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PubMed1999

Selenium bioaccumulation by the water boatman Trichocorixa reticulata (Guerin-Meneville).

The input of selenium from subsurface agricultural drainage into surface water systems can result in the accumulation of toxic concentrations of selenium in aquatic food chains. Elevated selenium concentrations in aquatic systems is a significant environmental problem in many areas of the United States. A laboratory investigation was conducted to determine the dominant route of selenium bioaccumulation by the corixid Trichocorixa reticulata, an important food chain organism. The roles of waterborne and foodborne exposure in selenium bioaccumulation were examined using 48-h bioassays. Waterborne selenium concentrations ranged from 0 to 1,000 microgram Se/L as selenate. A mixture of two species of blue-green algae cultured in media with selenium concentrations ranging from 0 to 1,000 microgram Se/L as selenate was used as a corixid diet in the foodborne treatments. Corixids exposed to waterborne selenate did not accumulate selenium above control concentrations. Corixids fed algae exposed to >/=100 microgram Se/L as selenate had significantly higher selenium concentrations than control organisms. These data suggest that corixids may be effectively isolated from the water and selenium accumulation is solely through dietary exposure.

Agrochemicals↗
PubMed2001

Determination of cadmium partitioning in microalgae and oysters: contribution to the assessment of trophic transfer.

Alternative methodologies have been applied to the study of cadmium transfer in a food chain: water, microalgae (Skeletonema costatum and Tetraselmis suecica), oysters (Crassostrea gigas). The potential bioavailability of Cd in organisms was assessed through partitioning at the cell or tissue levels, and the predictive value of this method was evaluated by determining directly the metal transfer in an experimental food chain model. Cd concentrations were lower in S. costatum than T. suecica, in controls as well as in contaminated algae. In both algal species, Cd was firmly bound to the cell wall or had entered the cell. Cytosolic Cd was bound to intracellular ligands, the biochemical characteristics of which were not consistent with the hypothesis of detoxification via phytochelatins. In both algal species, Cd was predominantly present in the insoluble fraction, but at pHs such as those existing in the digestive tract of bivalves, it was easily extracted from the cells. Thus, exposure to Cd through phytoplanktonic food induced a significant uptake of this metal in soft tissues of bivalves. Due to the difference in Cd accumulation in algae, Cd doses associated with S. costatum were lower than those bound to T. suecica. Moreover, oysters retained a lower percentage of the metal associated with S. costatum compared to T. suecica (9 and 20%, respectively, after 21 days of exposure). Cd doses potentially available to oysters exposed directly in sea water were considerably higher, and direct uptake induced the highest levels of Cd incorporation but only 2% of dissolved Cd was actually retained by oysters over 21 days of exposure. In the soft tissues of oysters, Cd was distributed equally between soluble and insoluble fractions. Cytosolic Cd was present predominantly in the heat-stable fraction and mainly bound to compounds of molecular weight equal to 13.5 kDa. Moreover, a positive correlation was observed between metallothionein-like protein (MTLP) levels and gross concentrations of Cd in the soft tissues of oysters. These data are consistent with the hypothesis of an important role of metallothioneins in Cd metabolism in oysters and suggest a potential availability of MT-bound fraction of Cd to the consumers. These data are in agreement with the response of oysters exposed to Cd in the field.

Animals↗
PubMed2002

Survey of arsenic in food composites from an arsenic-affected area of West Bengal, India.

An investigation of total arsenic in food composites, collected from the villagers, was carried out in arsenic-affected areas of the Murshidabad district, West Bengal where the agricultural system is mostly groundwater dependent. The shallow, large-diameter tubewells installed for agricultural irrigation contain an appreciable amount of arsenic (mean 0.085 mg/l, n=6). Even the soil is arsenic-contaminated (mean 11.35 mg/kg, n=36), so some arsenic can be expected in the food chain from crops cultivated in this area. The results revealed that the individual food composite and food groups containing the highest mean arsenic concentrations (microg/kg) are potato skin (292.62 and 104), leaf of vegetables (212.34 and 294.67), arum leaf (331 and 341), papaya (196.50 and 373), rice (226.18 and 245.39), wheat (7 and 362), cumin (47.86 and 209.75), turmeric powder (297.33 and 280.9), cereals and bakery goods (156.37 and 294.47), vegetables (91.73 and 123.22), spices (92.22 and 207.60) and miscellaneous items (138.37 and 137.80) for the Jalangi and Domkal blocks, respectively. Arsenic is absorbed by the skin of most of the vegetables. The arsenic concentration in fleshy vegetable material is low (mean 2.72 microg/kg, n=45). Higher levels of arsenic were observed in cooked items compared with raw. Daily dietary intakes of arsenic (microg) from the foodstuffs for adults are 171.20 and 189.13 and for children are 91.89 and 101.63 in the Jalangi and Domkal blocks, respectively.

