Cadmium in kidneys in Swedes measured in vivo using X-ray fluorescence analysis

An X-ray fluorescence (XRF) technique using plane polarized X-rays for excitation was used for in vivo measurements of cadmium in the kidney cortex among non-occupationally exposed members of the general population in southern Sweden. The measured concentrations of cadmium in the kidney cortex of smokers (median 28 g/g, n = 10) were significantly higher (P = 0.0036) as compared to those in non-smokers (median 8 g/g, n = 10), and so were the cadmium concentrations in blood and urine. The results show that smoking considerably increases the cadmium concentration in the kidney cortex and that smoking is a major source of cadmium exposure in the general population of Sweden. Except in the presence of very deeply situated kidneys, where the minimum detectable concentration is high, non-invasive in vivo XRF analysis of kidney cadmium should be a useful tool for evaluating the effects of long-term low-level exposure to cadmium and the risk of kidney damage.     

Transfer of cadmium in a phytoplankton-oyster-mouse food chain

The trophic transfer of cadmium (Cd) was studied in a phytoplankton-oyster-mouse food chain. Phytoplankton, grown in a continuous culture chemostat system containing CdCl₂ plus the isotope¹⁰⁹Cd, accumulated 70% of the total supplied cadmium. Oysters filtered out 85 to 95% of the phytoplankton. The rate of oyster Cd accumulation at 15 C increased linearly with seawater Cd concentration according to: y=0.066X – 0.15 (n =12, r=0.96); where X=g Cd/L seawater (between 2 and 22) and y=g Cd/g dry wt oyster/ day. About 59% of the Cd accumulated by the oysters came from the phytoplankton food source and 41% from the cadmium dissolved in the water. Sixty-one percent of the total supplied cadmium was retained in the whole soft body of the osyters. Mice fed 0.4 g of oyster-bound Cd per g of diet, retained 0.83% of the dietary cadmium consumed. Mouse kidney retention for organic oyster-bound cadmium was 0.14%. Extrapolation of these results to human risk assessment indicates that moderate consumption of oysters, which are not highly contaminated with cadmium, poses no significant health risk in terms of elevating kidney cadmium levels.     

Hazardous exposure of ground-living small mammals to cadmium and lead in contaminated terrestrial ecosystems

The dietary exposure to cadmium and lead of two ground-living species of small mammals,i.e., shrewsSorex araneus (Insectivora) and volesMicrotus agrestis (Rodentia), was investigated and related to metal loads in target organs (kidneys and liver). The study was done in two natural areas polluted with cadmium and lead originating from urban and industrial metal sources. The average intake of cadmium by the herbivorous voles varied between 0.1 and 0.4 g/g/day and of lead between 2 and 10 g/g/day. The carnivorous shrews showed a considerably higher metal intake rates,i.e., cadmium 3 to 16 g/g/day and lead 19 to 53 g/g/day, which was largely due to the consumption of contaminated earthworms (Oligochaeta). An average cadmium intake of 15 g/g/day or a lead intake of 20 g/g/day corresponded with critical renal metal loads of 120 g/g for cadmium and 25 g/g for lead, which are indicative of adverse health effects. The renal metal loads in shrews reached the critical level, but they remained far below this level in voles. The results indicate a greater risk of toxic exposure to cadmium and lead in soricine shrews than in microtine rodents.     

Effects of maternal exposure to zinc and cadmium on metallothionein in fetal rat liver

Experiments were made to observe the effects of the maternal administration of cadmium and zinc and their influence on the metal-binding capacity of metallothionein in the rat fetus. Metallothionein was detected in the fetal liver as early as day 16 of gestation and may have appeared earlier. The zinc concentration in the metallothionein fraction was low on day 16 but increased as gestation progressed. The metal-binding capacity was fairly high on day 16 but increased at a slower rate than the zinc concentration. Following the intraperitoneal administration of zinc (100 moles Zn/kg) or cadmium (5 moles Cd/kg) once a day on days 14, 15 and 16 of gestation to the dam, the concentration of zinc in the metallothionein fraction of the maternal liver was far greater than that in the fetal liver. In contrast, cadmium was found only in the metallothionein fraction of the maternal liver; it was not found in the fetal liver, which suggests an effective placental barrier to cadmium. The metalbinding capacity in the fetal liver was induced by the maternal administration of zinc, but not cadmium.     

