Stability of arsenic compounds in seafood samples during processing and storage by freezing

In this study, the stability of arsenic compounds in fresh and frozen samples of raw, boiled and fried Atlantic cod (Gadhus morhua), Atlantic salmon (Salmo salar) and blue mussel (Mytilus edulis) were examined. Results show that the total arsenic concentrations of the fresh Atlantic cod and Atlantic salmon samples were not different from the frozen samples within the same seafood type. For blue mussel, the total arsenic concentration decreased significantly after storage. Inorganic arsenic was found only in blue mussels and, importantly, no significant increase of inorganic arsenic was observed after processing or after storage by freezing. The content of tetramethylarsonium ion was generally low in all samples types, but increased significantly in all fried samples of both fresh and frozen seafood. Upon storage by freezing, the arsenobetaine content was reduced significantly, but only in the samples of blue mussels.     

Incidence of Listeria species in seafood and seafood salads

A total of 128 samples of seafood on the Icelandic market were tested for the presence of Listeria monocytogenes and other Listeria species. The samples included raw, smoked and dried fish, frozen shellfish and shrimps as well as several fish salads. These products are generally consumed without heating. Listeria spp. were present in 56% of the samples of raw fish, 29% of the smoked fish, 9% of the shrimps and 32% of the salads. No Listeria spp. were present in the shellfish or dried fish. In 46% of the positive samples L. monocytogenes could be demonstrated, either alone or together with L. innocua. The other positive samples contained L. innocua and, in one sample, L. welshimeri. All products sampled had been processed and packed in Iceland, mostly for use on the domestic market. It is suggested that consuming certain fish products and fish salads may form an additional risk factor for listeriosis in humans.     

Preserving the distribution of inorganic arsenic species in groundwater and acid mine drainage samples

The distribution of inorganic arsenic species must be preserved in the field to eliminate changes caused by metal oxyhydroxide precipitation, photochemical oxidation, and redox reactions. Arsenic species sorb to iron and manganese oxyhydroxide precipitates, and arsenite can be oxidized to arsenate by photolytically produced free radicals in many sample matrices. Several preservatives were evaluated to minimize metal oxyhydroxide precipitation, such as inorganic acids and ethylenediaminetetraacetic acid (EDTA). EDTA was found to work best for all sample matrices tested. Storing samples in opaque polyethylene bottles eliminated the effects of photochemical reactions. The preservation technique was tested on 71 groundwater and six acid mine drainage samples. Concentrations in groundwater samples reached 720 microg-As/L for arsenite and 1080 microg-As/L for arsenate, and acid mine drainage samples reached 13 000 microg-As/L for arsenite and 3700 microg-As/L for arsenate. The arsenic species distribution in the samples ranged from 0 to 90% arsenite. The stability of the preservation technique was established by comparing laboratory arsenic speciation results for samples preserved in the field to results for subsamples speciated onsite. Statistical analyses indicated that the difference between arsenite and arsenate concentrations for samples preserved with EDTA in opaque bottles and field speciation results were analytically insignificant. The percentage change in arsenite:arsenate ratios for a preserved acid mine drainage sample and groundwater sample during a 3-month period was -5 and +3%, respectively.     

食用菌中的总砷和砷形态分布研究

研究总砷超标食用菌样品中砷的形态分布,对食用菌中总砷含量与食用安全性的关系及其限量规定进行探讨。方法从2010年深圳口岸进出口食用菌批量监测结果的各种食用菌样品中选择总砷超标的几类样品,采用液相色谱-氢化物发生原子荧光光谱联用技术(LC-HGAFS)分析了不同种类食用菌中的砷形态,准确测定了总无机砷与总砷含量。结果发现形态分析方法能够准确定性定量食用菌中的总无机砷含量,而食用菌中总砷含量和总无机砷含量并不存在对应关系,干香菇中总砷和总无机砷含量均较高,有一定食用风险,而蘑菇中总砷含量高,总无机砷含量却很低,主要以一甲基砷等其他无毒的砷形态存在,可以放心食用。结论食用菌中砷形态分布测定更能科学体现砷超标和食用安全性的关系,我国现行食用菌卫生标准仅规定总砷限量指标,建议进行修订。     

X-ray absorption near-edge structure analysis of arsenic species for application to biological environmental samples

