Determination of Metals in Foodstuffs by Atomic Absorption Spectrophotometry after Dry Ashing: NMKL Interlaboratory Study of Lead, Cadmium, Zinc, Copper, Iron, Chromium, and Nickel

An interlaboratory study of a method for determination of lead, cadmium, zinc, copper, iron, chromium, and nickel in foodstuffs by atomic absorption spectrophotometry (AAS) after dry ashing at 450°C was conducted in 16 laboratories. The study was preceded by a practice round of familiarization samples and another round in which solutions were distributed and the metals were determined directly by AAS. The study included 5 different foods (liver paste, apple sauce, minced fish, wheat bran, and milk powder) and 2 composite diets. A single analysis was carried out on each sample. Suitable sample combinations were used as split level combinations for determination of the repeatability standard deviation. The relative reproducibility standard deviation for each of the elements ranged as follows: lead, 74-18% at 0.025-0.28 mg/kg; cadmium, 80-11% (0.002-0.51 mg/kg); zinc, 12-7% (44- 72 mg/kg); copper, 47-10% (0.48-41 mg/kg); iron, 35-9% (2-228 mg/kg); chromium, 48-21 % (0.008- 0.22 mg/kg); nickel, 64-39% (0.025-0.39 mg/kg).

Determination of Magnesium and Calcium in Foods by Atomic Absorption Spectrometry after Microwave Digestion: NMKL Collaborative Study

On the basis of results of the performed collaborative study, the 49th Annual General Meeting of the Nordic Committee on Food Analysis (NMKL) in The Faroe Islands, August 1995, approved this method to be printed and included in NMKL's collection of methods of analysis of foods. Eleven laboratories participated in an interlaboratory methods-performance (collaborative) study of a method for determining magnesium and calcium in foodstuffs by atomic absorption spectrometry (AAS) after wet microwave digestion. The study was preceded by a practice round of familiarization samples. The method was tested on 7 materials: 5 foods (apple, milk powder, minced fish, wheat bran, and chocolate cake) and 2 composite diets ranging in Mg content from 240 to 3900 mg/kg and in Ca content from 290 to 9300 mg/kg. The materials were presented to study participants as blind duplicates, and participants were asked to perform single determinations on each sample. Repeatability relative standard deviations (RSDr) ranged from 1.9 to 4.9% for Mg and from 2.2 to 8.1 % for Ca. Reproducibility relative standard deviations (RSDR) ranged from 4.0 to 13% for Mg and from 5.9 to 23% for Ca. For Ca, lowest RSDR values were found for samples with high concentrations of Ca (>3800 mg/kg sample) and with nitrate ion residues of <1.3% (w/v).

Determination of Arsenic, Cadmium, Mercury, and Lead by Inductively Coupled Plasma/Mass Spectrometry in Foods after Pressure Digestion: NMKL Interlaboratory Study

Thirteen laboratories participated in an interlaboratory method performance (collaborative) study on a method for the determination of arsenic, cadmium, mercury, and lead by inductively coupled plasma/mass spectrometry (ICP/MS) after pressure digestion including the microwave heating technique. Prior to the study, the laboratories were able to practice on samples with defined element levels (pretrial test). The method was tested on a total of 7 foodstuffs: carrot puree, fish muscle, mushroom, graham flour, simulated diet, scampi, and mussel powder. The elemental concentrations in mg/kg dry matter (dm) ranged from 0.0621.4 for As, 0.0328.3 for Cd, 0.040.6 for Hg, and 0.012.4 for Pb. The materials used in the study were presented to the participants as blind duplicates, and the participants were asked to perform single determinations on each sample. The repeatability relative standard deviations (RSDr) for As ranged from 3.8 to 24%, for Cd from 2.6 to 6.9%, for Hg from 4.8 to 8.3%, and for Pb from 2.9 to 27%. The reproducibility relative standard deviations (RSDR) for As ranged from 9.0 to 28%, for Cd from 2.8 to 18%, for Hg from 9.9 to 24%, and for Pb from 8.0 to 50%. The HorRat values were less than 1.5 for all test samples, except for the determination of Pb in wheat flour at a level close to the limit of quantitation (0.01 mg/kg dm). The study showed that the ICP/MS method is satisfactory as a standard method for elemental determinations in foodstuffs.

Determination of Sodium in Foods by Flame Atomic Absorption Spectrometry after Microwave Digestion: NMKL Interlaboratory Study

Nine laboratories participated in an interlaboratory method performance (collaborative) study of a method for the determination of sodium in foods by flame atomic absorption spectrometry after wet digestion, using a microwave oven technique. Before the study, the laboratories were able to practice on samples with defined sodium levels (pretrial test). The method was tested on a total of 6 foods (broccoli, carrot, bread, saithe fillet, pork, and cheese) with sodium concentrations of 1480–8260 mg/kg. The materials were presented to the participants in the study as blind duplicates, and the participants were asked to perform single determinations for each sample. The repeatability relative standard deviations (RSDr) for sodium ranged from 1.9 to 6.5%. The reproducibility relative standard deviations (RSDR) ranged from 4.2 to 6.9%. The HorRat values ranged from 0.9 to 1.6.

