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.

Changes in the chemical form of selenium observed during the manufacture of a selenium-enriched sourdough bread for use in a human nutrition study

High-performance liquid chromatography interfaced with inductively coupled plasma mass spectrometry, and hydride generation-inductively coupled plasma mass spectrometry were used, respectively, to investigate changes in both the chemical form and the concentration of selenium during its bio-incorporation and bio-accumulation into rye seedlings. A 60-fold increase in the total level of selenium in the seedlings ('control' biomass = 0.99 mg kg(-1), 'enriched' biomass = 55.27 mg kg(-1)) was accompanied by a change from selenite to several organo-selenium forms, with more than 40% being present as selenomethionine. The seedling biomass was dried, ground and used as an ingredient in the production of a fermented sourdough bread (popular in Poland and many Eastern European countries). The selenium in the resulting bread was also characterized in terms of its speciation, as well as its total selenium content ('control' bread = 0.06 mg kg(-1), 'enriched' bread = 3.56 mg kg(-1)). The breads were then fed to 24 volunteers as part of a human intervention study designed to establish the efficacy of this mode of selenium supplementation. The human study data subsequently showed the bread was a good source of dietary selenium.

Multi-element survey of wild edible fungi and blackberries in the UK

A survey of 12 metals including lead (Pb), copper (Cu), cadmium (Cd), mercury (Hg), arsenic (As) and platinum (Pt) was carried out using ICP-MS in 34 samples of wild fungi and 48 samples of wild blackberries collected from sites across the UK. On a fresh weight basis (mg/kg) levels of Pb were in the range 0.003-5.990, Cu 0.596-34.800, Cd<0.001-19.6, Hg<0.001-4.150, As 0.001-0.972 and Pt (microg/kg) 0.006-0.200, with higher concentrations found in fungi than in blackberries. The results of the survey showed that the concentrations of the metals were consistent with previous studies, where available. Concentrations in wild fungi of Pt, tin (Sn), and titanium (Ti) were significantly higher at urban sites than at rural sites. Urban blackberries had significantly higher levels of Pb, Ti, and Cd than rural ones, but lower levels of manganese (Mn). Pb, Ti and Sn concentrations were significantly higher in blackberries sampled near main roads rather than in rural areas.

Migration studies from paper and board food packaging materials. 1. Compositional analysis

A survey of 32 paper and board materials intended for food contact has been undertaken. Sample composition was analysed to identify chemicals with a potential to migrate to foods. Representative materials covering a range of uses such as aqueous and fatty foods, and use at ambient and elevated temperatures, were obtained from industry. The samples were examined in their unfinished state, even where the final form would have included lamination to plastics, printing, or other treatments. A comprehensive and systematic analytical approach was applied which included determination of volatiles by headspace GC-MS, extraction using water, ethanol and chloroform with subsequent analysis by GC-MS and HPLC, and multi-element screening by ICP-MS. The solvent extracts were also weighed to determine the total amount of material available for migration. A large number of volatile substances were identified with alkyl and aryl aldehydes predominating in the majority of samples. Substances identified in solvent extracts included 2,6-di-tert-butyl-4-hydroxytoluene (BHT), di-tert-butylphenol, benzophenone, 4,4'-bis(dimethyl amino) benzophenone (Michler's ketone), triphenyl methane, bicyclohexylphenylphenanthrene carboxylic acid (and its methyl ester) and abietic acid. Levels of these substances were however generally below 1 mg/kg paper. Of the inorganic elements, arsenic and mercury were not detected above the limits of determination of 1.8 and 0.4 mg/kg respectively in any of the 10 samples examined. Cadmium was detected in teabag tissue and in unbleached Kraft paper at 0.3 mg/kg. Chromium was present in seven samples at 1.1-7.8 mg/kg, whilst lead was present in nine of the 10 samples at levels ranging from 0.3 to 5.9 mg/kg.

