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PubMed2001

Integrated plastic microfluidic devices with ESI-MS for drug screening and residue analysis.

For this work, two different plastic microfluidic devices are designed and fabricated for applications in high-throughput residue analysis of food contaminants and drug screening of small-molecule libraries. Microfluidic networks on copolyester and poly(dimethylsiloxane) substrates are fabricated by silicon template imprinting and capillary molding techniques. The first device is developed to perform affinity capture, concentration, and direct identification of targeted compounds using electrospray ionization mass spectrometry. Poly(vinylidene fluoride) membranes sandwiched between the imprinted copolyester microchannels in an integrated platform provide continuous affinity dialysis and concentration of a reaction mixture containing aflatoxin B1 antibody and aflatoxins. The second microfluidic device is composed of microchannels on the poly(dimethylsiloxane) substrates. The device is designed to perform miniaturized ultrafiltration of affinity complexes of phenobarbital antibody and barbiturates, including the sequential loading, washing, and dissociation steps. These microfabricated devices not only significantly reduce dead volume and sample consumption but also increase the detection sensitivity by at least 1-2 orders of magnitude over those reported previously. Improvements in detection sensitivity are attributed to analyte preconcentration during the affinity purification step, limited analyte dilution in the microdialysis junction, minimal sample loss, and the amenability of ESI-MS to nanoscale sample flow rates.

Aflatoxin B1↗
PubMed2006

Antagonistic effects of methyl-mercury and PCB153 on PC12 cells after a combined and simultaneous exposure.

The study of interactions for those substances which tend to accumulate in food and affect the nervous system appears to be a fundamental point to characterize the combined exposure in vitro. In this study we included two food contaminants which are known neurotoxicants: methyl-mercury (Me-Hg) and the ortho-substituted PCB 153. PC12 cells were treated with Me-Hg (range 1e-7, 2e-6 M) and PCB153 (range 1e-5, 4e-4 M) in single and combined synchronous experiments and a mathematical model was set up according to the Loewe additivity criterion to evaluate the level of interaction between toxicants, using viability as end-point. At some concentrations (Me-Hg 5e-7 M and PCB153 1e-4 and 2e-4 M; Me-Hg 1e-6M and PCB153 5e-5 M; Me-Hg 1e-7 M and PCB153 4e-4 M), a statistically significant antagonist effect was observed. No interaction was observed for other combinations. The analysis of other toxicological parameters known to be modified in single exposure experiments (TBARS and intra-cellular dopamine) confirmed the viability results. The results of our work represent a starting point to generate novel information on the interactions between PCB153 and Me-Hg in vitro, as well as a new relevant experimental and mathematical approach useful to investigate the effects of different toxicant mixtures.

Animals↗
PubMed2006

Sampling: the weak link in the sanitary quality control system of agricultural products.

To ensure a high level of consumer protection, the European Union has in the past years published several regulations setting very low limits for a given number of food contaminants (pesticides, mycotoxins, heavy metals) in many agricultural products (cereals, oilseeds, dry fruits, coffee, spices, etc). These new regulations regarding the sanitary quality of agricultural products, compel both economic operators and officials of different EU member states to set up sampling plans and rigorous analyses aimed at checking whether a product lot complies with the required standards prior to its release on the market. While the laboratory analysis management today is outstanding thanks to the validated and efficient detection methods and procedures available for quality assurance in laboratories (accreditation), this is not necessarily true of the sampling operation, which seems to be the weak link in the sanitary control system for agricultural products. The sampling operation is often the main source of error when assessing the sanitary quality of a lot of agricultural commodities, with both commercial (downgrading of the product) and sanitary (marketing of a product which poses a health risk for the consumer) consequences. Therefore, it is essential for the operators involved to be aware of the significance and difficulties of the sampling operation, which requires important equipment and human resources. Furthermore, drawing up specific standards and guidelines, as well as setting up quality assurance procedures, at the level in charge of carrying out this delicate and important operation, are necessary.

Crops, Agricultural↗
PubMed2003

Evaluation of the most current and effective methods in the analysis of chlorinated dioxins in ground beef.

