Levels of selected trace metals in canned tuna fish produced in Turkey

Trace metals (iron, zinc, copper, cadmium, tin, mercury and lead) in canned tuna, obtained from 4 different brands in Turkey, were determined using Inductively Coupled Plasma-Mass Spectrometer (ICP-MS). The trace metals were found to be in the range of 20.2-38.7 mg/kg for iron, 8.20-12.4 mg/kg for zinc, 0.48-0.58 mg/kg for copper, 0.01-0.02 mg/kg for cadmium, 0.02-0.13 mg/kg for tin, 0.06-0.30 mg/kg for mercury, and 0.09-0.45 mg/kg for lead. These results showed that there is no risk in canned tuna with respect to the concentrations of zinc, copper, cadmium and tin. However, it was determined that some of the samples may contain iron, lead and mercury above the legal limits set by health authorities. It was concluded that trace metals in canned tuna must be monitored comprehensively and periodically with respect to the consumer health.     

Assessing arsenic,cadmium, and lead contents in major crops in Brazil for food safety purposes

The food chain is one of the major sources of human exposure to non-essential trace elements (TEs) present in soils. Human exposure to contaminated food is a worldwide health concern and a food safety issue that threatens agricultural trade. To assess the quality of Brazilian food products with respect to non-essential TEs, we evaluated arsenic (As), cadmium (Cd), and lead (Pb) contents in five major crops grown in Brazil: rice, wheat, corn, soybeans, and potatoes. The samples were collected from field trials with a record of long-term use of phosphate fertilizers in the states of Mato Grosso and Minas Gerais, Brazil. The TE concentrations in soils were all bellow the maximum allowable concentrations for agricultural soils. The mean concentrations of As, Cd, and Pb (μg kg⁻¹ dry weight) were as follows: below the detection limit <15, 29, and <40 for rice; 19, 23, and 64 for wheat; 47, 40, and 95 for corn; 65, 23, and 106 for soybeans; and 59, 22, and <40 for potatoes, respectively. Significant differences were found in the As and Cd contents of the different wheat cultivars. The levels of As, Cd, and Pb found in the studied crops are well below the values reported in the literature and are in accordance with the Codex Alimentarius and the European Union and Brazilian guidelines, indicating that the concentrations of these elements in the crops do not pose a risk to human health.     

佛山市禅城区蔬菜重金属污染现状及对人体健康风险分析

目的了解佛山市禅城区居民食用蔬菜重金属的污染状况,评价重金属经蔬菜途径摄入的健康风险。方法按照均匀分散多点的原则随机采集佛山市禅城区城郊4个主要种植地及市区内4个主要市场售卖的根茎、瓜果、叶菜3大类别73份蔬菜,对样品的锌（zn）、铜（Cu）、镉（cd）、铅（Pb）、铬（Cr）5种重金属元素含量进行测定。采用单因子污染和尼梅罗综合污染评价指数法评价蔬菜重金属污染状况,采用暴露剂量一反应外推法对蔬菜重金属进行健康风险评价。结果所抽取的蔬菜样品中有46．6％（34／73）的蔬菜重金属含量超标,Ph和cr超标率分别为32．9％（24／73）和19．2％（14／73）,2种金属同时超标的有4份,其余金属无超标。根茎类和瓜果类的综合污染指数分别为1．27及1．06,属轻度污染,主要受污染的品种为马铃薯、芹菜、丝瓜、茄瓜;叶菜类的综合污染指数为0．65,属安全级别;蔬菜中Cr、Cd、Ph、zn、cu的年平均个人摄入健康风险评价结果分别为4．43×10^-6、4．44×10^-6、7．40×10^-8、8．18×10^-9、1．02×10^-7,联合作用评价结果为4．48×10^-4,高于美国环保局与国际放射防护委员会分别推荐的标准。结论佛山市禅城区居民经蔬菜途径摄入重金属对人体具有一定潜在的健康风险,其风险主要来自化学致癌物Cr。应加强对蔬菜从种植至市场各环节监督和管理,确保人们的饮食安全。     

Spectrophotometric method for determination of aluminium content in water and beverage samples employing flow-batch sequential injection system