Determination of Mercury in Seafood by Flow Injection–Cold Vapor Atomic Absorption Spectrometry after Microwave Digestion: NMKL Interlaboratory Study

Ten laboratories participated in an interlaboratory method-performance (collaborative) study of a method for the determination of mercury in foods of marine origin by flow injection–cold vapor atomic absorption spectrometry after wet digestion using a microwave oven technique. The study was preceded by a training round of samples of known identity. The method was tested on a total of 7 seafood products: blue mussel (Mytilus edulis), cod muscle (Gadus morhua), crab (Cancer pagurus), scampi (Nephrops norwegicus), black scabbard fish (Aphnopus carbo), longnose velvet dogfish (Centroscymus crepidater), and Portuguese dogfish (Cenbroscymus coelolepis) with mercury concentrations of 0.14, 0.24, 0.35, 0.59, 1.42, 4.2, and 13.2 μg/g, respectively. The materials were presented to the participants in the study as blind duplicates, and the participants were asked to perform single determinations on each sample. Repeatability relative standard deviations (RSDr) for mercury ranged from 2.4 to 14.0%. Reproducibility relative standard deviations (RSDR) ranged from 7.7 to 16.6%. HORRAT values for all samples were <1.0.

Determination of Iodine in Seafood by Inductively Coupled Plasma/Mass Spectrometry

A method was developed for determination of total iodine content in different standard reference materials (SRMs) and seafood products by inductively coupled plasma/mass spectrometry (ICP/MS). If iodine is present as iodide and nitric acid is used in the wet digestion system, the observed signal is not stable when iodine is measured by ICP/MS at m/z 127. To stabilize the iodine signal, 3% ammonia solution (1 + 1, v/v) was added to the digest. The limit of quantitation of the method, defined as 6 times the standard deviation in the blank solution (n = 20) was estimated to be 15 mg/kg (using 0.2 g dry mass and a dilution factor of 50). The precision, expressed as repeatability of the iodine concentration, varied between 3.2 and 12% in SRMs, with concentrations of 4.70–0.17 mg/kg dry matter. The described method was compared with a method using tetramethylammonium hydroxide extraction. Both methods showed good precision and trueness by analyses of SRMs. The 2 methods were used to determine iodine in seafood from the Barents Sea, the Norwegian Sea, and the North Sea. The results showed great variation between different fish species as well as between individuals within a species. The lowest values of iodine were recorded in muscle of ling (Molva molva) with a mean of 0.07 mg/kg fresh weight and a variation between 0.03 and 0.11 mg/kg fresh weight. The highest values were found in cod (Gadus morhua) from the Barents Sea, with a mean of 2.5 mg/kg and a variation between 0.7 and 12.7 mg/kg fresh weight.

Determination of Metals in Foods by Atomic Absorption Spectrometry after Dry Ashing: NMKL1 Collaborative Study

A method for determination of lead, cadmium, zinc, copper, and iron in foods by atomic absorption spectrometry (AAS) after dry ashing at 450°C was collaboratively studied in 16 laboratories. The study was preceded by a practice round of familiarization samples and another round in which solutions were distributed and the metals were determined directly by AAS. The study included 5 different foods (liver paste, apple sauce, minced fish, wheat bran, and milk powder) and 2 simulated diets. A single analysis was carried out with each sample. Suitable sample combinations were used as split-level combinations for determination of the repeatability standard deviation. The reproducibility relative standard deviation for each of the elements ranged from 20 to 50% for lead concentrations of 0.040–0.25 mg/kg, from 12 to 352% for cadmium concentrations of 0.001–0.51 mg/kg, from 4 to 8% for zinc concentrations of 0.7–38 mg/kg, from 7 to 45% for copper concentrations of 0.51–45 mg /kg, and from 11 to 14% for iron concentrations of 4–216 mg/kg.

Determination of Arsenic in Seafood by Electrothermal Atomic Absorption Spectrometry after Microwave Digestion: NMKL Collaborative Study

Eight laboratories participated in an interlaboratory method performance (collaborative) study of a method for the determination of arsenic in foodstuffs of marine origin by electrothermal atomic absorption spectrometry after wet digestion using a microwave oven technique. The study was preceded by a practice round of familiarization samples. The method was tested on 8 materials (cod roe, krill, blue mussel, saithe, scampi, cod fillet, shrimp, and cod extract) ranging in As content from 2 to 75 mg/kg. The materials were sent to participants in the study as blind duplicates, and the participants were asked to perform single determinations on each sample. Repeatability relative standard deviations (RSDr) for As ranged from 6.8 to 17.4%. Reproducibility relative standard deviations (RSDR) ranged from 7.6 to 24%. The highest RSDR value was found for the sample with the highest concentration of As.

Total Mercury, Methylmercury, Inorganic Arsenic and Other Elements in Meat from Minke Whale (Balaenoptera acutorostrata) from the North East Atlantic Ocean

Meat samples of 84 minke whales (Balaenoptera acutorostrata) mainly from the Barents Sea, collected between 1 May and 16 August 2011, were analyzed for total mercury, methylmercury, cadmium, lead, total arsenic, inorganic arsenic and selenium. The average total mercury concentration found was 0.15 ± 0.09 mg/kg, with a range from 0.05 to 0.49 mg/kg. The molar ratio of selenium to mercury varied between 1.0 and 10.3. Cadmium content ranged from 0.002 to 0.036 mg/kg, while the content of lead in whale meat ranged from <0.01 to 0.09 mg/kg. None of the whale samples exceeded established EU maximum levels for metals in fish muscle, but 4.8% and 6.8% of the samples exceeded Japanese maximum levels for total mercury and methylmercury, respectively, in whale meat. There was only minor variations in element concentrations between whales from different geographical areas, and cadmium was the only element were the concentration increased with increasing length.

