Soft-tissue accumulation of lead in the blue tilapia,Oreochromis aureus (steindachner), and the modifying effects of cadmium and mercury

The interaction of mercury and cadmium with lead was investigated by exposingOreochromis aureus to two heavy metals simulataneously. The chronic accumulation prolife of lead was determined by analyzing the liver, brain, gill filaments, intestine, caudal muscle, spleen, trunk kidney, and gonads following exposure to lead alone and in mixtures with mercury and cadmium. Nominal exposure concentrations of lead were 0.05, 0.10, 0.50, and 1.00 mg/L. Mixtures of lead (0.50 or 0.05 mg/L) with cadmium (0.05 mg/L) and lead (0.50 or 0.05 mg/L) with mercury (0.05 mg/L) were also used. Following 140 d of exposure to lead, the highest concentrations of lead consistently accumulated in the trunk kidney. The concentration of lead in the kidney was decreased by coexposure to mercury or cadmium, but increased in the muscle and liver. Under all exposure regimes, the median concentration of lead in the muscle exceeded safety levels recommended for human consumption. In a food fish, such asO. aureus, a knowledge of toxic metal accumulation patterns is of great importance.     

Multielemental assay of autopsy tissues of smeltery and refinery workers pertinent to possible health effects

A multielemental assay (i.e., of 23 elements) in kidney, liver, and lung tissue of autopsy specimens from deceased workers in a smeltery and refinery in North Sweden, as well as from a control group, is discussed in the light of possible health effects. The following topics have been surveyed: Brief history of the occupational exposure conditions; nuclear and other techniques used as tools in the multielemental assay; accumulation of the various elements in kidney, liver, and lung; estimation of retention times—long retention times were observed for antimony, arsenic, cadmium, chromium, cobalt, lanthanum, lead, or selenium in certain tissues, especially pronounced in the lung tissue; elevated levels of antimony, arsenic, cadmium, lead, and lanthanum in lung tissue of exposed workers—a contribution to a multifactorial cause behind the excess mortality from lung cancer of the smeltery and refinery workers; and the protective effect of selenium on lung cancer of exposed workers.     

Cadmium, copper and zinc in tissues of deceased copper smelter workers

Workers at a copper and lead smelter in northern Sweden have a multifactorial exposure to a number of heavy metals. The concentrations of cadmium, copper and zinc in liver, lung, kidney and brain tissues have been determined by atomic absorption spectrometry in 32 deceased long-term exposed male lead smelter workers, and compared with those of 10 male controls. Furthermore, copper and zinc levels in hair and nails were determined by energy-dispersive X-ray fluorescence.

The highest cadmium concentrations among both workers and controls were observed in kidney, followed in order by liver, lung and brain. The levels in kidney, liver and lung were all significantly higher in the workers than in the controls (p < 0.03). Among the workers relatively strong positive correlations (p < 0.03) were observed between cadmium concentrations in liver and lung, liver and kidney, liver and brain, and lung and brain. In the exposed workers a positive correlation was observed between cadmium and zinc concentrations in the kidney (r_s = 0.38; p = 0.034). This is probably mainly due to the protein metallothionein, which is stored in the kidney, binding equimolar amounts of these two metals.

The highest concentrations of copper were found in hair and nails among both workers and controls, followed in order by liver, brain, kidney and lung. The tissue concentrations of copper in brain, lung and kidney were all significantly higher among the smelter workers than in the controls (p ≤ 0.036). Copper levels in lung and age at time of death were positively correlated among the exposed workers (r_s = 0.39; p = 0.029). In the same group, positive correlations between copper and zinc concentrations in kidney (r_s = 0.45; p = 0.009) and nails (r_s = 0.68; p < 0.001) were also observed, reflecting possible biological interactions between these two metals.

Among both workers and controls, the highest zinc concentrations were found in hair, followed in order by nails, liver, kidney, brain and lung. Significantly higher tissue concentrations among the workers as compared with the reference group were noted in kidney, liver and brain (p ≤ 0.033).

Neither copper nor zinc concentrations in hair and nails seemed to provide a useful measure of the trace element status of the smelter workers.     

Alterations in plasma sodium and potassium levels following chronic oral ingestion of lead, mercury and cadmium in male albino rats.

