Levels of Lead (Pb), Cadmium (Cd) and Cobalt (Co) in Cow Milk from Selected Areas of Zanzibar Island, Tanzania

Milk is one of the very important nutrients of human diet. The presence of toxic elements in milk may threaten the public health. This study reports the levels of Cadmium (Cd), Cobalt (Co) and Lead (Pb) in raw cow’s milk collected from different areas of Zanzibar Island during March - May 2016. The samples of raw milk were analyzed by Thermo Scientific-Atomic Absorption Spectrophotometer for quantitative determination of the metals in the matrix. The concentration of Co in this study ranged from ND at Mwanakwerekwe (MK1 and MK2) to a maximum of 0.004 mg/L at Mshelishelini (MS5) and Fuoni (F5) sites with mean concentration of 0.020 ± 0.003 mg/L for all sites. Concentration of Pb ranged between 0.05 - 0.51 mg/L at Fuoni (F7) and Mwanakwerekwe (MK1) respectively, with mean concentration of 0.263 ± 0.031 mg/L for all sites. However, Cd was only detected in one sample collected at Fuoni (F3) with a concentration of 0.001 mg/L. The results revealed that cow’s milk is contaminated with toxic metals, particularly Pb which exceeded the WHO maximum permissible level of 0.02 mg/L. The study furthermore sheds light on possible consequences to public health. It is recommended that, stakeholders especially in Zanzibar such as Zanzibar Food and Drug Authorities (ZFDA) and Zanzibar Bureau of Standards (ZBS) as well as researchers, use the findings of this study for policy making, future study plans, formulation of technical strategies to control milk contamination, risk assessment and develop new alternative methods to measure milk contamination even at a low detection limit for the sake of the consumers’ welfare before posing any serious effects to their health.

Effects of Cadmium, Lead, and Zinc on Size of MicrobialBiomass in Red Soil

A laboratory incubation experiment was conducted to study the influence of cadmium (Cd), lead (Pb)and zinc (Zn) on the size of the microbial biomass in red soil. All the three metals were applied, separately,at five different levels that were: Cd at 5, 15, 30, 60 and 100 μg g-1; Pb at 100, 200, 300, 450 and 600 μg g-1 and Zn at 50, 100, 150, 200 and 250 μg g-1 soil. In comparison to uncontaminated soil, the microbial biomass carbon and biomass nitrogen decreased sharply in soils contaminated with Cd, Ph and Zn. A more considerable increase in the microbial biomass C: N ratio was observed in the metal contaminated soils than the non-treated control. Among the tested metals, Cd displayed the greatest biocidal effect followed by Zn and Pb, showing their relative toxicity in the order of Cd > Zn > Pb.

Effects of field application of phosphate fertilizers on the availability and uptake of lead, zinc and cadmium by cabbage (Brassica chinensis L.) in a mining tailing contaminated soil

A field trial was conducted to evaluate the reduction of bioavailability of heavy metals including lead (Pb), zinc (Zn) and cadmium (Cd) in a soil contaminated by mining tailings in Shaoxing, Zhejiang, China. Three commercial phosphate (P) fertilizers including phosphate rock (PR), calcium magnesium phosphate (CMP), and single superphosphate (SSP) were applied to the plot at three P application rates, 50, 300, and 500 g/m2 with 9 treatments and control (CK). Plants, water soluble and exchangeable (WE) extra...

Evaluation of phytoextracting cadmium and lead by sunflower,ricinus,alfalfa and mustard in hydroponic culture

Soil contaminated with heavy metals cadmium （Cd） and lead （Pb） is hard to be remediated. Phytoremediation may be a feasible method to remove toxic metals from soil, but there are few suitable plants which can hyperaccumulate metals. In this study, Cd and Pb accumulation by four plants including sunflower （Helianthus annuus L.）, mustard （Brassicajuncea L.）, alfalfa （Medicago sativa L.）, ricinus （Ricinus communis L.） in hydroponic cultures was compared. Results showed that these plants could phytoextract heavy metals, the ability of accumulation differed with species, concentrations and categories of heavy metals. Values of BCF （bioconcentration factor） and TF （translocation factor） indicated that four species had dissimilar abilities of phytoextraction and transportation of heavy metals. Changes on the biomass of plants, pH and Eh at different treatments revealed that these four plants had distinct responses to Cd and Pb in cultures. Measurements should be taken to improve the phytoremediation of sites contaminated with heavy metals, such as pH and Eh regulations, and so forth.

