Cd Concentrations In Kidney Research Articles

Accumulation of potentially toxic elements in the body tissues of sheep grazed on grassland given repeated applications of sewage sludge

AbstractIngestion of sewage sludge with soil, together with herbage containing elevated concentrations of potentially toxic elements (PTEs) might pose a risk to the human food chain through the accumulation of PTEs in edible tissues of livestock grazed on pastures which have received repeated doses of sludge. The accumulation of PTEs in tissues of animals grazed on a permanent pasture which had received repeated applications of sewage sludge between 1981 and 1994 was studied over two consecutive grazing seasons by monthly serial slaughter. Blocks of six weaned lambs were allocated at random at the start of the grazing seasons to slaughter date. Blocks of lambs were also allocated at random to an adjacent untreated pasture and to initial slaughter groups. Animals grazed continuously for two periods of 181 days and 152 days in 1994 (experiment 1) and 1995 (experiment 2), respectively. An application of sewage sludge was made to the treated site between the two experiments. The concentration of cadmium (Cd) in soil samples taken to 25 cm depth from the treated site was close to the United Kingdom statutory limit of 3 mg Cd per kg dry matter (DM) and 1·67 times the limit at the soil surface. Concentrations of other PTEs in soil were below statutory limis. The concentrations of PTEs in herbage at the treated site increased as each grazing period advanced (P < 0·05). Mean concentrations of Cd, lead (Pb), copper (Cu) and zinc (Zn) were higher (P < 0·05) in both experiments for herbage at the treated site than at the untreated site. No differences were observed in the concentrations of PTEs in muscle tissue between lambs grazed on treated or untreated pastures. The concentration of Cd in kidneys of lambs grazed on the treated pasture increased as the grazing seasons progressed from 0·19 to 0·36 mg/kg DM (P < 0·01) in experiment 1 and from 0·03 to 2·57 mg/kg DM in experiment 2 (P < 0·001). There was no measurable accumulation of Pb into kidney in either experiment. Concentrations of Cu in kidney remained similar during experiment 1 but increased during experiment 2 in lambs grazed on the treated pasture only (P < 0·05). Similar trends to those for kidney were observed for Cd in liver in both experiments. The concentrations of Pb increased in liver for lambs grazed on the treated site in experiment 1 (P < 0·01) but not in experiment 2. The concentrations of Cu in lambs grazed on the treated pasture in liver decreased (P < 0·01) in experiment 1 from 139 to 28 mg Cu per kg DM. Liver concentrations of Cu in experiment 2 increased (P < 0·01) from 63·5 to 197 mg Cu per kg DM, possibly reflecting the application of sludge to the experimental site between the two experiments. The results indicated that soil and herbage concentrations of PTEs were elevated following repeated applications of sewage sludge to grassland. The accumulation of PTEs in edible body tissues was generally low, with the greatest being of Cd and Cu in the second experiment, possibly reflecting recent application of sludge.

Effect of calcium supplements to a maize-soya diet on the bioavailability of minerals and trace elements and the accumulation of heavy metals in growing rats.

Thirty-five (five groups with seven animals each) male albino rats (initial average weight = 44 g) were fed phytate-rich diets (analysed phytic acid concentration = 6.9 g/kg) based on maize and soy bean meal (5 g Ca, 3 g P, 1.2 g Mg, 23 mg Zn, 10 mg Pb, 5 mg Cd/kg diet). Experimental diets were supplemented with 0, 2, 4, 6 and 8 g calcium from CaCO3 per kg. The supplementation of increasing amounts of calcium resulted in a dose-dependent decrease in the apparent absorption of phosphorus. Furthermore, apparent zinc absorption and femur zinc concentration were moderately decreased due to the calcium supplementation. Kidney Cd concentration was significantly lower in rats that were fed the high calcium diets in comparison with the control animals. Femur lead concentration and hepatic delta-aminolevulinic acid dehydratase, which are known to be sensitive parameters of lead accumulation remained unchanged by the different dietary treatments. Magnesium absorption as well as liver and plasma zinc concentration and activity of plasma alkaline phosphatase were also unaffected. Although calcium supplementation may lead to a decrease in the accumulation of certain heavy metals such as cadmium, the carry-over of lead was not affected under the given experimental conditions. Furthermore, calcium-phytate-zinc interactions may adversely affect zinc bioavailability in growing rats.

