Relative Contribution Of Food Research Articles

Relative contribution of food and water to 27 metals and metalloids accumulated by caged Hyalella azteca in two rivers affected by metal mining

Hyalella were caged at three sites in each of the two rivers for 17 days. Food added to the cages consisted of plant and detrital material collected from the same, or other, sites. Concentrations of some metals in Hyalella (e.g., Cd and Cu), but not others (e.g., Se), appeared to reach steady-state within 5 days in one of the rivers. Metal accumulation was minimal by day 5 in the other river, possibly due to the very low temperatures in this river for the first part of the exposure period. Both analysis of variance and analysis of covariance, using site as a categorical variable and metal in food as either a categorical or continuous variable, indicated that Cd, Cu and Se were the only metals for which concentration in food had a significant effect on concentration in Hyalella. Nevertheless, water was still a major source for these metals as well. Other metals which varied by over fivefold in food but for which concentration in food had no effect on concentration in Hyalella included Ag, As, Bi, Sb, U and Zn. Concentrations of the remaining metals varied less than fourfold in food, making it difficult to determine if these were accumulated from food.

Relative contribution of food and water to the Cd burden in Balanus amphitrite in an urban tidal creek discharging into the Great Barrier Reef lagoon

The barnacle biomonitor Balanus amphitrite, its food sources (two class sizes of suspended particulate material, SPM, and microzooplankton) and water (dissolved phase) were sampled weekly for Cd concentrations along a tidal creek discharging into the Great Barrier Reef lagoon (Ross Creek, Townsville, Queensland). The Cd concentration in the dissolved phase increased upstream, ranging from 1.7 to 283 ng L −1. The Cd concentration in the barnacle's food sources exhibited the same pattern—ranging, for the small size class of SPM (0.45–50 μm), from <0.01 to 1.15 mg kg −1, for large SPM (50–200 μm) from 0.07 to 1.62 mg kg −1, and for microzooplankton (50–200 μm) from 0.03 to 0.80 mg kg −1. More than 95% of the total Cd in the Ross Creek water (<200 μm) was in the dissolved phase (<0.45 μm). A simple diffusion coefficient model estimated an export during the dry season from Ross Creek into the GBR lagoon of around 6 g Cd d −1. The Cd concentration in two populations of B. amphitrite increased upstream between two sites 2.2 km apart and ranged from 2.15 to 4.69 mg kg −1 and from 5.47 to 12.81 mg kg −1. In addition, their Cd concentrations varied over the three sampling months, exhibiting specific patterns for this variation, which suggests that changing the food sources' Cd concentration and relative abundance may result in a specific Cd concentration in B. amphitrite. Therefore, for monitoring programs, the interpretation of variations in metal concentration in a biomonitor would be improved by looking at its metal sources and their temporal variability.

Food, density, and microhabitat: factors affecting growth and recruitment potential of juvenile saltmarsh fishes

The relationships among microhabitat use, food habits, conspecific density and recent growth rate for estuarine-dependent juvenile spotted seatrout, Cynoscion nebulosus, and red drum, Sciaenops ocellatus, were studied to determine how nursery habitat influences early growth. Juvenile spotted seatrout and red drum were quantified along the marsh-edge ecotone from multiple drop samples, and their immediate environments characterized by a suite of physical and chemical variables along with substrate type and Spartina stem density. Recent daily growth of individual fish was modeled in a series of multiple regression analyses that considered the relative contributions of food, microhabitat, and conspecific density. The spotted seatrout model (p 0.0001) included five independent variables, otolith radius, temperature, salinity, depth and substrate, and explained 63.3% of the variation in daily growth. All variables were significant (p > 0.05), and all regression slopes were positive. Fish size (as estimated by otolith radius) accounted for most of the variance in the spotted seatrout (60.2%) and red drum (44.8%) models, while the remaining environmental variables were significant and responsible for 7.7 and 18.5%, respectively. Density variables were not selected for either model, suggesting that density-dependence was not an important influence on recent daily growth. Generally, physico-chemical variables such as temperature, salinity, and dissolved oxygen contributed more to growth than diet or extrinsic factors such as grass stem density.

