Levels Of Dietary Cadmium Research Articles

Detoxification Impacts of Ascorbic Acid and Clay on Laying Japanese Quail Fed Diets Polluted by Various Levels of Cadmium.

A total number of 360 laying Japanese quail (8 weeks of age) were randomly divided into 12 groups. Birds in all groups had nearly the same average initial body weight. A factorial arrangement (4 × 3) was performed including four levels of dietary cadmium (Cd) as cadmium chloride (0, 50, 100, and 150 mg/kg diet) and three levels of feed additives (without, 300 mg/kg ascorbic acid and 1.50% natural clay). Results revealed that Cd contaminated feed caused significant (p < 0.01) retardation in body weight, lower egg number and egg mass and worse feed conversion. On the other hand, the addition of ascorbic acid or natural clay to quail diets caused a significant (p < 0.01) improvement in all studied traits. With respect to the interaction among Cd and the experimental additives, results showed that within each Cd level, ascorbic acid or clay supplementation recorded the highest body weight, egg number, egg weight and mass in addition to improved feed conversion. Cadmium levels decreased (p < 0.05) blood total protein, albumen and A/G ratio. Both 300 mg ascorbic acid and 1.50% clay increased (p < 0.05) blood total protein and albumen compared to non-supplemented groups. It could be concluded that the consumption of polluted diets Cd causes deleterious effects on the productive performance of laying Japanese quail. The addition of ascorbic acid or natural clay to the diets causes beneficial effects on productive performance traits, improves egg quality criteria and diminishes the toxic effects of Cd.

An 112 Days Experiment on Dietary Cadmium Retention in Hepatopancreas in Adult Cantareus aspersus Snails

Cadmium is very hazardous pollutant with massive impact on aspects of everyday life. Little knowledge exists on kinetics of dietary cadmium retention in Cantareus aspersus for durations above three months although this species of land snails serves as excellent ecotoxicological model for studying cadmium hazard. Here was used a continuous 112-day exposure study design, in which test snails were exposed to a wide range of dietary cadmium levels, including human- and environmentally-relevant levels. Using Flame Atomic Absorption Spectrometry, cadmium levels in the hepatopancreas were found to increase significantly, and in dose-dependent manner starting from a dietary cadmium dose of 0.2 mg/kg dry weight. The results of the present study render the hepatopancreas of mature snails, C. aspersus, as excellent endpoints for assessing Cd toxicity over a broad range of concentrations. Hence, this species of land snails can be reliably used for both active and passive biomonitoring of environmental cadmium pollution.

Global burden of late-stage chronic kidney disease resulting from dietary exposure to cadmium, 2015

Chronic exposures to cadmium (Cd) are associated with reduced glomerular filtration rate (GFR), increasing the risk of chronic kidney disease (CKD). In support of the World Health Organization (WHO)’s initiative to estimate the global burden of foodborne diseases, a risk assessment was performed to estimate the Disability-Adjusted Life Years (DALYs) due to late-stage CKD associated with dietary exposures to cadmium. Using the distribution of population GFRs, the prevalence of CKD was calculated as the proportion of humans whose GFR fall in the ranges corresponding to Stage 4 or Stage 5 CKD. The increase in the CKD prevalence due to cadmium exposure was simulated based on a previously reported pharmacokinetic model describing the relationship between dietary cadmium intake and urinary cadmium (UCd), as well as a previously published dose-response relationship between UCd and GFR. Cadmium-related incidence rate, calculated as the change in the prevalence during a one-year period, were used to compute the mortality and DALY in all WHO regions. It is estimated that dietary cadmium would result in a median of 12,224 stage 4 and stage 5 new CKD cases per year worldwide, resulting in 2064 global deaths and 70,513 DALYs. These data translate into a median global burden of 1.0 DALY per 100,000 population, which account for 0.2% of the global DALYs of CKD. While these results suggest that the overall impact of dietary cadmium exposure on global CKD is low, they do indicate that reasonable efforts to reduce dietary exposure will result a positive public health impact. This would be particularly the case in areas with elevated levels of dietary cadmium.