Wintering greater scaup as biomonitors of metal contamination in federal wildlife refuges in the Long Island region.

Tissues of greater scaup (Aythya marila mariloides) and components of their habitat (sediment, plankton, macroalgae, and invertebrates) were collected for heavy metal analysis in the winter of 1996-97 from US Department of the Interior wildlife refuges in the Long Island region. Geographic and temporal relationships between the concentration of nine metals in tissue and in habitat components were examined. In greater scaup tissues and habitat components, concentrations of As and Se were highest in Branford, Connecticut; Pb values were greatest in Oyster Bay, New York; and Hg concentrations were largest in Sandy Hook, New Jersey. Over the course of the winter, the concentration of Hg in liver increased, and concentrations of Cd, Cr, Cu, Hg, Pb, Se, and Zn in kidney decreased. Based on several criteria derived from geographic and temporal trends, metals were ranked using the apparent biomonitoring efficacy of greater scaup (As = Cr > Cu = Pb = Zn = Hg > Se = Cd > Ni). Although the seasonal migration and daily mobility of greater scaup are drawbacks to using this species as a sentinel for metal pollution, it was possible to demonstrate a relationship between geographic and temporal patterns of metals in habitat and greater scaup tissue. However, most metal concentrations in tissue were below thresholds known to adversely affect health of waterfowl.

A model to predict kidney and liver cadmium concentrations in grazing animals

Cadmium (Cd) accumulation in the kidneys and liver of older grazing animals is a major concern in New Zealand and Australian agriculture. Use of phosphate fertilisers containing high Cd concentration is the main cause of this accumulation. A simple mathematical model running in a user‐friendly computer package was developed to predict annual accumulation of Cd in kidneys and liver of animals grazing pastures of known herbage Cd concentration and phosphate fertiliser history. Results from the model showed that kidney and liver Cd concentration of sheep were most sensitive to fertiliser Cd concentration, moderately sensitive to pasture ingestion rate, and least sensitive to soil ingestion rate. The model was validated using kidney Cd data from a farmlet‐scale sheep‐grazing trial. Kidney Cd concentrations predicted by the model were strongly correlated with measured mean kidney Cd concentrations. The relationship between the measured and predicted Cd concentrations is not statistically different from the 1:1 relationship indicating that the model can explain the variation in the measured mean kidney Cd concentration.

Induction of Metallothionein in Dogwhelk Nucella lapillus during and after Exposure to Cadmium

Induction of metallothionein (MT) was investigated in a common biomonitor, the dogwhelk Nucella lapillus (shell length: 27.7±1.4 mm; wet tissue weight: 667±196 mg), during and after exposure to cadmium (Cd) under controlled laboratory conditions (10±1°C and 34±1‰ salinity). The dogwhelks were exposed to 500μg Cd l−1 (2.2% of 96 h LC50) for 60 days and then placed into clean seawater for 110 days. MT concentration in whole animal increased during the exposure period, peaked at Day 70, and then declined gradually. Half-life of MT was ca. 40 days. MT concentration increased very significantly with increasing Cd concentration (r=0.74, n=24, P<0.001). Nevertheless, Cd concentration increased throughout the period of exposure and while in clean seawater, leveling off only after Day 120, indicating that Cd concentration could not be regulated by N. lapillus. Throughout the study, MT and Cd concentrations in gills, Leiblein gland, kidney, digestive gland, and gonad tissues increased gradually. Highest concentrations of MT and Cd were found in the Leiblein gland. Measurement of MT induction in the Leiblein gland of N. lapillus may therefore prove useful as a sublethal biological response to Cd contamination.

Effects of zinc supplementation during chelating agent administration in cadmium intoxication in rats.