A sensitive, precise and reliable flow-batch method for the determination of aluminium (Al) was developed using a sequential injection-monosegmented flow system incorporating a mixing chamber unit. Eriochrome cyanine R (ECR) was used as a chromogenic reagent in the presence of N,N-dodecyltrimethylammonium bromide (DTAB). The Al-ECR complex at pH 6 gave a maximum absorption at 584 nm. In-line single standard calibration and a standard addition procedure were developed employing the monosegmented flow technique. Under the optimum conditions, a linear calibration graph in the range of 0.0075–0.625 mg L⁻¹ Al was obtained with limits of detection and quantitation of 0.0020 and 0.0070 mg L⁻¹, respectively. Relative standard deviations were 0.8 and 1.3% for 0.010 and 0.025 mg L⁻¹ Al (n = 11), respectively. A sample throughput of 24 h⁻¹ using an in-line standard calibration approach and 6 h⁻¹ using four standard addition levels was achieved. The developed system was successfully applied to water samples and beverage samples. The results agreed well with those obtained from the ICP-AES method. Good recoveries between 85 and 104% were obtained.     

Risk assessment of exposure to pesticides through dietary intake of vegetables typical of the Mediterranean diet in the Basque Country

This study examined estimated dietary exposure among the Basque Country Autonomous Community (northern Spain) to pesticides resulting from dietary intake of unprocessed vegetables. Samples were collected according to a sampling plan established previously, which was performed taking into account statistical factors, such as the population distribution, the point of sale, (local shops or supermarkets), the season and the consumption frequency of each vegetable. A total of 221 samples were analyzed using gas chromatography tandem mass spectrometry (GC–MS/MS), and liquid chromatography tandem mass spectrometry (LC–MS/MS). Results showed that 48.0% of the samples contained no pesticide residues, while 52.0% contained pesticides, and 6.8% of all samples showed residues above the maximum residue limit (MRL). As for the pesticides detected, 56 different active substances were detected, including fungicides and insecticides as the main pesticide types. All of the positive samples were collected in local-area shops. The potential risk to the consumers through vegetable intake was estimated by calculating the Hazard Quotient (HQ), showing ranges between 0.001–0.214%. These results indicate that the exposure to pesticides from vegetable intake among Basque consumers did not raise health concerns.     

Heat-assisted slurry sampling GFAAS method for determination of lead in food standard reference materials

A valid method based on heat-assisted slurry sampling graphic furnace atomic absorption spectrometry (HASS-GFAAS) was developed for the accurate determination of trace Pb in food standard reference materials (SRMs). The HASS technique significantly improved Pb recovery and precision compared to conventional slurry sampling techniques. The optimized HASS procedure was performed as follows: first, the sample (particle size ≤ 150 μm) was diluted with 0.05% (v/v) Triton X-100 containing 2% HNO₃ and 1% H₂O₂ followed by heating for 20 min at 120 °C on a heating block. Next, the obtained slurry was sonicated in an autosampler cup, and finally, the slurry was introduced into a graphite tube and analyzed by the GFAAS with a Pb electrodeless discharge lamp (EDL). Calibration with aqueous standard solutions was used for Pb determination in food samples. The characteristic mass and limit of detection for Pb based on the integrated absorbance for a 2% (m/v) sample were 12 ± 0.6 pg and 0.003 mg kg⁻¹, respectively. The accuracy (95.1–102% recovery) and good precision (0.1–3.6%) of this procedure are illustrated by the results obtained for the 12 food reference materials. The proposed method is suitable for determination of trace Pb in solid food samples.     

Investigation of heavy metal concentrations in some Turkish wines

Research studies analysing heavy metal or trace elements in Turkish wines is scarce. This study was designed to fill this gap, analysing 43 wines produced in 4 different regions in Turkey. A total of 37 red and 6 white wines produced from various grapes from 2006 to 2008 in Marmara, Aegean, Central Anatolia and Eastern Anatolia regions were studied. Wines were analyzed for Cr, Mn, Fe, Co, Ni, Cu, Zn, Cd and Pb using atomic absorption spectrometer equipped (AAS) with electrothermal atomization unit (ET). Average results for red and white wines, respectively, were: Cr, 38.6 and 29.4 μg/L; Mn, 697 and 101 μg/L; Fe, 1.7 and 0.7 mg/L; Co, 6.3 and 0.5 μg/L; Ni, 134 and 573 μg/L; Cu, 131 and 158 μg/L; Zn, 389 and 2099 μg/L; Cd, 2.8 (red wine; white wine results were under limit of detection); Pb, 6.3 (red wine; white wine results were under limit of detection). These results were interpreted for grape types and regions. Accuracy was tested with standard addition method. Recoveries ranged from 96% to 107% after standard addition. Cr, Fe and Mn in red wines were higher in comparison to white wines, whereas white wines were higher in Ni and Zn. Non-essential Cd and Pb concentrations were very low in both red and white wines. Comparison with literature shows all heavy metal concentrations in the analyzed Turkish wines to be below the limits designated by World Health Organization.     