Arsenic is an element that is ubiquitous in the environment and is known to form compounds with toxic, even carcinogenic properties. Arsenic toxicity is a function of its chemical form (species). Identification of arsenic species is necessary to accurately determine the transformation and fate of arsenicals as well as the actual risk posed by arsenic contamination. We report X-ray absorption near-edge structure (XANES) measurements of 16 biologically important arsenic compounds. Solid and aqueous standards were studied for differences in XANES spectral features, white line positions, stability during exposure to the beam, and stability between two beam exposures separated by 48 h. Samples containing As(III) (11870.0-11871.7+/-0.5 eV) and As(V) (11872.6-11875.3+/-0.5 eV) were easily distinguished by white line energies and could be further subdivided into a total of seven groups. Valuable examples include As(III)-sulfur compounds (11870.0+/-0.5 eV), arsenobetaine and arsenocholine (11872.6+/-0.5 eV), and a dimethyl arsinyl riboside (11873.3+/-0.5 eV). A growing number of environmental and biological studies use X-ray absorption spectroscopy (XAS) results to complement their more traditional analyses. Results provided here are intended to help make XAS more accessible to new users interested in the study of arsenic in the environment.     

Jatropha platyphylla, a new non-toxic Jatropha species: Physical properties and chemical constituents including toxic and antinutritional factors of seeds

Local communities in Mexico consume Jatropha platyphylla seeds after roasting. The kernels of J. platyphylla contained ca. 60% oil and were free of phorbol esters. The kernel meal of this Jatropha species contained trypsin inhibitor, lectins and phytate. However, trypsin inhibitor and lectins are heat labile so this explains why the local people can eat roasted seeds without ill effects. Heat-treated J. platyphylla kernel meal (JPKM) was free of trypsin inhibitor and lectin activities. Crude protein content of JPKM was 75%. Heated JPKM and soybean meal were included in a standard diet (crude protein 36%) for Nile tilapia (Oreochromis niloticus) to replace 50% of the fish meal protein. The growth of fish in all the three groups was statistically similar and the blood biochemical parameters that serve as biomarkers for toxicity were within the normal ranges. This is the first study that confirms the non-toxic nature of J. platyphylla.     

Determination of total arsenic, inorganic and organic arsenic species in wine

Forty-five wine samples from the south of Spain of different alcoholic strength were analysed for total arsenic and its inorganic [As(III), As(V)] and organic (monomethylarsonic acid [MMAA], dimethylarsinic acid [DMAA]) species. The As levels of the wine samples ranged from 2.1 to 14.6 µg l^-1. The possible effect of the alcoholic fermentation process on the levels of the total arsenic and arsenical species was studied. The average total arsenic levels for the different samples were very similar, without significant differences between all types of wines. In table wines and sherry, the percentages of total inorganic arsenic were 18.6 and 15.6%, with DMAA or MMAA being the predominant species, respectively. In most samples, DMAA was the most abundant species, but the total inorganic aresenic fraction was considerable, representing 25.4% of the total concentration of the element. The estimated daily intakes of total arsenic and total inorganic arsenic for average Spanish consumers were 0.78 and 0.15 µg/person day^-1, respectively. The results suggest that the consumption of these types of wines makes no significant contribution to the total and inorganic arsenic intake for normal drinkers. However, wine consumption contributes a higher arsenic intake than through consumption of beers and sherry brandies.     

Prevalence of potentially pathogenic Vibrio species in the seafood marketed in Malaysia

Seafood samples obtained in seafood markets and supermarkets at 11 sites selected from four states in Malaysia were examined for the presence of nine potentially pathogenic species from the genus Vibrio between July 1998 and June 1999. We examined 768 sample sets that included shrimp, squid, crab, cockles, and mussels. We extensively examined shrimp samples from Selangor State to determine seasonal variation of Vibrio populations. Eight potentially pathogenic Vibrio species were detected, with overall incidence in the samples at 4.6% for V. cholerae, 4.7% for V. parahaemolyticus, 6.0% for V. vulnificus, 11% for V. alginolyticus, 9.9% for V. metschnikovii, 1.3% for V. mimicus, 13% for V. damsela, 7.6% for V. fluvialis, and 52% for a combined population of all of the above. As many as eight Vibrio species were detected in shrimp and only four in squid and peel mussels. The overall percent incidence of any of the eight vibrios was highest (82%) in cockles (Anadara granosa) among the seafoods examined and was highest (100%) in Kuching, Sarawak State, and lowest (25%) in Penang, Pulau Penang State, among the sampling sites. Of 97 strains of V. cholerae isolated, one strain belonged to the O1 serotype and 14 to the O139 serotype. The results indicate that the various seafood markets in Malaysia are contaminated with potentially pathogenic Vibrio species regardless of the season and suggest that there is a need for adequate consumer protection measures.     