Severe damage of cultured vascular endothelial cell monolayer after simultaneous exposure to cadmium and lead

This study evaluates the toxicity of lead in the presence or absence of cadmium on the maintenance of a monolayer of cultured bovine aortic endothelial cells. It was histologically shown that lead at 50 M or less induced a slight formation of de-endothelialized areas on the monolayer after a 24-h incubation. Although lead accumulated in endothelial cells in a dose-dependent manner, the cytotoxicity (evaluated by the [³H]adenine release assay) was not detected. However, cadmium (1.0 or 2.0 M)-induced de-endothelialized areas on the monolayer was considerably larger in the presence of lead at 10 M; the cytotoxicity of cadmium was significantly enhanced by lead. It was concluded that vascular endothelial cell monolayer is severely destroyed by a greater cytotoxicity of combination of cadmium with lead.     

Internal lead and cadmium exposure in 6-year-old children from western and eastern Germany

Lead and cadmium levels in blood and deciduous teeth (shed incisors only) of 6-year-old German children were determined in 1991 in a large epidemiological study carried out in rural and urban areas of western Germany (Duisburg, Essen, Gelsenkirchen, Dortmund, Borken) and eastern Germany (Leipzig, Halle, Magdeburg, Osterburg, Gardelegen, Salzwedel). In total, blood lead and cadmium levels of 2311 German children and tooth lead and cadmium levels of 790 German children were analyzed. Blood lead levels were generally low in all study areas with geometric means between 39.3 g/1 and 50.8 g/l in the western German and between 42.3 g/1 and 68.1 g/l in the eastern German study areas. The mean blood lead level of Turkish children (n = 213) living in the western German study areas was 50.1 g/l and thus 5.6 g/1 higher than the overall geometric mean of the western German children. The higher exposure may be explained by a higher oral uptake from food and different living conditions. These children were excluded from multiple regression analysis because they were all living in the western study areas. The mean tooth lead levels ranged between 1.50 and 1.74 g/g in the western and between 1.51 g/g and 2.72 g/g in the eastern study areas. Thus, they show a distribution pattern similar to blood. Blood and tooth lead levels were higher in urban than in rural areas and higher in the eastern German than in the western German study areas. With regard to the blood and tooth cadmium concentrations, no significant differences between the study areas could be found. The mean cadmium levels in blood ranged between 0.12 g/1 and 0.14 g/l and the mean tooth cadmium concentrations between 20.8 ng/g and 27.8 ng/g. Blood and tooth lead and cadmium levels of the eastern and western German children were thus mainly at a relatively low level in all rural and urban study areas. The study demonstrates and confirms that blood and tooth lead levels are influenced by several demographic, social, and environmental variables. The results indicate that there has been a further significant decrease of lead and cadmium exposure in western German children since our last epidemiological study carried out in the same study areas in 1985/1986.     

Mercury concentrations in hair from populations in Wau-Bulolo area, Papua New Guinea

Total mercury (Hg) concentrations were determined in scalp hair from the populations in the Wau-Bulolo area, eastern Papua New Guinea (PNG), where humans are exposed to large quantities of Hg through gold-mining activities by Hg amalgamation processes. Humans living upstream and not engaged in gold mining had a mean hair Hg concentration of 0.55 g g^–1 (range: 0.19–1.1 g g^–1) (n=80), which was recognized as the background level in this area. In contrast, the populations involved in gold-mining activities had a significantly higher level of hair Hg (mean: 1.2 g g^–1, range: 0.39–3.0 g g^–1) (n=86) than the background level, indicating direct or indirect exposure to Hg from gold mining. The hair Hg level in populations downstream of the gold-mining area was significantly higher than the background level, due to the consumption of Hg-contaminated fish. Mercury concentrations were significantly higher in males than in females, regardless of location properties.     