Evaluation of different digestion systems for determination of trace mercury in seaweeds by cold vapour atomic fluorescence spectrometry

Four methods for acid digestion of seaweeds were compared in 10 commercially available seaweeds: (i) in stainless steel-Teflon^®PTFE-bombs at high pressure and temperature, (ii) in closed-Teflon^®PFA-vessels at high pressure and temperature, (iii) in open-polypropylene-tubes with reflux caps in a graphite heating block at high temperature and (iv) in closed-TFM™PTFE-vessels with microwave-assisted controlled pressure and temperature. Hg was determined in all digests by cold vapour atomic fluorescence spectrometry (CV-AFS). Assessment of digestion methods was performed by comparison with the results obtained for total mercury determination by the Method EPA 7473, based on direct mercury analysis in the solid samples, and with a reference material BCR-279. The open vessel digestion system with reflux in a graphite heating block at high temperature constitutes the best choice since it was found to give the better Hg extraction (83–103%) as well as the lowest variability, being RSD < 10% for most of the studied seaweeds. A previous freeze-drying and intensive grinding was the best pre-treatment. Similar results were obtained with and without the presence of oxidizing agents (KMnO₄, K₂Cr₂O₇) and with different tube-materials (borosilicate glass, PTFE and polypropylene).     

Synthesis and characterization of functionalized silica with 3,6-ditia-1,8-octanediol for the preconcentration and determination of lead in milk employing multicommuted flow system coupled to FAAS

Novel functionalized silica, containing 3,6-dithia-1,8-octanediol (Si-DIO), was synthesized and characterized by infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), scanning electron microscope (SEM) and nuclear magnetic resonance (NMR) of ¹³C and ²⁹Si. The Si-DIO was used to pre-concentrate and determine the amount of Pb(II) in milk samples employing a multicommuted flow system coupled to flame atomic absorption spectrometry (FAAS). For the adsorption process, a pre-concentration minicolumn with 100 mg of Si-DIO, a solution of 0.005 mg L⁻¹ Pb(II) at pH 9.0 and HNO₃ as the eluent was used, obtaining an enrichment factor of 28 times with retention efficiency higher than 99%. The Pb(II) ion, using the multicommuted flow system coupled to FAAS, showed a linear response between 0.005 and 20.0 mg L⁻¹; a linear coefficient where r = 0.9939 and n = 7; a detection limit estimated at 0.001 mg L⁻¹ and a relative standard deviation of 3.8% (n = 50). Fifty pre-concentrations runs were tested in the minicolumn without significant variation in the analytical signal. The proposal system showed analytical applicability to determine Pb(II) ion in milk samples, presenting recovery of 90.7–102.5%.     

Human exposure in Italy to lead,cadmium and mercury through fish and seafood product consumption from Eastern Central Atlantic Fishing Area

The presence of cadmium (Cd), lead (Pb) and mercury (Hg) was investigated in fish and seafood products collected from the FAO Major Fishing Area 34, Eastern Central Atlantic. Samples were purchased from different retail outlets in Italy. Samples were selected so as to assess human exposure through diet. Metals were detected by Q-ICP-MS and Hg-AAS. All the metal concentrations detected were largely below the maximum levels (MLs) established by the European Union. The exposure assessment was undertaken by matching the concentration of Cd, Pb and total Hg in fish and other seafood products selected purposed according to Italian consumption data. The estimated weekly intakes (EWIs) for the evaluated elements related to the consumption of fish and other seafood products by the median of the Italian total population accounted for 14%, 2% and 14% of the standard tolerable weekly intake (TWI) for Cd and Hg as well as the provisional tolerable weekly intake (PTWI) for Pb, respectively.     