Chlorinated dioxins are the group of environmental pollutants consisting of 210 chlorinated dibenzo-p-dioxins and dibenzofurans. They are highly toxic and persistent. They are lipophilic and can easily biomagnify in the food chain, hence posing a serious threat to human health. The daily consumption of low-level contaminated food, mainly of animal origin, leads to the accumulation of dioxins in the human body. The exposures of the general human population to dioxins and the specific issues of a risk assessment of dioxin pose serious concerns in public environmental and nutritional health. This paper reviews the analysis of chlorinated dioxins in ground beef. The sources of contamination of chlorinated dioxins in ground beef are first reviewed to form a basis for a clear understanding of the health implications of chlorinated dioxins in the human food chain and why it is necessary to monitor the level of dioxins in animal food products, especially ground beef. The methods of collection, sampling, and processing of ground beef, and the methods of sample clean up prior to the analysis, are reviewed. Emphasis is laid on the new techniques that are available and that might be effective in the analysis of chlorinated dioxins in ground beef. Among these new methods and techniques are: the synergistic combination of ELISA/GC/MS, direct sample introduction to /GC/MS-MS, automated clean-up method, and the supercritical fluid extraction methods. The possible treatments of results from each method and technique are discussed and their respective efficiencies are compared. Finally, quality control and quality assurance parameters are evaluated for levels of accuracy, reproducibility, and precision.

Animals↗
PubMed2002

Steroid hormone receptors and dietary ligands: a selected review.

Members of the nuclear steroid hormone superfamily mediate essential physiological functions. Steroid hormone receptors (SHR) act directly on DNA, regulate the synthesis of their target genes and are usually activated by ligand binding. Both endogenous and exogenous compounds and their metabolites may act as activators of SHR and disruptors of endocrine, cellular and lipid homeostasis. The endogenous ligands are generally steroids such as 17beta-oestradiol, androgens, progesterone and pregnenolone. The exogenous compounds are usually delivered through the diet and include non-steroidal ligands. Examples of such ligands include isoflavanoids or phytooestrogens, and food contaminants such as exogenous oestrogens from hormone-treated cattle, pesticides, polychlorinated biphenyls and plasticisers. Certain drugs are also ligands; so nuclear receptors are also important drug targets for intervention in disease processes. The present review summarises recent reports on ligand-activated SHR that describe the selective regulation of a tightly-controlled cross-talking network involving exchange of ligands, and the control of major classes of cytochrome P450 (CYP) isoforms which metabolise many bioactive exogenous compounds. Many CYP have broad substrate activity and appear to be integrated into a coordinated metabolic pathway, such that whilst some receptors are ligand specific, other sensors may have a broader specificity and low ligand affinity to monitor aggregate levels of inducers. They can then trigger production of metabolising enzymes to defend against possible toxic nutrients and xenobiotic compounds. The influence of dietary intakes of nutrients and non-nutrients on the human oestrogen receptors (alpha and beta), the aryl hydrocarbon receptor, the pregnane X receptor, the constitutive androstane receptor, and the peroxisome proliferator-activated receptors (alpha and gamma), can be examined by utilising computer-generated molecular models of the ligand-receptor interaction, based on information generated from crystallographic data and sequence homology. In relation to experimental and observed data, molecular modelling can provide a scientifically sound perspective on the potential risk and benefits to human health from dietary exposure to hormone-mimicking chemicals, providing a useful tool in drug development and in a situation of considerable public concern.

Animals↗
PubMed2006

Study of Salmonella, Campylobacter, and Escherichia coli contamination in raw food available in factories, schools, and hospital canteens in Hanoi, Vietnam.

This study on the contamination rates of raw foods available in factory, school, and hospital canteens in Hanoi, Vietnam, with the bacteria of Salmonella, Campylobacter, and Escherichia coli (E. coli) was carried out between 2003 and 2004. A total of 177 raw food samples of vegetables, meat (beef and pork), fish, and poultry were examined to provide baseline data for evaluation of microbiological risks in general, and identification of potential vehicles for pathogenic cross-contamination in canteens. The study confirmed that unprocessed fish and poultry are likely to be contaminated with Salmonella and in the absence of proper kitchen hygiene and may contaminate processed foods. Raw poultry samples were highly contaminated with E. coli (45%), Campylobacter jejuni (C. jejuni) (28.3%), and Salmonella (8.3%) and classified as high-risk food. E. coli was also detected in raw meat, fish, and vegetables with the rate of 21.3%, 6.6%, and 18.5%, respectively. This article confirmed the importance of hygienic working practices when preparing food.

Animals↗
PubMedDate not supplied

A database for environmental contaminants in traditional foods in northern and Arctic Canada: development and applications.

