Journal of trace elements and minerals最新文献

Background

Dust is ubiquitous and humans are unavoidably in constant contact with it. Therefore, exposure to metal-laden dust from workplaces can be a serious threat to human health.

Objective

The objective of this study was to assess the concentrations of nine metals, namely, Cd, Pb, Cr, Ni Cu, Co, Mn, Zn and Fe, in dust from automobile mechanic workshops (AMWs) in urban and semi-urban areas of Delta State, Nigeria.

Methods

The dust samples were digested in aqua-regia and their metal content was determined by atomic absorption spectrometry.

Results

The concentrations of metals (mg kg^-1) in dust from the AMWs ranged from 0.12 to 4.20 for Cd, 11.3 to 3900 for Pb, 9.05 to 45.3 for Cr, 0.35 to 345 for Ni, 170 to 56,400 for Cu, 1.05 to 31.4 for Co, 51.3 to 310 for Mn, 143 to 634 for Zn, and 70,900 to 258,000 for Fe. The pollution indices indicated that Cd, Cu, Pb and Zn were the prominent contaminants in dust from the AMWs. Children's exposure to metal-laden dust from the AMWs could elicit adverse non-carcinogenic health effects. The carcinogenic risk values obtained for human exposure to metals in dust from the AMWs were above the safe level indicating possible induction of cancer or cancer-related illnesses. The sources of metals in dust from the AMWs are related to automobile emissions and discharges from vehicular components.

Conclusion

The activities in AMWs are potent sources of metals to the environment, especially Cd, Cu, Pb and Zn. Therefore, this study recommends regulatory control of activities conducted in AMWs so as to minimize widespread metal contamination and the consequent impact of metals in the affected dust on humans and the environment.

Introduction

Among the increasing number of cancer cases, colorectal cancer (CRC) cases are rising globally. The association of zinc in the neoplastic process of CRC is a major research avenue, yet the published reports have not provided any definitive conclusion.

Objectives

We examined the association between serum zinc levels and CRC to test the potential of zinc dysregulation as a CRC susceptibility factor.

Methods

In this systemic review and meta-analysis, we extensively searched EBSCOhost, EMBASE, Cochrane Library, ProQuest, PubMed/MEDLINE, Scopus, and Web of Science as well as manual screening by subject experts for studies reporting serum/plasma/blood zinc levels in CRC patients and control subjects till 27th August 2023. Based on a random effect model, we estimated the mean difference in serum/plasma/blood zinc levels between CRC cases and control subjects. Subgroup differences and publication bias were also investigated, along with a critical appraisal of included studies.

Results

Eighteen studies with 8330 participants were included. The difference in serum zinc between CRC patients and control subjects was –5.01 µg/dl [95 % CI: −21.76 to 11.74; p = 0.56]. Omitting a highly influential outlier study, made this difference statistically significant at –13.28 µg/dl [95 % CI: −20.66 to -5.90, p < 0.01]. The difference between study effects could not be explained by the difference in analytical methods for zinc assessment, or type of blood samples.

Conclusion

CRC patients had lower serum zinc levels. Some factors, such as different tumor grades of CRC, adenomas, and colonic polyps need to be further considered for a more conclusive association between serum zinc levels and risk for CRC.

Background

This research employs response surface methodology, specifically Central Composite Design (CCD), to optimize the process parameters for the effective production of biodiesel. Jatropha oil was utilized as the raw material to minimize expenses. A nanocatalyst was utilized as a solid catalyst, developed from CaCO₃ via waste snail shells, offering advantages such as recyclability and improved catalytic activity during a transesterification process. The developed nanocatalyst was analyzed using various techniques, including dynamic light scattering (DLS), scanning electron microscopy (SEM), Brunauer–Emmett–Teller (BET) analysis, and Fourier-transform infrared (FTIR). The BET analysis revealed a surface area of 5.1m²/g and the Barrett-Joyner-Halenda (BJH) analysis provided insights into the pore volume and diameter of the synthesized nano-CaO, showing values of 0.002556 cc/g and 1.1 nm, respectively, indicating the presence of both microspores and active sites on the external surface of the nano-CaO catalyst. Biodiesel conversion was controlled by adjusting factors like the methanol to oil ratio, catalyst weight, reaction time, reaction temperature, and agitation speed. A quadratic model was established to explore the correlation between the independent variables and the biodiesel conversion rate. The results showed a maximum biodiesel conversion rate of 96.73% under the optimal conditions: methanol to oil ratio (6:1), catalyst weight (1.4 wt%), reaction time (60 min), reaction temperature (55 °C), and agitation speed (250 rpm). These parameters were determined through 32 experimental trials. The RSM technique yielded impressive results with a determined coefficient of determination (R²) of 0.9834, adjusted R² of 0.8503, predicted R² of 0.8309, and a coefficient of variance (CV) 0.75%. Based on the analysis of variance (ANOVA) findings, the model exhibits a high level of significance (p<0.0001), which is less than 0.05 and F- Value 29.71.The study aims to enhance the yield and efficiency of the transesterification process, thereby increasing the overall production of fatty acid methyl ester from Jatropha oil. This innovative approach efficiently generates biodiesel from renewable resources, in a manner that is both environmentally friendly and maximizes the effectiveness of the process parameters. The evaluation conform that the quality of the biodiesel met the standards set by ASTM D 6751 and EN 14214.

