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PubMed2004

[Contamination of the food chain with caesium-137 and strontium-90 in Switzerland].

One task of the field physiology of nutrition is the monitoring of the quality of feedstuffs. Rations may consequently be prepared with unadulterated components. This review uses the example of contamination with the radionuclides caesium-137 und strontium-90 and shows how these two unwanted substances reach the end host via the food chain and how their untoward effects are expressed in animals and humans. The extent of the contamination with artificial radioactivity is followed with periodical measurements according to the program of the Division for Radiological Protection of the Swiss Federal Office of Public Health. The interpretation of the measurements and the directives of this division are designed to protect primarily human health, but also that of animals.

Animals↗
PubMed1996

Effects of productivity, consumers, competitors, and El Niño events on food chain patterns in a rocky intertidal community.

We experimentally manipulated nutrient input to a rocky intertidal community, using nutrient-diffusing flowerpots, to determine (i) whether nutrients limited intertidal productivity, (ii) how a large-scale oceanographic disturbance (an El Niño event) affected patterns of nutrient limitation, (iii) the relative impacts of molluscan grazers and nutrient limitation, and (iv) if responses to experimental nutrient addition among trophic levels were more consistent with prey-dependent or ratio-dependent food chain models. Nutrients measurably increased the abundance of micrograzers (amphipods and chironomid larvae), but not algal biomass, during the summer of an El Niño year. Nutrients had no effects in two non-El Niño years and during the autumn of an El Niño year. Adding nutrients did not affect food chain stability as assessed by temporal variation in algal biomass and micrograzer abundance. Large molluscan grazers caused large reductions in micrograzers and smaller reductions in algae, indicating consistent consumer effects. The results demonstrate that in this intertidal community, nutrient limitation can occur under conditions of nutrient stress, that top-down grazing effects are typically stronger than bottom-up nutrient effects, and that prey-dependent models are more appropriate than ratio-dependent models.

Journal Article↗
PubMed2004

Comparison of paralytic shellfish poisoning toxin between carnivorous crabs (Telmessus acutidens and Charybdis japonica) and their prey mussel (Mytilus galloprovincialis) in an inshore food chain.

Paralytic shellfish poisoning toxin in two shore crab species, Telmessus acutidens and Charybdis japonica, were compared with the toxin in the prey mussel Mytilus galloprovincialis and causative dinoflagellates Alexandrium tamarense, all having been collected at Onahama, Fukushima Prefecture, in the northern part of Japan. When the toxicities were detected in mussels by mouse bioassays, 73.7% of the sampled T. acutidens were toxic in the hepatopancreas. T. acutidens has been found to become toxic for three years, therefore, it can be concluded that the crab commonly and repeatedly accumulate the toxins via the food chain at Onahama. C. japonica was also expected to be a possible vector species, because small quantities of the toxins were detected in eight specimens of the crab by HPLC analysis. By the comparison of the toxin profiles in the dinoflagellates, mussels and the crab T. acutidens, reductive conversions of GTX1 and GTX4 were observed when the toxins passed through the three species in the food chain. But increases of STX and neoSTX by further reductive process were not observed in the crab. The absence of the STX group toxins in the crab suggests that the crab eliminates the toxin before such reductive process occur.

Animals↗
PubMed1989

Effects of cadmium on a microbial food chain, Chlamydomonas reinhardii and Tetrahymena vorax.

A steady-state microbial food chain consisting of the green alga Chlamydomonas reinhardii and the ciliated protozoan Tetrahymena vorax was established in a two-stage, nitrogen-limited chemostat. The lowest concentration of cadmium which produced a toxic effect at the population level was between 7.5 and 10 micrograms l-1. The algal population acclimated to the presence of cadmium up to 40 micrograms l-1 added in increments over time, but demonstrated lowered cell numbers and reduced cell weights. Protozoan populations acclimated to 40 micrograms Cd l-1 added incrementally if the rate of dilution was lowered. Abrupt elevation of the cadmium concentration to 40 micrograms l-1 resulted in extreme fluctuations in the specific growth rates of both populations and the incipient loss of all cells from the system (washout).

Animals↗
PubMed1993

Boron, molybdenum, and selenium in aquatic food chains from the lower San Joaquin River and its tributaries, California.