The role of some feed additives in fish fed on diets contaminated with cadmium.

The decline of cadmium pollution in fish farms is needed by any adequate method. The present study was designed to explore the effect of dietary cadmium contamination and its amelioration by using dietary clay, probiotic (Bactocell®), vitamin C, and vitamin E supplementation in Nile tilapia fish diet on growth rate, feed efficiency, blood components, and cadmium residues. Fish were separated into 15 groups, each group of fish was stocked into three aquaria and each contains 20 fishes. The fish of the first five groups were fed the basal diet, the second five groups were fed the basal diet contaminated with 25mg cadmium/kg, and the third five groups were fed the same diet contaminated with 50mg cadmium/kg. Within each dietary cadmium level, the first group was fed the diet without any supplementation, the second was fed the diet supplemented with natural clay (bentonite) at level 3%, the third group was fed the diet supplemented with 1g Bactocell®/kg, the fourth group was fed the diet supplemented 50mg vitamin E/kg, and the fifth group was fed the diet supplemented with 100mg vitamin C/kg. Live body weight, daily body weight gain, and feed intake of Nile tilapia decreased significantly (P<0.001) with increasing dietary cadmium level, while feed conversion was impaired. Fish group fed on diets contaminated with 50mg cadmium/kg recorded the lowest live body weight and weight gain. Serum total protein and albumin concentration significantly (P<0.001) decreased, while serum creatinine, AST, and ALT significantly (P<0.001) increased with increasing cadmium level in fish diets. Blood hemoglobin and total erythrocyte (RBCs) significantly (P<0.001 or 0.05) decreased with cadmium contamination in fish diets, while leukocytes were insignificantly affected. Body cadmium residues increased significantly (P<0.001) by increasing cadmium level in fish diets. Live body weight, daily body weight gain, and feed intake of Nile tilapia increased significantly (P<0.001) with feed additive supplementation in diets, also while feed conversion improved. Fish group fed on diets supplemented with probiotic Bactocell® or natural clay recorded higher body weight and gain rate than the other experimental groups. Serum total protein, blood hemoglobin, and total erythrocyte increased, while urea-N, creatinine, ALT, AST, and leukocytes decreased as affected with the feed additive supplementation. Feed additive supplementation in fish diets significantly (P<0.001) decreased cadmium residues in fish bodies. Irrespective of dietary cadmium level, feed additive supplementation in fish diet improved the growth rate and decreased the concentrations of serum creatinine and ALT. The obtained results indicated that feed additive supplementation could modify the function of the kidney and liver in fish exposed to the cadmium toxicity.

94 - Lung Cysteine/cystine Redox Potential Increase Is Associated with Worse Inflammation and Disrupted Metabolism during H1N1 Infection and Exposure to Dietary Levels of Cadmium

Influenza A virus subtype H1N1 is seasonally active in the United States, affecting millions of people each year and claiming tens of thousands of lives since the 2009 pandemic. Public health efforts have focused on vaccination, but exposed individuals who become sick face severe inflammation and possibly death. Cadmium (Cd) is a ubiquitous heavy metal that interacts with thiols such as metallothionein and GSH. Public dietary exposure has remained steadily constant, potentially worsening health risks. Emerging evidence suggests Cd may worsen lung disease at levels achievable in the diet. To assess the role of dietary Cd in lung inflammation, mice were exposed to 1 mg/l CdCl 2 in drinking water for 16 weeks. 10 days prior to study completion, mice were intranasally given sub-lethal H1N1 or sterile saline. H1N1 caused a 20% body weight loss and 7-fold increase in airway enhanced pause after 10 days, and Cd exposure caused a 4.8-fold increase in lung tissue Cd without detectable changes in urine or plasma. Infected and Cd-exposed mice had worse lung inflammation, which was comprised of neutrophils, monocytes and T cells, and increased KC, IP-10, IFN-γ and IL-6. Lung tissue cysteine/cystine redox potential (Eh[CySS]) was progressively increased by Cd, H1N1 and the combination, unlike glutathione redox potential (Eh[GSSG]). A similar, less significant trend was observed in plasma Eh[GSSG]. Reducing Eh[CySS] clustered with myogenesis and complement pathway genes by associating with inflammation-sensitive metabolism such as kynurenine conversion to anthranilic acid. These data suggest lung Eh[CySS] coordinates tissue responses to viral-induced inflammation and that ingested Cd may significantly worsen lung inflammation during respiratory infections.

