Evaluation of lead, cadmium, chromium, copper and zinc by atomic absorption spectroscopy in durum wheat milling products in relation to the percentage of extraction

Evaluation and Dietary Exposure Assessment of Selected Toxic Trace Elements in Durum Wheat (Triticum durum) Imported into the Italian Market: Six Years of Official Controls

Durum wheat grains, which are mostly used for the production of pasta and several baked goods, represent a main source of vegetable proteins and calories. Concurrently, many contaminants, including toxic trace elements, may accumulate in them, posing a potential severe hazard to human health. In this context, for official control and food safety purposes, 346 samples of whole durum wheat imported into the Italian market from six countries (Australia, Canada, Kazakhstan, Russia, Turkey, and the United States) during the period 2015-2020 were analysed for cadmium (Cd), lead (Pb), and mercury (Hg) content using inductively coupled plasma mass spectrometry (ICP-MS). All the analysed samples were compliant with Food Agriculture Organization-World Health Organization and European Union regulations. The mean values were 0.0322 and 0.0162 mg kg-1, respectively, for Cd and Pb, while all samples showed levels below the limit of detection (0.004 mg kg-1) for Hg. The results were construed in terms of seasonality, year, and country of production, and compared with reference tolerance values. Confirming previous exposure studies, the obtained data and the dietary intake assessment showed that durum wheat-based products may have a significant impact on exposure to Pb and Cd (20-50%) in the overall population, particularly in more sensitive and/or exposed subgroups (infants, toddlers, and females).

Cadmium absorption and retention by rats fed durum wheat (Triticum turgidum L. var. durum) grain

A whole-body radioassay procedure was used to assess the retention and apparent absorption by rats of Cd in kernels of durum wheat (Triticum turgidum L. var. durum) harvested from plants grown hydroponically in 109Cd-labelled nutrient solution. Wholegrain wheat, containing 5 micromol Cd (570 microg)/kg dry weight labelled intrinsically with 109Cd, was incorporated into test meals fed to rats that had been maintained on diets containing marginally adequate, adequate or surplus levels of Zn (0.12 mmol (8 mg), 0.43 mmol (28 mg) or 1.55 mmol (101 mg) Zn/kg respectively), and either 0 or 50 g durum wheat/kg. Regardless of diet, all rats consumed about 99 % of the test meal offered. In rats fed diets without wheat, initial Cd absorption averaged 7.7, 4.6 and 2.4 % of the dose when the diet contained 0.12 mmol (8 mg), 0.43 mmol (28 mg) or 1.55 mmol (101 mg) Zn/kg diet respectively. In rats fed wheat-containing diets, initial Cd absorption averaged 3.8 and 2.6 % of the dose when dietary Zn concentration was 0.12 mmol (8 mg) and 0.43 mmol (28 mg)/kg diet respectively. The amount of Cd retained in the body at 15 d postprandial was <2 % of the dose in all rats, and decreased as Zn in the diet increased. Even at 15 d postprandial, 32 to 44 % of the Cd retained in the body was still in the gastrointestinal tract. The results show that: (1) the bioavailability to rats of Cd in wholegrain durum wheat was depressed when wholegrain wheat was part of the regular diet; (2) increased intake of dietary Zn lowered Cd absorption and retention; (3) retention of Cd in the body at 15 d postprandial from diets containing adequate Zn was <1.3 %.

Trace metals in soft and durum wheat from Italy

A survey was carried out with the aim to assess the levels of some toxic (cadmium, lead) and essential (copper, zinc) trace metals in wheat grown in Italy. A total of 178 samples of soft wheat grain and 239 samples of durum wheat grain from all the Italian wheat-growing regions were pooled into 35 and 38 representative samples respectively. After dry ashing, cadmium and lead were determined by graphite furnace atomic absorption spectrometry (GFAAS), whereas copper and zinc were determined by flame atomic absorption spectrometry (FAAS). In soft wheat the mean and median contents of all samples were (on a dry weight basis) 40 and 33 micrograms kg-1 for cadmium, 16 and 14 micrograms kg-1 for lead, 3.4 and 3.2 mg kg-1 for copper, 33 and 32 mg kg-1 for zinc. Similar levels were found in durum wheat. In this latter case the mean and median were 42 and 39 micrograms kg-1 for cadmium, 15 and 14 micrograms kg-1 for lead, 3.5 and 3.2 mg kg-1 for copper, 34 and 34 mg kg-1 for zinc. Significant differences were detected for some metals in relation to geographical provenance and variety. The average intake of the four selected elements from wheat-based products was estimated for the Italian population.

Lead and cadmium in some cereal products on the Finnish market 1990-91

Lead and cadmium contents were determined in representatively collected (commercial mills, wholesalers) samples of rye flour, breakfast cereals, porridge flakes, muesli cereals and pasta products. The samples were digested by heating them overnight in concentrated HNO3. Lead and cadmium concentrations were determined by GFAAS using a platform and (NH4)H2PO4 as a matrix modifier. ARC/CL coded wheat flour and other reference materials (NBS 1567a, BCR no. 189, BCR no. 191) were employed for the analytical quality control. Lead and cadmium contents found in the above samples were generally much lower than the present tolerance limits in Finland (300 micrograms/kg and 100 micrograms/kg respectively). The mean cadmium and lead contents of rye flours studied were very low, being 9 micrograms/kg and 16 micrograms/kg respectively. The mean contents of lead and cadmium in wheat-based breakfast cereals were 22 and 42, in rye products 19 and 26, in oats 17 and 2, in maize products 11 and 18 and in rice products 31 and 10 micrograms/kg, respectively. The mean contents of lead and cadmium in muesli cereals were 34 and 27 micrograms/kg. Remarkably high cadmium contents were found in some pastas made from imported durum wheat. The mean cadmium content of all past products was 79 micrograms/kg with a range of 26-182 micrograms/kg. Lead contents were low, with a mean of 18 micrograms/kg, and a range of 8 to 66 micrograms/kg. Cereals contribute about 59% of the average total dietary cadmium intake in Finland. Nearly 60% of the total cereal consumption is wheat and 27% rye. Since rye has a lower cadmium content than wheat, rye is preferable to wheat. About 15% of lead is derived from cereals. As the total intake of heavy metals is very low in Finland, there is no need to alter cereal consumption.