Fast extraction methodologies for the determination of toxic arsenic in meat

A nonchromatographic analytical procedure has been developed for the determination of arsenic in meat samples including the major toxic arsenic species arsenite, arsenate, monomethylarsonic acid (MMA) and dimetylarsinic acid (DMA). The method is based on the extraction of arsenic species in mild conditions, selective trivalent hydride formation and final determination by hydride generation atomic fluorescence spectroscopy (HG‐AFS). Different extractant agents and two different procedures, microwave‐assisted extraction (MAE) and ultrasound assisted extraction at room temperature, were evaluated for As species extraction. The method provided a limit of detection of 0.013 ng mL^?1 and a mean relative standard deviation in actual samples of 0.3%. Data found for toxic As in meat samples varied from 0.42 ng g^?1 in chicken muscle to 68 ng g^?1 in pork liver. Percentage of toxic As respect to total As varied in the 9–46% range depending on the meat product.     

不同前处理对原子荧光法测定海产品总砷的影响

对氢化物-原子荧光法测定海产品中总砷的前处理进行研究,探讨了微波消解、干法灰化、湿法消解、微波-湿法消解四种前处理方法对原子荧光法测定海产品中总砷结果的影响。实验证明不同的前处理方法对样品结果有很大影响:微波消解不适于海产品总砷的前处理,干法灰化不适用紫菜类植物性海产品的前处理,硝酸-高氯酸-硫酸体系的湿法消解、微波-湿法消解(加高氯酸、硫酸)可以作为一般海产品的前处理,且两种前处理的回收率均大于90%。     

Mercury,lead, arsenic,and cadmium in Norwegian seafood products and consumer exposure

ABSTRACT

Seafood can be a source of contaminants, which may raise health concerns. The aim of this study was to analyse the levels of inorganic contaminants in commercially available seafood products and assess consumer exposure. Commercially available samples were collected from 2015–2018 and analysed as composite samples for mercury, lead, arsenic, and cadmium, using accredited methods. Levels of cadmium, lead, and arsenic were low and human exposure of these metals would be minimal from consumption of the analysed seafood products. Mercury levels were well below the EU maximum limit for mercury in fish. However, children, who are high consumers, might be at risk of exceeding the tolerable weekly intake for methyl mercury, when eating products with the highest mercury levels. The collected data can be used for future risk-benefit assessments as intake of processed seafood products represent a large proportion of the populations' seafood intake in Europe.     

Assessment of lectin activity in a toxic and a non-toxic variety of Jatropha curcas using latex agglutination and haemagglutination methods and inactivation of lectin by heat treatments

Lectin activity in a toxic (Cape Verde) and non-toxic (Mexico) variety of Jatropha curcas seed meal was investigated using latex agglutination and haemagglutination assays. Lectin activity expressed as reciprocal of the minimum quantity (in mg) of Jatropha meal per ml of the assay mixture which produced agglutination with the latex beads was 2·88 ± 0·57 and 1·71 ± 0·00 (mean ± SD, n = 3) for the toxic and the non-toxic varieties, respectively, which did not differ significantly (P > 0·05), while with the haemagglutination assay these values were 102 and 51, respectively, and differed significantly (P < 0·05). The lectins were inactivated by heating and moist heat was more effective than dry heat. The results suggest that lectins may not be responsible for short term toxicity caused by consumption of raw Jatropha meal. © 1998 SCI.     