Effects of Different Dietary Cadmium Levels on Growth and Tissue Cadmium Content in Juvenile Parrotfish, Oplegnathus fasciatus.

This feeding trial was carried out to evaluate the effects of different dietary cadmium levels on growth and tissue cadmium content in juvenile parrotfish, Oplegnathus fasciatus, using cadmium chloride (CdCl2) as the cadmium source. Fifteen fish averaging 5.5±0.06 g (mean±SD) were randomly distributed into each of twenty one rectangular fiber tanks of 30 L capacity. Each tank was then randomly assigned to one of three replicates of seven diets containing 0.30 (C0), 21.0 (C21), 40.7 (C41), 83.5 (C83), 162 (C162), 1,387 (C1,387) and 2,743 (C2,743) mg cadmium/kg diet. At the end of sixteen weeks of feeding trial, weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) of fish fed C21 were significantly higher than those of fish fed C83, C162, C1,387 and C2,743 (p<0.05). Weight gain, SGR and FE of fish fed C0, C21 and C41 were significantly higher than those of fish fed C162, C1,387 and C2,743. Protein efficiency ratio of fish fed C0, C21 and C41 were significantly higher than those of fish fed C1,387 and C2,743. Average survival of fish fed C0, C21, C41 and C162 were significantly higher than that of fish fed C2,743. Tissue cadmium concentrations increased with cadmium content of diets. Cadmium accumulated the most in liver, followed by gill and then muscle. Muscle, gill and liver cadmium concentrations of fish fed C0, C21, C41 and C83 were significantly lower than those of fish fed C162, C1,387 and C2,743. Based on the ANOVA results of growth performance and tissue cadmium concentrations the safe dietary cadmium level could be lower than 40.7 mg Cd/kg diet while the toxic level could be higher than 162 mg Cd/kg diet.

Bone resorption acceleration and calcium reabsorption impairment in a Thai population with high cadmium exposure

Some residents of the Mae Sot district in Thailand have suffered long-term exposure to elevated dietary levels of cadmium. To test the hypothesis that chronic dietary cadmium exposure can cause imbalance in calcium dynamics and accelerate bone resorption, a group of these residents (156 men and 256 women aged ≥ 50) were selected on the basis of previous records of elevated urinary cadmium and tested for urinary and blood cadmium, bone formation and resorption markers, and the renal tubular dysfunction markers. Both genders had high levels of blood and urinary cadmium and high urinary levels of the markers for renal dysfunction and bone resorption in a dose–response relationship to urinary cadmium. The excretion of bone resorption markers was positively correlated to the ratio of excreted calcium and urinary cadmium. The results of a multivariate regression analysis indicated that bone resorption was accelerated by impaired calcium reabsorption in renal tubules.

Effect of dietary cadmium level on the growth, body composition and several hepatic enzymatic activities of juvenile yellow catfish,Pelteobagrus fulvidraco

The present study was conducted to investigate the effect of dietary cadmium (Cd) level on the growth, body composition and several enzymatic activities of juvenile yellow catfish, Pelteobagrus fulvidraco. The experimental diets were formulated with CdCl2·2.5H2O at levels of 0, 0.01, 0.1 and 1.0 g kg−1 diet, resulting in four dietary Cd levels of 0.25 (control), 4.92, 48.57 and 474.7 mg Cd kg−1 diet respectively. They were fed to juvenile yellow catfish (mean initial weight: 3.26±0.07 g, mean±SD) for 4 weeks. Weight gain, specific growth rate, feed intake and protein efficiency ratio tended to decline with increasing dietary Cd levels (P 0.05). Hepatic alkaline phosphatase, glutathione peroxidase and lactate dehydrogenase activities increased (P 0.05). The present study provided for the first time the toxic assessment of dietborne Cd in yellow catfish, based on growth performance and the changes in hepatic enzymatic activities for the fish species.