Adult male albino rats were orally administered 0, 25, 50 and 100 ppm of lead nitrate, mercuric chloride and cadmium chloride for 60, 120 and 180 days. The plasma sodium levels were decreased in rats exposed to varying doses of lead and mercury up to 180 days, while animals which consumed cadmium chloride showed an increase in sodium levels. In lead and mercury treated animals, plasma potassium levels were increased up to 180 days. The levels were decreased in cadmium exposed rats. These observations suggest that chronic exposure to these heavy metals considerably influences plasma sodium and potassium levels depending on the dose and duration of exposure.     

Body Fat Percentage and Hemoglobin Levels Are Related to Blood Lead, Cadmium, and Mercury Concentrations in a Korean Adult Population (KNHANES 2008–2010)

Body stores of lead, cadmium, and mercury are determined by the levels in the circulation, and their levels in blood may be related to hemoglobin levels and their absorption by soft tissue and bone. We investigated the association of body fat percentage, hemoglobin levels, and nutrient intakes with the blood concentrations of lead, cadmium, and mercury in a Korean adult population. This study was based on data from the 2008–2010 Korean National Health and Nutritional Examination Survey (n?=?4,522, aged ≥20 years), which examined nutritional, biochemical, and health-related parameters. A multiple regression analysis after controlling for covariates of age, body mass index, residence area, education level, smoking and drinking status, and bone mineral density for men, with menopausal status added for women in addition to covariates for men indicated that blood lead and mercury levels were negatively associated with body fat percentage only in men, and blood lead, cadmium, and mercury levels were positively related to hemoglobin levels in both genders. Additionally, blood lead levels were negatively associated with fat and carbohydrate intake in both men and women but blood mercury levels were only in men, but not women. Sodium intake was a positive predictor of blood lead levels in both genders but was a positive predictor of blood cadmium levels only in men. In conclusion, body fat percentage and hemoglobin levels need to be recognized as confounding factors when considering blood levels of lead, cadmium and mercury as biomarkers for their exposure. Fat, carbohydrates and sodium intakes are also associated with heavy metal levels in the circulation.     

Zinc,cadmium, mercury and selenium in minke whales,belugas and narwhals from West Greenland

Summary Samples of muscle, liver and kidney from 24 minke whales (Balaenoptera acutorostrata), 43 belugas (Delphinapterus leucas), and 98 narwhals (Monodon monoceros) were analyzed for zinc, cadmium, mercury, and selenium. Highly significant age accumulation of mercury was found. A lower level of significance of age accumulation of cadmium in belugas and narwhals is probably due to the fact that some of the highest cadmium concentrations are in subadults and young adults. The maximum concentrations of cadmium and mercury are very high: 1.68, 73.7, and 125 g cadmium, and 9.88, 42.8, and 4.61 g mercury per g wet weight of narwhal muscle, liver and kidney, respectively. The cadmium concentrations are correlated in the three organs, as are mercury and to a lesser extent selenium concentrations. The concentrations of mercury and selenium in liver are highly correlated.     

In vivo neutron activation analysis of organ cadmium burdens

In vivo neutron activation measurements of liver and kidney cadmium have been mae in 77 exposed workers and 101 referents. Cadmium levels were higher in exposed workers than in referents; both in liver, 25.7 cf. 0.6 μg/g, and kidney, 17.9 cf. 2.7 mg. The 19 referents who never smoked had lower mean organ cadmium burdens than the other referents, the difference achieving statistical significance in the kidney,p<.01. Cigaret smoking was estimated to increase cadmium body burden by 370-140 μg/pack year. These referent cadmium levels are similar to, although slightly below, previous in vivo and autopsy data.

     

Comparative distributions of zinc, cadmium and mercury in the tissues of experimental mice

Different groups of mice were injected with cadmium, zinc and mercury. Zinc injections had no effect on zinc tissue levels while both mercury and cadmium accumulated in various tissues. Cadmium persisted in the tissues much longer than mercury, and while the mercury concentrations began to decline as soon as dosing ceased, cadmium concentrations in kidney and intestine increased even after dosing ceased. There appeared to be an interrelationship between cadmium concentrations in spleen and intestine which warrants some further investigations. There was a linear, but discontinuous, effect of cadmium on zinc concentrations in liver, kidney and pancreas which may depend on metallothionein biochemistry. Mercury injections had no effect on zinc metabolism. It is proposed that differences in the rate of excretion of cadmium and mercury from the kidney could explain the differential accumulation of cadmium and mercury in animals.     

