Chukwujindu M. A. Iwegbue

Concentrations of selected metals in candies and chocolates consumed in southern Nigeria

Results are presented for the determination of levels of Ca, Cd, Ni, Cr, Cu, Pb, Mn, Zn Fe, Co and Mg in candies and chocolates consumed in southern Nigeria. Mean concentrations of metals in both confectionaries ranged 7.7–1405.2 µg/g1 for Ca, <0.001–0.2 µg/g for Cd, 1.4–7.9 µg/g for Ni, 0.4–3.0 µg/g for Cr, <0.08–2.3 µg/g for Pb, 0.4–12.6 µg/g for Mn, 0.6–8.0 µg/g for Zn, 1.7–12.3 µg/g for Fe, <0.05–1.49 µg/g for Co, and 8.4–576.1µg/g for Mg. The data showed that that these metals are not present at harmful levels. Concentrations of nickel and chromium were slightly elevated but were comparable to levels reported in similar food items elsewhere in the world.

Chemical fractionation of some heavy metals in soil profiles in vicinity of scrap dumps in Warri, Nigeria.

Abstract The lability of Cr, Ni, Pb, Fe, Mn, Cd and Cu in soils contaminated by scrap dumps in Warri, Nigeria was assessed by a sequential chemical extraction procedure (SCE) to fractionate the metals into MgCl2extractable fraction, Na-acetate extractable fraction, hydroxylamine hydrochloride extractable fraction, HNO3/H2O2 extractable fraction and HF/aqua-regia extractable fraction. The results indicate that Pb is associated with HF/aqua-regia and hydroxylamine hydrochloride extracted fraction. Copper and chromium was associated with HNO3/H2O2 and HF/aqua-regia extracted fractions. Cd, Mn and Fe were associated with HF/aqua-regia and hydroxylamine hydrochloride extracted fractions. However, in some sites up to 45% of Cd was found in the MgCl2 and Na-acetate extracted fractions. The metals associated with hydroxylamine hydrochloride and HNO3/H2O2 extractable fractions may be available to the biota when the pH and the redox potential of the soil changes. Data presented provides information on the lability of metals in soil profiles in the vicinity of scrap dumps.

Safety evaluation of metal exposure from commonly used moisturizing and skin-lightening creams in Nigeria

The concentrations of ten metals (Cd, Pb, Ni, Cr, Cu, Co, Fe, Mn, Zn and Al) were measured in some commonly used moisturizing and skin-lightening creams in Nigeria with a view to providing information on the risk of exposure to metals from the use of these products. The metal concentrations in these products were measured by atomic absorption spectrometry after acid digestion of the samples. The measured concentrations of metals in the skin moisturizing creams ranged from <0.15 to 6.3 μg/g Cd, <0.02 to 17.5 μg/g Cu, 2.25 to 6.25 μg/g Cr, <0.25 to 124.3 μg/g Al, 0.2 to 7.3 μg/g Pb, <0.03 to 10.7 μg/g Ni, 17.3 to 372.0 μg/g Zn, <0.02 to 1.0 μg/g Co, 17.75 to 28.8 μg/g Mn, <0.1 to 89.8 μg/g Fe while the concentrations of metals in the skin-lightening products ranged from <0.15 to 16.5 μg/g Cd, <0.02 to 10.0 μg/g Cu, 4.25 to 8.0 μg/g Cr, <0.25 to 128.0 μg/g Al, 0.5 to 4.5 μg/g Pb, <0.03 to 1.65 μg/g Ni, 24.7 to 267.5 μg/g Zn, <0.02 to 2.5 μg/g for Co, 19.3 to 31.8 μg/g Mn, 9.5 to 211.63 μg/g Fe. In a significant number (>93%) of the samples investigated the concentrations of Pb, Cd, Ni and Co were below the specified limit, or the maximal limit for impurities in colour additives in cosmetics for external use. However, Cr was found at concentrations above the allergenic limit of 1 μg/g. The results also showed that skin-lightening creams contained higher concentrations of the studied metals than the moisturizing creams, except for Ni, which indicates that persons who uses skin-lightening creams in preference to moisturizing ones, are exposed to higher concentrations of metals.

Polycyclic aromatic hydrocarbon concentrations in commercially available infant formulae in Nigeria: Estimation of dietary intakes and risk assessment