Biological and environmental monitoring of occupational exposure of pharmaceutical plant workers to methotrexate

Summary The exposure of 11 pharmaceutical plant workers to methotrexate (MTX) was studied. Personal air samples were taken during the different manufacturing processes: drug compounding, vial filling, and tablet preparation. The uptake of MTX was established by the determination of MTX in urine. MTX was analyzed using the fluorescence polarization immunoassay (FPIA), a method that is frequently used for monitoring serum levels in patients treated with MTX. The FPIA method was modified in such a way that MTX could be measured quickly and efficiently in air and urine samples. MTX was detected in air samples of all workers except for those involved in the vial filling process (range: 0.8–182 g/m³; median: 10 g/m³). The highest concentrations were observed for workers weighing MTX (118 and 182 g/m³). MTX was detected in urine samples of all workers. The mean cumulative MTX excretion over 72–96 h was 13.4 g MTX-equivalents (range: 6.1–24 g MTX-equiva g MTX-equivalents (range: 6.1–24 g MTX-equivalents). lents). A significantly lower background level of 10.2 g A significantly lower background level of 10.2 g MTX-equivalents was measured in urine of 30 control persons (range: 4.9–21 g MTX-equivalents).     

Cadmium kinetics in freshwater clams. III. Effects of zinc on uptake and distribution of cadmium inAnodonta cygnea

Freshwater clams (Anodonta cygnea) were exposed to Cd²⁺ (25 g/L) or to Cd²⁺ (25 g/L) plus Zn²⁺ (2.5 mg/L). In the presence of zinc, uptake of cadmium in whole clam was halved. In organs such as the gills, mantle, and labial palps a still larger reduction of Cd accumulation occurred. By contrast, accumulation in midgut gland and kidney was hardly affected by the presence of zinc. It is shown that in the gills zinc competes with cadmium for metal binding sites both within the particulate fraction and the high-molecular weight fraction of the cytosol. Zinc probably did not induce an enlarged synthesis of specific metal-binding, metallothionein-like, proteins. In conclusion, zinc exerts antagonistic effects on uptake of cadmium by gills, and accelerates Cd transport from the gills towards the internal organs.     

Cadmium in beavers translocated from the Elbe river to the rhine/meuse estuary,and the possible effect on population growth rate

Beavers (Castor fiber) from the Middle Elbe region were re-introduced in the Biesbosch, The Netherlands, an estuary contaminated with cadmium (Cd) by the rivers Rhine and Meuse. The Middle Elbe region was also polluted with Cd, but the beavers released in the Biesbosch originated from two relatively clean habitats within this region. The Biesbosch population grew slower than other released beaver populations in Europe, and it was hypothesized that Cd intoxication was responsible for this. The beavers fed primarily on the bark and leaves of willow and poplar trees, which contained great concentrations of Cd. The average Cd concentration in the food (6.9 g/g_dry) was above the maximum tolerable concentration for large domestic herbivores. The Cd concentrations of the kidneys and hair of the beavers were correlated with those in the bark of the trees. The Cd concentration in the hair increased threefold after the release in the Biesbosch, and the geometric mean Cd kidney concentration was 55 g/g_dry. Using three different models, an average Cd kidney concentration in the beavers of >100 g/g_dry was predicted in the Biesbosch in the near future. Such a concentration causes kidney damage in some other mammals. Beaver kidneys from the Mulde, a tributary of the Elbe, contained on average 467 g Cd/g_dry, the greatest concentration reported in herbivores. Nevertheless, the fertility along the Mulde was high, due to the fact that it is an otherwise optimal beaver habitat. Furthermore, the low fertility in the Biesbosch was due to a small fraction of successful breeding pairs. We conclude that the initial low population growth rate in the Biesbosch was probably not caused by contamination with Cd. However, future effects on the individual (reproductive) life span cannot be ruled out.     