Histamine levels in seventeen species of fresh and processed South African seafood

Histamine levels were determined in fresh and processed seafood from a representative range of 10 outlets after several incidents of scombroid seafood poisoning occurred. Species included seventeen fresh and processed scombroid- and non-scombroid fish, marine mollusks and crustaceans. Histamine levels in fresh seafood were generally low (0–9 ppm) with the exception of one sample of snoek (scombroid fish; >50 ppm) and one sample of yellowtail (non-scombroid fish; >50 ppm). Both species are rich in free histidine (1.5–5.3 ppb), a precursor of histamine. Processed seafood had, in general, low histamine concentrations (0–3 ppm) with the exception of fish meal (76 ppm), salted herring (47 ppm), one sample of smoked snoek (>50 ppm) and dried tuna (8000 ppm). In total, 5 of 80 examined samples (6%) contained histamine concentrations above the legal limit of 50 ppm. Experimental formation of histamine was demonstrated to be strongly temperature- and time-dependent. Samples were not contaminated with Vibrio spp., Pseudomonas spp., Klebsiellas spp. or Enterobacteria.     

Total and inorganic arsenic in fish samples from Norwegian waters

The contents of total arsenic and inorganic arsenic were determined in fillet samples of Northeast Artic cod, herring, mackerel, Greenland halibut, tusk, saithe and Atlantic halibut. In total, 923 individual fish samples were analysed. The fish were mostly caught in the open sea off the coast of Norway, from 40 positions. The determination of total arsenic was carried out by inductively coupled plasma mass spectrometry following microwave-assisted wet digestion. The determination of inorganic arsenic was carried out by high-performance liquid chromatography–ICP-MS following microwave-assisted dissolution of the samples. The concentrations found for total arsenic varied greatly between fish species, and ranged from 0.3 to 110?mg?kg^–1 wet weight. For inorganic arsenic, the concentrations found were very low (<0.006?mg?kg^–1) in all cases. The obtained results question the assumptions made by the European Food Safety Authority (EFSA) on the inorganic arsenic level in fish used in the recent EFSA opinion on arsenic in food.     

Preservation of inorganic arsenic species in groundwater

The objective of this research was to develop a robust preservation method for stabilizing inorganic As(IlI/V) species in synthetic and actual groundwaters. Ethylenediaminetetraacetic acid (EDTA), H2SO4, H3PO4, and EDTA-acetic acid (HAc) were evaluated in synthetic groundwater containing 3 mg/L Fe(ll) in the pH range 6.5-8.4 and Eh range -100 to +200 mV at room temperature. In the absence of strong UV light, only EDTA-HAc was found to be an effective preservative under all the experimental conditions tested. A total of 89 samples (including 16 samples in triplicate) from 55 drinking waterwells in Minnesota, California, and North Dakota were preserved with a combination of EDTA-HAc and speciated to evaluate its effectiveness for preserving inorganic arsenic species in actual groundwater samples. The preserved and field-speciated samples were repeatedly speciated and analyzed in the laboratory for up to 85 days after collection. Field-speciated As(lll) concentrations were compared with the As(lll) concentrations in the preserved samples. The results were highly correlated (slope 0.9773, R2 = 0.9986), which indicates that during sample transportation and storage the distribution of arsenic species did not change for samples preserved with EDTA-HAc.     

Listeria species in seafood: isolation and characterization of Listeria spp. from seafood in San Luis, Argentina

One hundred seafood samples (fish, squid and mussel) were collected from the Argentine Atlantic coast and screened for Listeria spp. The isolates were characterized by biochemical tests, serotyping, phage typing and macrorestriction enzymes analysis of DNA (pulsed-field gel electrophoresis). The overall frecuency (n=100) ofListeria spp. was 12%. Of the 12 isolated strains, three strains isolated from different squid samples were identified as L. monocytogenes and nine strains from fish, mussels and squid as L. innocua. All three L. monocytogenes strains belonged to serovar 4b; eight strains of L. innocua were serovar 6a and one strain of L. innocua was serovar 6b. All three L. monocytogenes strains, but only one of the nine L. innocua strains, were phage-typeable. One restriction profile was detected with Apa I and Asc I for L. monocytogenes strains and three with the same enzymes for L. innocua strains. The combination of these patterns allowed definition of four distinct groups within the 12 strains. The results of this study showed that phenotypic methods remain appropriate but that pulsed-field gel electrophoresis is useful for epidemiological purposes.     