A baseline study of metals in herring (Clupea harengus) from the Norwegian Sea, with focus on mercury, cadmium, arsenic and lead

The Norwegian spring spawning (NSS) herring is an ecologically and economically important fish population in the Norwegian Sea. It was the first of several Norwegian fish stocks subject to a baseline study designed to give a comprehensive account of the levels of contaminants in a fish species from most of its area of distribution and during different seasons. During 2006 and 2007, 800 individual herring were sampled in their feeding areas in the Norwegian Sea in spring and autumn and at their spawning grounds off the coast of Norway during late winter. Metals including Hg, Cd, As and Pb were determined in muscle samples of individual herring, and mean concentrations±sd (mg kg(-1) ww) were: Hg: 0.04±0.03, Cd: 0.010±0.006, As: 2.2±0.6 and Pb: <0.01-0.10. Apart from one sample, no individual herring exceeded the EU's maximum level for any of these elements, as has been seen also in previous monitoring. Hg and Cd concentration increased with increasing fish age and As concentration varied seasonally, possibly due to uptake during feeding (summer), elimination during starvation (winter) and up-concentration during spawning (spring).

A baseline study on levels of polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, non-ortho and mono-ortho PCBs, non-dioxin-like PCBs and polybrominated diphenyl ethers in Northeast Arctic cod (Gadus morhua) from different parts of the Barents Sea

This study is one of several baseline studies on commercially important Norwegian wild fish species that will provide information concerning metals and persistent organic pollutants (POPs) and food safety. The cod liver is a traditional food product in Norway and a potential source for POPs in the diet. The concentrations of dioxins and furans (PCDD/Fs), dioxin-like PCBs (DL-PCBs), non-dioxin-like PCBs (NDL-PCBs, PCB6) and polybrominated flame retardants (PBDEs) were determined in the liver of 784 individual Northeast Arctic cod caught at 32 positions in the Barents Sea in the period from 2009-2010. In addition, muscle samples from 30 individual cod were analysed for the same substances. The mean concentration of the sum of PCDD/Fs and DL-PCBs for all samples was 14.2 ng TEQ who-2005/kg ww with a variation between 1.0 and 151 ng TEQ/kg ww. The concentrations of POPs in the fillet samples were very low.

A baseline study of metals in cod (Gadus morhua) from the North Sea and coastal Norwegian waters, with focus on mercury, arsenic, cadmium and lead

This study is one of several baseline studies that will provide basic and reliable information about the content of undesirable substances in important species of fish caught in Norwegian waters. Concentrations of metals in the muscle and livers of 516 cod caught at 22 positions in the North Sea were analysed. An additional 687 cod were caught from 13 fjords and coastal areas along the coast of Norway. Three out of 1203 samples of muscle exceeded the maximum limit of 0.5 mg Hg kg(-1) wet weight set by the EU for foodstuffs. The mercury concentration in cod muscle was higher and the cadmium concentration in the liver was lower in the North Sea and coastal areas in the southern part of Norway than in the Barents Sea and coastal areas in the northern part of Norway. These differences are perhaps caused by differences in the cod diet.

A baseline study of levels of mercury, arsenic, cadmium and lead in Northeast Arctic cod (Gadus morhua) from different parts of the Barents Sea

This study is one of several baseline studies that will provide basic and reliable information about the content of undesirable substances in important species of fish caught in Norwegian waters. Concentrations of metals in the muscle and liver of more than 800 Northeast Arctic cod caught at 32 sites in the Barents Sea are reported. The highest concentration of both mercury in the muscle and cadmium in the liver was found in cod caught in the western part of the Barents Sea, while the highest concentration of total arsenic was found in cod from the eastern part. The arsenic concentrations varied greatly among individual fish, ranging from 0.3 to 170 mg kg(-1) wet weight in the muscle. Such high levels of total arsenic have never previously been reported in any fish, and the primary factor for these high concentrations is likely to be the shrimp in the cod diet.

Concentrations of mercury and other toxic elements in orange roughy, Hoplostethus atlanticus, from the Mid-Atlantic Ridge

Concentrations of the elements mercury, arsenic, cadmium and lead were measured in the muscle tissue of Orange roughy (Hoplostethus atlanticus) obtained from the Mid-Atlantic Ridge during the MAR: -ECO: expedition in the North Atlantic Ocean in 2004. The age of the fish varied from 1 to 139 years. To the best of our knowledge, the concentration of the heavy metals presented here is for one of the oldest fish in the literature, in addition to the fact that very little information on arsenic in Orange roughy has been previously published. The concentration of mercury in the fillet of the fish varied between 0.06 and 1.1 μg g⁻¹ w.w. Mercury was the only element that was positively correlated to the age. The concentrations of mercury were found to be below the maximum limits for Orange roughy set by EU at 1.0 μg g⁻¹ w.w, except for a 134 year fish sample with a concentration of 1.1 μg g⁻¹ w.w.

Carry-over of dietary organochlorine pesticides, PCDD/Fs, PCBs, and brominated flame retardants to Atlantic salmon (Salmo salar L.) fillets

Information on carry-over of contaminants from feed to animal food products is essential for appropriate human risk assessment of feed contaminants. The carry-over of potentially hazardous persistent organic pollutants (POPs) from feed to fillet was assessed in consumption sized Atlantic salmon (Salmo salar). Relative carry-over (defined as the fraction of a certain dietary POP retained in the fillet) was assessed in a controlled feeding trial, which provided fillet retention of dietary organochlorine pesticides (OCPs), dioxins (PCDD/Fs), polychlorinated biphenyls (PCBs), and brominated flame retardants (BFRs). Highest retention was found for OCPs, BFRs and PCBs (31-58%), and the lowest retentions were observed for PCDD/Fs congeners (10-34%). National monitoring data on commercial fish feed and farmed Atlantic salmon on the Norwegian market were used to provide commercially relevant feed-to-fillet transfer factors (calculated as fillet POP level divided by feed POP level), which ranged from 0.4 to 0.5, which is a factor 5-10 times higher than reported for terrestrial meat products. For the OCP with one of the highest relative carry-over, toxaphene, uptake and elimination kinetics were established. Model simulations that are based on the uptake and elimination kinetics gave predicted levels that were in agreement with the measured values. Application of the model to the current EU upper limit for toxaphene in feed (50 μg kg(-1)) gave maximum fillet levels of 22 μg kg(-1), which exceeds the estimated permissible level (21 μg kg(-1)) for toxaphene in fish food samples in Norway.