A pilot study of lead and cadmium exposure in young children in Stockholm,Sweden: Methodological considerations using capillary blood microsampling

A capillary blood microsampling technique was tested among urban young children in Stockholm. Blood lead (BPb) and hemoglobin (Hb) concentrations were determined in capillary blood obtained by fingerstick from 41 children, 13–20 months old, and the accompanying parent. The quality control included control for lead (Pb) and cadmium (Cd) contamination of material and equipment used for blood sampling, washing procedures for the hands and fingers to be punctured, comparisons of Pb and Cd concentrations in blood obtained by fingerstick and by brachial vein puncture from the same individuals, analysis of external quality control samples for Pb and Cd in blood together with the collected samples, and evaluation of the analytical performance using linear regression analysis.The results showed that blood sampling material may contaminate the blood samples with amounts of Pb and Cd that would seriously influence the monitoring results in the low concentration range (<100 g Pb/L and <1 g Cd/L). However, it is possible to obtain reliable BPb concentrations (>10 g Pb/L), but not BCd concentrations (<1 g Cd/L), with the capillary blood microsampling technique tested provided that a strict quality control is applied. The sampling procedure tested was well accepted by the children and their parents. The children's median BPb concentration (27 g/L; range 9–73 g/L) was similar to the median BPb concentration of their parents (27 g/L; range 7–74 g/L). However, the correlation between child and parent BPb concentrations was poor (R²=0.20), which may indicate different sources to Pb exposure in children and parents.     

Mercury vapor as an atmospheric contaminant of dental offices

Airborne mercury from dental offices was selectively trapped by silver gauze elements in borosilicate glass absorbers, followed by heat-desorption and spectrophotometric measurement at 2537A. As little as 0.4 ng of Hg could be accurately determined, which is equivalent to 49 ppt in a one-L air sample on a v/v basis. Over 860 air samples were taken over a range of locations and working conditions at 88 different dental offices, and at the Dental Training Clinic of the University of Manitoba. The Hg vapor concentrations at the dental facilities ranged from 0.45 to 742g/m³ of air; 29% of the samples were within 0.45 to 5g; 37.8 were within 5.1 to 25g; and 33.2% were above 25g. Mercury concentrations varied during the working day, depending on the time of sampling, the number of amalgams placed, and the interval between placements. The lowest concentrations were obtained in the morning. Disturbance of residual mercury droplets on floors or working areas by sweeping or dusting, or immediately after attempted clean-up of a mercury spill, sharply increased the amount of airborne mercury.     

Copper/Metal Ratios in the Gills of Rainbow Trout (Oncorhynchus mykiss) Provide Evidence of Copper Exposure Under Conditions of Mixed-Metal Exposure

Previous work has suggested that the ratio of copper residues to zinc in the gills of rainbow trout may indicate short-term exposure to increased levels of waterborne copper. However, the effect of exposure to a combination of increased copper and zinc concentrates in the water column was unknown. We exposed rainbow trout to 8 ± 2 g L^–1, 40 ± 2 g L^–1 and 90 ± 9 g L^–1 of waterborne copper and 21 ± 3 g L^–1, 129 ± 40 g L^–1, and 202 ± 40 g L^–1 of waterborne zinc in a 2-factor experiments and gill copper and zinc residues were examined. Other gill parameters analyzed included the concentrations of calcium, magnesium, sodium, and potassium, liver copper and zinc concentrations and plasma copper, calcium, sodium, and potassium are also reported here. Copper residues in the gill filaments were significantly higher in the highest level of copper exposure (high Cu, 4.06 g g^–1; low Cu 2.41 g g^–1; 0 Cu 2.01 g g^–1; P = 0.001), whereas no differences were seen in zinc concentrations at any treatment level. Gill sodium and plasma calcium concentrations were also decreased at the highest waterborne copper concentrations. Although copper–zinc ratios in the gills were significantly different between the highest and lowest copper treatments (P = 0.002, F = 6.59), copper–sodium and copper–magnesium ratios were more sensitive to waterborne copper exposure (P = 0.001, F = 17.91 and P = 0.002, F = 15.45, respectively). These copper–metal ratios may be better indicators of copper loading in the water column.     