The concentrations and profiles of polycyclic aromatic hydrocarbons (PAHs) in commercially available infant formulae and follow-up formulae in Nigeria were determined with a view to providing information on the health risks to children from the consumption of these infant foods. The concentrations of PAHs were measured by means of gas chromatography-mass spectrometry (GC-MS) after extraction by ultrasonication with acetone/dichloromethane and clean-up. The concentrations of the Σ16 PAHs in these infant formulae ranged from 0.102 to 1.98 μg kg(-1), 0.054-1.98 μg kg(-1), 0.081-2.54 μg kg(-1) and 0.51-0.70 μg kg(-1) for infants of ages 0-6 months, 6-12 months, 1-3 years and 0-12 months respectively. The concentrations of benzo(a)pyrene (BaP) in all samples investigated were below the 1 μg kg(-1) European Commission permissible limit for BaP in foods meant for infants. The estimated daily intake of PAHs based on the European Food Safety Authority (EFSA) suggested indicators of occurrence and effects of PAHs in foods were not detected (nd) to 2.67 ng BaP kg(-1) bw day(-1), nd-5.29 ng PAH2 kg(-1) bw day(-1), nd-11.20 ngPAH4 kg(-1) bw day(-1) and nd-34.96 ng PAH8 kg(-1) bw day(-1). The estimated margin of exposure (MOE) values: BaP-MOE, PAH2-MOE, PAH4-MOE and PAH8-MOE values were greater than 10,000 which indicates that there are no health risks from the consumption of these products by infants. The concentrations and dietary exposure to PAHs from these products were similar to values reported in the literature for European Communities.

Effects of processing on the proximate and metal contents in three fish species from Nigerian coastal waters.

The effects of culinary practices such as boiling, frying, and grilling on the proximate compositions and concentrations of metals (Cd, Pb, Cr, Zn, Fe, Cu, Mn, Ni, and Hg) in commonly consumed fish species from the Nigerian coastal waters were investigated. The selected fish species were Polydactylus quadratifilis, Chrysicthys nigrodigitatus and Cynoglossus senegalensis. The culinary practices lead to increased protein, fat, and ash contents and decreased moisture contents of these fish species. The culinary practices resulted significant increase in the concentrations of most of the studied metals and decrease in the concentrations of Fe, Cr, and Pb in some fish types. The concentrations and estimated dietary intakes of Cd, Pb, Cr, Zn, Fe, Cu, Mn, Ni, and Hg from consumption of the processed fish were within their statutory safe limits. The individual metal target hazard quotient (THQ) values and the total THQs were less than 1 which indicates that no health risks would arise from the long-term consumption of these fish species.

Evaluation of Human Exposure to metals from some popular brands of underarm cosmetics in Nigeria

The concentrations of metals (Cd, Pb, Ni, Cr, Cu, Co, Fe, Mn, Zn and Al) were determined in thirty brands of popular of underarm cosmetics in Nigeria with a view to providing information on the levels of metals and the risk of exposure to metals by humans through long time usage of these products. The concentrations of metals in these samples of underarm cosmetics were measured by using atomic absorption spectrometry after acid digestion. The concentrations of metals in these types of underarm cosmetics studied ranged from <0.15 to 1.2 μg g(-1)Cd, <0.02 to 11.2 μg g(-1)Pb, <0.03 to 4.9 μg g(-1)Ni, <0.1 to 25.0 μg g(-1), <0.02 to 2.8 μg g(-1)Co, 2.0 to 6.4 μg g(-1)Cu, 4.7 to 91.2 μg g(-1)Fe, <0.05 to 14.1 μg g(-1)Mn, 77.9 to 132 μg g(-1) and 69.2 to 83,500 μg g(-1)Al. The results of this study indicate that Cd, Pb, Ni, Cr and Co were presents in these types of underarm cosmetics at concentrations below the regulatory control limits for metal impurities in color additives for cosmetics and suggested limits following good manufacturing practice. The estimated margin of safety (MoS) indicated that the concentrations of the examined metals in these underarm cosmetic products present no potential risk to the users. The continuous use of these brands of underarm cosmetics represents a potential source of human exposure to metals such as aluminum in the local area of the breast, particularly to the upper outer quadrant.

Impact of Land-Use Patterns on Chemical Properties of Trace Elements in Soils of Rural, Semi-Urban, and Urban Zones of the Niger Delta, Nigeria

The study of the concentrations of Cr, Zn, Cd, Pb, Ni, and Cu in soils under different land uses in rural, semi-urban, and urban zones in the Niger Delta was carried out with a view to providing information on the effects of the different land uses on the concentrations of trace elements in soils. Our results indicate significant variability in concentrations of these metals in soils under different land uses in rural, semi-urban, and urban zones. The maximum concentrations of metals in the examined soil samples were 707.5 mg.kg−1, 161.0 mg.kg−1, 2.6 mg.kg−1, 59.6 mg.kg−1, 1061.3 mg.kg−1, and 189.2 mg.kg−1 for Cr, Zn, Cd, Pb, Ni, and Cu, respectively. In the rural zone, the cassava processing mill is a potent source of Ni, Cr, Cu, and Zn while agricultural activities are a source of Cd, and automobile emissions and the use of lead oxide batteries constitute the major sources of Pb. In the urban zone, soils around the wood processing mill showed elevated concentrations of Cu, Cr, Zn, and Ni, while soils around automobile mechanic works and motor parks showed elevated levels of Pb. Elevated Cd concentrations were observed in soils under the following land uses: urban motor park, playground, welding and fabrication sheds, and metallic scrap dump. The contamination/pollution index of metals in the soil follows the order: Ni > Cd > Cr > Zn > Cu > Pb. The multiple pollution index of metals at different sites were greater than 1, indicating that these soils fit into “slight pollution” to “excessive pollution” ranges with significant contributions from Cr, Zn, Cd, Ni, and Cu.