Reducing persistent organic pollutants while maintaining long chain omega-3 fatty acid in farmed Atlantic salmon using decontaminated fish oils for an entire production cycle

Oily fish are an important source of health promoting nutrients such as the very long chain marine omega-3 (VLC-n3) fatty acids and simultaneously a source of potentially hazardous contaminants. Fish oils that are used in fish feed are the main source for both contaminants and VLC-n3. Decontamination techniques have recently been developed to effectively remove persistent organic contaminants from fish oils. The aim of the present study was to assess the level of potentially hazardous contaminants and the health beneficial fatty acids in Atlantic salmon reared on novel decontaminated feeds. Atlantic salmon were fed for 18 months (an entire seawater production cycle) on diets based on decontaminated or non-treated (control) fish oils until market size (approximately 5 kg). The level of known notorious persistent organic pollutants (POPs, i.e. dioxins, dioxin-like polychlorinated biphenyls (DL-PCBs), non dioxin-like PCBs, poly brominated diphenyl ethers (PBDE), and organochlorine pesticides), as well as fatty acid composition were analysed in fish oils, the two diets, and Atlantic salmon fillet. The oil decontamination process was a two-step procedure using active carbon and short path distillation. The fillet levels of POPs in market size fish were reduced by 68-85% while the concentration of very long chain omega-3 fatty acids was reduced by 4-7%. No differences in biomarkers of dioxin-like component exposures, such as hepatic gene expression of CYP1A or AhR2B, CYP1A protein expression and 7-ethoxyresorufin O-deethylase (EROD) activity, were observed between salmon raised on normal or decontaminated feeds, thus indicating that the difference in POPs levels were of no biological significance to the fish. Atlantic salmon reared on decontaminated feeds had sum polychlorinated dibenzodioxins/furans (PCDD/Fs) and DL-PCB concentrations that were comparable with terrestrial food products such as beef, while the level of marine omega-3 fatty acids remained as high as for commercially farmed Atlantic salmon.

Organ distribution and food safety aspects of cadmium and lead in great scallops, Pecten maximus L., and Horse Mussels, Modiolus modiolus L., from Norwegian waters

The purpose of the study was to determine the levels and organ distribution of the potentially harmful inorganic elements cadmium and lead in great scallops and horse mussels from unpolluted Norwegian waters. The scallops far exceeded the EU-limit for cadmium in bivalves when all soft tissues were analysed. When only muscle and gonad were included, however, the level of cadmium was acceptable, because cadmium accumulated in the digestive gland with a mean of 52 mg/kg ww (wet weight). In horse mussel, lead was the most problematic element and the concentration varied from 1.4 to 6.6 mg/kg ww with a mean of 3.7 mg/kg ww, exceeding the EU limit of 1.5 mg Pb/kg. The highest concentration of lead was found in the kidney with an average of 120 mg/kg ww and with a maximum value of 240 mg/kg ww. The kidney tissue accounted for approximately 94% of the lead burden in the horse mussel. In order to consume these bivalves, only muscle and gonad of great scallops should be used for consumption and the kidney of horse mussel should be removed prior to consumption.

Determination of arsenic, cadmium, mercury, and lead by inductively coupled plasma/mass spectrometry in foods after pressure digestion: NMKL interlaboratory study

Thirteen laboratories participated in an interlaboratory method performance (collaborative) study on a method for the determination of arsenic, cadmium, mercury, and lead by inductively coupled plasma/mass spectrometry (ICP/MS) after pressure digestion including the microwave heating technique. Prior to the study, the laboratories were able to practice on samples with defined element levels (pretrial test). The method was tested on a total of 7 foodstuffs: carrot puree, fish muscle, mushroom, graham flour, simulated diet, scampi, and mussel powder. The elemental concentrations in mg/kg dry matter (dm) ranged from 0.06-21.4 for As, 0.03-28.3 for Cd, 0.04-0.6 for Hg, and 0.01-2.4 for Pb. The materials used in the study were presented to the participants as blind duplicates, and the participants were asked to perform single determinations on each sample. The repeatability relative standard deviations (RSDr) for As ranged from 3.8 to 24%, for Cd from 2.6 to 6.9%, for Hg from 4.8 to 8.3%, and for Pb from 2.9 to 27%. The reproducibility relative standard deviations (RSDR) for As ranged from 9.0 to 28%, for Cd from 2.8 to 18%, for Hg from 9.9 to 24%, and for Pb from 8.0 to 50%. The HorRat values were less than 1.5 for all test samples, except for the determination of Pb in wheat flour at a level close to the limit of quantitation (0.01 mg/kg dm). The study showed that the ICP/MS method is satisfactory as a standard method for elemental determinations in foodstuffs.