Impact of cadmium on aquatic bird Cairina moschata

The impact on palmiped Cairina moschata of two levels of dietary cadmium (Cd) contamination (C1: 1 mg kg(-1) and C10: 10 mg kg(-1)) was investigated on liver gene expression by real-time PCR. Genes involved in mitochondrial metabolism, in antioxidant defences, detoxification and in DNA damage repair were studied. Metallothionein (MT) protein levels and Cd bioaccumulation were also investigated in liver, kidneys and muscle. Male ducks were subjected to three periods of exposure: 10, 20 and 40 days. Cd was mainly bioaccumulated in kidneys first and in liver. The concentrations in liver and kidneys appeared to reach a stable level at 20 days of contamination even if the concentrations in muscle still increased. Cd triggered the enhancement of mitochondrial metabolism, the establishment of antioxidant defences (superoxide dismutase Mn and Cu/Zn; catalase) and of DNA repair from 20 days of contamination. Discrepancies were observed in liver between MT protein levels and MT gene up-regulation. MT gene expression appeared to be a late hour biomarker.

Chronic renal failure among farm families in cascade irrigation systems in Sri Lanka associated with elevated dietary cadmium levels in rice and freshwater fish (Tilapia)

Chronic renal failure (CRF), in the main agricultural region under reservoir based cascade irrigation in Sri Lanka has reached crisis proportion. Over 5,000 patients in the region are under treatment for CRF. The objective of this study is to establish the etiology of the CRF. Concentrations of nine heavy metals were determined in sediments, soils of reservoir peripheries, water and Nelumbo nucifera (lotus) grown in five major reservoirs that supply irrigation water. All five reservoirs carried higher levels of dissolved cadmium (Cd), iron (Fe) and lead (Pb). Dissolved Cd in reservoir water ranged from 0.03 to 0.06 mg/l. Sediment Cd concentration was 1.78-2.45 mg/kg. No arsenic (As) was detected. Cd content in lotus rhizomes was 253.82 mg/kg. The Provisional Tolerable Weekly Intake (PTWI) of Cd based on extreme exposure of rice is 8.702-15.927 microg/kg body weight (BW) for different age groups, 5-50 years. The PTWI of Cd due to extreme exposure of fish is 6.773-12.469 microg/kg BW. The PTWI on a rice staple with fish is 15.475-28.396 microg/kg BW. The mean urinary cadmium (UCd) concentration in CRF patients of age group 40-60 years was 7.58 microg Cd/g creatinine and in asymptomatic persons UCd was 11.62 microg Cd/g creatinine, indicating a chronic exposure to Cd. The possible source of Cd in reservoir sediments and water is Cd-contaminated agrochemicals. The CRF prevalent in north central Sri Lanka is a result of chronic dietary intake of Cd, supported by high natural levels of fluoride in drinking water, coupled with neglecting of routine de-silting of reservoirs for the past 20 years.

Effect of Dietary Cadmium Levels on Nutrient Digestibility and Retention of Iron, Copper and Zinc in Tissues of Growing Pigs

This experiment was conducted to investigate the effect of cadmium levels on weight gain, nutrient digestibility and the retention of iron, copper and zinc in tissues of growing pigs. A total of one hundred and ninety-two crossbred pigs (barrows, Duroc×Landrace×Yorkshine, 27.67±1.33 kg of average initial body weight) were randomly allotted to four treatments. Each treatment had three replicates with 16 pigs per pen. The corn-soybean basal diets were supplemented with 0, 0.5, 5.0, 10.0 mg/kg cadmium respectively, and the feeding experiment lasted for eight-three days. Cadmium chloride was used as cadmium source. The results showed that pigs fed the diet containing 10.0 mg/kg cadmium had lower ADG and FCR than any other treatments (p<0.05). Apparent digestibility of protein in 10.0 mg/kg cadmium-treated group was lower than that of other groups (p<0.05). There was lower iron retention in some tissues of 5.0 mg/kg and 10.0 mg/kg cadmium treatments (p<0.05). However, pigs fed the diet 10.0 mg/kg cadmium had higher copper content in most tissues than that of any other groups (p<0.05). There was a significantly increase of zinc retention in kidney of 10.0 mg/kg cadmium additional group (p<0.05) and zinc concentrations in lymphaden, pancreas and heart of 10.0 mg/kg cadmium treatment were lower than those of the control (p<0.05). This study indicated that relatively high cadmium level (10.0 mg/kg) could decrease pig growth performance and change the retention of iron, copper and zinc in most tissues during extended cadmium exposure period. (Asian-Aust. J. Anim. Sci. 2004. Vol 17, No. 7 : 1007-1013)