Aluminium and the risk for alzheimer's disease

AbstractThe strength of the evidence implicating aluminium as an important factor in the dementia of Alzheimer's disease (AD) is reviewed. We submit that the weight of the epidemiological and biological arguments is considerable. While a complete understanding has not been achieved, we recommend lowering aluminium exposure in municipal drinking water to below 50 μg/l in at least the province of Ontario. The Ministry of Energy and the Environment of Ontario maintains a drinking water surveillance programme which has provided a database for more than 10 years. This database has permitted assessment of the relative risk for AD using four independent measures of disease prevalence: 1. weighted residential history as a measure of exposure in autopsy‐verified AD cases and controls; 2. first admission hospital discharge diagnoses of AD and controls; 3. death certificate rates for AD and presenile dementia; 4. impairments in cognitive function in elderly males. Taken together, many of the criticisms applied to epidemiological studies conducted elsewhere and reaching similar conclusions have been met. A vast experimental database on aluminium neurotoxicity, rapid advances in the understanding of the molecular basis of AD, and comparison studies between human brains exposed to chronic low dose aluminium exposure secondary to renal failure and AD, lend strong biological support to the conclusions reached by the epidemiological studies. The factors initiating AD, how aluminium gains access to the brain in AD, and the relative contributions of food, pharmaceuticals and skin absorption, remain unknown. While a full understanding is not in hand, the devastating nature of the disease, the lack of an effective treatment or prevention and the high cost to the health care system, together with the human costs, weighed against the relative cost of moderately reducing drinking water aluminium concentration to reduce exposure indicate that action is both reasonable and timely.

Stable Isotope Identification of Lead Sources in Preschool Children – The Omaha Study

The objective was to determine, from analysis of the naturally occurring stable isotopes of lead, the relative contribution of food, handdust, housedust, soil and air lead to the absorbed (urinary) lead and the blood lead of children living in a former smelter city. A longitudinal 12 month study was conducted of 21 children, 2 - 3 years of age, living in central Omaha, balanced for race, gender and socioeconomic status. Field clean samples were collected monthly of 24 hour duplicate diet, handwipe and urine, with quarterly blood lead, annual environmental lead, weekly air for total lead and 206Pb, 207Pb and 208Pb by thermal ionization/mass spectrometry with a 205Pb spike in a Class II laboratory. Despite residence in a smelter city each child had a unique isotopic ratio of handwipe, blood and urine lead, the latter being identical. There was no correlation of handwipe isotopic ratio with proximity to a lead emission source or to the decade of the housing stock. The isotopic ratio of the annual mean handwipe lead predicted 43% of the variance of the annual mean blood and urine lead ratio (r2 = .43; p = .001). Handwipe lead ratios correlated (p < or = .05) with those of the windowsills and air ducts. The mean isotopic ratios of blood and urine lead were lower than those of handwipe and food, consistent with a contribution by endogenous bone lead. Clean catch urine provides a noninvasive index of blood lead isotopic ratio in children, as in adults.

Relative contributions of food and water in the accumulation of 60Co by a freshwater fish

In order to assure an accurate evaluation of the relative importance of food and water as 60Co sources to the carp, the experiment was carried out simultaneously on 3 homogeneous groups of 10 juvenile fish. The individuals of the first group were maintained in separate aquaria and offered 45 daily rations of labelled food over a 63-day period. Each carp of the two other groups was placed in one of the twenty compartments of a 2101. tank and exposed to 6.8 × 10 4 Bq 60 Co 1 −1 . One group was fed with radioactive food, the other with non-radioactive food. The contamination kinetics showed that the steady state should be reached after 165 days for fish exposed to 60Co in food, 92 days for fish exposed to 60Co in water and 120 days for fish exposed to 60Co in both sources. According to the 60Co concentration in the fish of the 3 treatment groups the accumulation from water accounted for 75% of the total radioactivity and the accumulation of the radionuclide from both water and food was additive. Depuration of 60Co from carp was a relatively intensive process reflecting a high Co turnover. Biological half-lives for loss from the long-lived compartment ranged from 53 days in fish previously contaminated from food to 87 days in fish previoulsy contaminated from water. At the end of the depuration phase the fish were dissected to determine the 60Co distribution in their tissues. There was no significant difference between the fish of the 3 treatment groups; the greatest fraction of residual radiocobalt resided in digestive tract that accounted for 20–25% of the total 60Co body burden.

