Toxic Elements in Food: Occurrence, Binding, and Reduction Approaches.

Toxic elements such as mercury, arsenic, cadmium, and lead, sometimes called heavy metals, can diminish mental and central nervous system function; elicit damage to blood composition as well as the kidneys, lungs, and liver; and reduce energy levels. Food is considered one of the main routes of their entry into the human body. Numerous studies have been performed to examine the effects of common food processing procedures on the levels of toxic elements in food. While some studies have reported negative effects of processing, several have shown that processing practices may have a positive effect on the reduction of toxic elements in foodstuffs. A number of studies have also introduced protocols and suggested chemical agents that reduce the amount of toxic elements in the final food products. In this review, the reported methods employed for the reduction of toxic elements are discussed with particular emphasis on the chemical binding of both the organic and inorganic forms of each element in various foods. The molecular groups and the ligands by which the food products bind with the metals and the types of these reactions are also presented.

Is it possible to agree on a value for inorganic arsenic in food? The outcome of IMEP-112.

Two of the core tasks of the European Union Reference Laboratory for Heavy Metals in Feed and Food (EU-RL-HM) are to provide advice to the Directorate General for Health and Consumers (DG SANCO) on scientific matters and to organise proficiency tests among appointed National Reference Laboratories. This article presents the results of the 12th proficiency test organised by the EU-RL-HM (IMEP-112) that focused on the determination of total and inorganic arsenic in wheat, vegetable food and algae. The test items used in this exercise were: wheat sampled in a field with a high concentration of arsenic in the soil, spinach (SRM 1570a from NIST) and an algae candidate reference material. Participation in this exercise was open to laboratories from all around the world to be able to judge the state of the art of the determination of total and, more in particular, inorganic arsenic in several food commodities. Seventy-four laboratories from 31 countries registered to the exercise; 30 of them were European National Reference Laboratories. The assigned values for IMEP-112 were provided by a group of seven laboratories expert in the field of arsenic speciation analysis in food. Laboratory results were rated with z and ζ scores (zeta scores) in accordance with ISO 13528. Around 85 % of the participants performed satisfactorily for inorganic arsenic in vegetable food and 60 % did for inorganic arsenic in wheat, but only 20 % of the laboratories taking part in the exercise were able to report satisfactory results in the algae test material.

Humans seem to produce arsenobetaine and dimethylarsinate after a bolus dose of seafood.

Seafood is the predominant food source of several organoarsenic compounds. Some seafood species, like crustaceans and seaweed, also contain inorganic arsenic (iAs), a well-known toxicant. It is unclear whether human biotransformation of ingested organoarsenicals from seafood result in formation of arsenicals of health concern. The present controlled dietary study examined the urinary excretion of arsenic compounds (total arsenic (tAs), iAs, AB (arsenobetaine), dimethylarsinate (DMA) and methylarsonate (MA)) following ingestion of a single test meal of seafood (cod, 780 µg tAs, farmed salmon, 290 µg tAs or blue mussel, 690 µg tAs or potato (control, 110 µg tAs)) in 38 volunteers. The amount of ingested tAs excreted via the urine within 0-72 h varied significantly among the groups: Cod, 74% (52-92%), salmon 56% (46-82%), blue mussel 49% (37-78%), control 45% (30-60%). The estimated total urinary excretion of AB was higher than the amount of ingested AB in the blue mussel group (112%) and also ingestion of cod seemed to result in more AB, indicating possible endogenous formation of AB from other organoarsenicals. Excretion of iAs was lower than ingested (13-22% of the ingested iAs was excreted in the different groups). Although the ingested amount of iAs+DMA+MA was low for all seafood groups (1.2-4.5% of tAs ingested), the urinary DMA excretion was high in the blue mussel and salmon groups, counting for 25% and 11% of the excreted tAs respectively. In conclusion our data indicate a possible formation of AB as a result of biotransformation of other organic arsenicals. The considerable amount of DMA excreted is probably not only due to methylation of ingested iAs, but due to biotransformation of organoarsenicals making it an inappropriate biomarker of iAs exposure in populations with a high seafood intake.

Review of Potentially Toxic Rare Earth Elements, Thallium and Tellurium in Plant-based Foods.

In the last decades, there is an increasing inclusion of various trace metals and metalloids such as thallium, tellurium and rare earth elements (REEs; lanthanides, scandium, and yttrium) in the composition and production of alloys, in agricultural and medicinal applications, as well as in the manufacturing of hi-tech products. All these activities have led to an accumulation of the aforementioned elements both in soil and water bodies and consequently in the food chain, through discharges from mining and mineral processing, liquid industrial waste or disposal of urban and industrial products. It has been demonstrated that chronic exposure to some of these elements, even at low doses, might lead to a wide range of adverse health effects, even from the early stages of life, such as neurotoxicity, neurodevelopmental toxicity and hepatic alterations. Particularly in children, there have been studies suggesting that some of these elements might negatively affect the children's spatial learning and memory ability indirectly. Such effects are triggered by processes like the production of reactive oxygen species (ROS), lipid peroxidation and modulation of antioxidant activities. Nevertheless, the limited data from toxicological studies and their so-far naturally low occurrence levels in the environment acted as a deterrent in measuring their concentrations during routine analyses of metals in foodstuff. Thus, it is important to collect information on their occurrence data both in adults and in children's daily diet. This review sumrises the current knowledge on the concentration of these elements, in plant-based food products to identify whether a potential health risk occurs. As side projects, this Fellowship provided hands-on training on the evaluation of new biocides application and participation in the given advice to the Danish Food and Veterinary Administration, Danish Environmental Protection Agency, the Danish Medical Agency and the European Chemicals Agency.