The potential health effects of environmental contaminants in traditional food has become a concern among northern communities because of the presence of environmental contaminants in the Arctic ecosystem. Exposure assessments are needed but they require comprehensive dietary information and contaminant data. Over the last 10 years, there has been considerable effort to monitor the level of contaminants in fish and wildlife collected from different regions in northern and Arctic Canada. The development of a database and its application for dietary contaminant exposure assessment are described. We conducted an extensive literature review on levels of environmental contaminants in northern and Arctic Canada. The ranges of levels of four contaminants of major concern (chlordane, mercury, polychlorinated biphenyls and toxaphene) in 81 species of marine mammals, terrestrial mammals, birds, fish and plants are summarized. These data represent 69% of the 117 species of fish, wildlife and plants mentioned in our dietary interviews conducted in the northern communities. A significant percentage of the foods had contaminant levels exceeding the guidelines used by Health Canada for market food consumed by the 'southern' populations. Mathematic modelling of the distributions of the data showed that contaminant levels in most food groups are log-normally distributed and have a typical coefficient of variation of about 100%. Examples are presented to demonstrate the use of the data for contaminant exposure assessment. Average contaminant exposure levels estimated using the database for two communities are comparable to those obtained previously using community specific data. With the current knowledge of environmental contaminant levels in the northern traditional food system, it may be feasible to conduct preliminary risk assessment of dietary exposure of environmental contaminants when some diet information for a community is available. Further sampling and analysis may be needed only for confirmation purposes.

Animals↗
PubMed1995

Assessment of exposure to chemical contaminants in water and food.

UNLABELLED: The main questions on the validity of the studies and routine monitoring (e.g., in the scope of the WHO/UNEP GEMS programme) assessing exposure to chemicals through water and food (i.e., through digestion) relate to the following. (a) SAMPLING: variations due to sampling strategy and approach usually exceed analytical errors. (b) MEASUREMENT: quality assessment and quality control (QA/QC) procedures are essential. However, potential limitations of measurement errors resulting from implementation of these procedures should be kept in perspective with other errors and confounding factors. (c) METHODOLOGY: which depends on the variability of the intake patterns in the population, as well on the adequacy of the information on the consumption of food of a specified type as an indicator of the intake of a specific chemical. These factors should be considered in particular in studies using 'food basket' methods. Whenever possible, structure of the population in respect to the factors determining typical diet should be registered. (d) Form of reporting: limiting possibilities for re-analysis of the exposure estimates. In conclusion, the routinely collected data on exposure through food and water should be used with care in epidemiological studies. Assessment of the exposure conducted specially for the epidemiological study should consider possible changes of the diet with time. The data on confounders are crucial for exposure estimates.

Cadmium↗
PubMed1993

Microbial contamination of enteral feeding solution and its prevention.

In an investigation of microbial contamination of enteral feeding solutions, all 22 residual solutions obtained immediately after administration were contaminated at concentrations of 10(3) to 10(6) viable counts/ml. Major contaminants were glucose-nonfermenting gram-negative bacilli such as Pseudomonas aeruginosa and Acinetobacter calcoaceticus var anitratus. Contamination seemed to have been caused by frequent reuse of bag-type containers and the infusion tubes connected to the bags, neither of which can be washed or dried. Decontamination methods were evaluated by using polypropylene containers that can be washed and disinfected for administration. Few Serratia marcescens on the inside wall of the container were removed by rinsing with tap water, alone or in combination with detergent scrub. Tap water and detergent plus air-drying at 56 degrees C for 1 hour reduced Serratia marcescens only somewhat. Tap water and detergent plus immersion in 0.01% sodium hypochlorite for 1 hour or in water at 70 degrees C for 3 minutes eliminated all 10(11) cells of Serratia marcescens.

Bacteria↗
PubMedDate not supplied

Prions: who should worry about them?

Prion diseases, also called transmissible spongiform encephalopathies (TSEs), are a family of neurodegenerative disorders affecting both humans and animals. They are caused by the accumulation of an abnormal form of a protein known as prion that results in neuronal death and a characteristic spongiform appearance of the brain tissue. Human prion diseases can be sporadic, acquired or hereditary. Acquired prion diseases have been linked to entering contaminated food into the human food chain, failure to completely disinfect or sterilize contaminated surgical instruments, patients receiving tissues and organs from infected donors, recipients of blood and other biological contaminated products, and potentially to cross infection in dental procedures. At present, there is unfortunately no efficient therapy that can be administered to clinically infected patients with prion diseases. Moreover, there are no simple diagnostic tests that can be used to show the agent of transmissible spongiform encephalopathy during the preclinical phase of the disease. Therefore, to prevent the spread of this emerging infectious agent it is necessary to implement several health control strategies and maintain surveillance for subclinical infections.

Communicable Diseases, Emerging↗
PubMed2006

Rapid determination of acrylamide contaminant in conventional fried foods by gas chromatography with electron capture detector.