Etude de la retention du 65Zn absorbe par voie trophique chez Cyprinus carpio L. influence du rythme d'ingestion et de la teneur en radiozinc de la nourriture

Published results on the relative contribution of food and water in the accumulation of 65Zn by freshwater fish are contradictory and it is observed that the retention rate of radiozinc absorbed from food varies over a wide range (from 5 to 70%) depending on the authors (Chipman et al., 1958; Nakatani and Liu, 1964; Pentreath, 1973, 1975; Berg and Brazzelli, 1975; Merlini et al., 1976; Baudin, 1981). The present paper aims to highlight the variability of the retention rate of the radionuclide absorbed from contaminated food. Two experiments were carried out using the soft tissue of previously contaminated lymnaea as food. The first experiment was conducted over a 9 week period on three groups of carp, each receiving food of identical composition, the only difference concerning the splitting up of the weekly food intake. The second experiment was carried out over a 40 day period on a group of 15 carps which received 26 daily meals (Table I). In the first experiment, the pattern of contamination is similar in the three cases, but the carps in groups A and B were more contaminated than those in group C (Table 2, Fig. 1). The same observations apply to the trophic transfer factor (Fig. 2). These differences are explained by a lower retention of 65Zn absorbed with each of the 9 weekly food intakes for the carps in group C than for those in groups A and B (Table 3). The global rate of retention of radiozinc develops in accordance with an exponential model (Fig. 3), reaching maximum value of approx. 14% (group C) to 25% (groups A and B). The similarity of the results for groups A and B can be explained by the fact that the difference in the distribution frequency of the food constituting the weekly intake (2 and 4 days) is insufficient to bring about a significant difference in either the transit rate or the digestibility of the food (Grayton and Bremish, 1977; Luquet et al., 1981; Hudon and De la Noue, 1984). In the case of group C, the lower value of the global retention rate can be explained by an incomplete absorption of the nutriments due to a faster food transit rate in the digestive tract (Possompes et al., 1975; Hudon and De la Noue, 1984). In the second experiment, correlatively with the strong contamination of the ingested food, an increased accumulation of 65Zn is observed in the carp. However, contrary to what was observed in the first experiment, the global rate of retention decreases as a function of time (Table 5). The differences which can be observed between the results of the two experiments do not only concern the level but also the development of the parameters. Thus, for the concentration (Fig. 4a) and the trophic transfer factor (Fig. 4b) the evolution corresponds to power functions, but the slope of the curves indicates that the kinetics are different. This is the consequence of the conflicting evolution of the retention rate 65Zn by the carp in the two experiments (Fig. 4c). The homeostatic regulation of zinc, proposed by Berg and Brazzelli (1975), cannot justify the observed difference in retention of 65Zn. The hypothesis concerning the influence of the nature of the food proposed by several authors (Pentreath, 1975; Berg and Brazzelli, 1975; Merlini et al., 1976) can hardly explain such differences. According to an analysis of results obtained during several experiments (Table 6), it can be also hypothesized that the rate of retention of radiozinc by the carp is inversely proportional to the quantity of radionuclide absorbed with the food, due to a slow turnover of zinc. The faeces are a very important pathway of the radionuclide excretion (Table 4). This fact agrees with high radioactivity levels measured in the digestive tract of fish contaminated from water or placed in decontamination for several days or weeks (Hibiya and Oguri, 1961; Joyner, 1962; Pentreath, 1975; Aprosi, 1978; Suzuki et al., 1979; Baudin, 1977, 1981).

Accumulation and retention of cesium-137 by the common goby.

Accumulation and retention of 137Cs by the common gogy, Acanthogobius flavimanus from environmental water and were and food were investigated in order to obtain quantitative information on the food chain transfer of the nuclide in coastal sea enveronment. It was found that the accumulation of 137Cs by the fish from water and food showed a gradual increasing tendency during the experimental period and required long period to reach an equilibrium level. Using a single exponential model, it was estimated that the accumulation of 137Cs by the fish required more than 90 days to reache equilibrium state. From the experimental results, it was suggested that the relative contribution of food in the accumulation of 137Cs by the fish was comparatively higher in comparison with direct absorption.