The concomitant administration of zinc during chelation of cadmium (Cd) with meso-2,3-dimercaptosuccinic acid (DMSA) or calcium trisodium diethylenetriamine penta-acetic acid (DTPA) was investigated in male rats subchronically exposed to Cd. The results suggest that the administration of zinc alone after cadmium exposure does not elicit any protective effects. However, when supplemented during treatment with DTPA it produced a significant turnover in the altered biochemical variables and a depletion of Cd concentration in liver and kidneys. Cadmium-induced elevated hepatic metallothionein (MT) contents remained practically unaltered on Zn-DTPA administration, but there was a significant increase in renal MT levels compared to rats administered Cd-DTPA or Cd alone.

Accumulation of potentially toxic elements by sheep given diets containing soil and sewage sludge. 2. Effect of the ingestion of soils treated historically with sewage sludge

AbstractCurrent European Union legislation will increase the level of disposal of sewage sludge to agricultural land in the next 10 years. This increase may lead to an increase in ingestion, by grazing animals, of herbage with elevated levels of potentially toxic elements (PTEs) derived from sludge adhered to the herbage or sewage sludge-amended soil resulting in the accumulation of PTEs in body tissues, especially the liver and kidney. To assess the possible accumulation of PTEs from soils treated historically with sewage sludge, eight groups of housed weaned lambs were given either dried grass as a sole food (grass control), or diets comprising dried grass (0·9 of total diet dry matter (DM)) and soil (0·1 of total diet DM) from two experimental sites, plots within which had been treated 14 years previously with different quantities of sewage sludge. Soils from the two sites (Cassington and Royston) had contrasting physical characteristics, pH and contents of calcium. The soil from the site at Cassington was slightly acidic (pH 6·0) and had a concentration of calcium of 7·92 g/kg DM whereas the soil from the site at Royston was alkaline (pH 8·0) and had a high concentration of calcium (23·5 g/kg DM). Plots at each site had a range of concentrations of cadmium (Cd) in the soil up to three times the United Kingdom (UK) statutory limit of 3 mg Cd per kg DM. The soils from these two sites were designated control — no amendment with sewage sludge (0·69 mg Cd per kg DM), low (3·55 mg Cd per kg DM), medium (6·63 mg Cd per kg DM) and high (8·82 mg Cd per kg DM; Cassington soil only). Voluntary DM intake of diets by weaned lambs (mean 1436 glday) was not affected significantly by any dietary treatment. The concentrations of Cd in liver increased (P &lt; 0·001) from 0·061 and 0·072 mg/kg DM (Royston and Cassington control, respectively) to 0·218 and 0·403 mg/kg DM (Royston and Cassington medium, respectively) and 0·500 mg/kg DM (Cassington high). The concentrations of Pb in liver increased (P &lt; 0·001) from 0·733 and 0·627 mg/kg DM (Royston and Cassington control, respectively) to 118 and 1·25 mg/kg DM (Royston and Cassington medium, respectively) and 1·18 mg/kg DM (Cassington high). Similar changes were observed for concentrations of Cd and Pb in kidney. A depletion of the concentration of Cu in the liver was observed in all treatments containing soil in the diet. The rate of accumulation of Cd in the liver ranged from 0 to 0·35 μg/g daily tissue DM growth and in the kidney ranged from 0 to 0·44 μg/g daily tissue DM growth. The rate of accumulation of Pb in the liver ranged from 0 to 6·01 μg/g daily tissue DM growth and in the kidney ranged from 0 to 0·63 μg/g daily tissue DM growth. No significant accumulation of PTEs was observed in muscle tissue. It is concluded that the current UK statutory limits for the concentrations ofCd and Pb in soils treated with sewage sludge should be reviewed in the light of these results, though they require confirmation in the grazing situation.