Adult↗
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↗
PubMedDate not supplied

[Model for calculation of fish contamination by 137Cs and its application for Lake Kozhanovskoe (Bryansk Region)].

A dynamic model was developed for evaluation of the fish contamination by 137Cs. The dynamics of the accumulation of the radionuclide and the elimination is calculated taking into account the ecological and physiological characteristics of the fish, such as growth and metabolic rates, its position in the food chains of the aquatic ecosystem. The biological elimination of 137Cs from the freshwater fish is proportional to the metabolic rate of the fish. The dimensionless coefficient of the proportionality is equal to epsilonA = 0.3 +/- 0.1. The model was applied for the reconstruction of the long-term dynamics of 137Cs in the food chain "goldfish-pike" from Lake Kozhanovskoe (Bryansk Region, Russia). In 1990-1999 the specific activity of 137Cs in goldfish (generation of 1990) varied in range about 5-20 kBq/kg, whereas the specific activity of 137Cs in pike (generation of 1989) varied in range about 20-40 kBq/kg. The comparison with the data of the observations confirmed that the presented method allows to evaluate adequately the levels and the dynamics of 137Cs accumulation by the freshwater fish.

Animals↗
PubMed2002

Prevalence of Toxoplasma gondii in commercial meat products as monitored by polymerase chain reaction--food for thought?

DNA was extracted from 71 meat samples obtained from UK retail outlets. All of these DNA preparations gave the expected polymerase chain reaction products when amplified with primers specific for the species from which the meat originated. A second polymerase chain reaction analysis, using primers specific for the Toxoplasma gondii SAG2 locus, revealed the presence of this parasite in 27 of the meat samples. Restriction analysis and DNA sequencing showed that 21 of the contaminated meats contained parasites genotyped as type I at the SAG2 locus, whilst six of the samples contained parasites of both types I and II. Toxoplasma- positive samples were subjected to further polymerase chain reaction analysis to determine whether any carried an allele of the dihydropteroate synthase gene that has recently been shown to be causally associated with sulfonamide resistance in T. gondii. In all cases, this analysis confirmed that parasites were present in the samples and, additionally, revealed that none of them carried the drug-resistant form of dihydropteroate synthase. These results suggest that a significant proportion of meats commercially available in the UK are contaminated with T. gondii. Although none of the parasites detected in this study carried the sulfonamide-resistance mutation, a simplified procedure for monitoring this situation merits development.

Alleles↗
PubMed2002

Lactic acid bacteria in a changing legislative environment.

The benefits of using lactic acid bacteria in the food chain, both through direct consumption and production of ingredients, are increasingly recognised by the food industry and consumers alike. The regulatory environment surrounding these products is diverse, covering foods and food ingredients, processing aids, feed additives and dietary supplements. On a global basis, there are different approaches taken by the various regulatory authorities. While in Europe, the national legislation is gradually being harmonized, predominantly through the Novel Foods Regulation, there is still a wide disparity between the stringency of regulation of microbial products fed to animals and the comparatively relaxed approach to 'non-novel' microbial products intended for human consumption. In the United States, the onus is on self-regulation of the manufacturer, with the Generally Recognised As Safe (GRAS) and Dietary Supplement Health Education Act (DSHEA) notification schemes encouraging industry to be more open about the ingredients they market. In Japan, the Foods for Special Health Use system continues to gain recognition as more products are approved, and is a potential model for other countries in regulating functional foods. Despite the different approaches to regulating these products, safety of microorganisms such as lactic acid bacteria in the food chain is paramount in all countries. This paper discusses the regulatory requirements of microbial products, predominantly lactic acid bacteria within the global markets, focusing mainly on the developments in Europe.

Dietary Supplements↗
PubMed2004

[Monitoring and risk assessment of campylobacter infections].