Hormesis and stage specific toxicity induced by cadmium in an insect model, the queen blowfly, Phormia regina Meig.

Hormesis is an adaptive response, commonly characterized by a biphasic dose–response that can be either directly induced, or the result of compensatory biological processes following an initial disruption in homeostasis [Calabrese and Baldwin, Hum. Exp. Toxicol., 21 (2002), 91]. Low and environmentally relevant levels of dietary cadmium significantly enhanced the pupation rate of blowfly larvae, while higher doses inhibited pupation success. However, dietary cadmium at all exposure levels adversely affected the emergence of the adult fly from the pupal case. Such findings represent the first report of a heavy metal displaying a hormetic-like biphasic response for pupation success, while at the same time displaying stage-specific toxicity at a later developmental period. These conclusions are based on substantial experimentation of over 1750 blowflies, in seven replicate experiments, involving 10 concentrations per experiment. These findings indicate the need to assess the impact of environmental stressors over a broad range of potential exposures as well as throughout the entire life cycle.

Increased metallothionein in mouse liver, kidneys, and duodenum during lactation.

Lactation-induced increases in cadmium absorption and retention have been demonstrated in mid-lactating mice, but no systematic measurements of endogenous metal-binding protein concentrations during lactation have been reported. Using Cd/hemoglobin radioassay, this study detected significant increases in metallothionein (MT) concentrations in liver (4-fold), kidneys (2-fold), and duodenum (2-fold), but not jejunum, of mouse dams on days 13 and 20 of lactation. These increases occurred in the absence of cadmium exposure and were specific to the lactation period; dams 5 days after weaning showed MT levels that were similar to those of nonpregnant (NP) mice. Similarly, Northern blot analyses of livers from lactating mice demonstrated that MT mRNA concentrations in maternal liver during mid-lactation were 6-fold higher than those observed 5 days after pups were weaned. Gel filtration of final supernatants from the Cd/hemoglobin assay confirmed that the Cd-binding molecule induced during lactation was indeed metallothionein. In addition, chromatographic analyses of cytosols from tissues taken from dams administered small amounts of Cd (66 ng/mouse) showed that the trace amounts of Cd absorbed through the maternal gastrointestinal tract during mid-lactation were also bound to the MT. These results indicate MT induction in mouse dams occurs as a physiological consequence of lactation, requiring no external stimulus. This induced MT participates in binding low levels of dietary cadmium consumed by the dam. During lactation, elevated maternal MT may affect pathways for essential trace metals as well as sequester toxic metals harmful to the neonate. Multiparous humans may have increased risk of accumulating environmental Cd.

Dietary cadmium decreases lipid peroxidation in the liver and kidneys of the bank vole ( Clethrionomys glareolus)

The effect of elevated levels of dietary cadmium on lipid peroxidation in the liver and kidneys of a small rodent, the bank vole, was determined in the present study. Males and females, aged 1 month, were given diets containing 0.40 and 80 mg Cd per kg; liver and kidneys were removed for TBA-RS as well as iron, copper, zinc, cadmium and metallothionein analyses at the end of 6 weeks. Dietary Cd significantly decreased the TBA-RS level in the liver and kidneys of both sexes; however, this effect appeared to be dose-dependent only for the male liver. The changes in hepatic and renal TBA-RS paralleled closely those of tissue iron. Copper concentration decreased significantly only in the male liver, while hepatic and renal zinc were not influenced by dietary Cd. The concentrations of Cd and metallothionein in the liver and kidneys increased significantly in a dose-dependent fashion. Regression analysis confirmed that TBA-RS in both organs correlated closely with iron. The data suggest that dietary Cd decreases hepatic and renal lipid peroxidation indirectly, through lowering the tissue iron concentration.