Introduction

The concentrations and risks of metals (Cd, Pb, Cr, Ni, Cu, Co, Mn, Zn and Fe) in organs of sheep from Southern Nigeria were investigated in this study.

Methodology

A total of 105 sheep organs (kidney, liver and muscles) were collected from abattoirs in five widely distributed areas (Asaba, Benin, Onitsha, Sapele and Warri) in southern Nigeria. The organs were digested using a mixture of nitric and perchloric acids and thereafter the metal concentrations in the digested sample solutions were determined using an atomic absorption spectrophotometer.

Results

The mean concentrations of metals (mg kg⁻¹) were as follows: Cd: 0.05–0.37, Pb 0.86 to 1.99, Cr: 2.20–3.03, Ni: 1.87–3.54, Cu: 17.4–24.3, Co: 1.45–4.30, Mn 192–410, Zn: 41.8–117 and Fe: 423–1068. The concentrations of the metals in the organs were in the order of Fe > Mn > Zn > Cu > Ni > Cr > Co > Pb > Cd while the ability of the sheep organs to accumulate the studied metals followed the order of liver > kidney > muscles. The estimated daily intake values suggested that except for Mn, the intake of metals from the ingestion of these sheep organs was below their respective PTDI. The hazard index and total cancer risk values show that there are no possible risks of non-cancer and cancer risks associated with the consumption of the sheep's organs.

Conclusion

Although there are no health risks associated with the metals in the sheep organs from southern Nigeria, there is, however, a need for continuous monitoring of contaminants in sheep and other animal organs.

Background

Food crop consumption is one of the primary routes through which the environment is polluted with radionuclides, metals, and metalloids. In recent years, the negative impacts of metals, metalloids, and radionuclides on crop quality via the food-human system have jeopardized both human health and food security. Because some metals, metalloids, and radionuclides are persistent and non-biodegradable, they build up in the human body's essential organs, causing a variety of serious health issues, including cancer. It is therefore absolutely essential to evaluate the potential cancer risks of radionuclides as well as metals and metalloids in the food crops consumed in the study area to avoid negative health consequences.

Objective

The aim of this study was to assess the potential cancer risks of metals and metalloids (As, Cd, Cr, and Pb) and Radionuclides (U-238, Th-232, and K-40) via consumption of food crops cultivated around the Riruwai mining area, northeastern Nigeria.

Methodology

Thirty-three (33) food crops (15 vegetables and 18 cereal crops) were collected directly from the farmlands in the study area. The concentrations of radionuclides, metals, and metalloid in each food crop were assessed using a microwave-plasma atomic emission spectrometry (MP-AES) and a high-purity germanium (HPGe) gamma-ray spectrometer, respectively. The measured concentrations of radionuclides, metals, and metalloid were used to calculate their lifetime cancer risks (LTCRs).

Results

The findings of the study revealed that the concentrations of As, Cd, Cr, and Pb in all the investigated food crops were above the threshold limits, while lower activity concentrations in all the investigated food crops below the world average standard were observed in U-238, Th-232, and K-40. LTCRs of all the individual metal and metalloid as well as radionuclide in each food crop were determined to be below the global threshold limits, indicating no likelihood of cancer risk from consuming the food crops. However, it was discovered that the total cumulative LTCRs of all the metals and metalloid in all food crops combined were 2.51E-04, which was over twofold the acceptable limit of 1.00E-04

Conclusion

The individual metal, metalloid, and radionuclide LTCRs in each food crop were found to be below global threshold limits, indicating no cancer risk from consumption. However, the cumulative LTCRs of all the metals and metalloid in all food crops were found to exceed the acceptable level, which requires proper monitoring and government intervention. Cancer risk is influenced by factors beyond food consumption, such as alcohol consumption, heredity, and air pollution, so multidimensional studies are needed before making a final decision on cancer risks in the study area.