The aim of a national study of a "Quantitative Risk Assessment of Campylobacter infections and broiler chicken" at the Federal Institute for Risk Assessment is to estimate the chicken meat associated risk of Campylobacteriosis in Germany by using probabilistic models. Furthermore, process parameters (modelling parameters) with the most vital impact on the risk of Campylobacteriosis due to chicken meat have to be elaborated to give recommendations for risk management options in the whole food chain. The outcome of Joint FAO/WHO Expert Consultations on Risk Assessment of Microbiological Hazards in Foods (JEMRA) with respect to Campylobacter spp. in broiler chickens are the baseline for the national approach. In addition, national studies from Canada, Denmark and The Netherlands have to be considered. Typical regional data with respect to the disease, to risk factors in Germany and to the qualitative and quantitative occurrence of Campylobacter in broiler chickens along the "farm-to-fork" continuum have to be collected and validated for elaboration of the four elements of a risk assessment. Data on the prevalence of the agent at different stages of the food chain given in available surveillance systems in Germany are limited with respect to their suitability as incoming parameters for the models. A monitoring programme, as required in the Directive 2003/99/EC on the monitoring of zoonoses and zoonotic agents, as well as coordinated programmes for the official food control authorities, could improve the data baseline for risk assessment studies for instance. To collect all necessary information on the quantitative load of Camylobacter in broiler chickens will go beyond the scope of any existing or future monitoring systems. Results can only be achieved by detailed studies. Beside this, regional data on production and processing of broiler chicken, consumption data and information on the behaviour of consumers in households when preparing broiler chicken products are relevant for assessing the final risk to the consumers. For some questions, especially with respect to the dose-response-relation, internationally used models have to be applied. The national study is embedded in a national epidemiological network of "Foodborne Infections in Germany" which is coordinated by the Robert-Koch-Institute and supported by the Federal Ministry of Education and Research (BMBF).

Animal Husbandry↗
PubMed2000

[Bovine spongiform encephalopathy and food safety].

The governments of Great Britain and France disagree on the safety of British beef with respect to bovine spongiform encephalopathy (BSE). Eventually the consumer might have the burden to decide whether beef from Britain is safe to eat with regard to the new variant of Creutzfeldt-Jakob disease (vCJD). Outside Britain the incidence of BSE increases. Probably in continental Europe, the use of high risk material, derived from non-British cattle in the subclinical stage of BSE, poses a greater threat than beef imported from Great Britain. The risk to contract vCJD depends on two unknown factors: the susceptibility of man to BSE and the amount of success in keeping infectious tissue of BSE-incubating cattle out of the human food chain. Until the susceptibility of humans to BSE and the extent to which our food is contaminated become known, no clear-cut advice can be given on the safety of certain food items. There appears to be a genetic predisposition to vCJD, i.e. methionine homozygosity at codon 129 of the normal human prion protein gene. The European Community should ban the use of any high risk material for production of food, except in production processes for which inactivation of the BSE agent has been proven. The facts that are known at this moment allow the conclusion that gelatin and beef products of unknown origin and composition pose a greater health threat than eating genuine beef (muscle tissue).

Animals↗
PubMed2001

Impact of a toxic and a non-toxic strain of Microcystis aeruginosa on the crayfish Procambarus clarkii.

The occurrence of cyanobacteria in many water bodies where crayfish such as Procambarus clarkii are abundant leads to the possibility of toxin accumulation and food chain transfer. This paper describes the accumulation and depuration of microcystins from a microcystin and a non-microcystin producing strain of Microcystis aeruginosa, on the survivorship, growth and nutritional status of P. clarkii. Crayfish larvae were resistant to cyanobacteria and their toxins, surviving cyanobacteria densities during acute exposures. Juvenile crayfish tolerated toxic cyanobacteria better than non-toxic ones. This effect was also observed when analysing nutritional status of crayfish fed toxic and non-toxic cyanobacteria with the former having better lipid and protein contents than those fed non-toxic Microcystis. P. clarkii accumulated up to 2.9 microg MCYST/dry crayfish weight and the depuration pattern was similar to that observed for mussels by other authors. Due to the fact that the major part of the toxin is accumulated in the intestine and in the hepatopancreas, there is no significant risk in terms of human health if these parts are removed prior to crayfish consumption. Nevertheless, their use in dairy food and the possible transference of toxins along food chains should not be disregarded.

Animals↗
PubMed2004

Food safety and animal production systems: controlling zoonoses at farm level.