Bioavailability of Soil-Adsorbed Cadmium in Orally Exposed Male Rats

During the last few decades, the industrial production and use of Cd resulted in the release of significant quantities of Cd into the environment. Concern about health risks of human exposure to this toxic metal, which may be contained in soil and other environmental compartments, has increased significantly in recent years. Soil ingestion is a potentially important pathway of exposure to soil-absorbed environmental contaminants, especially for young children exhibiting hand-to-mouth behavior. Health risk assessments are usually based on unchanged bioavailability of soil-absorbed pollutants, e.g., heavy metals, neglecting interactions of metals with the soil matrix, which may lead to relatively lower bioavailability. This study was conducted to determine the bioavailability of Cd absorbed to soil in rats. Eight-week-old male Lewis rats were given either a soil polluted with CdCl2 (150 micrograms Cd/rat) dissolved in 5% gun acacia or an equal amount of Cd as CdCl2 dissolved in saline. Control rats were gavaged with isotonic saline. Cd concentrations in liver, kidney, brain, heart, and blood, as well as Cd content of urine and feces were analyzed using graphite furnace atomic absorption spectrometry. Tissue Cd concentrations in soil-treated animals were significantly lower than the tissue concentrations in the Cd-saline group; in the liver and kidneys of the Cd-saline and Cd-soil groups, 4 and 2.7% respectively, of the original doses were recovered. Relative bioavailability, calculated on the basis of blood Cd levels for the Cd-soil group as compared to the Cd-saline group, appeared to be 43%. No differences in the excretion pattern of Cd into feces were observed between the Cd-saline and Cd-soil groups. After 6 days, over 91% of the original dose was recovered in the feces of both Cd-treated groups. Cd excretion via urine was very low, but in the Cd-soil group a significant increase in urinary Cd was observed as compared to the control group. However, the amount of Cd excreted into urine of the Cd-soil group during the experimental period corresponded to only 0.01% of the original dose. In the Cd-saline group, no additional Cd was excreted into urine as compared to the control group. These results indicate that the soil matrix significantly reduced the absorption of Cd in the gastrointestinal tract. Consequently, exposure assessment models, assuming an unaffected bioavailability of soil-absorbed Cd, overestimate the internal dose and thereby overestimate health risks associated with direct ingestion of soil particles.

Cadmium and atherosclerosis in the rabbit: Reduced atherogenesis by superseding of iron?

This study evaluated the effect of dietary cadmium (Cd) on atherosclerosis in the rabbit. Cholesterol was added to the diet to initiate and/or accelerate atherogenesis. Cd was added to the diet at two dose levels. Uptake of Cd was 55 μg/kg body weight (BW)/day at the low dose level and 1350 μg/ kg BW/day at the high dose level. Five groups of rabbits were fed five different diets for 9 months: (l) basal diet without additional constituents; (2) background diet, which was basal diet to which cholesterol had been added; (3) the low-dose level Cd diet, which was background diet to which 2 mg Cd/kg had been added; (4) high-dose level Cd diet, which was background diet to which 50 mg Cd/kg had been added; and (5) basal diet to which 50 mg Cd/kg had been added. Dietary cholesterol increased blood total leucocyte count, serum and liver total cholesterol concentrations, serum total bilirubin concentration, low-density lipoprotein vitamin E concentration and induction of atherosclerotic plaques in the aorta and coronary arteries. Cd in the diet increased liver and kidney Cd concentrations in a dose-dependent way, decreased prothrombin time and temporarily increased urea and creatinine clearances. Slight kidney damage was induced by Cd only in animals fed the high-dose level Cd diet (with or without cholesterol). Dietary Cd partly counteracted the dietary cholesterol-induced increases of serum and liver total cholesterol concentrations, and tended to reduce plaque formation in the aorta. Dietary Cd in rabbits fed cholesterol-containing diets influenced cholesterol metabolism and tended to decrease atherosclerosis in a dose-related fashion. This is in contrast with limited epidemiological human data. Dietary Cd also decreased serum ferritin concentration and increased serum transferrin concentration. Free iron concentration is associated with myocardial infarction in man and augments the development of atherosclerosis in rabbits. It is concluded that the observed reduction in atherogenesis is related to dietary Cd-induced changes in cholesterol metabolism, increased rheology of blood and/or, most likely, reduced free iron concentration.