Comparison of hair, nails and urine for biological monitoring of low level inorganic mercury exposure in dental workers.

Creatinine-corrected urine mercury measurements in spot urine samples are routinely used in monitoring workers exposed to inorganic mercury. However, mercury measurement in other non-invasive biological material has been used in some epidemiological studies. Dentists and dental nurses remain a group of workers with potential exposure to inorganic mercury through their handling of mercury-containing amalgam, although changes in work practices have reduced the current, likely exposure to mercury. Therefore, dental workers remain an occupational cohort in whom the value of using different biological media to identify exposure to low level inorganic mercury can be investigated. Samples of head hair, pubic hair, fingernails, toenails and urine were analysed for mercury content from a cohort of UK dentists (n=167) and a socioeconomically similar reference population (n=68) in whom any mercury exposure was primarily through diet. The mercury content in all biological material was significantly higher in the dental workers than in the control population (p<0.0001). The geometric mean and 90th percentile mercury concentrations in the urine samples from dentists were 1.7 and 7.3 micromol mol(-1) creatinine, respectively, with only one sample having a value at around the UK's Health and Safety Executive biological monitoring health guidance level of 20 micromol mol(-1) creatinine. Receiver operator characteristic analyses suggested that the ability of the biological material to discriminate between dentists and referents were fingernails>urine approximately equal to toenails>pubic hair approximately equal to head hair. Further investigation is warranted as to why fingernails appear to be such a good discriminator, possibly reflecting some contribution of direct finger contact with amalgam or contaminated surfaces rather than systemic incorporation of mercury into growing nails. Good correlation between head hair and pubic hair mercury levels in all subjects was obtained (r=0.832), which was significantly improved when hair samples weighing <10 mg were excluded (r=0.868). Therefore, under these exposure conditions and using the described pre-analytical washing steps, there is little influence from atmospheric contamination on the level of mercury content of head hair. The choice of non-invasive biological materials for mercury analysis depends on a number of considerations. These include the toxicokinetics of urinary mercury excretion, the growth rates of hair and nail, the nature and time-frame of exposure, and the fact that urine mercury may not reflect the body burden level from dietary methyl mercury. However, the data from this study suggests that urine mercury remains the most practical and sensitive means of monitoring low level occupational exposure to inorganic mercury.     

Association between urinary indicators of renal dysfunction and metal concentrations in workers chronically co-exposed to cadmium,zinc and lead

The study was carried out in 31 workers co-exposed to cadmium, lead and zinc fumes and dusts in a zinc ore refinery. Urinary cadmium, lead, zinc, β₂-M levels and NAG activities were determined to evaluate the possible dose-effect relationship between these parameters. A correlation was found between urinary cadmium, lead and zinc concentrations, and urinary β₂-M levels and NAG activities of the exposed group. A statistically significant increase was also observed for urinary NAG activity in exposed workers who had urinary cadmium concentrations > 2 μg g^?1 creatinine. However, in the same exposed group, the increment of β₂-M was not statistically significant. In conclusion, the present study thus confirms the earlier observations and may suggest the notion that the urinary NAG seems to be a more sensitive indicator than urinary β₂-M level in early stages of renal injury of moderately cadmium co-exposure with lead and zinc even at urinary cadmium concentration as low as 2 μg g^?1 creatinine. When the earlier studies on the irreversibility of cadmium-induced tubular dysfunction and the present results were taken into consideration, the present health-based biological limit proposed by the WHO (5 μg g^?1 creatinine) seems to be high for the occupational exposure to cadmium.     

Cytogenetic investigations on leucocytes of workers from a cadmium plant.

Chromosome analysis has been performed on workers from a cadmium plant who were exposed to fumes and dust of cadmium and lead. The 35 workers were classified, according to the type and duration of exposure, into a group (cadmium service) exposed to high levels of lead and cadmium in the absence of zinc (23 people) and a group of rolling-mill workers subjected mostly to zinc but also to lower levels of lead and cadmium (12 people). A higher yield of severe chromosome anomalies (chromatid exchange, disturbance of spiralization, chromosome translocation, ring and dicentric chromosomes) together with a total lower number of structural aberrations was observed in the cadmium workers when compared with the rolling-mill group.     