Effect of dietary phytic acid and cadmium on the availability of cadmium, zinc, copper, iron, and manganese to rats.

The main route of cadmium intake for general population, both human and animal, is via ingestion. The intestinal absorption of cadmium is relatively low, 6% of a single oral dose for humans and less than 2% for various animal species. However, due to poor excretion, accumulation of cadmium occurs, primarily in kidney. The chronic exposure even to low levels of dietary cadmium can lead to the development of renal disturbances. Fox (1988) suggests that phytic acid might be a dietary component capable to influence the intestinal absorption of cadmium. Phytic acid naturally occurs as the major phosphorus storage constituent of most cereals, legumes, and oilseeds. At physiological pH, phytic acid is ionized and has a strong affinity for divalent cations. The potential of phytic acid to decrease the availability of Zn has been for long time of concern for nutritionists. Phytic acid has also been reported to decrease the availability of other trace metals. For nonessential elements, reduced availability of lead has been observed. The experimental data concerning the effect of dietary phytic acid on the availability of dietary cadmium are limited to the work of Rose and Quarterman (1984). The objective of this experiment was to examine: (1) themore » effect of dietary phytic acid on the availability of cadmium under conditions of chronic dietary exposure of rats to cadmium, and (2) the effect of dietary phytic acid and of chronic dietary exposure to cadmium on the availability of zinc, copper, iron, and manganese to rats. 19 refs., 4 tabs.« less

The effect of cadmium on iron metabolism in rats

The effect of various dietary cadmium levels on iron metabolism in growing male Wistar rats was studied in a 6-week experiment. The diets contained 0, 6, 11 and 24 μg Cd/g diet and equal iron concentrations (approx. 33 μg/g). The increase in dietary cadmium from 6 to 24 μg/g resulted in its higher concentration in liver, kidney and duodenum. The highest level of cadmium in the diet decreased significantly diet consumption. All cadmium doses caused inhibition in rat growth, decrease in liver weight and ceruloplasmin concentration in plasma. Hematocrit, liver and duodenum iron concentrations were statistically lower in all cadmium-treated groups, while the transferrin concentration in plasma was higher and the saturation of transferrin with iron was markedly lower when compared to the control group. Two higher doses of cadmium (11 and 24 μg/g) caused a marked reduction of the apparent absorption of iron, hemoglobin concentration as well as iron storage in kidney.

Effects of different dietary levels of cadmium, lead, copper, and zinc on the vitality of the forest pest insect Lymantria dispar L. (Lymantriidae, Lepid)

Lymantria dispar (gypsy moth) larvae were reared on both a natural diet of oak leaves and an artificial medium contaminated independently with four different metal nitrates. Larvae were contaminated up to pupation either from 1st or 4th instars at four concentrations differing by a factor of 5. The lowest concentration levels were 2 μg/g Cd, 4 μg/g Pb, 10 μg/g Cu, and 100 μg/g Zn based on nutrient medium dry weight. Developmental rate, growth, mortality and reproductive success were determined. No-Observed-Effect-Concentrations (NOECs) calculated were dependent on the metal, the parameter investigated and the stage at which exposure commenced. In general, larvae exposed from the 4th instar were less susceptible to metal toxification than those exposed from hatching. Considering all parameters investigated, dietary NOECs were determined to be 2 μg/g Cd, 4 μg/g Pb, 10 μg/g Cu, and 100 μg/g Zn.