Biosorption of cadmium(II) and lead(II) ions from aqueous solutions onto dried activated sludge

The removal of heavy-metal ions from aqueous solutions by using dried activated sludge has been investigated in batch systems. Effect of solution pH, initial metal ion concentration, and temperature were determined. The results of the kinetic studies showed that the uptake processes of the two metal ions（Cd（Ⅱ） and Pb（Ⅱ）） followed the pseudo-second-order rate expression. The equilibrium data fitted very well to both the Langmuir and Freundlich adsorption models. The FT-IR analysis showed that the main mechanism of Cd（Ⅱ） and Pb（Ⅱ） biosorption onto dried activated sludge was their binding with amide I group.

Environmental contamination and health hazard of lead and cadmium around Chatian mercury mining deposit in western Hunan Province,China

A field survey concerning lead and cadmium pollution in environment mediums and hair samples around the Chatian mercury mining deposit in western Hunan Province,China,was conducted to preliminarily evaluate their health hazard to local inhabitants.The results show that mining wastes,especially tailing,contain high cadmium level with the maximum of 79.92μg/g. High levels of lead and cadmium are accumulated in surface water and paddy soil,respectively,and both metals pollution occurs in brown rice.The average daily intake dose(ADD)of lead for local adults via three routes reaches up to 7.7μg/(kg·d),exceeding the provision tolerable daily intake by JECFA of 3.5μg/(kg·d),and drinking water exposure route contributes the highest daily intake.As an indicator for heavy metal exposure,the hair of local population contains Pb(5.06±3.02)μg/g.The average daily intake dose of cadmium for adults is 0.119μg/(kg·d).More attention must be paid on health risk from lead pollution compared with cadmium.

Simultaneous adsorption of lead and cadmium on MnO_2-loaded resin

MnO2-10aded D301 weak basic anion exchange resin has been used as adsorbent to simultaneously remove lead and cadmium ions from aqueous solution. The effects of adsorbent dosage, solution pH and the coexistent ions on the adsorption were investigated. Experimental results showed that with the adsorbent dosage more than 0.6 g/L, both Pb^2＋ and Cd^2＋ were simultaneously removed at pH range 5-6. Except for HPO4^2-, the high concentration coexistent ions such as Na^＋, K^＋, Cl^-, NO3^-, SO4^2- and HCO3^-, showed no significant effect on the removal efficiency of both Pb^2＋ and Cd^2＋ under the experimental conditions. The coexistence of Mg^2＋, Ca^2＋ caused the reduction of Cd^2＋ removal, but not for Pb^2＋. The adsorption equilibrium for Pb^2＋ and Cd^2＋ could be excellently described by the Langmuir isotherm model with R^2 〉 0.99. The maximum adsorption capacity was calculated as 80.64 mg/g for Pb^2＋ and 21.45 mg/g for Cd^2＋. The adsorption processes followed the pseudo first-order kinetics model. MnO2-loaded D301 resin has been shown to have a potential to be used as an effective adsorbent for simultaneous removal of lead and cadmium ions from aqueous solution.

Influences of phosphate nutritional level on the phytoavailability and speciation distribution of cadmium and lead in soil

A pot experiment was conducted to examine the influence of phosphate levels on the phytoavailability and speciation distribution of cadmium （Cd）, lead （Pb） in soil. Spring wheat （Triticum aestivum L.） was selected as the tested plant. There were 5 phosphate fertilizer（Ca（H2PO4）2） levels including 0, 50, 100, 200, and 400 mg P2O5/kg soil, marked by P0, P1, P2, P3, and P4, respectively. CdCl2·2.5H2o and Pb（NO3）2 were added to soil as the following levels： Cd ＋ Pb = 25＋0, 0＋1000, and 25＋1000 mg/kg, marked by T1, T2, and T3, respectively. The results showed that the P fertilizer promoted the dry weight of wheat in all treatments and alleviated the contamination induced by Cd and Pb. With increasing levels of the additional P fertilizer, Cd concentration in different parts （root, haulm, chaffand grain） of wheat decreased at the P1 level at first and then increased. The soluble plus exchangeable （SE） fraction of Cd in soil decreased at the P1 level and then increased from P2 to P4 levels. The moderate P fertilizer reduced the phytoavailability of Cd. The application of P could obviously restrain the uptake of Pb by wheat and there were significantly negative correlations between the levels of P and the uptake of Pb. Phosphorus supply resulted in a decrease in the SE fraction of Pb and there was a significantly negative correlation between the levels of P and the SE fraction of Pb in soil. All the levels of the P fertilizer in this experiment could reduce the phytoavailability of Pb. Thus, it is feasible to apply the P fertilizer （Ca（H2PO4）2） to Pb contaminated soils. However, the levels of P application should be restricted in case that redundant P may increase the phytoavailability of Cd.