Boron (B), molybdenum (Mo), and selenium (Se) were measured in water, sediment, particulate organic detritus, and in various biota--filamentous algae, net plankton, macro-invertebrates, and fishes--to determine if concentrations were elevated from exposure to agricultural subsurface (tile) drainage during the spring and fall 1987, in the San Joaquin River, California. Concentrations of B and Se, but not Mo, were higher in most samples from reaches receiving tile drainage than in samples from reaches receiving no tile drainage. Maximum concentrations of Se in water (0.025 microgram/mL), sediment (3.0 micrograms/g), invertebrates (14 micrograms/g), and fishes (17 micrograms/g) measured during this study exceeded concentrations that are detrimental to sensitive warmwater fishes. Toxic threshold concentrations of B and Mo in fishes and their foods have not been identified. Boron and Mo were not biomagnified in the aquatic food chain, because concentrations of these two elements were usually higher in filamentous algae and detritus than in invertebrates and fishes. Concentrations of Se were lower in filamentous algae than in invertebrates and fishes; however, concentrations of Se in or on detritus were similar to or higher than in invertebrates and fishes. These observations suggest that high concentrations of Se accumulated in invertebrates and fishes through food-chain transfer from Se-enriched detritus rather than from filamentous algae.

Animals↗
PubMed2000

Polyunsaturated fatty acids in the food chain in Japan.

The amount of polyunsaturated fatty acids (PUFAs) in the food chain in Japan is reviewed on the basis of the newest nutrition survey data. The Japanese are currently consuming, on average, approximately 26% of energy as fats with ratios of polyunsaturated to saturated fats and n-6 to n-3 fatty acids of approximately 1.2:1 and 4:1, respectively. The significant contributors to this relatively high n-3 PUFA intake are not only fish and shellfish but also edible vegetable oils, almost exclusively rapeseed and soybean oils. Thus, the dietary habits of the Japanese have made possible a high n-3 PUFA intake within a low-fat regimen. In this context, the gradual decline, particularly in younger persons, in fish consumption habits weighs on our minds. Analyses of health indexes, including the increased average life span, support the superiority of the current Japanese eating pattern that harmonizes with the Western regimens. However, at present it cannot be disregarded that food intake varies considerably in all age groups, and only a limited number of people are consuming the recommended allowance for dietary fats.

Adult↗
PubMed1989

Human cancer and the food chain: an alternative etiologic perspective.

Oncogenic viruses are among the known or presumed initiating agents of human cancer. Although evidence suggests that DNA and RNA oncoviruses may be acquired through multiple routes, our attention focuses chiefly on the ingestion pathway. We have two reasons for this. One is the possibility that viral as well as nonviral oncogenic amino acid sequences might be acquired at the top of the food chain. The other is that the food chain-infection hypothesis may reconcile several biological, ecological, and epidemiological phenomena. Transfection experiments suggest that the concept of infection may have to be broadened to embrace the cellular precursors of oncogenic viruses. Accumulating circumstantial evidence from viral oncology and molecular biology provides a basis for the belief that oncogenic viruses and their cellular precursors might be transmitted from animals to humans through the ingestion pathway. The possibility that such transmission may give rise to some human cancers must now be considered. The ingestion and genomic integration of food-associated DNA sequences may directly account for the increased risk of human cancer associated with an elevated intake of animal fat and protein. This paper addresses the role of infective oncogenic agents as the initiators, rather than the promoters, of cancer.

Animals↗
PubMed2000

Organic contaminant distributions in sediments, polychaetes (Nereis virens) and American lobster (Homarus americanus) from a laboratory food chain experiment.