Nutritional content,mercury, and trace element analyses of two skate (Rajidae) species in the Gulf of Alaska

Seafood is recognized as an important source of proteins and long chain omega-3 fatty acids. However, one of the primary concerns with seafood consumption is the level of heavy metals, particularly mercury, present in fish tissues, which may influence the demand of certain fishery products. We sampled muscle and liver tissues from 20 big (Beringraja binoculata) and 20 longnose (Raja rhina) skates collected near Kodiak and Cordova, Alaska, and analyzed their nutritional content (protein, moisture and lipid content and fatty acid profiles), heavy metal (mercury, arsenic, cadmium, lead) and trace element (selenium) load. Big and longnose skate muscle was composed of lean protein (14.7% ± 0.7% SD) with 1.2% (±0.4%) lipids and 83% (±0.8%) moisture. Skate livers were very high in lipids, between 52.5 and 57.5% and had high percentages of omega-3 fatty acids (30.2%). Mercury in these skates had mean levels of 0.21 mg/kg, lower than average levels found in Pacific halibut (Hippoglossus stenolepis). Overall, the risk/benefit ratio of consuming skate muscle was slightly positive (3.62%) based on the balance of mercury toxicity and omega-3 fatty acid benefits. Big skates were overall more beneficial to consume, and only longnose skates from Cordova had a negative risk/benefit ratio. These data can be used by the fishing industry to understand current and future market demands for skate products, and to be aware of any health concerns of consuming Gulf of Alaska skates.     

Toxic and essential trace element concentrations in the freshwater shrimp Macrobrachium amazonicum in the Lower Amazon,Brazil

This study aimed to evaluate the concentrations of toxic elements (As, Cd, Hg, Pb) and essential trace elements (Co, Cu, Cr, Fe, Mn, Mo, Ni, Se, Zn) in the freshwater shrimp M. amazonicum in the region of Santarem (lower Amazonia), which is affected by mining activities. The level of metal accumulation in the shrimp was found to be similar to that measured in other regions affected by anthropogenic polluted in both in Brazil and elsewhere, and does not pose a significant risk for human consumption. The different patterns of metal accumulation between the Amazon and Tapajos basins appear to be (at least partly) related to respectively bauxite exploitation and gold mining in the region. Bioaccumulation of the trace elements Co, Fe, and Mn mainly occurred in the visceral part of the shrimps from the Amazon river.     

Rapid assessment of metal contamination in commercial fruit juices by inductively coupled mass spectrometry after a simple dilution

A simple and fast method for the determination of Ca, Cd, Co, Cu, Fe, Mn, Mo, Na, Ni, Pb, Rb, Sr, V and Zn in fruit juices samples, by inductively coupled plasma mass spectrometry (ICP-MS) after only a sample dilution, is proposed. For comparison, the samples were also digested with nitric acid and hydrogen peroxide in a microwave oven. The same conditions could be used for aqueous standard solution and diluted sample and the sensitivity was similar in both media, thus external calibration against aqueous standard solutions could be used for quantification. The results were in agreement with those obtained after digestion, according to the t-test at a 95% confidence level. The good accuracy was also confirmed by the recovery test. The precision expressed by the relative standard deviation (RSD) was between 1 and 3%. The detection limits were between 0.1 (Pb) and 2000 μg L⁻¹ (Ca). Similar values for detection limits and RSD were obtained after sample digestion or when the internal standard was not used. The compositions of 20 samples were evaluated by multivariate analysis techniques: principal component analysis (PCA) and hierarchical cluster analysis (HCA), showing that samples are grouped by the brand and not by the fruit, what could be due to soil characteristics where the plant was grown and to the different processing and storage conditions used by the different brands, including water and additives.     

Study of mercury content in wild edible mushrooms and its contribution to the Provisional Tolerable Weekly Intake in Spain

The study determined total mercury (Hg) content of 10 wild edible mushroom species collected in southern Spain. Results indicated that the highest Hg level corresponded to Boletus aereus with 10.28 ± 2.92 mg/kg DW (dry weight), while the lowest Hg level was found in Terfezia arenaria with 0.09 ± 0.08 mg/kg DW. Regarding the anatomic parts of the mushrooms, caps showed significantly higher Hg concentrations than stems in B. aereus, Amanita caesarea and Macrolepiota procera. The percentage of contribution to the Provisional Tolerable Weekly Intake (PTWI) for Hg was also calculated. Based on consumption data in Spain (0.011 kg/person/week), %PTWI was calculated ranging between 0.06 and 3.5% for mean Hg levels. When a high level of consumption was assumed (0.100 kg/person/week), %PTWI ranged between 0.58 and 31%. Results suggest that wild edible mushrooms in southern Spain could contribute with high Hg levels to the Spanish diet. However, the lack of consumption data for wild edible mushrooms made it difficult to give more definitive conclusions; hence further studies including specific consumption data will be needed.     