Ultrastructural changes in Dunaliella minuta following acute and chronic exposure to copper and cadmium

The ultrastructural changes taking place after shortterm acute exposure to copper, cadmium and a combination of the two metals were examined. Additionally, the effects of long-term (8 months) exposure to ambient concentrations of these metals were investigated. Exposure to 0.34 M cadmium affected the photosynthetic potential of this alga, by reducing the relative volume of the chloroplast by 23.27%. It also led to 74.6% increase in the relative volume of starch granules. Cells challenged with 0.34 M cadmium and 7.57 M copper had 33.49% larger volumes than controls, and their relative lipid volumes increased by 170%. In contrast, the relative volume of their pyrenoids decreased by 41.46%. Similar results were obtained after chronic exposure to 4.9×10^–4 M copper with the relative volume of the pyrenoid being 28% smaller than the controls.This work was submitted by Ioanna Visviki to the Department of Biology of the Graduate School of the City University of New York for the partial fulfillment of the requirements of the PhD degree.     

Current external and internal exposure to naphthalene of workers occupationally exposed to polycyclic aromatic hydrocarbons in different industries

Objectives: External and internal exposure to naphthalene was examined in the most important industries that are typically concerned with polycyclic aromatic hydrocarbon (PAH)-induced diseases (cancer). Furthermore, a control collective from the general population was investigated. Methods: External naphthalene was determined by personal air sampling (n=205). The internal exposure was examined by urinary metabolites 1-naphthol and 2-naphthol (n=277). Results: Highest median concentrations of naphthalene in air were found in converter infeed (93.2 g/m³) and coal-tar distillation (35.8 g/m³). Moderate and low levels were determined in coking plants (14.5 g/m³) and in the production of refractories (6.1 g/m³) and graphite electrodes (0.7 g/m³). Biological monitoring revealed concentrations of the sum of both metabolites [(1+2)-NOL] in smokers to be increased by 1.6–6.4 times compared with that in non-smokers at the same workplaces. Among non-smokers we found high median (1+2)-NOL levels in converter bricklayers (120.1 g/l), in coal-tar distillation workers (56.0 g/l) and in coking plant workers (29.5 g/l). (1+2)-NOL concentrations around 10 g/l were found in the production of refractories and graphite electrodes. There was a rough coherency between external and internal naphthalene exposure. In the controls, median (1+2)-NOL concentrations were 10.9 g/l in non-smokers urine and 40.3 g/l in smokers urine samples. Conclusions: Actual conditions of occupational hygiene at the workplaces investigated in this comprehensive study are better than those that current limit values of 50,000 g/m³ (TLV, TRK) seem to induce. It has become obvious that tobacco smoking is a crucial confounding factor in biological monitoring of naphthalene-exposed humans, making interpretation of occupationally increased naphthol excretions very difficult at low exposure levels.     

Urinary chlorophenols in sawmill workers

Summary The concentration of urinary chlorophenol was assayed for 230 sawmill workers. Information on the work tasks was obtained through questionnaires from occupational health centres. The workers were divided into three groups on the basis of the type of exposure: (1) those with skin absorption as the main route, (2) those with skin and respiratory route of equal importance and (3) those with respiratory tract as the main route. The concentrations of urinary chlorophenol were higher in workers with skin absorption as the main route (median concentration: 7.8 mol l^–1; range 0.1 to 210.9 mol l^–1) than in those with both routes of equal importance (1.4 mol l^–1; range 0.1 to 47.8 mol l^–1, P<0.001) or in those with mainly respiratory route (0.9 mol l^–1; range 0.1 to 13.3 mol l^–1, P<0.001). The urinary chlorophenol concentration was below 15 moll^–1 in all workers with the lungs as the main absorption route. In nine out of 112 workers whose main absorption route was the skin, the urinary chlorophenol values were above 50 mol l^–1. Six were loaders when the through-dipping method was used. In two of them urinary chlorophenol concentrations were as high as 170.8 and 210.9 mol l^–1, These results emphasize the need to develop and use simple methods of protection against skin contact with chlorophenols.     