Joint effects of cadmium and lead on seedlings of four Chinese cabbage cultivars in northeastern China

In northeastern China, large area of vegetable land has been simultaneously polluted by cadmium （Cd） and lead （Pb）. Joint effects of Cd and Pb on Chinese cabbage （Brassica pekinensis L.） were investigated using the seed germination and sand culture method. Four Chinese cabbage cultivars including Kangbingjinchun （KB）, Dongyangchunxia （DY）, Qinglvwang （QL） and Qiangshi （QS） from Shenyang in northeastern China were adopted in this study. The results showed that there were positive linear relationships between the inhibitory rate of biomass, root and shoot elongation and the concentrations of Cd and Pb. In particular, root elongation was more sensitive to joint stress of Cd and Pb. The activity of superoxide dismutase and the content of malondialdehyde （MDA）, soluble protein （SP） and proline （PRO） changed significantly with increasing exposure concentration of Cd and Pb. The decrement in the activity of antioxidative enzymes, the content of SP and accumulation of MDA were relatively low in KB and QS. PRO played an important role in resisting Cd and Pb stress.

Applications of Crown Ether Cross-Linked Chitosan for the Analysis of Lead and Cadmium in Environmental Water Samples

A new type of crown ether cross-linked chitosan was synthesized by the reaction of chitosan with 4,4′-dibromodibenzo-18-crown-6 (Br-DBC). Its token structure was analyzed with FT-IR and NMR and the adsorption behaviors for lead and cadmium in environmental water samples by FAAS were studied. In addition the best analysis conditions were discussed and the adsorption mechanism was explained. As the enrichment factor is above 100, both recoveries are 94%–106%, the detection limits of lead and cadmium are 0.5μg·L?1 and 0.04 μg·L?1 and the relatively standard deviations of lead and cadmium are 3.1% and 2.8% respectively, this new method was successfully applied to the determination of environmental water samples. This method is fast and simple and it greatly enhances the determination ability of FAAS for lead and cadmium.

Cadmium and lead effects on chlorophyll fluorescence,chlorophyll pigments and proline of Robinia pseudoacacia

Heavy metal contamination is one of the most important abiotic stresses affecting physiological activities of plants.We investigated the effects of cadmium（Cd） and lead（Pb） on chlorophyll fluorescence（Fv/Fm,Fo,and Fm）,photosynthetic pigments（chlorophyll a and b）,and proline in one-year-old seedlings of Robinia pseudoacacia.The seedlings were treated twice over a period of 10 days with Cd and Pb at concentrations of 0,250,500,1000 and2000 mg L-1.Saline solution containing Cd and Pb was sprayed on the leaves.Chlorophyll and proline contents were measured after 10 days.Chlorophyll fluorescence of R.pseudoacacia was affected slightly by high concentrations（1000,2000 mg L-1） of Cd and Pb.Chlorophyll a and a/b increased at 1000 and 2000 mg L-1of Cd and proline content of leaves was similar in all treatments of Cd and Pb.Our results indicated that photosynthetic sensitivity of R.pseudoacacia to Cd and Pb contamination was weak.Photosystem II chlorophyll pigments were not damaged by Pb and Cd stress.We conclude that chlorophyll fluorescence along with chlorophyll and proline contents are useful indicators of Cd and Pb stresses in R.pseudoacacia which widely planted in urban polluted regions in Iran.

Use of Atomic Absorption Spectrometry in Assessment of Biomonitor Plants for Lead,Cadmium and Copper Pollution

Eleven plant species were collected from the vicinity of lead-battery plant in the city of Gaziantep,Turkey.Lead,cadmium and copper concentrations in the soil and leaves of plants were determined by atomic absorption spectrometry.Lead,Cd and Cu concentrations in the soil samples taken from battery area were found to be in the ranges of 304～602,0.4～0.44 and 31～37 mg·kg-1,respectively.Significantly increased lead concentration up to 2 750 mg·kg-1 was found in the leaves of Eleagnus angustifolia L.plant.The lead concentrations in the other plant leaves taken from 50 m around battery factory followed the order Ailanthus altissima>Morus sp.>Juglans regia L.>Ficus carica L.>Cydonia oblonga Miller>Prunus x domestica L.The plants,Populus nigra L.,Eleagnus angustifolia L.and Salix sp.were found useful for Cd,and the plant,Eleagnus angustifolia L.for Pb,to be considered as potential biomonitor.Especially,leaves of trees and plants taken from the distance of 50 m from battery plant have relatively higher Pb concentrations.Therefore,people who and animals which live in this area and benefit from these soil and plants have vital risks.