A laboratory experiment was conducted to investigate the transfer of organic contaminants from an environmentally contaminated marine sediment through a simple marine food chain. The infaunal polychaete, Nereis virens, was exposed to contaminated sediment collected from the Passaic River, NJ, USA, for 70 days. These polychaetes were then fed to the American lobster, Homarus americanus, for up to 112 days. Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), 2,4,6,8-tetrachlorodibenzothiophene (TCDT), polychlorinated biphenyls (PCBs), and several chlorinated pesticides were accumulated by polychaetes following exposure to the contaminated sediment. Some of these contaminants were also accumulated by lobsters which were exposed to the contaminated sediment and/or fed contaminated polychaetes. Only the lesser chlorinated PCDDs and PCDFs (mostly tetra- and pentachlorinated congeners) and 2,4,6,8-TCDT were detected in the polychaetes and lobster. Significant alterations were noted in the PCB patterns found in both species, particularly the lobster. The non-ortho-substituted PCBs (such as congeners 77 and 126) became enriched in the PCB mixtures of the polychaetes and especially the lobsters relative to the sediment, probably because these congeners were not metabolized. These congeners and the 2,3,7,8-tetrachlorodibenzo-p-dioxin toxicity equivalents of the PCB mixtures were enriched by a factor of about six in the lobsters relative to the sediment. Elimination of PCB congeners containing vicinal hydrogens in the meta-para region is consistent with cytochrome P450IIB-type metabolism. Based on the concentration trends for some PCB congeners and chlorinated pesticide ratios measured in the lobsters during this experiment, it appears that this metabolic system is inducible in the American lobster.

Animals↗
PubMed1998

Field evaluation of a mathematical model of PCB transfer through the freshwater aquatic food chain.

A mathematical model of the transfer of PCBs through the freshwater aquatic food chain is described. The model predicts concentrations of 11 selected individual PCB congeners in forage fish and pike, from source terms of atmospheric deposition and watershed soil concentrations. Model performance has been evaluated using data from a field study conducted in a section of the River Severn near Birmingham, UK. Results demonstrate that with the exception of congener 52, overall model predictions of individual PCB concentrations in both forage fish and pike underestimate measured concentrations by factors of between approximately 3 and 25 for individual congeners. Closer examination suggests that whilst model equations contribute to these underestimations, a significant factor is the lack of knowledge of additional PCB inputs to the waterbody.

Animals↗
PubMed2006

Organotin accumulation in an estuarine food chain: comparing field measurements with model estimations.

The bioaccumulation model OMEGA (optimal modelling for ecotoxicological applications) is used to explore accumulation of organotins in the Western Scheldt food chain, consisting of herbi-detritivores, primary and secondary carnivorous fish and a piscivorous bird. Organotins studied are tributyltin (TBT) and triphenyltin (TPT) and the respective di- and mono-organotin metabolites. Empirical elimination rate constants are compared to model predictions for organic substances and metals. It is found that field bioaccumulation ratios are higher than predicted based on elimination kinetics relevant for organic compounds. The results indicate that uptake of organotins mainly occurs via hydrophobic mechanisms, whereas elimination may occur via metal-like kinetics. This results in very low elimination rates, which are comparable to model predictions for metals.

Animals↗
PubMed2004

Nutrient enrichment and food chains: can evolution buffer top-down control?

We show how evolutionary dynamics can alter the predictions of classical models of the effects of nutrient enrichment on food webs. We compare an ecological nutrient-plant-herbivore food-chain model without evolution with the same model, including herbivore evolution, plant evolution, or both. When only herbivores are allowed to evolve, the predictions are similar to those of the ecological model without evolution, i.e., plant biomass does not change with nutrient addition. When only plants evolve, nutrient enrichment leads to an increase in the biomass of all compartments. In contrast, when plants and herbivores are allowed to coevolve, although these two classical patterns are common, a wide variety of other responses is possible. The form of the trade-offs that constrain evolution of the two protagonists is then critical. This stresses the need for experimental data on phenotypic traits, their costs and their influence on the interactions between organisms and the rest of the community.

Adaptation, Biological↗
PubMed2006

Transfer of Cd, Cu, Ni, Pb, and Zn in a soil-plant-invertebrate food chain: a microcosm study.

The transfer of Cd, Cu, Ni, Pb, and Zn was evaluated in a soil-plant (lettuce, Lactuca sativa)-invertebrate (snail, Helix aspersa) food chain during a microcosm experiment. Two agricultural soils, polluted and unpolluted, were studied. Lettuce was cultivated for eight weeks before introduction of snails into the microcosms (M-snails). In a parallel experiment, snails were exposed to lettuce only (i.e., without soil) in simpler exposure devices called containers (C-snails). Snail exposure duration was eight weeks for both M- and C-snails. No effects on snail survival were found. Both M- and C-snails exposed to polluted soil showed a growth reduction, but only after two weeks of exposure. Time-dependent accumulation in M-snails exposed to the polluted environment showed a regular increase of Cd and Zn concentrations over time and a rapid increase of Pb concentrations within the first two weeks, which then remained stable. Copper and Ni concentrations did not increase during any of the experiments. Concentrations in M- and C-snails were compared to estimate the relative contribution of soil and plant to the total bioaccumulation. The results suggest that the soil contribution may be higher than 80% for Pb, from 30 to 60% for Zn, and from 2 to 40% for Cd.