Distribution and Retention of Cadmium in Metallothionein I and II Null Mice

Cadmium (Cd) is known to have a long biological half-life in the body, possibly due to its binding to metallothionein (MT). This study was designed to determine the role of MT in the tissue distribution and retention of Cd using MT-I and -II null (MT-null) mice. Mice were given109CdCl2(15 μmol/kg, 25 μCi/kg, ip), and radioactivity was quantified in 14 major organs at 2 hr, 1, 2, 3, 7 and 15 days thereafter. The lack of MT in MT-null mice did not affect the initial tissue distribution of Cd, as similar amounts of Cd were distributed in control (C57BL/6J) and MT-null mice 2 hr after Cd administration (74% vs 72% of the dose, respectively). However, the elimination of Cd was much faster in MT-null mice than in control mice. In control mice, approximately 40% of Cd administered was found in liver 24 hr after administration, and the majority was bound to MT. In contrast, only 20% of Cd was found in liver of MT-null mice, which was not bound to MT. Cd concentrations in kidney, pancreas, and spleen were also lower in MT-null than in control mice 1 week after administration. No apparent difference in Cd retention in other organs was noted between control and MT-null mice over the 15-day period. Cd concentration in kidney continued to increase with time in control but not in MT-null mice, indicating that an important source of Cd in the kidney is the uptake of CdMT. In conclusion, the present data indicate that MT does not play a role in the initial distribution of Cd to tissues, but does play a major role in the elimination of Cd, especially from liver, kidney, and pancreas. These data support the conclusion that the persistence of Cd in the body is at least partially due to Cd binding to MT in tissues.

Accumulation of cadmium with time in Romney sheep grazing ryegrass-white clover pasture: effect of cadmium from pasture and soil intake

Cadmium (Cd) concentrations in various tissues of Romney sheep and rates of accumulation, as affected by Cd concentrations in pasture and soil, DM intake, and animal age, were determined in a 25-month study. After weaning, 6 groups of 10 wether lambs were grazed on a low Cd (0.l8 � 0.08 8g Cd/g DM) or high Cd (0.52 � 0.17 8g Cd/g DM) pasture in 3 replicates. The rate of accumulation of Cd (8g /day) into the liver and kidney was greatest in sheep aged about 6 months (for the low and high Cd pastures: kidney 0.27 and 0.56; liver 0.35 and 1 I), after which it declined with age (kidney 0.02 and 0.03: liver &lt;0901 and 0.05; at 28 months of age). Total content of Cd in the organs continued to increase. In 6-month-old animals, 0.25% of total Cd ingested was retained by the kidney and liver, but this proportion decreased to about 0.05% of Cd intake with 28-month-old animals. Net retention of Cd in the fleece-free body as a percentage of daily Cd intake for both the control and treatment animals was estimated between 0- 35 and 0 5%. Except for muscle tissue from sheep in the treatment group, for which the mean Cd concentration was lower than that of the control group (2.0 � 0.24 and 3 9 � 0.63 r)g Cd/g fresh tissue, respectively), Cd concentrations in kidney, liver, thymus, muscle, and lung tissue increased over the first 3 months for both groups of animals. After 2 years, animals on the treatment pastures had approximately 3-fold greater Cd concentrations in liver, kidney, and duodenal tissue tissue than those grazing the control pastures (liver, 361 � 58 v. 97 � 11; kidney, l485 � 200 v. 352f48; duodenal tissue, 32f 4 v. 18f 2.5 t)g Cd/g FW, respectively). At higher Cd intakes, the adaptive effect of increased metallothionein synthesis enabled the animal to be more efficient in binding Cd, which restricted accumulation of Cd in muscle. The regression ([Cd] kidney = -205 + 0. 981Cdintake + 0 - 726Time; r = 0.82, P &lt; 0.001) gave the best fit for the observed Cd concentration in the kidney tissue. Daily Cd intake was also a better predictor of the Cd concentration in liver tissue than the concentration of Cd in pasture by itself ([Cd]liver, = 24.7 + 0.353Cdintake; r = 0.81, P &lt; 0.001). Accurate predictions of the potential for Cd accumulation in young grazing animals will enable more effective management strategies to be implemented to reduce Cd accumulation and therefore minimise the potential impact relating to both environment and market.