Determination of sodium in foods by flame atomic absorption spectrometry after microwave digestion: NMKL interlaboratory study

Nine laboratories participated in an interlaboratory method performance (collaborative) study of a method for the determination of sodium in foods by flame atomic absorption spectrometry after wet digestion, using a microwave oven technique. Before the study, the laboratories were able to practice on samples with defined sodium levels (pretrial test). The method was tested on a total of 6 foods (broccoli, carrot, bread, saithe fillet, pork, and cheese) with sodium concentrations of 1480-8260 mg/kg. The materials were presented to the participants in the study as blind duplicates, and the participants were asked to perform single determinations for each sample. The repeatability relative standard deviations (RSDr) for sodium ranged from 1.9 to 6.5%. The reproducibility relative standard deviations (RSDR) ranged from 4.2 to 6.9%. The HorRat values ranged from 0.9 to 1.6.

Norwegian monitoring programme on the inorganic and organic contaminants in fish caught in the Barents Sea, Norwegian Sea and North Sea, 1994-2001

The results from part of a monitoring programme of contaminant levels in fish and other seafood products initiated by the Directorate of Fisheries in Norway in 1994 are presented. Concentrations of 22 elements (four are presented here: As, Cd, Hg and Pb) and HCB, HCH, PCB 28, 52, 101, 105, 118, 138, 153, 156, 180, pp-DDD, p-DDE, p-DDT, sum DDT and (137)Cs were determined in 17 species of fish caught in three sampling locations: the Barents Sea, the Norwegian Sea and the North Sea. The fish species analysed in the survey were limited to species of commercial importance for Norway with catching volumes of at least 10,000 metric tons year(-1). The survey started in 1994 and is expected to continue beyond 2010. The analyses were carried out on 25 individual fish from each species and each sampling location, and the locations were representative of commercial fishing grounds for the species in question. The concentrations of contaminants found were considerably lower than the maximum levels permissible in fish set by CODEX and the European Union for contaminants in seafood products.

Fluoride, calcium and magnesium intake in children living in a high-fluoride area in Ethiopia. Intake through food

OBJECTIVE

The aim of this study was to assess the daily dietary fluoride intake in children living in two neighbouring villages in the Wonji Shoa Sugar Estate, a rural part of the Ethiopian Rift Valley.

METHODS

The villages depended on water from different sources: Village A used either river water (Awash River, with 1.8 mg F(-)/L) or ground water (2.1 mg F(-)/L), while village K was served ground water with 14 mg F(-)/L. Fifteen fully weaned children below the age of 5 years were selected in each of the villages. Over a four-day period the total food intake for these children was assessed by using a duplicate portion technique. The food was analysed for fluoride by using a fluoride ion-selective electrode after the dry ashing. Furthermore, the energy of the food was measured, as well as the calcium and magnesium contents (atomic absorption spectrometry after microwave digestion with nitric acid and hydrogen peroxide). The mothers gave a description of the ingredients used for preparing the food. Relevant background information concerning food habits, etc. was collected through a food frequency questionnaire.

RESULTS

This study shows that considerable amounts of fluoride may be retained in food prepared on high-fluoride water. In village A, food contributed 2.3 mg F(-)/day, while a dietary fluoride intake of 4.8 mg/day was found in children in village K. Interestingly, the sevenfold higher fluoride concentration of the water used for food preparation in village K compared to village A, gave only a doubling in fluoride intake through food. Calcium intake was relatively low while magnesium intake was above the recommended level.

CONCLUSION

As the energy intake by both groups was low, some systematic underreporting might be suspected. Thus, the fluoride intake in the group may be even higher than what was actually found in this study.

Fluoride intake in children living in a high-fluoride area in Ethiopia - intake through beverages

INTRODUCTION

The present study was conducted in Wonji Shoa, a sugar estate in the Ethiopian Rift Valley. Drinking water in the area is provided either by the Awash River or by high-fluoride ground water wells. Defluoridation plants have been installed, but are not in regular use, and fluorosis, dental as well as skeletal, is endemic. The aim of this study was to assess daily fluoride intake from drinking water and beverages in children from neighbouring villages with varying fluoride concentration in the drinking water.

SUBJECTS AND METHODS

Thirty families were selected from two of the plantation villages (A and K). The criterion for being included in the project was the presence in the household of at least one child, fully weaned and below the age of 5 years. For sampling of beverages, the duplicate portion technique was used. The fluoride concentration in the beverage samples was determined using standard methods, using a fluoride ion-selective electrode.

RESULTS

Ten of the selected households in Village A fetched water from the Awash River (1.8 mg F-/L) while five relied upon water from a local well (2.1 mg F-/L). All 15 households in Village K used water from a local well with fluoride concentration of 14.4 mg/L. The mean daily fluoride intake from drinking water and beverages during the four days, varied from 1.2 to 1.5 mg and 5.9 to 8.8 mg in Village A and K, respectively. Low variety in types of beverages consumed was reported both during the study period and through the questionnaire. Only local water was used for beverage preparation. Children who consumed milk had a reduced fluoride intake. Tea, which was part of the children's diet, was not found to be a main source of fluoride.

CONCLUSION

A2n effective defluoridation of the drinking water or a change of water source would seem to be the only options for avoidance of dental and possibly skeletal fluorosis.

Determination of mercury in seafood by flow injection-cold vapor atomic absorption spectrometry after microwave digestion: NMKL interlaboratory study. Nordic Committee on Food Analysis

Ten laboratories participated in an interlaboratory method-performance (collaborative) study of a method for the determination of mercury in foods of marine origin by flow injection-cold vapor atomic absorption spectrometry after wet digestion using a microwave oven technique. The study was preceded by a training round of samples of known identity. The method was tested on a total of 7 seafood products: blue mussel (Mytilus edulis), cod muscle (Gadus morhua), crab (Cancer pagurus), scampi (Nephrops norwegicus), black scabbard fish (Aphnopus carbo), longnose velvet dogfish (Centroscymus crepidater), and Portuguese dogfish (Cenbroscymus coelolepis) with mercury concentrations of 0.14, 0.24, 0.35, 0.59,11.42, 4.2, and 13.2 microg/g, respectively. The materials were presented to the participants in the study as blind duplicates, and the participants were asked to perform single determinations on each sample. Repeatability relative standard deviations (RSDr) for mercury ranged from 2.4 to 14.0%. Reproducibility relative standard deviations (RSDR) ranged from 7.7 to 16.6%. HORRAT values for all samples were <1.0.