Lipid Peroxidation and Ultrastructural Modifications in Brain after Perinatal Exposure to Lead and/or Cadmium in Rat Pups

Objective To assess lipid peroxidation and ultrastructural modifications in rat brains following perinatal exposure to lead （Pb） and/or cadmium （Cd）. Methods Female rats were divided into four groups： control group, Pb （300 mg/L） group, Cd group （10 mg/L） and Pb＋Cd （300 mg/L, 10 mg/L） group. The compounds were delivered in the drinking water throughout pregnancy and lactation. Results The levels of compounds in blood and brain of the Pb＋Cd group were similar to those of other groups, but the effects of Pb＋Cd on pups＇ body and brain weights were higher than on other compounds. Electron microscopy revealed that Pb and Cd had effects on mitochondrial swelling, disruption and cristae loss, Nissl body dissolution, degenerated organelles and vacuoles, cytomembrane disappearance, and nuclear chromoplasm concentration. The activity of glutathione peroxidase （GSH-Px）, superoxide dismutase （SOD）, catalase （CAT）, acetylcholinesterase （ACHE） was decreased, whereas the activity of maleic dialdehyde （MDA） was increased. Conclusion Perinatal exposure to low doses of Pb and Cd can produce alterations in lipid peroxidation and ultrastructural modifications in rat brains, and exposure to both metals can result in greater damages.

Toxicity of cadmium and lead on tropical midge larvae,Chironomus kiiensis Tokunaga and Chironomus javanus Kieffer(Diptera:Chironomidae)

Objective:To investigate the acute toxicity of cadmium and lead on larvae of two tropical Chironomid species,Chironomus kiiensis(C.kiiensis) Tokunaga and Chironomus javanus(C. javanus) Kieffer.Methods:Different larval instars(first-fourth) were exposed using a sialic non-replacement testing procedures to various concentrations of cadmium and lead.Results: In general,younger larvae(first and second instars) of both species were more sensitive to both metals than older larvae(third and forth instars).The toxic effects of the metals on C.kiiensis and C. javanus were influenced by the age of the larvae(first to fourth instars),types of metals(cadmium or lead) and duration of larval exposure(24,48,72 and 96 h) to the metals.Conclusions:Cadmium was more toxic to the chironomids than lead and C.javanus was significantly more sensitive to both metals than C.kiiensis(P<0.05).

Wood anatomical changes due to uptake of cadmium and lead from contaminated soils in Acer velutinum seedlings

We investigated wood anatomical changes due to uptake and accumulation of cadmium and lead from contaminated soils in Acer velutinum Boiss seedlings. Two-year old seedlings were exposed for 180 days to soil concentrations with varying cadmium and lead concentra- tions. We measured three wood anatomical traits, average vessel area （gm2）, vessel number per square millimetre, and vessel lumen area per- centage （%）. For assessing the cadmium and lead accumulation, we measured the concentrations in the soil, leaf, stem, and root. Average vessel area and vessel lumen area percentage were similar （p〉0.05） in control and treated seedlings. Vessel number per square millimetre showed a decreasing trend from pith to bark in control and treated seed- lings, and the trend was more pronounced in treated seedlings. We con- clude that vessel number per square millimetre in A. velutinum is influ- enced by soil contamination. A. velutinum Boiss is not a suitable species for remediation of soils contaminated by cadmium and lead but it can be used as an indicator of the soil lead contamination, because lead concentrations in seedlings increased with increasing amount of lead in the soil.

National Food Contamination Monitoring Programmes-Levels of Mercury, Lead and Cadmium in Chinese Foods

Six hundred and thirty-four food samples of six kinds were collected from Beijing,Shanghai, Jiangsu, Sichuan, Jilin and Guangdong areas, China and Hg, Pb, Cd contents were determined. The results showed that their levels in the Chinese foods were low; their levels in meat, egg, milk and fish were generally below the national hygienic standard. The average daily dietary intake of Hg, Pb, Cd were 7.25 μg, 103.77μg and 30.72 μg respectively and they were all less than the ADI established by WHO

Neuroprotective effects of combined lead and cadmium,as well as N-acetylcysteine,on cerebral cortical neurons following lipid peroxidation injury