Renal Cadmium Concentrations in Mice and Shrews Collected from Forest Lands Treated with Biosolids

AbstractThis study examined the long‐term effects of biosolids (mixed domestic‐industrial anaerobically digested sewage sludge) application to forested lands on kidney Cd concentration in omnivorous mice (Peromyscus sp.) and insectivorous shrews (Sorex sp.). Animals from eight biosolids‐treated sites, located in two different areas in western Washington, were examined and compared with those captured on seven control sites. Varying amounts of biosolids had been applied either 4, 11, or 15 yr previously. Kidney Cd was significantly greater in Sorex than in Peromyscus on all treatment sites. Though Cd levels in Peromyscus from some treatment sites were significantly increased over corresponding controls, levels from the highest dose treatment sites were comparable to controls found at other sites, so it is doubtful that biosolids had a significant long‐term effect on the omnivores. Cadmium levels in Sorex from all treatment sites except those receiving the lowest dose of biosolids were significantly greater than controls. Kidney Cd concentrations in shrews trapped from the 11‐yr postapplication sites were approximately equivalent to those in shrews trapped 2 yr after application on those same sites. However, the elevated levels of Cd found in Sorex, while highly significant statistically, did not appear to be biologically significant.

Importance of Prey Choice for Cd Uptake by Carp (Cyprinus carpio) Fingerlings

Carp (Cyprinus carpio) fingerlings were fed contaminated midge larvae (Chironomus riparius) or contaminated mussels (Dreissena polymorpha) to study the hypothesis that prey choice is important for cadmium accumulation in fish. Both types of prey were exposed to nominal water concentrations of 100 μg Cd/L for 2 wk. Before being fed to carp, midges contained more Cd (260 mg Cd/kg dry wt) than mussels (160 mg Cd/kg dry wt). After 1-4 wk of feeding, Cd concentrations in intestine, liver, gill, kidney, and muscle of the carp were analysed. Significant Cd accumulation took place in all fish organs studied, except muscle. The highest Cd concentration was found in the intestine. Despite the higher Cd levels in midges, Cd concentrations in liver, kidney, and gill of the carp were about twice as high after eating contaminated mussels than after eating contaminated midges. We conclude that the uptake of Cd by fish depends on the prey species eaten, but the hypothesis that the consumption of less contaminated prey species leads to lower accumulation by the fish was falsified by the results of this study.

Soil and agronomic factors associated with cadmium accumulations in kidneys of grazing sheep

Mean concentration of cadmium (Cd) in kidneys of hogget sheep from 67 flocks grazing in the Agricultural Region of Western Australia was tested for association with soil, pastoral, climatic and nutritional factors. Hoggets grazing pastures on acidic soils and soils with a sandy-textured surface had higher Cd concentrations in kidneys than hoggets grazing pastures on more alkaline soils or soils with a clay-textured surface. Application of more than 100 kg of phosphatic fertiliser during the past 3 years to loamy soils was also associated with greater Cd concentration in kidneys of the grazing animals.

Bioavailability of metals and arsenic to small mammals at a mining waste-contaminated wetland.

In support of a baseline ecological risk assessment evaluating the impacts of mining wastes at the Milltown Reservoir Sediments Superfund site in Montana, a food chain transfer analysis was performed for resident small mammals. Deer mice (Peromyscus maniculatus) and meadow voles (Microtus pennsylvanicus) were trapped from a 200 A portion of a mixed upland and palustrine wetland, and concentrations of As, Cd, Cu, Pb, and Zn in carcass, liver, kidney, and testes were quantified. Concurrent to small mammal trapping, samples of grasses, forbs, and soils were collected and analyzed for metal and As residues. Using a linear multimedia food-chain model, assuming a forage base of wetland vegetation from the site, ingestion of local surface water, and incidental ingestion of soils with vegetation, body burdens of the metals and As in the herbivores were estimated. As a means of estimating potential element bioavailability at the site, the modeled body burdens were compared with measured element concentrations in herbivore tissues. The analysis indicates that the bioavailabilities of As, Cd, Cu, Pb, and Zn were equal to or less than 0.2% for internal organs and 0.1% for carcasses, on a microgram/g tissue wet weight basis. Available site data on soil pH, cation exchange capacity, and extractable elements fraction supported the limited release of soil elements. These results suggest that the bioavailable fraction of mining waste metals in riparian wetland soils may be quite small, and, for the Milltown Reservoir site, lower than originally anticipated.