Heavy metal (HM) pollution in agricultural soils represents a hidden danger to food security worldwide. In this paper, the spatio-temporal trends of heavy metals from eight countries and 50 soil samples from agricultural farmland were evaluated through a combination of field surveys and meta-analysis to provide a comprehensive report on heavy metal pollution. The soil samples were analysed using inductively coupled plasma–mass spectrometry (ICP-MS) (Perkin Elmer Nixon 300Q). The contamination factor (CF) and pollution load index (PLI), and diagnostic tests on the extracted data were calculated. The results of the CF in the soils indicate extreme contamination for Cr, suggesting ecotoxicological effects, while the PLI values range from baseline to moderate pollution for Cd, Hg, Cu, Zn, and Ni, except for Cr, which shows very high pollution, suggesting that the soils have undergone some form of deterioration. The meta-analysis results of the 50 reviewed articles published between 2010 and 2023 showed increasing trends for all the HMs. The weighted mean values of Cd, Cr, Hg, Cu, Zn, As, and Ni were in the range of 0.0-222.7, 0.08-289.2, 0.03-193, 2.94-198.1, 0.0-771.1, 0.0-231, and 1.71-99.75.6 mg/kg, respectively. The mean values of Cd, Hg, Zn and As exceeded two to three times the values of China National Environmental Monitoring Centre (CNEMC) European Union's most cited guideline (MEF), and the rock crust guideline. The results of the correlation matrix heatmap revealed a highly positive correlation between Cr and Ni (R² = 0.66), suggesting that these elements have the same source and are likely prevalent in agricultural soils. The spatial origin of the publications reveals that 82% of the studies were from China followed by South Africa and Italy accounting for 4% respectively while Nigeria, Egypt, Morocco, Iran, and Turkey account for 2% each. The findings of this study have important implications for environmental regulation on agricultural food protection from heavy metal pollution. Unlike previous meta-analysis studies which often adopt a “silos” method, this study highlights a nexus approach that integrates both meta-analysis and experimental studies which could establish a more comprehensive understanding of heavy metal pollution in agricultural soils.

Objective

The present study aimed at investigating the probable health risk associated with potentially toxic metals (PTMs) in irrigable wetland soils from Ogun and Lagos states, Southwestern Nigeria.

Methodology

A total of 36 composite soil samples were collected from twelve monitoring sites and analyzed for potentially toxic metals [cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), nickel (Ni), lead (Pb), and zinc (Zn)] using atomic absorption spectrophotometry. PTM data underwent inferential and descriptive statistical analysis using IBM SPSS. Health risk indices were assessed for hazard quotient (HQ), hazard index (HI), and cancer risk (CR) using the standard method. Ecological and pollution risks were also assessed.

Results

Fe (1465±977 to 47,785±12,049  mg kg⁻¹) was the most abundant metal observed in irrigable wetland soils. The distribution pattern of PTMs in irrigable wetland soils followed the decreasing order of Fe > Zn > Cu > Cr > Pb > Ni > Co > Cd. The pollution index risk indicated values greater than 1.0 for Cd (2.43–133), Zn (1.60–6.32), Cu (1.49–5.89), and Pb (1.15–2.94). Cadmium indicated a considerable ecological risk index (4002), a moderate-to-high pollution level according to the Nemerov integrated pollution index (12.33), and a very high enrichment factor (14.1–227). The HQs of PTMs were generally less than 1.0 for adults, while a HI greater than 1.0 was observed for children. The CRs exceeding the threshold limit of 1.0 × 10⁻⁴ were observed for Co, Cd, Cr, and Ni [at one or more sampling sites] in the wetland soils exposed to by adults and children.

Conclusion

In this study, the irrigated wetland soils showed high ecological, pollution, and carcinogenic risks of Cd, particularly at the Odo Aro monitoring site. The findings from the study could offer a theoretical basis and data support for pollution monitoring, assessment, and control in the study area.