Cadmium-induced alterations in essential trace element homoeostasis in the tissues of scallop Mizuhopecten yessoensis

Studies were performed regarding the effect of cadmium accumulation on the levels of essential elements (copper, zinc and iron) in the tissues of a marine bivalve mollusc, Mizuhopecten yessoensis, exposed to cadmium at 250 ppb during 2 weeks. It was found that the concentration of cadmium in the tissues increased in the order gonads < gills < hepatopancreas < kidney during exposure time. However, the highest value of concentration factor was recorded in the gills. Our data demonstrate that cadmium accumulation in all mollusc tissues is followed by the alterations in copper, zinc and iron concentration, but that the pattern of these changes varies with each tissue. Cadmium had the most pronounced effects on essential trace element homoeostasis in the kidney. The present study suggests that levels of the essential metals in a particular tissue can be modified depending on the level of cadmium accumulation. The possible mechanisms of the effects of cadmium on the essential trace elements are discussed.     

Accumulation profiles of lead and cadmium in the edible tissues of Oreochromis aureus during acute exposure

Acute exposure of Oreochromis aureus to cadmium or lead resulted in different tissue accumulation profiles. Trunk kidney accumulated the highest lead concentrations of all tissues analysed after 24-h or 1-week exposure to 0.1 mg l^–1 lead as PbCl₂ while exposure to 0.1 mg l ^–1 cadmium as CdCl₂ for 24 h or 1 week resulted in the highest accumulations of cadmium in the intestine. Caudal muscle consistently accumulated the lowest levels of lead or cadmium after a 1-week exposure period.     

Mercury concentrations in hair exposed in vitro to mercury vapor

Hair is often used as an index of environmental and industrial exposure to different metals. The interpretation of metal levels in hair is difficult because of the risk of external contamination. The aim of this study was to define the degree of external contamination of hair exposed in vitro to mercury vapor. Specimens of hair were exposed to concentration: 0.026, 0.21, and 2.7 mg Hg/m³ for 2–28 d. Mercury levels in hair increased during 28 d of exposure 2, 3 and 13, times, respectively, when compared to initial values. Mercury levels in hair exposed to the first and second (but not third) concentration of mercury vapor attained a steady state on the 21st d of exposure. The contamination of hair with mercury could not be removed by washing with water, solvent, and detergent. Hair may be used as an index of internal uptake of mercury provided that it was not externally exposed to mercury vapor. In cases of occupational exposure to mercury vapor, hair could become a useful tool for monitoring exposures.     

Cadmium accumulation and interactions with zinc, copper, and manganese, analysed by ICP-MS in a long-term Caco-2 TC7 cell model

The influence of long-term exposure to cadmium (Cd) on essential minerals was investigated using a Caco-2 TC7 cells and a multi-analytical tool: microwave digestion and inductively coupled plasma mass spectrometry. Intracellular levels, effects on cadmium accumulation, distribution, and reference concentration ranges of the following elements were determined: Na, Mg, Ca, Cr, Fe, Mn, Co, Ni, Cu, Zn, Mo, and Cd. Results showed that Caco-2 TC7 cells incubated long-term with cadmium concentrations ranging from 0 to 10 μmol Cd/l for 5 weeks exhibited a significant increase in cadmium accumulation. Furthermore, this accumulation was more marked in cells exposed long-term to cadmium compared with controls, and that this exposure resulted in a significant accumulation of copper and zinc but not of the other elements measured. Interactions of Cd with three elements: zinc, copper, and manganese were particularly studied. Exposed to 30 μmol/l of the element, manganese showed the highest inhibition and copper the lowest on cadmium intracellular accumulation but Zn, Cu, and Mn behave differently in terms of their mutual competition with Cd. Indeed, increasing cadmium in the culture medium resulted in a gradual and significant increase in the accumulation of zinc. There was a significant decrease in manganese from 5 μmol Cd/l exposure, and no variation was observed with copper.     