Effect of ambient and dietary cadmium on pavement cells, chloride cells, and Na +/K +-ATPase activity in the gills of the freshwater teleost Oreochromis mossambicus at normal and high calcium levels in the ambient water

The effects of cadmium on the gills of the African freshwater cichlid Oreochromis mossambicus in water with normal and relatively high calcium concentrations were studied for periods up to 35 days. The exposure was either through the ambient water or via the diet. Changes in the ultrastructure of the gill epithelium upon exposure to cadmium in the ambient water indicated degeneration of pavement cells and chloride cells, and acceleration in the turnover of the chloride cells. Studies of the Na +/K +-ATPase activity of the gills indicated that a transient increase in the total number of chloride cells was not associated with an increase, but rather a decrease of the total ion-exchange capacity of the chloride cells. Macrophages, lymphocytes, rodlet cells and neutrophilic granulocytes infiltrated the filament epithelium. Recovery of the gills was observed after 35 days. Dietary cadmium caused similar, although delayed, effects. High water calcium concentration reduced the impact of water-borne cadmium, but had no ameliorating effect on dietary cadmium. The data indicate that the disturbance of ion regulation in fish caused by sublethal levels of dietary cadmium is the result of effects of the metals on the gills rather than on the kidney.

The effect of dietary cadmium intake on the growth performance and retention of cadmium in growing pigs

Thirty-five pigs were randomly allocated at 8 kg liveweight to seven dietary treatments consisting of no supplemental cadmium, either 0.44, 0.89, 2.21 or 4.43 mg Cd kg −1 supplied in the form of Cd Cl 2, 2 1/2 H 2O or either 0.60 or 1.20 mg Cd kg −1 supplied by rock phosphate. Pigs were fed protein-adequate diets on a restricted basis and were slaughtered at 90 kg liveweight. The growth rate and feed efficiency of pigs between 8 and 90 kg liveweight were unaffected by dietary cadmium level. Samples of meat, fat, liver, kidney, hair and blood collected at slaughter were analysed for cadmium and expressed on a wet tissue basis. Cadmium could not be detected in meat and fat samples (<0.3 mg Cd kg −1) or in blood samples (<0.002 mg Cd kg −1) from any pigs irrespective of dietary treatment. However, cadmium levels in both kidney and liver increased in a linear manner as dietary cadmium content increased, irrespective of the source of cadmium. Cadmium accumulated at much higher concentrations in the kidney than in the liver. The relationship between cadmium in the diet ( X mg kg −1) and cadmium in kidney ( Y mg kg −1) was described by the regression equation Y = 2.73 X−0.03; R 2 = 0.93, P < 0.01.

Comparison of the toxicity of inorganic and liver-incorporated cadmium: A 4-wk feeding study in rats

The toxicity of cadmium was examined in rats fed diets containing either tissue-incorporated cadmium or cadmium salt for 4 wk. The test diets contained 30 mg cadmium/kg either as cadmium chloride, or as cadmium incorporated in pigs' livers; the control group was fed a diet containing liver from a pig not treated with cadmium. Over 90% of the cadmium present in the pigs' livers was bound to metallothionein. Analysis of the diet and determination of the food consumption revealed that both cadmium-fed groups were exposed to similar dietary cadmium levels. There was no adverse effect on general health or survival. Feeding cadmium resulted in growth retardation and slightly decreased water intake. Moreover, both cadmium-treated groups showed clear signs of anaemia and increased plasma aspartate and alanine aminotransferase activities. For the group fed cadmium chloride, all of these effects were more pronounced than for the group fed cadmium incorporated in liver. Microscopic examination of the liver and kidneys, however, did not reveal any lesion that could be attributed to the cadmium treatment. After exposure to cadmium the spleen showed decreased extramedullary haematopoiesis, an effect that was also more pronounced after feeding of the cadmium chloride than after feeding liver-incorporated cadmium. The differences in the extent of the toxic effects between the inorganic and the tissue-incorporated cadmium were accompanied by differences in the cadmium concentrations in liver and kidneys: the feeding of cadmium incorporated in pigs' livers resulted in about half the accumulation of cadmium in the rats' livers that took place after intake of a diet containing cadmium chloride. In contrast a much less marked difference in cadmium accumulation was observed in the kidneys. Since humans are usually exposed to tissue-incorporated cadmium these findings deserve further investigation, with special attention to the observed difference in tissue accumulation.