The effect of copper-treated net pens on farmed salmon (Salmo salar) and other marine organisms and sediments

Samples of Atlantic salmon (Salmo salar), saithe (Pollacius virens), blue mussel (Mytilus edulis), brown seaweed (Ascophyllum nodosum) and sediment were collected from six different fish farms. Five of the farms used net pens treated with copper-containing coatings, whereas one farm did not use copper-containing coating (this was used as a reference location). Samples of muscle, liver and gills of Atlantic salmon and saithe, blue mussel and brown seaweed were freeze dried, homogenised, wet digested and analysed for copper by flame atomic absorption spectrometry. The results showed no significant differences in copper concentrations among the samples from the different locations. The copper contents of some of the samples appeared to be in the upper part of the normal concentration range. From a nutritional point of view, the use of copper-coatings on net pens did not affect the quality of the seafood products either within, or around the net pen.

Determination of iodine in seafood by inductively coupled plasma/mass spectrometry

A method was developed for determination of total iodine content in different standard reference materials (SRMs) and seafood products by inductively coupled plasma/mass spectrometry (ICP/MS). If iodine is present as iodide and nitric acid is used in the wet digestion system, the observed signal is not stable when iodine is measured by ICP/MS at m/z 127. To stabilize the iodine signal, 3% ammonia solution (1 + 1, v/v) was added to the digest. The limit of quantitation of the method, defined as 6 times the standard deviation in the blank solution (n = 20) was estimated to be 15 mg/kg (using 0.2 g dry mass and a dilution factor of 50). The precision, expressed as repeatability of the iodine concentration, varied between 3.2 and 12% in SRMs, with concentrations of 4.70-0.17 mg/kg dry matter. The described method was compared with a method using tetramethylammonium hydroxide extraction. Both methods showed good precision and trueness by analyses of SRMs. The 2 methods were used to determine iodine in seafood from the Barents Sea, the Norwegian Sea, and the North Sea. The results showed great variation between different fish species as well as between individuals within a species. The lowest values of iodine were recorded in muscle of ling (Molva molva) with a mean of 0.07 mg/kg fresh weight and a variation between 0.03 and 0.11 mg/kg fresh weight. The highest values were found in cod (Gadus morhua) from the Barents Sea, with a mean of 2.5 mg/kg and a variation between 0.7 and 12.7 mg/kg fresh weight.

Cadmium, lead, copper and zinc in blue mussels (Mytilus edulis) sampled in the Hardangerfjord, Norway

Cadmium, lead, copper and zinc were determined in the soft tissues of blue mussels (Mytilus edulis) sampled from four locations along the Hardangerfjord in western Norway. A source of pollution is located at the head of the fjord and the sampling was performed at various distances from this source. The results obtained in this study (1998) were compared with results from similar studies carried out in 1983 and 1992. The mean cadmium concentrations in blue mussels sampled at Måge (13 km from the source of pollution) were approximately 18 mg kg-1 fresh weight in 1983, 2.4 mg kg-1 fresh weight in 1992 and 1.1 mg kg-1 fresh weight in 1998. The mean cadmium concentrations in blue mussels sampled at Varaldsøy (105 km from the source of pollution) were approximately 5 mg kg-1 fresh weight in 1983, 0.5 mg kg-1 fresh weight in 1992 and 0.4 mg kg-1 fresh weight in 1998. The mean lead concentration in blue mussels sampled at Måge was 140 mg kg-1 fresh weight in 1983. The mean lead concentrations in 1992 and 1998 had decreased to 6 and 3 mg kg-1 fresh weight, respectively. The mean lead concentrations in blue mussels from Gravdal were 15 mg kg-1 fresh weight in 1982, 1 mg kg-1 in 1992 and less than 1 mg kg-1 fresh weight in 1998. The mean copper concentrations in blue mussels were relatively constant over this period at all locations, with a variation between 0.6 and 1.2 mg kg-1 fresh weight. The mean zinc concentration in blue mussels sampled at Måge decreased from 120 to 30 mg kg-1 fresh weight in the period between 1983 and 1998.

Determination of arsenic in seafood by electrothermal atomic absorption spectrometry after microwave digestion: NMKL collaborative study

Eight laboratories participated in an interlaboratory method performance (collaborative) study of a method for the determination of arsenic in foodstuffs of marine origin by electrothermal atomic absorption spectrometry after wet digestion using a microwave oven technique. The study was preceded by a practice round of familiarization samples. The method was tested on 8 materials (cod roe, krill, blue mussel, saithe, scampi, cod fillet, shrimp, and cod extract) ranging in As content from 2 to 75 mg/kg. The materials were sent to participants in the study as blind duplicates, and the participants were asked to perform single determinations on each sample. Repeatability relative standard deviations (RSDr) for As ranged from 6.8 to 17.4%. Reproducibility relative standard deviations (RSDR) ranged from 7.6 to 24%. The highest RSDR value was found for the sample with the highest concentration of As.

