigate disease and economic burdens.

Environmental health risk assessment of heavy metal exposure among children living in an informal e-waste processing village in Viet Nam

This study was conducted to compare the exposure levels of five heavy metals via different pathways based on the field samplings and questionnaire surveys of children residing in an informal e-waste processing village and a reference village in Viet Nam. The findings revealed that levels of the total average daily intake (ADI) of the five heavy metals collected from a child at the exposed village were 3.90 times higher (p < 0.01) than that of a child at the reference village. Ingestion of cooked rice was the largest contributor to the total ADI of the children tested at both villages. However, the risks from water drinking and dermal contact of soil were negligible. The total non-carcinogenic risk and carcinogenic risk in an exposed child were significantly higher (p < 0.01) than their respective risks in a reference child. The non-carcinogenic risk to an exposed child was likely to occur, while the risk to a reference child was negligible. The carcinogenic risks found in children from both of the villages, however, were higher than the acceptable values, indicating the potential health risks to the children from both villages. The susceptibility of children to heavy metal contaminations shown in this study suggests that a mitigating measure need to be initiated jointly by a public agency and a private organization to prevent children from the risks of being exposed to the contaminants.

Speciation and accumulation pattern of heavy metals from soil to rice at different growth stages in farmland of southwestern China

Paddy rice, one of the most important food crops in Southeast Asia, is considered a main source of human exposure to heavy metal contamination because it efficiently accumulates heavy metals. In the present study, of Japonica rice grains, straw, roots, leaves, and husks and rhizosphere paddy soils (0-20 cm and 20-40 cm depth) were collected from Zunyi in northern Guizhou Province, China. The forms of heavy metals, including Cr, Cd, Pb, Cu, and Zn, in the two soil profiles were investigated using Tessier's five-stage sequential extraction procedure. There was no heavy metal pollution in the study area based on the evaluation of the geo-accumulation index and the potential ecological risk index. Accumulation varied from one area to another, and the highest metal accumulation was found in the order of root > stems > leaves. The bioaccumulation factor (BCF) results revealed that during the grain-filling stage, the rice had high BCF values (> 1) for Cd and Zn. The target hazard quotient (THQ) of ingestion peaked for Cd and reached its minimum level for Zn in not only in adults but also in children. The THQ was ranked as Cd > Cu > Pb > Cr > Zn for both adults and children. The hazard index values for adults and children for the five heavy metals were 1.81 × 10^-3 and 1.55 × 10^-3, respectively, indicating that these metals have little effect on the human body. The lifetime carcinogenic risk values for local adults and children were 4.28 × 10^-5 and 5.92 × 10^-5, respectively, both of which were within the tolerable to acceptable risk range. In summary, obvious hazards for local adults and children were not observed in this study. Considering the total amount and chemical forms of Cd, it is necessary to notify the appropriate departments about the possible rice contamination caused by Cd in the soil.

Glycine Betaine Accumulation, Significance and Interests for Heavy Metal Tolerance in Plants

Unexpected biomagnifications and bioaccumulation of heavy metals (HMs) in the surrounding environment has become a predicament for all living organisms together with plants. Excessive release of HMs from industrial discharge and other anthropogenic activities has threatened sustainable agricultural practices and limited the overall profitable yield of different plants species. Heavy metals at toxic levels interact with cellular molecules, leading towards the unnecessary generation of reactive oxygen species (ROS), restricting productivity and growth of the plants. The application of various osmoprotectants is a renowned approach to mitigate the harmful effects of HMs on plants. In this review, the effective role of glycine betaine (GB) in alleviation of HM stress is summarized. Glycine betaine is very important osmoregulator, and its level varies considerably among different plants. Application of GB on plants under HMs stress successfully improves growth, photosynthesis, antioxidant enzymes activities, nutrients uptake, and minimizes excessive heavy metal uptake and oxidative stress. Moreover, GB activates the adjustment of glutathione reductase (GR), ascorbic acid (AsA) and glutathione (GSH) contents in plants under HM stress. Excessive accumulation of GB through the utilization of a genetic engineering approach can successfully enhance tolerance against stress, which is considered an important feature that needs to be investigated in depth.

Human Health Risk Assessment of Trace Metals in the Commonly Consumed Fish Species in Nakuru Town, Kenya

The present study was conducted to determine daily intake of cadmium (Cd), copper (Cu), and lead (Pb) and to assess noncarcinogenic human health risk caused by these trace metals in the commonly consumed fish species (Oreochromis niloticus, Rastrineobola argentea, Lates niloticus, and Protopterus aethiopicus) in Nakuru town, Kenya. Trace metal determination in the composite samples of the commonly consumed fish species was done using flame atomic absorption spectrophotometer. Cd, Cu, and Pb content in the muscle tissues of the commonly consumed fish species ranged from 0.11 ± 0.045 to 1.11 ± 0.931 mg kg-1 for Cd, 0.48 ± 0.013 to 3.00 ± 0.009 mg kg-1 for Cu, and 3.42 ± 0.045 to 12.78 ± 0.108 mg kg-1 for Pb. Cu concentrations were within Food and Agriculture Organization (FAO) recommended limits for this trace metal in fish. In contrast, Cd and Pb had values above their respective permissible limits in fish. The assessment of human exposure to trace metals indicated that exposure doses of Cd and Cu were safe for fish consumers. Conversely, target hazard quotient (THQ) values of Pb suggested possible health risks for consumers of the commonly consumed fish species in Nakuru town, Kenya.

Sentinel species for biomonitoring and biosurveillance of environmental heavy metals in Nigeria

Nigeria receives copious annual precipitation to nourish its forests and agriculture, it has an extensive river drainage system, and it possesses valuable mineral deposits that stimulate both commercial and artisan mining activities. The combination of these features complicates Nigeria's efforts to produce adequate amounts of healthy foods to support its population. Toxic heavy metals like lead, cadmium, and mercury, and toxic metalloids such as arsenic, are also present in its mineral deposits and they migrate gradually into the soil and water of Nigeria by natural means. However, mining activities can liberate higher levels of toxic metals, which adversely affect Nigerian ecosystems and its food chains. Thus, environmental pollution due to anthropogenic activities is a major public health concern in Nigeria. This review covers the importance of native Nigerian and African wild and cultivated plants along with livestock and wild animals as sentinel species to evaluate heavy metals as environmental stressors and the use of sentinel species for food safety monitoring and for predicting potential risks to human health.

Toenail Metal Exposures in Fishermen from Bodo City, Nigeria

We conducted exposure assessment using toenails from 20 fishermen living in Bodo City, a community of the Niger delta region in Nigeria. This community has been affected by over 4000 oil spills and environmental disasters. Fishing is the primary source of food and income for individuals in this community. Previous research in Bodo City found elevated metal levels in fish. Toenails were used as a biomarker to investigate the feasibility for use in risk assessment studies in developing countries. The toenails collected had significantly higher manganese levels (median 5.8 µg/g) and lead levels (median 0.98 µg/g) than those reported in more developed countries, comparable levels to those from other low-middle incomes countries. These exposure levels are likely a direct result of exposures from the environmental disasters the community has experienced and would be related to increased risks for many diseases previously associated with heavy metal exposures.