Antioxidant enzyme activity and lipid peroxidation in liver of female rats co-exposed to lead and cadmium: Effects of vitamin E and Mn2+

The oxidative status of liver of female rats exposed to lead acetate and cadmium acetate either alone or in combination at a dose of 0.05?mg/kg body wt intraperitoneally for 15 days was studied. After the administration of lead alone, the activity of superoxide dismutase (SOD) decreased in liver, whereas no changes were observed in catalase (CAT) activity, and glutathione (GSH) and thiobarbituric acid (TBARS) levels. Cadmium exposure and combined exposure to lead and cadmium led to decrease in GSH content and increased TBARS levels. Moreover, animals exposed to either cadmium alone or in combination with lead showed a decrease in SOD activity and an increase in CAT activity. The in vitro experiments showed that vitamin E failed to restore the antioxidant enzyme activities in metal treated postmitochondrial supernatant fraction of liver. But Mn²⁺ ions protected the mitochondria from lipid peroxidation and could completely restore Mn-superoxide dismutase (Mn-SOD) activity following metal intoxication. The results of this study indicate that despite the ability of lead and cadmium to induce oxidative stress the effect in liver is not intensified by combined exposure to both lead and cadmium. The observed changes in various oxidative stress parameters in the liver of rats co-exposed to lead and cadmium may result from an independent effect of lead and /cadmium and also from their interaction such as changes in metal accumulation and content of essential elements like Cu, Zn and Fe. These results suggest that when lead and cadmium are present together in similar concentrations, cadmium mediates major effects due to its more reactive nature.     

Heavy metal concentrations in the breast milk of Saudi women

Lead, cadmium, and mercury concentrations were determined in breast milk of Saudi lactating mothers from Riyadh and Al-Ehssa regions in Saudi Arabia who were not occupationally exposed. The mean levels for cadmium, lead, and mercury were 1.732 μg/L, 31.671 μg/L, and 3.100 μg/L, respectively. In contrast to mercury, mothers living in the Al-Ehssa region had significantly higher cadmium and lead concentrations in their breast milk than those in the Riyadh region. The estimated weekly intakes of cadmium, lead, and mercury of breast-fed infants in this study were in some cases higher than the Provisional Tolerance Weekly Intake (PTWI) recommended by FAO/WHO, which pose a threat to their health. This necessitates the urgent need to undertake a comprehensive study to determine the sources of exposure to these heavy metals. Breast-feeding is of great benefical value for the infant’s development; therefore, efforts should be made to prevent its contamination with environmental pollutants.     

Comparative and interactive effects of mercury, cadmium and lead on tissue GSH levels in Oreochromis aureus (Steindachner): implications for monitoring heavy metal pollution

The effects of 45 days exposure to mercury, cadmium and lead on tissue GSH levels were studied in Oreochromis aureus (Steindachner). Liver, brain, gill filaments, intestine and caudal muscle were assayed after exposure to these heavy metals singly, or in combination. Significant increases in intestinal GSH concentrations consistently occurred after exposure to mixtures of heavy metals. Exposure to cadmium or lead did not change hepatic GSH levels, while exposure to two different concentrations of mercury caused significant increases in hepatic GSH.     

Effects of Lead and/or Cadmium on the Oxidative Damage of Rat Kidney Cortex Mitochondria

Lead acetate (300 mg/L) and/or cadmium chloride (50 mg/L) were administered as drinking water to Sprague–Dawley rats for 8 weeks to investigate the possible combined effects of these metals on the damage in renal cortex mitochondria. Increased malonaldehyde levels due to exposure to these metals were detected by colorimetric method, which demonstrated the lipid peroxidation in the renal cortex. Ultrastructural observations and real-time quantitative PCR analyses were performed on kidney cortex pieces to identify the mitochondrial damage and quantify the relative expression levels of cytochrome oxidase subunits (COX-I/II/III), respectively. The most striking ultrastructural modifications involved distortion of mitochondrial cristae and an unusual arrangement, which were more evident when the mixture was ingested. There were significant differences in the expression levels of COX-I, II, and III between the control group and the exposed groups, whereas those in the (lead+cadmium) group were all significantly lower than that in the lead or cadmium group. In conclusion, there was an obvious synergistic oxidative damage effect of lead combined with cadmium on rat kidney cortex mitochondria, which increased defects in mitochondrial oxidative metabolism.