Animals↗
PubMed2006

Bioaccumulation of cadmium in an experimental aquatic food chain involving phytoplankton (Chlorella vulgaris), zooplankton (Moina macrocopa), and the predatory catfish Clarias macrocephalus x C. gariepinus.

The accumulation of cadmium (Cd) was studied in an experimental aquatic food chain involving the phytoplankton Chlorella vulgaris as the primary producer, the zooplankton Moina macrocopa as the primary consumer, and the catfish Clarias macrocephalus x Clarias gariepinus as the secondary consumer. C. vulgaris was first exposed to Cd solutions at 0.00, 0.35, and 3.50 mg l(-1), referred to as control group and experimental groups 1 and 2, respectively. Subsequently, each group was fed to three corresponding groups of M. macrocopa. Finally, three groups of catfish were fed these corresponding groups of M. macrocopa. After C. vulgaris was exposed to 3.50 mg l(-1) Cd (experimental group 2), the residual Cd in solution was only 4.01 microg l(-1), lower than the maximum allowable limit of Cd in natural water sources (5 microg l(-1)). Cd concentrations in C. vulgaris were 0.01+/-0.00 microg g(-1) (dry wt) in the control group, 194+/-1.80 microg g(-1) (dry wt) in experimental group 1, and 1140+/-20.06 microg g(-1) (dry wt) in experimental group 2. The Cd concentrations in M. macrocopa were 0.01+/-0.00 microg g(-1) (dry wt) in the control group, 16.48+/-2.23 microg g(-1) (dry wt) in experimental group 1, and 56.6+/-3.23 microg g(-1) (dry wt) in experimental group 2. The Cd concentrations in catfish muscle increased with increasing Cd concentrations in the food. After 60 days of fish culture, the mean concentrations of Cd in fish muscle were 0.01+/-0.00 microg g(-1) (dry wt) in the control group, 0.61+/-0.02 microg g(-1) (dry wt) in experimental group 1 and 1.04+/-0.06 microg g(-1) (dry wt) in experimental group 2. Cd concentration in fish muscle of experimental group 2 was equal to the permissible limit. Cd accumulation affected fish growth: at the end of the study, the mean fresh weight (12.81 g) of catfish in the control group, was significantly higher than those experimental group 1 (10.43 g) and experimental group 2 (10.00 g). The results showed that the measurement of Cd concentration in water does not necessarily give a measure of the safety of aquatic organisms as human food. Hence, heavy metal contamination is a matter for concern when organisms are harvested, for fish and human consumption, from natural water sources.

Animals↗
PubMed2005

Heavy metal concentrations in a soil-plant-snail food chain along a terrestrial soil pollution gradient.

We investigated concentrations of Zn, Cu, Cd and Pb in the compartments of a soil-plant (Urtica dioica)-snail (Cepaea nemoralis) food chain in four polluted locations in the Biesbosch floodplains, the Netherlands, and two reference locations. Total soil metal concentrations in the polluted locations were 4-20 times higher than those in the reference locations. Positive relationships between the generally low leaf concentrations and the soil concentrations were found for Zn only (r2 = 0.20). Bioaccumulation of Zn, Cu and Cd was observed in the snail tissues. We found positive relationships between the snail and leaf concentrations for all metals (range r2 = 0.19-0.46). The relationships between soil and snail concentrations were also positive, except for Cu (range r2 = 0.15-0.33). These results suggest transfer of metals to C. nemoralis snails from U. dioica leaves and from the soil. Metal transfer from polluted leaves to C. nemoralis is more important than transfer from the soil.

Animals↗
PubMed2006

Exposure to polychlorinated biphenyls in residents near a chemical factory in Italy: the food chain as main source of contamination.