The disposition of cadmium and zinc inPandalus montagui

Cadmium uptake rates in various tissues ofPandalus montagui exposed to sea water containing 37 gCd/L for 14 days ranged from 0.002–0.06 g/g dry tissue/hr. During depuration for 57 days, the levels in most tissues decreased slightly, but continued to rise in the hepatopancreas indicating Cd redistribution. Exposure to 65 g Zn/L produced no substantial change in Zn content of the tissues. An increase occurred in eggs and hepatopancreas during the first six days of depuration. During exposure to Cd and Zn combined (40 g Cd/L + 70 g Zn/L), tissue Zn levels responded as with Zn alone. In the presence of Zn, Cd concentration was doubled in the hepatopancreas, depressed by one-third in the carcass, and did not change in the other tissues. Increased amounts of Zn (up to 410 g Zn/L) had no effect on the Cd levels of the tissues except that the Cd level in the hepatopancreas was depressed, although the level was still greater than in the case of exposure to Cd alone. The possible role of metallothionein is discussed.     

Acute and chronic exposure of Dunaliella salina and Chlamydomonas bullosa to copper and cadmium: Effects on growth

Effective copper and cadmium concentrations which limited the growth of two chlorophytes by 50%, EC(50)s, after 96 h of static exposure were determined. EC(50)s were 5.94 gM copper and 4.55 M cadmium for Dunaliella salina, and 0.78 M copper and 0.025 M cadmium for Chlamydomonas bullosa. The relationship of the two cations was synergistic towards the growth of both species. Chronic exposure to 4.5×10^–6 M cadmium or 4.9×10^–4 M copper increased the sensitivity of C. bullosa by 26% and 29% towards cadmium and copper, respectively. Changes in co-tolerance were not observed. Cd-treated D. salina was 50% more tolerant towards this cation, whereas Cu-treated cultures showed extreme sensitivity towards copper and co-sensitivity towards cadmium. Furthermore, the phylogenetic hypothesis, predictive of toxic response, failed to hold at the familial level.This work was submitted by Ioanna Visviki to the Department of Biology of the Graduate School of the City University of New York in partial fulfillment of the requirements of the PhD degree.     

A suggestion on how to use measurements of cadmium in blood as a cumulative dose estimate

Summary The individual cumulative cadmium dose was estimated for 44 smelter workers in a cadmium-copper alloy plant. Two different principles were used: cumulative respiratory dose and cumulative average annual blood-cadmium dose. Out of eight workers with a cumulative respiratory dose exceeding 500 mg Cd · h/m³, two of them (25%) had signs of a cadmium-induced renal dysfunction. These two men were the only workers that had a cumulative average annual blood cadmium dose exceeding 200 g Cd · year/1. Our results suggest that measurements of cadmium in the blood can be used as an indicator of the cadmium exposure of each individual and that, in order to prevent renal dysfunction, the average blood-cadmium concentration should not exceed 10 Cd/1 over periods of many years (decades).     

The effects of poly chlorinated biphenyls and methylmercury,singly and in combination on mink. II: Reproduction and kit development

Adult ranch-bred mink (Mustela vison) were fed diets containing either 0, 1.0 g/g polychlorinated biphenyls (PCB) (Aroclor^® 1254), 1.0 g/g methylmercury (MeHg), a combination of 1.0 g/g PCB plus 1.0 g/g MeHg, or 0.5 g/g PCB plus 0.5 g/g MeHg. Fertility of adult male mink, percentage of females whelped or number of kits born per female were not affected by the treatments. However, growth rate of kits nursed by mothers exposed to 1.0 g/g PCB was significantly reduced. There was a synergistic effect of PCB and MeHg which reduced kit survival in groups receiving both chemicals simultaneously. Kit survival to weaning in the control, 0.5 g/g PCB/MeHg, and 1.0 g/g PCB/MeHg groups was 72.0%, 62.7% and 35.8%, respectively. The results suggest that growth and survival of mink kits are adversely affected at dietary levels of PCB and MeHg currently present in some environments.