In vitro model improves the prediction of soil arsenic bioavailability: worst-case scenario

There is a strong interest in developing an in vitro arsenic (As) model that satisfactorily estimates the variability in in vivo relative oral bioavailability (RBA) measurements. Several in vitro tests have been developed, but none is universally accepted due to their limited success in predicting soil As RBA. A suite of amorphous and crystalline solid As phases were chosen, utilizing a worst-case scenario (WCS) that simulated fasting children's gastric solution chemistry. The objectives of this study were to (i) determine the effects of residence time, pH, and solid-to-solution ratio on As bioaccessibility and speciation in the in vitro gastric test; (ii) provide the fundamental basis for an optimized in vitro model constrained by the WCS; and (iii) validate the optimized in vitro test with the in vivo RBA obtained with BALB/c mice. The gastric pH was the only significant (p < 0.05) factor influencing solid As bioaccessibility. Bioaccessible As retained the oxidation state after its release from the solid into the gastric solution. The optimized in vitro model adequately predicted RBA values for a suite of solid As phases typically encountered in soils, with the exception of aluminum-based solids. This study is an excellent starting point for developing an in vitro test applicable to different As-contaminated soils.     

In vitro gastrointestinal bioavailability of arsenic in soils collected near CCA-treated utility poles

Because of the potentially high arsenic concentrations found in soils immediately adjacent to chromated copper arsenate (CCA)-treated wood structures and utility poles, CCA-contaminated soil ingestion may be a significant exposure route to arsenic for children. Therefore, a strong need exists to provide accurate data on oral relative bioavailability (RBA) of arsenic (in vivo or in vitro) in field-collected CCA-contaminated soils. The objectives of this study were (1) to assess arsenic bioaccessibility in contaminated soils collected near in-service CCA-treated utility poles, (2) to determine the influence of soil properties and arsenic fractionation on arsenic bioaccessibility, and (3) to estimate an average daily arsenic intake from incidental soil ingestion. Arsenic bioaccessibility (in vitro gastrointestinal (IVG) method) was determined on surface soil samples collected immediately adjacent to 12 CCA-treated utility poles after 18 months of service. Bioaccessible arsenic was also determined in 3 certified reference materials. Total arsenic concentrations in soils (<300 microm) varied from 37 +/- 2 to 251 +/- 12 mg/kg, irrespective of soil organic matter contentwith the major soil-bound arsenic species being As(V). Arsenic bioaccessibility ranged between 25.0 +/- 2.7 and 66.3 +/- 2.3% (mean value 40.7 +/- 14.9%). The mean value was in agreement with the in vivo arsenic RBA reported by Casteel et al. (2003) in soil near CCA-treated utility poles. Bioaccessible arsenic was positively correlated with total organic carbon content (r2 = 0.36, p < 0.05) and with water-soluble arsenic (2 = 0.51, p < 0.01), and was negatively correlated with clay content (r2 = 0.43, p < 0.05). Using conservative exposure parameters, the mean daily arsenic intake from incidental ingestion of contaminated soil near CCA-treated utility poles was 0.18 +/- 0.09 microg As kg(-1) d(-1). This arsenic intake appeared negligible compared to the daily intake of inorganic arsenic from water and food ingestion for children.     

Photometric determination of arsenic in biological samples (author's transl)]

A modified method by means of absorption of AsH3 in chloroform with an addition of 0,5% hexamethylene-tetramine is described. The detection limit amounts to 0,5 mug arsenic. Arsenic contents of some higher burdened foodstuff are amended.     

Determination of arsenic species in rice grains using HPLC-ICP-MS

Determination of As species in rice is necessary because inorganic As species (arsenate (As^V) and arsenite (As^III)) are more toxic than organic As (monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA)). This study evaluated the As species in Korean and USA rice grains. Levels were determined using microwave extraction and high performance liquid chromatography coupled with inductively coupled plasma-mass spectrometry (HPLC-ICPMS). Arsenite and DMA were the major species detected in Korean and USA rice. The percentage of inorganic As was 76.94% (54.50–87.86%) for Korean rice and 69.28% (52.94–72.92%) for USA samples. The order and percentage of As species observed in Korean and USA rice were As^III (70%)>DMA (24%)>As^V (5%)>MMA (1%), and As^III (64%)>DMA (28%)>As^V(5%)>MMA (3%), respectively. The As^III concentrations were not significantly different in Korean rice grains, compared to USA grains. The high As^III predominance indicates an elevated toxic effect of As in rice grains and needs further attention.