An automated preconcentration system for the determination of manganese in food samples

In this work, an on-line automated system for the preconcentration and evaluation of manganese in food samples is proposed. The preconcentration of manganese ions is carried out using two mini-columns packed with 4-(5′-bromo-2′-thiazolylazo)orcinol (Br-TAO) loaded polyurethane foam. After a preconcentration step, a stream of hydrochloric acid is passed through the mini-column in order to transport the manganese directly to the flame atomic absorption spectrometer. The sample frequency was 60 h⁻¹ for a 60 s preconcentration time. The limit of detection and enrichment factor were 0.70 μg L⁻¹ and 17, respectively. The accuracy of the procedure was evaluated by analysis of biological reference materials (spinach leaves, tomato leaves and pine needles). The procedure was successfully applied for the evaluation of manganese in several food samples, such as corn, rice and cassava flour.     

Determination and health risk assessment of heavy metals in imported rice bran oil in Iran

In this current study, the contents of heavy metals including Pb, As, Cr, Cd, Zn, Cu, and Mn in imported rice bran oil in Iran were investigated with microwave digestion method based on an inductively coupled plasma optical emission spectrometry system (ICP-OES). The concentrations range of Pb, Cr, Cd, As, Zn, and Cu in rice bran oil samples were measured as 0.066–0.30, 0.008–0.014, 0.005–0.01, 0.047–0.01, 0.025–0.74 and 0.01–0.096 μg/g, respectively. A significant difference (p-value < 0.05) in the mean concentration of Pb in imported rice bran oils samples was observed. The sum of incremental lifetime cancer risk (ILCR) for heavy metals for children and adults were 2.6 × 10⁻⁴ and 2.4 × 10⁻⁵, respectively, which an acceptable level proposed values (10⁻⁴–10⁻⁶) by U.S. EPA. Moreover, the target hazard quotients (THQs) of As, Pb, Cr, Cd, Cu, and Zn for children were limited to between 1.17 × 10^-5 and 9.49 × 10⁻⁹, and in adults were limited to 2.33 × 10⁻⁷and 6.82 × 10^-7, which were lower than the acceptable limit (THQ < 1). There have been concerns regarding heavy metals since past up to now in all foodstuffs. We demonstrated in this study that there are traceable concentrations of heavy metals in six brand of rice bran oils.     

Levels and daily intake of lead (Pb) and six essential elements in gari samples from Ondo State,Southwest Nigeria: A potential risk factor of health status

Gari, a staple food in most West African countries is a processed product of cassava plant. It supplies about 70% of the daily calorie intake in these countries. In this study, levels of lead (Pb), zinc (Zn), manganese (Mn), cobalt (Co), copper (Cu), calcium (Ca) and iron (Fe) in gari samples that were collected from four major Nigerian cities: Akure, Ondo, Isua and Ore – all located in Ondo State, Southwest, Nigeria were determined. The estimated daily intakes (EDI) of these elements were determined and compared to the recommended dietary intake limits or requirements. The mean concentrations of Pb in gari samples was 0.16 ± 0.09 mg/kg while for essential elements the concentrations were 4.13 ± 0.95, 0.00497 ± 0.00078, 12.98 ± 1.48, 1.01 ± 0.47, 512.6 ± 9.12 and 23.22 ± 2.32 mg/kg for Zn, Mn, Co, Cu, Ca and Fe, respectively. The mean estimated dietary intakes were 0.0333 ± 0.00443, 0.88 ± 0.21, 1.06 ± 0.36, 0.00278 ± 0.00068, 0.22 ± 0.04, 109.7 ± 4.22 and 4.97 ± 1.07 mg/day for Pb, Zn, Mn, Co, Cu, Ca and Fe respectively. The estimated mean Pb dietary intake from gari consumption alone was almost the same as the benchmark dose lower confidence limit (BMDL) for Pb, thus inferring that dietary route is a potential source of Pb contamination for gari consumers in Southwest Nigerian. Also, the data from this study indicated that gari is a good source of some essential elements like Mn, Co, and Cu but not exceptionally rich in Zn, Fe and Ca. It is therefore recommended that gari diets should be complemented with other food substances like beef, vegetables and low fat cheese that are good sources of the deficient elements.     