Controlling zoonotic agents in animal and poultry reservoirs has the effect of reducing the challenge to food safety management systems in processing and further along the food chain. Producing and maintaining healthy stock requires good husbandry practices, which include stock selection and veterinary attention. Feed is a key input, both as a source of pathogen-free nutrients and as a balanced dietto maintain healthy livestock. Safe water, appropriate vermin and wildlife control and an optimum environment to reduce stress are important if animals are to perform. Farms are not sterile environments and initiatives to reduce the zoonotic hazards have to be practical, economically feasible and flexible, depending on the scale of the enterprise, the species being farmed, and the epidemiology of the zoonotic agents in the particular geographical region. Education of farmers and stockmen is crucial to successful on-farm control of zoonoses, as an understanding of why control measures are necessary, and how they can be applied, will improve compliance with protocols and procedures. This understanding is a first step towards the implementation of a longitudinal integrated food safety assurance approach to zoonosis control in the pre-harvest phase of the food chain.

Animal Diseases↗
PubMed2005

Chernobyl radioactivity persists in reindeer.

Transfer of 137Cs in the soil-plant/lichen-reindeer food chain was studied in central (Østre Namdal) and southern Norway (Vågå) during 2000-2003. Reindeer from these areas have been continuously subjected to countermeasure application since the 1986 Chernobyl accident. In both areas no decline in 137Cs concentrations was detectable in reindeer slaughtered in autumn since 1995, or in reindeer slaughtered in winter since 1998-1999. Seasonal differences in 137Cs concentrations in reindeer have been less pronounced in recent years, with 137Cs concentrations occasionally higher in autumn than in winter. Soil-to-plant 137Cs transfer was significantly higher in Østre Namdal than in Vågå. Climatic influences on lichen growth and abundance, and on soil properties that influence the availability of 137Cs for plant uptake, are hypothesized to have a larger impact on long-term transfer of radiocaesium in the soil-plant/lichen-reindeer food chain than has been previously observed.

Animals↗
PubMed2000

A system dynamic model for the assessment of different exposure routes in aquatic ecosystems.

With the exception of a limited number of highly persistent lipophilic pollutants, waterborne exposure is considered the most relevant exposure route for aquatic organisms, and even the only relevant exposure route in lower tier assessment, while the potential for bioaccumulation is only evaluated as secondary poisoning for birds and mammals. In addition, some evaluations consider that only the dissolved fraction is bioavailable for pelagic organisms. The lack of easy and cost-effective assessment methods is probably the main reason to disregard the contribution of other routes. This paper presents a system dynamics model that estimates the time-dependent accumulation of toxic chemicals through the food chain, and has also the potential to include the exposure from sediment. The generic ecosystem includes a primary producer and three levels of consumers, represented by unicellular algae, cladoceran invertebrates, cladoceran-eating fish and fish-eating fish, respectively. Nevertheless, the model, built using Microsoft Excel software, allows any number of levels and ecological-exposure relationships. The results obtained for four illustrative pollutants demonstrate that factors such as the binding to algae and other edible particles or food chain exposure for lipophilic non-persistent chemicals may constitute significant exposure routes. The current low tier European ecological risk assessment guidelines do not cover these aspects, and therefore may under estimate the real risk for both aquatic organisms and their predators. The model includes a simplified worst-case alternative that normally can be calculated using the existing information. Under a tiered approach, the simplified alternative is proposed to trigger the need of the toxicokinetics assays required to perform the complete time-dependent calculation.

Animals↗
PubMed2002

Dioxin reservoirs in southern Viet Nam--a legacy of Agent Orange.

In the isolated Aluoi Valley of central Viet Nam, very high levels of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) were measured in soil, fish fat, duck fat, pooled human blood and breast milk samples collected from A So village between 1996 and 1999. The village was situated on a former military base occupied by US Special Forces between 1963 and 1966. TCDD was a contaminant of the herbicide "Agent Orange", aerially sprayed in the valley between 1965 and 1970, and stored at the A So base. Measured levels were lower near the sites of two other former US bases in the valley which had been occupied for shorter periods of time. In areas where Agent Orange had been applied by low-flying aircraft, levels of TCDD in soil, food and human samples were elevated, but lower than those near the three former US bases. We confirm the apparent food chain transfer of TCDD from contaminated soil to cultured fish pond sediments to fish and duck tissues, then to humans as measured in whole blood and breast milk. We theorize that the Aluoi Valley is a microcosm of southern Viet Nam, where numerous reservoirs of TCDD exist in the soil of former military installations south of the former demilitarized zone. Large quantities of Agent Orange were stored at many sites, used in ground and aerial applications, and spilled. TCDD, through various forms of soil disturbance, can be mobilized from these reservoirs after decades below the surface, and subsequently, introduced into the human food chain.