Trace element levels in harp seal (Pagophilus groenlandicus) and hooded seal (Cystophora cristata) from the Greenland Sea. A multivariate approach

Concentrations of the essential trace elements, iron, copper, zinc and selenium and the non-essential elements arsenic, cadmium, total mercury and lead, were measured in the meat, liver and kidney of two species of seals, harp seal (Pagophilus groenlandicus) and hooded seal (Cystophora cristata) collected in the Greenland Sea. The spread among the individual seals was considerable. However, multivariate statistics simplified the evaluation of the data. The muscle tissue contained lower levels of the elements than kidney and liver. The kidney and liver tissue were also different, in particular with higher levels of iron in the liver and higher levels of cadmium in the kidney. Species differences were clear in both liver and kidney tissue, with higher levels of most of the elements in the hooded seals, while the harp seals had a higher burden of arsenic in the two tissues. Male hooded seals had higher levels of mercury and selenium than the females in all tissues. For harp seal there was a slight difference between the sexes in the muscle tissue, while no difference was observed in the liver and kidney tissues. The juvenile seals generally had lower levels of the elements in their tissues than the adults, although copper and zinc were higher in the muscles and livers of the juveniles as was iron in the muscles. No correlation between age and trace element levels in the tissues of the adult seals was observed.

Determination of inorganic arsenic in marine food samples by hydrochloric acid distillation and flow-injection hydride-generation atomic absorption spectrometry

A simple, rapid, and reliable method was developed for determination of inorganic As in biological samples such as fish fillet. Inorganic AS was distilled from the sample as AsCl3 with HCl. The separated inorganic AS was determined by flow-injection hydride-generation atomic absorption spectrometry after prereduction with KI and HCl. The influences of various concentrations of KI, ascorbic acid, and HCl in the prereduction stage; NaBH4 as the reductant; and HCl as the carrier solution on analytical results were studied. Digestion was performed in a Kjeldahl digestion system for 75 min with 4 mL nitric acid and 1 mL sulfuric acid at 380 degrees C. The concentrations of inorganic As in samples were less than 0.1 mg/kg dry weight for fish fillet and somewhat higher for crustaceans and bivalve molluscs. The total and inorganic As contents of various marine biological samples and certified reference materials were determined.

Studies of critical factors in the determination of arsenic in Standard Reference Materials of Marine origin by ETAAS: ;NMKL * interlaboratory study

A study to determine factors which are known to influence the electrothermal atomic absorption (ETAAS) determination of As has been performed. The study has been carried out using five sample solutions of marine Standard Reference Materials distributed to four participating laboratories. Uncoated and pyrolytically coated graphite tubes with L'vov platform and Ni and Pd/Mg as chemical modifiers have been tested. No differences in results have been obtained between AAS instruments equipped with Zeeman correction or deuterium arc background correction. Small differences in concentration levels of arsenic as well as in characteristic mass were found when chemical modifiers were compared. Pd/Mg will be recommended in order to avoid a contamination of the graphite furnace with nickel. The characteristic mass was improved by using pyrolytically coated graphite tubes with the L'vov platform compared with uncoated graphite tubes with the L'vov platform. In the interlaboratory study, the standard addition procedure will be recommended.

Levels of environmental pollutants in flounder (Platichthys flesus L.) and cod (Gadus morhua L.) caught in the waterway of Glomma, Norway. II. Mercury and arsenic

The present study is a survey on mercury and arsenic pollution in two sedentary fish species stationed in or close to the Glomma estuary in the Hvaler archipelago, Norway. Mercury and arsenic were determined individually in 80 flounder (Platichthys flesus L.) and 100 cod (Gadus morhua L.). The fish were caught at five different localities near or in the relatively polluted Glomma estuary. There were significantly higher mercury and arsenic concentrations in fillets of flounder than in fillets of cod (wet weight), 0.15 vs. 0.08 mg/kg and 5.2 vs. 4.1 mg/kg, respectively. Seasonal variation in mercury concentration was only found in flounder, with a significantly higher level in spring than in autumn. A significant increase in mercury content with increasing age was found for both species. For cod, a significantly higher arsenic level was found on the outer stations as compared to the inner stations, while arsenic levels in flounder was less dependent on sampling site.

Ascorbate-2-sulfate as a dietary vitamin C source for Atlantic salmon (Salmo salar): 2. Effects of dietary levels and immunization on the metabolism of trace elements

Atlantic salmon fingerlings were fed a vitamin C deficient diet for four months. The fish were then provided a dry, practical fishmeal based diet supplemented with 0, 500 or 5000 mg vitamin C/kg as L-ascorbic acid or equivalent amounts of ascorbate-2-sulfate. After six weeks on these diets ten fish in each group were injected with a soluble antigen (NIP11-LPH). Six weeks thereafter blood, liver, kidney, spleen and vertebrae were examined for trace elements. The livers were also analysed for metallothionein.The vitamin C deficient fish were anemic despite the significantly elevated iron concentrations in the liver. Vitamin C had no positive effect in lowering tissue levels of cadmium. The highest level of dietary vitamin C given as ascorbic acid reduced the liver selenium concentrations. In response to antigen injection, the fish in all groups showed increased levels of hepatic metallothionein, copper, zinc and cadmium, while hepatic selenium and iron levels were less affected. The elemental composition in other organs was affected by the antigen injection to a minor extent.