Survey of trace element composition of commercial infant formulas in the Nigerian market

Concentrations of zinc (Zn), copper (Cu), cadmium (Cd), lead (Pb), iron (Fe), nickel (Ni), chromium (Cr), vanadium (V) and cobalt (Co) were measured in 190 samples covering 19 different brands of popular baby foods in Nigeria to assess whether the intakes complied with the recommended desired levels for essential metals and permissible levels for toxic elements. The mean concentrations of Zn, Cu, Cd, Pb, Fe, Ni, Cr, V and Co in different types of infant foods were found to vary from 1.8–7.8; <0.001–0.1; <0.001–0.02; 0.01–0.1; 4.4–25.8; 0.03–0.06; 0.1–1.6; <0.001–0.1 to <0.001–0.1 µg g−1, respectively. The average concentrations of these metals were higher in soy-based formulas than milk-based infant foods. The estimated average daily intakes of metals through the consumption of these brands of infant foods for ages 0–6 and 7–12 months were 118.6 and 163.5; 1.0 and 1.9; 0.2 and 0.3; 1.3 and 1.8; 294.8 and 530.6; 1.0 and 1.1; 15.1 and 20.6; and 0.8 and 4.0 µg kg−1 body weight (bw) day−1 for Zn, Cu, Pb, Cd, Fe, Ni, Cr and Co, respectively. The daily intakes of non-essential elements of these metals through baby foods are well below the recommended tolerable levels. Similarly, the daily intake levels of essential elements (e.g. Zn, Co, Cu and Fe) were also significantly lower than the recommended desirable levels in infant foods.

Assessment of heavy metal speciation in soils impacted with crude oil in the Niger Delta, Nigeria

Abstract Chemical fractionation of Cd, Cu, Pb, Ni, Cr, Zn and Mn in soils that had received a significant impact of crude oil spillage in the Niger Delta, Nigeria was studied using a sequential chemical extraction method. The results revealed that significant amounts of the metals (Cd, Cu, Pb, Ni, Cr, Zn and Mn) were found in the most labile fractions as compared to the control site. On average, Ni, Cr and Zn were mostly associated with the residual fraction; Pb and Mn with the Fe–Mn oxides; Cu with the organic fraction and Cd with the exchangeable fraction. Among the non-residual fractions, metals were mostly associated with the Fe–Mn oxides fraction. The mobility factors of these metals were higher at the impacted sites as compared with the control site. High mobility of the metals in the impacted soils was associated with the oil spillage, since exogenous metals are usually weakly bound to soil particles. The mobility factors for the metals follow the order: Cd>Zn>Pb>Ni>Mn>Cu>Cr.

Concentrations and Distribution of Trace Metals in Water and Streambed Sediments of Orogodo River, Southern Nigeria

The distribution of Cd, Pb, Ni, Cr, Cu, Mn, Fe, and Zn in sediment and surface water, and some physico-chemical characteristics of Orogodo river sediments, were evaluated. The sediment pH ranged from 5.1–7.3; conductivity values ranged from 34.5 to 389.0 μScm−1. Total nitrogen values ranged from 0.06–0.10%, NH3-N values ranged from 0.25–0.44 mgkg−1, percent total organic carbon ranged from 0.21–1.68%, and total phosphorus values ranged from 0.004–0.02% for dry and wet seasons. The sand fraction consists of 87–95%, silt fractions ranged from 0–2%, and clay fraction between 4–13%. The mean concentrations of metals (dry weight basis) in the streambed sediments ranged from 1.92–17.37 mgkg−1 for Cu, 0.98–4.78 mgkg−1 for Ni, 0.01–32.98 mgkg−1 for Mn, 353.22–2045.64 mgkg−1 for Fe, 69.96–100.16 mgkg−1 for Zn, 0.21–1.32 mgkg−1 for Cr, and Cd was less than 0.001 mgkg−1 for wet and dry seasons. The mean concentrations of metals in the surface water ranged between 0.01–0.05–0.05 mg/L for Cu, nd-0.11 mg/L for Ni, 0.001–0.31 mg/L for Pb, 0.001–1.82 mg/L Mn, 0.01–3.52 mg/L for Fe, 0.16–0.61 mg/L for Zn, nd-0.007 mg/L for Cr, and <0.001 mg/L for Cd. Based on principal component analysis, two main sources of metals in the Orogodo River can be identified: (i) Cr, Cu, Pb, and Fe are mainly derived from industrial sources; (ii) Mn, Zn, and Ni associated with traffic activities. No element examined had a contamination/pollution index value greater than unity (pollution ranges). This implies that the multiple pollution indices obtained from the analysis showed that Orogodo River sediments were not polluted with heavy metals.