Heavy metal contamination in organs of red deer ( Cervus elaphus) and wild boar ( Sus scrofa) and the effect on some trace elements

In order to determine the contamination level for cadmium (Cd) and lead (Pb) in free ranging red deer ( n = 50) and wild boar ( n = 118) in ‘The Veluwe’, a nature reserve in the central part of The Netherlands, concentrations of these metals were measured in liver and kidney. In addition relations between Cd and Pb concentrations and iron (Fe), copper (Cu) and zinc (Zn) concentrations in these organs were studied. The levels of Cd and Pb in wild animals were higher than in farmed animals of the same age, especially in the kidneys. Kidney Cd and Pb concentrations were generally higher than concentrations in liver. However, in wild boar also high Pb concentrations were found. Unlike the kidney there was a saturation in liver Cd accumulation which might be due to an insufficient Cd binding capacity of the liver as the exposure to Cd persisted. There was a strong increase of the kidney Cd concentrations with age in red deer and wild boar, which indicates substantial chronic exposure to this metal. However, concentrations of Cd and Pb were not high enough to be toxic or to affect Fe, Cu, or Zn concentrations in the animal. Compared to other wildlife species in other countries, the kidney Cd concentrations were high in our animals; Pb concentrations in liver and kidney were about the same as Pb concentrations in wildlife in other countries. Because of the high contamination levels of red deer and wild boar from this study it was concluded that De Veluwe is a relatively highly contaminated area, resulting in liver and kidney which are unsuitable for human consumption.

Stress protein synthesis induced by cadmium-cysteine in rat kidney

Biomarkers are important tools which enable toxicologists to reliably predict and detect exposures to xenobiotics and resultant cell injury, ultimately improving risk assessments. Since the de novo synthesis of stress proteins can be detected early after exposure to some agents, analysis of toxicant-induced changes in gene expression, i.e. alterations in patterns of protein synthesis, may be useful to develop as biomarkers of exposure and toxicity. We are utilizing various xenobiotics as tools to study stress protein synthesis in target organs in order to evaluate the target tissue-specificity of this response. Previous data from this laboratory have demonstrated that induction of stress proteins in rat liver, but not kidney, after acute exposure to CdCl 2 precedes hepatotoxicity. Since kidney is a target tissue after chronic Cd exposure, it was of interest to examine stress protein synthesis in this tissue. However, dose-limiting hepatotoxicity precluded this evaluation. Cd complexed with molecules such as cysteine (cys) or metallothionein has been used in acute dosing regimens as a tool in order to study the nephrotoxicity of Cd. Therefore, this study was undertaken in order to evaluate Cd-induced stress protein synthesis in an important tissue known to be injured after chronic exposure, i.e. kidney. Specific objectives included comparing stress protein synthesis in rat kidney and liver after acute exposure to Cd-cys and CdCl 2, determining the Cd threshold concentration for renal stress protein synthesis and assessing the relationship between stress protein synthesis and nephropathy. Male rats were exposed to equivalent doses of Cd as CdCl 2 or Cd-cysteine (molar ratio Cd:cys=1:15). Kidney Cd concentrations increased 5-fold after a.v. injection of Cd-cys compared to CdCl 2, mimicking Cd distribution following chronic exposure. After exposure to Cd, tissue slices were incubated with 35S-methionine. Slices were subsequently homogenized and centrifuged, and the 16 000 g supernatants were subjected to SDS-polyacrylamide gel electrophoresis. Proteins which had incorporated 35S-methionine were detected by autoradiography. De novo synthesis of 70, 90 and 110 kDa proteins was enhanced in liver, but not in kidney, 4 h after injection of 2 mg Cd/kg as CdCl 2. In contrast, dose-related increases in synthesis of these proteins were observed in kidney 4 h after injection of 1 and 2 mg Cd/kg as Cd-cys, but not at lower dosages. In addition, synthesis of a 68 kDa kidney protein was inhibited at 2 mg Cd/kg as Cd-cys, The threshold for Cd-induced stress protein synthesis was shown to be between 4 and 8 μg Cd/g tissue. These alterations in protein synthesis in kidney occured at tissue Cd concentrations lower than those which resulted in renal injury, as assessed by histopathology and PAH uptake into renal slices. Thus, altered patterns of protein synthesis may serve as markers of cell injury or indicators of cellular stress in target organs.