Speciation of zinc in fish feed by size exclusion chromatography coupled to inductively coupled plasma mass spectrometry - using fractional factorial design for method optimisation and mild extraction conditions.

Zinc (Zn) is an element essential to all living organisms and it has an important role as a cofactor of several enzymes. In fish, Zn deficiency has been associated with impaired growth, cataracts, skeletal abnormalities and reduced activity of various Zn metalloenzymes. Fish meal and fish oil traditionally used in salmon feed preparation are being replaced by plant-based ingredients. Zinc additives are supplemented to salmon feed to ensure adequate Zn levels, promoting good health and welfare in Atlantic salmon (Salmo salar). The main objective of the present study was to evaluate Zn species found in an Atlantic salmon feed. This work describes a Zn extraction method that was optimized using a fractional factorial design (FFD), whereby the effect of six factors could be studied by performing only eight experiments. The effects of the type of extraction solution and its molar concentration, pH, presence of sodium dodecyl sulphate, temperature and extraction time on Zn extraction were investigated. Mild extraction conditions were chosen in order to keep the Zn species intact. Total Zn (soluble fractions and non-soluble fractions) was determined by inductively coupled plasma mass spectrometry (ICP-MS). The highest Zn recovery was obtained using 100 mM Tris-HCl, pH 8.5 at a temperature of 4 °C for 24 h where the total Zn in soluble fraction and non-soluble fraction was 9.9 ±â€¯0.2% and 98 ±â€¯6%, respectively. Zinc speciation analysis (on the soluble fractions) was further conducted by size exclusion inductively coupled plasma mass spectroscopy (SEC-ICP-MS). The SEC-ICP-MS method provided qualitative and semi-quantitative information regarding Zn species present in the soluble fractions of the feed. Four Zn-containing peaks were found, each with different molecular weights: Peak 1 (high molecular weight - ≥600 kDa), peak 2 and peak 3 (medium molecular weight - 32 to 17 kDa) were the least abundant (1-6%), while peak 4 (low molecular weight - 17 to 1.36 kDa) was the most abundant (84-95%).

Accuracy of a method based on atomic absorption spectrometry to determine inorganic arsenic in food: Outcome of the collaborative trial IMEP-41.

A collaborative trial was conducted to determine the performance characteristics of an analytical method for the quantification of inorganic arsenic (iAs) in food. The method is based on (i) solubilisation of the protein matrix with concentrated hydrochloric acid to denature proteins and allow the release of all arsenic species into solution, and (ii) subsequent extraction of the inorganic arsenic present in the acid medium using chloroform followed by back-extraction to acidic medium. The final detection and quantification is done by flow injection hydride generation atomic absorption spectrometry (FI-HG-AAS). The seven test items used in this exercise were reference materials covering a broad range of matrices: mussels, cabbage, seaweed (hijiki), fish protein, rice, wheat, mushrooms, with concentrations ranging from 0.074 to 7.55mgkg(-1). The relative standard deviation for repeatability (RSDr) ranged from 4.1 to 10.3%, while the relative standard deviation for reproducibility (RSDR) ranged from 6.1 to 22.8%.

Determination of ultra-trace amounts of arsenic(III) by flow-injection hydride generation atomic absorption spectrometry with on-line preconcentration by coprecipitation with lanthanum hydroxide or hafnium hydroxide.

A time-based flow-injection (FI) procedure for the determination of ultra-trace amounts of inorganic arsenic(III) is described, which combines hydride generation atomic absorption spectrometry (HG-AAS) with on-line preconcentration of the analyte by inorganic coprecipitation-dissolution in a filterless knotted Microline reactor. The sample and coprecipitating agent are mixed on-line and merged with an ammonium buffer solution, which promotes a controllable and quantitative collection of the generated hydroxide on the inner walls of the knotted reactor incorporated into the FI-HG-AAS system. Subsequently the precipitate is eluted with 1 mol 1(-1) hydrochloric acid, allowing ensuing determination of the analyte via hydride generation. The preconcentration of As(III) was tested by coprecipitation with two different inorganic coprecipitating agents namely La(III) and Hf(IV). It was shown that As(III) is more effectively collected by lanthanum hydroxide than by hafnium hydroxide, the sensitivity achieved by the former being approximately 25% better. With optimal experimental conditions and with a sample consumption of 6.7 ml per assay, an enrichment factor of 32 was obtained at a sample frequency of 33 samples h(-1). The limit of detection (3sigma) was 0.003 microg 1(-1) and the precision (relative standard deviation) was 1.0% (n = 11) at the 0.1 microg 1(-1) level.