Gas chromatography coupled with electron capture detector (GC-ECD) was successfully developed and applied for the rapid determination of acrylamide in conventional fried foods, such as potato crisps, potato chips, and fried chicken wings. The method included defatting with n-hexane, extraction with aqueous solution of sodium chloride (NaCl), derivatization with potassium bromate (KBrO3) and potassium bromide (KBr), and liquid-liquid extraction with ethyl acetate. The final acrylamide extract was analyzed by GC-ECD for quantification and by GC-MS for confirmation. The chromatographic analysis was performed on the HP-INNOWax capillary column, and good retention and peak response of acrylamide were achieved under the optimal conditions (numbers of theoretical plates N = 83,815). The limit of detection (LOD) was estimated to be 0.1 microg kg(-1) on the basis of ECD technique. Recoveries of acrylamide from conventional samples spiked at levels of 150, 500 and 1000 microg kg(-1) (n = 4 for each level) ranged between 87 and 97% with relative standard deviations (RSD) of less than 4%. Furthermore, the GC-ECD method showed that no clean-up steps of acrylamide derivative would be performed prior to injection and was slightly more sensitive than the MS/MS-based methods. Validation and quantification results demonstrated that this method should be regarded as a new, low-cost, and robust alternative for conventional investigation of acrylamide.

Acrylamide↗
PubMed2004

Evaluation of the microbial safety of a new 1.5 l enteral feeding diet reservoir system.

BACKGROUND & AIMS: Microbial safety is essential during enteral nutrition (EN) as it can be the origin of gastrointestinal symptoms, but can also lead to systemic infections. The use of large-volume diet reservoirs could limit the risk of contamination and reduce nursing time, due to fewer repeated manipulations. The aim of the study was to evaluate in vivo the microbial safety of a new 1.5l enteral feeding diet reservoir system. METHODS: After validation of the study settings under standard laboratory conditions, 86 EN lines with sealed fittings were connected to 1.5l diet reservoirs under hospital/patient conditions. Microbial identification and quantification at different sampling times and points were performed. RESULTS AND CONCLUSIONS: No microbial contamination was observed in the diet reservoirs and in the nutrition lines above the drip chamber, demonstrating the microbial safety of this system. Retrograde contamination of the distal nutrition line end at completion of EN was observed and may be affected by the cumulative time of use of the tube. The contaminating microbial species were essentially bacteria of normal oral and digestive flora.

Bacteria↗
PubMed2004

Mould contamination in production of semi-hard cheese.

Air, equipment, plastic film, brine and milk were sampled from four cheese factories in Norway during the period September 1997 to May 1999 in order to identify the critical points for mould contamination in the production process. Altogether, 672 samples were collected. Penicillium brevicompactum was the most frequently isolated species from three of the factories, while Geotrichum candidum was the most frequently isolated species from the fourth. P. commune, P. palitans, P. solitum and P. roqueforti ss. roqueforti, all common contaminants on cheese, were found in samples of air and equipment, and the former was also isolated from plastic film. The results in the present study showed that the mould levels in the cheese factories varied between the different control points. The mould levels at some of the air control points had high mould counts while the mould levels in milk and brine, on equipment and on plastic film, generally were low. The fungi at the control points with high mould levels consisted of common cheese contaminants as well as species not commonly isolated from cheese. The statistical analysis showed that air was the major source of the important cheese contaminants P. commune and P. palitans during the production process. High quality air with low number of cheese contaminants in production rooms, especially the wrapping room, is important in order to reduce mould contamination.

Air Microbiology↗
PubMed2004

Different genotypes of Yersinia enterocolitica 4/O:3 strains widely distributed in butcher shops in the Munich area.

The distribution of Yersinia spp. in butcher shops in the Munich area was studied. The isolates recovered were then characterised with pulsed-field gel electrophoresis (PFGE) to identify possible contamination routes. A total of 298 samples were collected from eight small butcher shops between June and August in 2001. Of these, 113 were surface samples from carcasses, offal and raw pork products, and 185 were environmental surface samples from tools, equipment and processing areas. The samples were studied with direct plating, overnight enrichment in nonselective broth and selective enrichment in two different enrichment broths. The Yersinia isolates recovered were characterised with PFGE using NotI, ApaI and XhoI DNA restriction enzymes. Yersinia was recovered from all eight butcher shops, and pathogenic Yersinia enterocolitica 4/O:3 was present in six shops. The occurrence of this pathogen on raw pork products varied from 8% to 25%. Pathogenic Y. enterocolitica 4/O:3 was isolated from two environmental samples: a worktable and a chain glove. Most (18/24) of the Yersinia-positive samples were found already after direct plating. Forty-nine Yersinia isolates from 24 samples were studied with PFGE. Twelve genotypes (I-XII) were obtained among Y. enterocolitica 4/O:3 when 33 isolates from 16 samples were characterised with NotI, ApaI and XhoI enzymes. The genotypes of Y. enterocolitica 4/O:3 strains differed among butcher shops. In most (5/6) shops, more than one genotype was found, indicating different contamination sources. In conclusion, raw pork products from butcher shops are frequently contaminated with different genotypes of pathogenic Y. enterocolitica 4/O:3, thus serving as an important transmission vehicle from butcher shops to humans.