Simultaneous analysis of 21 elements in foodstuffs by ICP-MS after closed-vessel microwave digestion: Method validation

This paper describes a validation process for the simultaneous analysis of 21 elements: lithium (Li), aluminium (Al), vanadium (V), manganese (Mn), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), arsenic (As), strontium (Sr), molybdenum (Mo), silver (Ag), cadmium (Cd), tin (Sn), antimony (Sb), tellurium (Te), barium (Ba), mercury (Hg) and lead (Pb) in food samples by inductively coupled plasma-mass spectrometry (ICP-MS) after closed-vessel microwave digestion. This validation was realized in parallel with the analysis of the 1322 food samples of the second French Total Diet Study (TDS) by the National Reference Laboratory (NRL) of the French Food Safety Agency (AFSSA). Several criteria such as linearity, limits of quantification (LOQ), specificity, precision under repeatability conditions and intermediate precision reproducibility were evaluated. Furthermore, the method was supervised by several internal and external quality controls (IQC and EQC). Results indicate that this method could be used in the laboratory for the routine determination of these 21 essential and non-essential elements in foodstuffs with acceptable analytical performance.     

Comparison of the chemical composition of British and Continental European bottled waters by multivariate analysis

The elemental composition of 37 bottled waters from the UK and continental Europe has been determined. Ca, K, Mg, Na, Al, As, Ba, Cd, Cr, Co, Cu, Fe, Mn, Mo, Ni, Pb, Sb, Sr, U, V and Zn were determined by ICP-OES and ICP-MS, in addition to inorganic and total organic carbon. The composition of all the waters analysed fell within the guideline values recommended by the World Health Organization. Na, Ca, Sr and Ba showed the widest variation in concentrations, ranging over two orders of magnitude. Levels of Fe were below the limit of detection (30 μg L⁻¹) in all samples analysed. Waters produced in the UK generally showed lower levels of most major elements and trace metals, with the exception of Ba (up to 455 μg L⁻¹). Italian waters showed the highest concentrations of Sr (3000–8000 μg L⁻¹) and U (8–13 μg L⁻¹), whereas waters produced in Slovakia and the Czech Republic showed the highest levels of Pb (0.7–4 μg L⁻¹). The use of multivariate analysis reveals an association between high alkaline metal content and high concentrations of As and Cr. There also appears to be a correlation between high Ca and Sr content and high levels of U. Analysis of variance (ANOVA) indicates that the composition of bottled water can be distinguished primarily by the country of origin, over other factors including the geological environment of the source. This would suggest that composition reflects, and is biased towards, consumer preferences.     

Selenium,zinc and copper in the Polish diet

The aim of the study was to assess daily dietary intakes of selenium (Se), zinc (Zn) and copper (Cu) in a representative group of Polish individuals using analytical and calculation method, and to determine the contents of Zn and Cu in different foodstuffs available on the Polish market, in order to complete our previous data on Se content in Polish food. Daily intakes of the microelements were assessed analytically in 469 daily food rations, 439 of which were collected from various public canteens and 30 by duplicate portion method from private individuals. Calculated daily intakes were obtained by analysing 157 diet recalls and by the use of our previous and current data on Se, Zn and Cu contents in food, including 235 different food products. Mean intakes in different groups, as shown analytically, ranged from 20 to 59 μg/day for Se, 3.2 to 13.5 mg/day for Zn and from 0.4 to 2.2 mg/day for Cu. Mean daily intakes calculated from 24-h diet recalls were lower than the majority of the mean values obtained analytically and amounted to 30 ± 11 μg for Se, 5.3 ± 1.8 mg for Zn and 0.8 ± 0.3 mg for Cu. Mean concentrations of Zn and Cu in food varied from 0.4 to 17.4 μg/g and from 0.3 to 7.2 μg/g, respectively.