The use of bird feathers for the monitoring of cadmium pollution

The cadmium contamination mechanism in bird feathers was investigated using starlings fed with diets containing 10 and 50 ppm Cd for five months. The experiment started about two months before the beginning of the annual complete feather molt and lasted until most of the birds completed the molt of the primaries. Concentrations of Cd in liver, kidney, and uropygial gland were highly correlated, but uropygial gland concentration was about 100 times lower. Cadmium was found both in old and new feathers, in a dose-related manner. Old. feathers showed higher metal concentrations than new ones and primaries higher than secondaries. Feather Cd concentration correlated with Cd concentration in liver, kidney, and the uropygial gland. The use of bird feathers are, therefore, a reliable method for monitoring cadmium pollution, but differences between feather type and age must be considered to correctly interpret data collected in the field.

Cadmium accumulation and metallothionein concentrations after 4-week dietary exposure to cadmium chloride or cadmium-metallothionein in rats

The distribution of cadmium was examined in rats fed diets containing either cadmium-metallothionein (CdMt) or cadmium chloride (CdCl 2) for 4 weeks. The test diets contained 3, 10, or 30 mg Cd/kg diet (3, 10, or 30 ppm) as CdMt or 30 mg Cd/kg diet (30 ppm) as CdCl 2. A second study was performed to establish the Cd content in liver and kidneys after exposure to low doses of both CdMt and CdCl 2 (1.5 and 8 ppm Cd). The feeding of CdMt resulted in a dose- and time-dependent increase of the Cd concentration in liver, kidneys, and intestinal mucosa. Rats fed 30 ppm CdMt consistently showed less Cd accumulation in liver and intestinal mucosa than did rats fed 30 ppm CdCl 2. However, renal accumulation in rats fed 30 ppm was similar until Day 28 regardless of Cd form. At lower dietary Cd levels (1.5 and 8 ppm), relatively more Cd is deposited in the kidneys, although even at these doses the kidney/liver ratio of Cd is still higher with CdMt than with CdCl 2. Tissue metallothionein (Mt) levels in the intestinal mucosa were relatively constant but always higher after CdCl 2 exposure than after CdMt exposure. Mt levels in both liver and kidney increased after CdCl 2 or CdMt exposure during the course of study. Although Mt levels in liver were higher after CdCl 2 intake (30 ppm) than after CdMt intake (30 ppm), renal Mt concentrations were the same for both groups. In fact on Day 7, CdMt administration resulted in slightly higher Mt levels than CdCl 2 administration, suggesting a direct accumulation of exogenous CdMt in the kidneys. In conclusion, after oral exposure to CdMt in the diet there is a relatively higher Cd accumulation in the kidneys. However, the indirect renal accumulation via redistribution of Cd from the liver might be lower than after CdCl 2 exposure. Which of these two phenomena is decisive in the eventual level of renal toxicity of Cd after long-term oral intake could determine the toxicological risk of the chronic intake of biologically incorporated Cd.

Cadmium bioaccumulation in organs of the scallopMizuhopecten yessoensis

Cadmium and Zinc content was determined in organs of the Japanese scallopMizuhopecten yessoensis, collected in 1984 from the Sea of Japan and aged between 1 and 8 yr. Under conditions of background Cd, Cd concentration in hepatopancreas and kidney increased linearly with age from 39 to 400µg g−1 dry wt in hepatopancreas, and from 100 to 640µg g−1 dry wt in kidney. Such a pattern was not determined for Zn. Cd concentration in muscle, mantle and gill did not exceed 6µg g−1 dry wt in the oldest scallops. In subcellular fractions of the hepatopancreas, cytosolic Cd accounted for 71.7% in 1-yr-old scallops and 98.8% in 8-yr-olds. A similar ratio was established for gills, although gill Cd content was an order of magnitude lower. Analysis of Cd distribution in cytoplasmic proteins (of different molecular weight) in the hepatopancreas, showed that the amount of Cd bound to metallothionein-like proteins increases with scallop growth. A considerable amount of Cd also was detected in high molecular weight proteins. Thus, Cd accumulation, with age, in organs of the Japanese scallop is due to metal binding by cytoplasmic proteins.