The evolution of medical staff credentialing

As medicine has developed more and more into a business, the process of medical staff credentialing has evolved. Today, physicians need to be affiliated with a hospital or other health care entity in order to practice. Health care entities, in turn, must be able to ensure quality of care and efficiency. The mechanisms that have developed to achieve these purposes comprise the process of medical staff credentialing as it now exists and will shape the continued evolution of credentialing in the future.

Lead in feed incident--multi-element analysis of cattle feed and tissues by inductively coupled plasma-mass spectrometry and co-operative quality assurance scheme for lead analysis of milk

Contaminated cattle feed was imported into the UK in 1989 and resulted in lead toxicity in some animals. Rapid analyses for lead and several other possible contaminating elements were required for feed and cattle tissues. Microwave dissolution of samples with measurement by ICP-MS was used for multi-element determinations. Lead was found to be the major contaminant. Lead levels in milk samples were measured by several laboratories during the crisis and an analytical quality assurance scheme was devised to monitor the quality of the data. The scheme allowed any poorly performing laboratories to be rapidly identified and excluded from the survey.

Lead contamination during domestic preparation and cooking of potatoes and leaching of bone-derived lead on roasting, marinading and boiling beef

Lead concentrations were measured in boiled, mashed potatoes and in baked potatoes that had been prepared and cooked in domestic kitchens. Levels of lead in the boiled, mashed potatoes ranged from below the 1 microgram/kg limit of detection up to 18 micrograms/kg with a mean of 6 micrograms/kg (wet weight). In the large majority of cases the lead in the tap water was the predominant source of the metal. Higher amounts of lead (range 11 micrograms/kg to 56 micrograms/kg, mean 27 micrograms/kg) were present in baked potatoes and this was attributed to soil adhering to the potato skin. The extent of leaching of lead from bone during cooking has also been investigated. For beef stocks there was little evidence to suggest that significant migration of bone lead occurred. For beef casseroles, marinaded in red wine, some leaching did occur from beef joints containing elevated amounts of bone lead; however the levels were all below 350 micrograms/kg and, on average, less than double that found in casseroles prepared from normal joints where the bone lead levels were an order of magnitude less.

Aluminium levels in milk and infant formulae

Aluminium levels in infant formulae purchased in 1990 and prepared as for consumption were in the range 530 micrograms/l to 640 micrograms/l for soya-based products and 27 micrograms/l to 120 micrograms/l for cows' milk-based formulae. Mean aluminium concentrations in these soya and cows' milk-based samples were, on average, 37% and 45% lower, respectively, than those of the same brands purchased between 1985 and 1987. Levels of aluminium in breast milk were in the range 3 micrograms/l to 79 micrograms/l. In the case of retail cows' milk, values ranged from 4 micrograms/l to 33 micrograms/l whilst more variable amounts of between 5 micrograms/l and 285 micrograms/l were detected in retail soya milk.

The aluminium content of infant formula and tea

Tea and infant formulae have been examined for the presence of aluminium. Concentrations in 13 different tea infusions ranged from 2.2 mg/l to 4.5 mg/l. In cow's milk-based infant formulae as made up for consumption, aluminium levels of between 0.03 mg/l and 0.20 mg/l were detected. Higher amounts were present in soya-based formulae with concentrations ranging from 0.64 mg/l to 1.34 mg/l.

A procedure for the determination of lead in green vegetables at concentrations down to 1 microgram/kg

An accurate and highly sensitive dry ashing/graphite furnace atomic absorption spectrometry (GFAAS) procedure has been developed for the measurement of lead in green vegetables. The accuracy of the method was established by analysis of standard reference materials and confirmed by isotope dilution using an inductively coupled plasma-mass spectrometer (ICP-MS). The limit of detection (wet weight) of the technique is 1-3 micrograms/kg with relative standard deviations ranging from 6% for a sample of kale containing 500 micrograms/kg to 20% for cabbage containing 3.0 micrograms/kg.