BACKGROUND： Studies have reported the antioxidant effects of lead and cadmium in the central nervous system, but very few have addressed the combined toxicity of lead and cadmium. The mechanisms by which these combined heavy metals are toxic, as well as how to protect cells from these agents, remains poorly understood. OBJECTIVE： Primary cultured rat cortical neurons were used to determine the effects of combined lead and cadmium on levels of glutathione peroxidase （GSH-Px）, superoxide dismutase （SOD）, catalase （CAT）, and acetylcholinesterase （ACHE）, as well as malondialdehyde （MDA）, and to evaluate the neuroprotective effects of N-acetylcysteine （NAC）. DESIGN, TIME AND SETTING An in vitro toxicological observation was performed at the Comparative Medicine Center of Yangzhou University from August 2007 to April 2008. MATERIALS： Lead acetate, cadmium acetate, and NAC were purchased from Sigma-Aldrich （St. Louis, USA）. Commercial kits of GSH-Px, SOD, CAT, ACHE, and MDA were purchased from Nanjing Jiancheng Bioengineering Institute, Nanjing, China. METHODS： The cerebral cortical neurons were isolated from newborn Sprague dawley rats at 24 hours after birth and primary cultured for 6 days. Thereafter, the cells were treated with a range of cadmium doses （0, 5.0, and 10.0μmol/L）, lead doses （0, 1.0, and 2.0 μmol/L）, or a combination of the two for 12 hours at 37℃in a 5% CO2 incubator, respectively. In addition, the cells were incubated with different doses of cadmium and/or lead and （0 and 50 μmol/L） NAC for 12 hours to assess the protective effects on cell survival. MAIN OUTCOME MEASURES： The activity of SOD, GSH-Px, CAT, and ACHE, as well as MDA content, in the cell lysates was detected using commercial kits. RESULTS： At 12 hours after treatment, compared to the control group, activity of GSH-Px, SOD, and AChE in the lead, cadmium, or combined treated cells was significantly decreased with increasing doses of cadmium/or lead （P 〈 0.05）, but CAT activity and MDA levels were significantly increased （P 〈 0.05）. The combination of cadmium and lead led to higher levels of toxicity than individual exposure. CONCLUSION： The degree of oxidative damage increased when the two heavy metals were combined. NAC protected neonatal cortical neurons by increasing activity of anti-oxidative enzymes and reducing lipid peroxidation, but the reduction was not statistically significant.

Lead and Cadmium Adsorption onto Iron Oxides and Manganese Oxides in the Natural Surface Coatings Collected on Natural Substances in the Songhua River of China

Natural surface coatings collected from natural substances （NSCsNS） were employed to study the roles of the main chemical components （iron oxides, manganese oxides, and other components） in controlling the adsorption of lead（Pb） and cadmium（Cd） in aquatic environments. The selective chemical extraction followed by the adsorption of Pb and Cd experiments and statistical analysis, were used to investigate the adsorption property of each component. Hydroxylamine hydrochloride was used to remove manganese oxides selectively, and sodium dithionite was used to extract iron oxides and manganese oxides. The result indicated that iron oxides and manganese oxides played an important role in the adsorption of Pb and Cd on NSCsNS, and the relative contribution was about two-thirds. The contribution of manganese oxides was the greatest, with a lesser role indicated for other components. The adsorption ability of manganese oxides for Pb and Cd was greater than that of iron oxides or other components for Pb and Cd. The Pb adsorption observed in each component was greater than Cd adsorption.

Study on the response of wheat to lead, cadmium and zinc

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Simultaneous Determination of Cadmium and Lead Using PEDOT/PSS Modified Glassy Carbon Electrode

In this work, we report the simultaneous determination of cadmium and lead using glassy carbon electrodes (GCE) modified by poly(3,4-ethylenedioxythiophene) (PEDOT) for linear sweep anodic stripping voltammetry (LSASV). The modification allows metal detection without involving oxygen removal, mechanical stirring and introduction of alloying additions such as Hg, Bi, Sb, etc. during the pre-concentration step. Introduction of poly (4-styrenesulphonate) (PSS) as dopant in the PEDOT matrix improves reproducibility, stability and sensitivity in the detection. Both cadmium and lead peaks were readily quantifiable over the linear range of 2 - 10 ?g/ml and the detection limit being 1.47 ?g/ml and 1.15 ?g/ml respectively. The calibration plot shows a linear response with correlation coefficient of 0.9911 and 0.9944 for cadmium and lead respectively. Thus, the GC/PEDOT/PSS modified electrode suggested as a suitable matrix for rapid monitoring of these heavy metals at trace levels.