Animals↗
PubMed2005

Effects of electrolyzed oxidizing water on reducing Listeria monocytogenes contamination on seafood processing surfaces.

The effects of electrolyzed oxidizing (EO) water on reducing Listeria monocytogenes contamination on seafood processing surfaces were studied. Chips (5 x 5 cm(2)) of stainless steel sheet (SS), ceramic tile (CT), and floor tile (FT) with and without crabmeat residue on the surface were inoculated with L. monocytogenes and soaked in tap or EO water for 5 min. Viable cells of L. monocytogenes were detected on all chip surfaces with or without crabmeat residue after being held at room temperature for 1 h. Soaking contaminated chips in tap water resulted in small-degree reductions of the organism (0.40-0.66 log cfu/chip on clean surfaces and 0.78-1.33 log cfu/chip on dirty surfaces). Treatments of EO water significantly (p<0.05) reduced L. monocytogenes on clean surfaces (3.73 log on SS, 4.24 log on CT, and 5.12 log on FT). Presence of crabmeat residue on chip surfaces reduced the effectiveness of EO water on inactivating Listeria cells. However, treatments of EO water also resulted in significant reductions of L. monocytogenes on dirty surfaces (2.33 log on SS and CT and 1.52 log on FT) when compared with tap water treatments. The antimicrobial activity of EO water was positively correlated with its chlorine content. High oxidation-reduction potential (ORP) of EO water also contributed significantly to its antimicrobial activity against L. monocytogenes. EO water was more effective than chlorine water on inactivating L. monocytogenes on surfaces and could be used as a chlorine alternative for sanitation purpose. Application of EO water following a thorough cleaning process could greatly reduce L. monocytogenes contamination in seafood processing environments.

Chlorine↗
PubMed2006

Effect of water activity on ochratoxin A production by Aspergillus niger aggregate species.

The effect of water activity (a(w)) (0.82-0.99) on growth and ochratoxin A (OTA) production by twelve Aspergillus niger aggregate strains, cultured in Czapek Yeast Autolysate agar (CYA) and Yeast Extract Sucrose agar (YES), was studied for an incubation period of 30 days. The strains were selected to include diverse sources, different reported abilities to produce OTA and different ITS-5.8 S rDNA Restriction Fragment Length Polymorphism (RFLP) pattern. They were characterized by Random Amplification of Polymorphic DNA (RAPD) and ITS-5.8 S rDNA and 28 S rDNA (D1/D2) sequencing. Regardless of the a(w) value tested, YES was a better culture medium than CYA for OTA production. The a(w) range for OTA production was narrower than that for growth. OTA was produced from 0.90, 0.92, 0.94 or 0.96 to 0.99 a(w) depending on the strain and the culture medium. The molecular study differentiated strains into two groups which corresponded to the RFLP types N and T although it did not distinguish them by their source of isolation or OTA producing abilities. Our results show that A. niger aggregate strains are able to grow and produce OTA over a wide a(w) range. These results will lead to a better understanding of the contribution of A. niger aggregate in OTA contamination of food and feed.

Agar↗
PubMed1989

Non-aqueous size-exclusion chromatography coupled on-line to reversed-phase high-performance liquid chromatography. Interface development and applications to the analysis of low-molecular-weight contaminants and additives in foods.

An interface has been developed which permits the on-line coupling of size-exclusion chromatography in tetrahydrofuran with aqueous reversed-phase high-performance liquid chromatography. The interface isolates the required size exclusion chromatography fraction and dilutes it with water to ensure reconcentration of analytes on the reversed-phase column prior to gradient elution. Operational parameters and the influence of analyte polarity have been examined in detail. A predictive system is presented for determining the applicability of the system to any analyte, based on solute retention times on an ODS phase eluted with a methanol-water gradient. The method is illustrated with examples of direct analyses of crude lipid extracts from a snack product for 2,6-di-tert.-4-methylphenol and from chocolate for dibutyl phthalate. Detection limits of ca. 0.5 mg/kg have been achieved.

Chromatography, Gel↗