Urinary excretion of arsenicals following daily intake of various seafoods during a two weeks intervention.

The excretion pattern of arsenic (As) species after seafood intake varies widely depending on species ingested and individual handling. We have previously reported the 72 h urinary excretion of arsenicals following a single dose of seafood. Here, we report the excretion patterns in the same 37 subjects following 15 days daily consumption of either 150 g cod, salmon, blue mussels or potato (control), followed by a 72 h period with a low-As diet. In all seafood groups, total As (tAs) in plasma and urinary excretion of tAs, arsenobetaine (AB) and dimethylarsinate (DMA) increased significantly after the intervention. Confirming the single dose study AB and DMA excreted were apparently endogenously formed from other arsenicals ingested. Total tAs excretion was 1386, 763 and 303 µg in the cod, blue mussel and salmon groups, respectively; about twice the amounts after the single dose study indicating accumulation of arsenicals. In the cod group, rapid excretion after the single dose was associated with lower total As in blood and less accumulation after two weeks with seafood indicating lower accumulation. In the blue mussels group only, inorganic As (iAs) excretion increased significantly, whilst methylarsonate (MA) strongly increased, indicating a possible toxicological concern of repeated mussel consumption.

Method validation and analysis of nine dithiocarbamates in fruits and vegetables by LC-MS/MS.

An analytical method for separation and quantitative determination of nine dithiocarbamates (DTCs) in fruits and vegetables by using LC-MS/MS was developed, validated and applied to samples purchased in local supermarkets. The nine DTCs were ziram, ferbam, thiram, maneb, zineb, nabam, metiram, mancozeb and propineb. Validation parameters of mean recovery for two matrices at two concentration levels, relative repeatability (RSDr), relative within-laboratory reproducibility (RSDR) and LOD were obtained for the nine DTCs. The results from the analysis of fruits and vegetables served as the basis for an exposure assessment within the given commodities and a risk assessment by comparing the calculated exposure to the acceptable daily intake and acute reference dose for various exposure groups. The analysis indicated positive findings of DTCs in apples, pears, plums, table grapes, papaya and broccoli at concentrations ranging from 0.03 mg/kg to 2.69 mg/kg expressed as the equivalent amount of CS2. None of the values exceeded the Maximum residue level (MRL) set by the European Union, and furthermore, it was not possible to state whether illegal use had taken place or not, because a clear differentiation between the various DTCs in the LC-MS/MS analysis was lacking. The exposure and risk assessment showed that only for maneb in the case of apples and apple juice, the acute reference dose was exceeded for infants in the United Kingdom and for children in Germany, respectively.

Major and minor arsenic compounds accounting for the total urinary excretion of arsenic following intake of blue mussels (Mytilus edulis): a controlled human study.

Blue mussels (Mytilus edulis) accumulate and biotransform arsenic (As) to a larger variety of arsenicals than most seafood. Eight volunteers ingested a test meal consisting of 150 g blue mussel (680 µg As), followed by 72 h with an identical, low As controlled diet and full urine sampling. We provide a complete speciation, with individual patterns, of urinary As excretion. Total As (tAs) urinary excretion was 328 ± 47 µg, whereof arsenobetaine (AB) and dimethylarsinate (DMA) accounted for 66% and 21%, respectively. Fifteen minor urinary arsenicals were quantified with inductively coupled plasma mass spectrometry (ICPMS) coupled to reverse-phase, anion and cation-exchange high performance liquid chromatography (HPLC). Thio-arsenicals and non-thio minor arsenicals (including inorganic As (iAs) and methylarsonate (MA)) contributed 10% and 7% of the total sum of species excretion, respectively, but there were large individual differences in the excretion patterns. Apparently, formation of thio-arsenicals was negatively correlated to AB formation and excretion, possibly indicating a metabolic interrelationship. The results may be of toxicological relevance since DMA and MA have been classified as possibly carcinogenic, and six of the excreted As species were thio-arsenicals which recently have been recognized as toxic, while iAs toxicity is well known.

Survey of pesticide residues in table grapes: determination of processing factors, intake and risk assessment.

The differences in residue pattern between Italy and South Africa, the main exporters of table grapes to the Danish market, were investigated. The results showed no major differences with respect to the number of samples with residues, with residues being found in 54-78% of the samples. Exceedances of the European Union maximum residue limit (MRL) were found in five samples from Italy. A number of samples were rinsed to study the possible reduction of residues. For copper, iprodione, procymidone and dithiocarbamates a significant effect of rinsing was found (20-49% reduction of residues). However, no significant effect was found for organophosphorus pesticides and pyrethroids, whereas the number of samples with residues of benzilates, phenylamids and triazoles was insufficient to demonstrate any significant effects. An intake calculation showed that the average intake from Italian grapes was 3.9 microg day(-1) for pesticides and 21 microg day(-1) for copper. Correspondingly, the intakes from South African grapes were 2.6 and 5.7 microg day(-1), respectively. When the total exposure of pesticides from grapes were related to acceptable daily intake, expressed as the sum of Hazard Quotients, the exposure were approximately 0.5% for Italian samples and 1% for South African samples.