High levels of PCBs were recently found in soil, food and some farmers living close to a chemical factory which until the 1980s had produced polychlorinated biphenyls (PCBs) in Brescia, North Italy. We performed a survey on a random sample of subjects aged 20-79 years living in various areas of the town with different levels of soil pollution to investigate factors associated with increased levels of PCB in serum (24 congeners were tested). Total PCB values were closely related to age (Spearman r=0.68; p<0.0001). The 166 consumers of locally produced food had higher PCB levels than non-consumers (median=1143 versus 719; 95th centile=9301 versus 2635ng/g lipid) with the highest levels among consumers of food produced in the most contaminated area close to the factory (median=2551; 95th centile=33464ng/g lipid). A dose-effect relationship between consumption of food produced in this area and PCB blood levels was observed (Spearman r=0.52, p=0.0014). Consumers of only plant food produced in this area had higher levels of PCB than non-consumers (median=1100; 95th centile=10,800ng/g lipid). Three subjects who had worked at the factory in the past showed high PCB levels. Distribution of PCB congeners did not differ between consumers of locally produced food and non-consumers, apart from PCB 209 which was found at high levels in former factory workers and was more common among consumers of food produced in the polluted area. In conclusion, we found high serum PCB levels in humans living in a highly polluted area in an industrialized town in Italy, due mainly to consumption of food produced in polluted areas.

Adult↗
PubMedDate not supplied

The relationship between the supply of fast-food chains and cardiovascular outcomes.

OBJECTIVE: To examine the extent to which inter-regional differences in fast-food concentrations account for variations in all-cause mortality and acute coronary syndromes throughout Ontario, Canada. METHODS: Nine distinct fast-food chains were selected based on top sales data in 2001. The per capita rate of fast-food outlets per region was calculated for each of 380 regions throughout Ontario. Outcome measures, obtained using 2001 vital statistics data and hospital discharge abstracts, included regional per capita mortality rates and acute coronary syndrome hospitalization rates; head trauma served as a comparator. All regional outcomes were adjusted for age, gender, and socio-economic status, and were analyzed as continuous and rank-ordered variables as compared with the provincial average. RESULTS: Mortality and admissions for acute coronary syndromes were higher in regions with greater numbers of fast-food services after adjustment for risk. Risk-adjusted outcomes among regions intensive in fast-food services were more likely to be high outliers for both mortality (Adjusted Odds Ratio (OR): 2.52, 95% confidence intervals (CI): 1.54 - 4.13, p < 0.001) and acute coronary hospitalizations (Adjusted OR: 2.62, 95% CI 1.42 - 3.59, p < 0.001) compared to regions with low fast-food service intensity. There was no relationship between the concentration of fast-food outlets and risk-adjusted head-trauma hospitalization rates. INTERPRETATION: Inter-regional cardiac outcome disparities throughout Ontario were partially explained by fast-food service intensity. Such findings emphasize the need to target health promotion and prevention initiatives to highest-risk communities.

Cardiovascular Diseases↗
PubMed2006

Dynamic modeling of food-chain accumulation of brominated flame retardants in fish from the Ebro River Basin, Spain.

Since the 1980s, brominated flame retardants (BFRs) have been detected in air, sewage sludge, sediment, fish, shellfish, birds, and mammals, including humans. However, model studies regarding BFR food-chain accumulation are scarce. In the present study, the accumulation of hexabromocyclododecane and brominated diphenyl ethers (BDEs) 47, 153, 154, and 183 in benthivorous barbel (Barbus graellsii) and pelagic bleak (Alburnus alburnus) from four locations in the Ebro river basin in Spain was modeled using a first-order, one-compartment model with sediment interaction. The model accounted for BFR uptake from water, ingested sediment, and food; release via water and feces; growth; and in situ binding of BFRs to black carbon. Rate constants were derived from allometric regressions. For most BFRs, dynamically modeled biota-sediment accumulation factors (BSAFs) were close to measured values, whereas steady-state model BSAFs were too high, especially for BDEs 153, 154, and 183. Differences between BSAFs for individual fish were explained by differences in age, growth, and feeding behavior. On average, modeled BSAFs for barbel were 50% higher than those for bleak because of extra BFR uptake through sediment ingestion and older age of barbel specimens.

Animals↗