Trace elements intake in the Faroe Islands. III. Element concentrations in human organs in populations from Bergen (Norway) and the Faroe Islands

Flameless as well as flame atomic absorption spectrophotometry were used for the analysis of six elements (calcium, iron, zinc, selenium, cadmium and mercury) in human organs (liver, kidney cortex and medulla, heart, pancreas and spleen) from 13 bodies from Bergen and 10 from the Faroe Islands. Samples were taken at autopsy and the organs selected were without pathological signs. All patients were born between 1899 and 1923. Element concentrations in the organs studied were comparable to previous studies, except for high mercury and selenium values in the liver, the kidney cortex and medulla of subjects from the Faroe Islands. The high mercury and selenium values may be explained by the high consumption of pilot whales by the Faroe Islands population.

Gravimetric determination of ash in foods: NMKL collaborative study

A gravimetric method for the determination of ash was collaboratively studied in 14 laboratories. The food is ashed at 550 degrees C to constant weight and the ash is determined by weighing. Seven samples of various food commodities with estimated ash contents varying between low and high (0.07-8.0 g/100 g) were included in the study. The relative standard deviations for reproducibility varied, ranging from 1.0 and 1.3 for ash contents of 7.2 and 8.0 g/100 g, to 11 +/- 1% for low ash contents of 0.07 and 0.27 g/100 g.

A comparison of dressed crab and a cadmium salt (CdCl2) as cadmium sources in rat diets

1. A long term low level exposure experiment was conducted on rats in order to determine the metabolic patterns of realistic environmental dietary levels of cadmium from different sources. 2. Male and female rats were fed a diet for 6 months with a high crab content containing 4 mg Cd/kg as organic bound cadmium from dressed crab, a diet with low crab content containing 0.2 mg Cd/kg as organic bound cadmium, a casein based diet containing 4 mg Cd/kg as cadmium chloride and a low cadmium level control diet. 3. Analysis of the cadmium levels in the kidney, liver and spleen showed that uptake from the dressed crab was only half of that from the diet fortified with cadmium chloride.

Determination of silver in biological samples using graphite furnace atomic absorption spectrometry based on Zeeman effect background correction and matrix modification

A method for the determination of silver in human body fluids and biological material is described. The silver in an acid digest of biological samples and diluted body fluids is quantified using Zeeman graphite furnace atomic absorption spectrometry (ZGFAAS). The effects of NH4H2PO4 as matrix modifier and standard addition are discussed. Atomization from the graphite tube wall and from the pyrolytical tube with platform is also discussed and the peak height and the peak area are compared. The best results were achieved by using matrix modification, stabilized temperature platform furnace, integrated absorbance and standard addition technique. The calibration was linear up to 15 micrograms X L-1; the between-run precision was 5.9% at 40 micrograms X kg-1 of silver.

Subcellular distribution of selenium in the liver from rats fed selenium from fish: selenocystine and inorganic selenite

Four groups of rats of a normal selenium status were given different selenium compounds during a long-term feeding experiment (28 days). The selenium supplementations (per kg diet) were sodium selenite (1 mg), selenocystine (2 mg), and two different concentration levels of selenium from fish (0.1 and 1 mg). Differential pelleting of liver homogenates demonstrated that selenium was present in all the subcellular fractions, with a recovery of 55-60% in the cytosols. Gel permeation high-performance liquid chromatography of the cytosol fractions demonstrated the presence of protein-bound selenium at a molecular weight of 70,000 daltons. The subcellular distributions as well as the protein binding of selenium in the cytosols were identical in all dietary groups. This indicates a similar long-term liver metabolism of the four selenium compounds tested in the rat.

Comparative utilization of fish selenium and inorganic selenite by rats of normal selenium status

Rats of a normal selenium status were fed diets based on fish (rainbow trout) as the main protein source. A 4-week experiment with three dietary groups (low fish selenium, high fish selenium and selenite supplementation) was performed, and the selenium absorption, excretion and retention were recorded. Samples of blood serum, liver, kidneys, testes, hairs, spleen, lungs, heart, brain and skeletal muscle were collected for analysis of selenium. Glutathione peroxidase activity was measured in the blood serum. A selenium supplementation of approximately 1 mg/kg (high fish selenium and selenite group) yielded a selenium retention of only 7% of the intake, while in the group with a dietary selenium concentration of approximately 0.1 mg/kg (low fish selenium group) the selenium retention was 50%, resulting in almost the same absolute selenium retention in all three groups. The liver and kidneys showed the highest accumulations of selenium, reflecting the participation of these organs in the excretion of surplus selenium. The highest relative uptake of selenium was recorded in the testes, which increased equally in all dietary groups. The selenium concentration in the other tissues investigated, as well as the glutathione peroxidase activity in the blood serum responded little to the selenium supplementations. These results showed that the selenium levels normally found in fish were sufficient to satisfy the need for this element in rats of a good selenium status, and that inorganic selenite was absorbed and excreted at a high rate already after 1 week.

Acute response of parathyroid hormone in congenital osteopetrosis

Indices of calcium and phosphorus metabolism were studied in 3 children with osteopetrosis before and after infusion of bovine parathyroid hormone extract. Basal plasma concentrations of calcium, alkaline phosphatase and 25-hydroxy vitamin D tended to be low. Plasma immunoreactive PTH levels were at the upper normal range in two patients. A marked increase in urinary cyclic AMP in all patients was solely due to an increase in the nephrogenous cAMP. After vitamin D treatment urinary cAMP was essentially unchanged with the same preponderance of nephrogenous cAMP. Following PTH infusion plasma cAMP showed a brisk rise. There was also a prompt rise in urinary cAMP and a distinct decrease in the calcium to sodium clearance ratio indicating increased calcium reabsorption. Phosphaturic effect was only observed when PTH was given in the highest dose level. The findings are consistent with a state of low grade hyperparathyroidism which could not be related to the plasma levels of 25-hydroxy vitamin D or calcium.