2,4,5-Trichlorophenoxyacetic Acid↗
PubMed2005

Circulation of copper in the biotic compartments of a freshwater dammed reservoir.

This study concerns a chronic copper release in an aquatic ecosystem: Mirgenbach reservoir; which is characterized by high salinity, conductivity and hardness, a eutrophic state and a high temperature. To study the bioavailability of copper in the biotic compartments, the sampling covered the entire food chain (phyto- and zooplankton, macroalgae, aquatic plants, crustaceans, mollusks, and fish). Of the organisms present, the filter feeder Dreissena polymorpha, the detritivorous Bithynia tentaculata and Orconectes limosus were most contaminated by copper. The level of copper found in fish was the lowest. Body copper concentrations recorded in the present study show large variability between species even in some that are closely related. In most cases, however, the metal handling strategy, feeding habits, morphology and ecology can, at least partially, explain the metal content recorded. Pollution factors have been used to assess the state of contamination of the food chain. This study showed finally that the copper in the lake is bioavailable and bioaccumulated by organisms up to high levels and some effects of long-term toxicity of copper on benthic community and planktonic biomass were pointed out.

Animals↗
PubMed2000

Functional diversity governs ecosystem response to nutrient enrichment.

The relationship between species diversity and ecosystem functioning is a central topic in ecology today. Classical approaches to studying ecosystem responses to nutrient enrichment have considered linear food chains. To what extent ecosystem structure, that is, the network of species interactions, affects such responses is currently unknown. This severely limits our ability to predict which species or functional groups will benefit or suffer from nutrient enrichment and to understand the underlying mechanisms. Here our approach takes ecosystem complexity into account by considering functional diversity at each trophic level. We conducted a mesocosm experiment to test the effects of nutrient enrichment in a lake ecosystem. We developed a model of intermediate complexity, which separates trophic levels into functional groups according to size and diet. This model successfully predicted the experimental results, whereas linear food-chain models did not. Our model shows the importance of functional diversity and indirect interactions in the response of ecosystems to perturbations, and indicates that new approaches are needed for the management of freshwater ecosystems subject to eutrophication.

Animals↗
PubMed2003

Biomagnification of cyanobacterial neurotoxins and neurodegenerative disease among the Chamorro people of Guam.

We here report biomagnification (the increasing accumulation of bioactive, often deleterious molecules through higher trophic levels of a food chain) of the neurotoxic nonprotein amino acid beta-methylamino-l-alanine (BMAA) in the Guam ecosystem. Free-living cyanobacteria produce 0.3 microg/g BMAA, but produce 2-37 microg/g as symbionts in the coralloid roots of cycad trees. BMAA is concentrated in the developing reproductive tissues of the cycad Cycas micronesica, averaging 9 microg/g in the fleshy seed sarcotesta and a mean of 1,161 microg/g BMAA in the outermost seed layer. Flying foxes (Pteropus mariannus), which forage on the seeds, accumulate a mean of 3,556 microg/g BMAA. Flying foxes are a prized food item of the indigenous Chamorro people who boil them in coconut cream and eat them whole. Chamorros who die of amyotrophic lateral sclerosis/parkinsonism-dementia complex (AL-SPDC), a neurodegenerative disease with symptoms similar to amyotrophic lateral sclerosis, Parkinson's disease, and Alzheimer's disease, have an average of 6.6 microg/g BMAA in their brain tissues. The biomagnification of BMAA through the Guam ecosystem fits a classic triangle of increasing concentrations of toxic compounds up the food chain. This may explain why the incidence of ALS-PDC among the Chamorro was 50-100 times the incidence of amyotrophic lateral sclerosis elsewhere. Biomagnification of cyanobacterial BMAA may not be unique to Guam; our discovery of BMAA in the brain tissue from Alzheimer's patients from Canada suggests alternative ecological pathways for the bioaccumulation of BMAA in aquatic or terrestrial ecosystems.

Amino Acids, Diamino↗