The critical level of cadmium in renal cortex: the concept and its limitations

Because renal cortex is a primary target organ of Cd the seriousness of human exposure is commonly assessed in terms of the extent to which it permits renal cortical Cd concentrations to approach a critical value. The critical value has been defined in terms of PCC-10, the population critical concentration at which 10% of exposed individuals may be expected to show abnormal renal function. In chronically exposed human populations, PCC-10 appears to lie in the range of 180 to 220 μg Cd/gram fresh weight of cortex. However, Cd accumulated in the kidney under these conditions is distributed between more than one compartment, in all likelihood differing greatly in their toxicological characteristics. For instance, a major fraction of this Cd is bound to metallothionein, and may as such be relatively inert. Compartmentation of tissue Cd, in turn, is strongly influenced by the nature of exposure, and the PCC-10 value of 200 μg/g may therefore have limited general significance. The problem of risk assessment is further complicated by the high variability of Cd absorption. Nevertheless, human renal Cd levels commonly reach values as high as 1/3 to 1/6 of the chronic PCC-10, and further increases in Cd intake should therefore be avoided.     

Influence of uraniferous black shales on cadmium,molybdenum and selenium in soils and crop plants in the Deog-Pyoun-g area of Korea

The influence of naturally occurring uraniferous black shales on cadmium, molybdenum and selenium concentrations in soils and plants is examined. The possible implications of element concentrations to animal and human health are considered for the Deog-Pyoung area. Geochemical surveys have been undertaken within 13 river tributary valleys in the area underlain by uraniferous black shales and black slates or grey chlorite schists. Sampling of rocks, soils and plants has been carried out along transect lines within each valley. Samples were analysed for trace elements by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) and for uranium by Neutron Activation Analysis (NAA). Soil pH, cation exchange capacity, loss on ignition and particle size distribution have been measured for selected samples. Average trace element concentrations of the Okchon uraniferous black shales were 6.3 μg g⁻¹ Cd, 136 μg g⁻¹ Mo and 8.6 μg g⁻¹ Se. Soils derived from these rocks tend to reflect their extreme geochemical composition. Trace element concentrations in alluvial soils derived in part from these black shales averaged 1.2 μg g⁻¹ Cd, 20 μg g⁻¹ Mo and 1.5 μg g⁻¹ Se. Trace element concentrations in plants were found to be influenced by those of soils. Cadmium accumulated in tobacco leaves up to 46 μg g⁻¹ (D.M.) and leafy plants such as lettuce contain up to 0.5 μg g⁻¹ Se (D.M.). In addition to total concentrations in soils, soil pH is a major factor influencing uptake of Mo into crop plants and soil texture for Se. Concentrations of trace elements in plants also varied between plant species. The relative concentrations of Cd were found to vary in the order tobacco > lettuce > red pepper > rice grain. Elevated concentrations of Cd in crop plants and in tobacco may possibly have deleterious effects on human health in this area. The low Cu:Mo ratio in rice stalk of 2.65:1 may be associated with disturbed Cu metabolism in ruminant animals which regularly consume this material.     

Human risk assessment of As,Cd, Cu and Zn in the abandoned metal mine site

The cancer risk and the non-cancer hazard index for inhabitants exposed to As, Cd, Cu and Zn in the soils and stream waters of the abandoned Songcheon Au–Ag mine area were evaluated. Mean concentrations of As, Cd, Cu, Pb and Zn in agricultural soils were 230, 2.5, 120, 160, and 164 mg kg⁻¹, respectively. Mean concentrations of As, Cd and Zn of the water in the stream where drinking water was drawn was 246 μg L⁻¹, 161 μg L⁻¹ and 3899 μg L⁻¹, respectively. These levels are significantly higher than the permissible levels for drinking water quality recommended by Korea and WHO. The resulting human health risks to farmers who inhabited the surrounding areas due to drinking water were summarized as follows: (1) the non-cancer health hazard indices showed that the toxic risk due to As and Cd in drinking water were 10 and 4 times, respectively, greater than those induced by the safe average daily dosages of the respective chemicals. (2) the cancer risk of As for exposed individuals through the drinking water pathway was 5 in 1000, exceeded the acceptable risk of 1 in 10,000 set for regulatory purposes.     

Uranium in stream and mineral water of the Federal Republic of Germany

The concentration of uranium was determined in 944 samples from stream water by the inductively coupled plasma quadrupole mass spectrometry (ICP-QMS) method and represented on a color-shaded contour map. Uranium concentrations in surface water were determined to be between 0.007 μg/l and 43.7 μg/l with median of 0.33 μg/l. The regional distribution of uranium is influenced primarily by lithological and anthropogenic factors. In Mecklenburg, northern Brandenburg, and eastern Schleswig-Holstein, elevated uranium concentrations coincide with the extent of the last Weichselian ice sheet. The maximum concentrations are observed in the surface waters of the old mining districts in the western part of the Ore Mountains and in eastern Thuringia. Elevated concentrations are found in areas of agriculturally used loess soils. These concentrations correlate with the use of phosphate fertilizers. There is a zone of elevated concentrations up to 10.0 μg U/l in the Keuper Sandstone area south of the Thuringian Forest and from northwest of Stuttgart as far as Coburg. The distribution of elevated values in mineral water shows a clear correlation with the elevated values in surface water and the geology of those locations. Bunter and Keuper strata are the most important uranium source.     

Accumulation of cadmium and zinc in <Emphasis Type="Italic">Evodiopanax innovans</Emphasis>

The use of tree species for phytoremediation of contaminated soil offers the advantage of a large biomass in which to store contaminants. We investigated the cadmium (Cd) and zinc (Zn) accumulation ability of Evodiopanax innovans, a common deciduous tree species belonging to the Araliaceae family and widely found in secondary forests in Japan. Sampling was conducted at an old silver mine. Leaf samples were collected from nine tree species, including E. innovans. The seasonal variation of metal concentrations in the leaves and the detailed distribution of metals in the leaves and twigs of E. innovans were measured. We also analyzed the contents of organic acids in the leaves. The highest concentration of Cd in the leaves of E. innovans was 118 μg/g, which exceeds the threshold level for being considered a Cd hyperaccumulator (100 μg/g). For Zn, the highest value was 1040 μg/g in leaves, which is less than required to qualify as a Zn hyperaccumulator. Both Cd and Zn were found to accumulate in the petioles and veins of leaves and the bark of twigs. Since the oxalic acid content of leaves showed a weak correlation with Cd concentration, oxalic acid may play an important role in the accumulation of Cd. Taking both the Cd concentration level and the biomass of this woody plant into consideration, it may be possible to use E. innovans for the phytoremediation of Cd-contaminated soils.     

A 25-year record of polycyclic aromatic hydrocarbons in soils amended with sewage sludges

We studied polycyclic aromatic hydrocarbons (PAHs) in crop soils amended with 1000 tonnes dry weight of sewage sludges per 10,000 m² from 1974 to 1992, then after sludges addition from 1993 to 1999. The absence of variations of total PAHs levels of control soils, averaging at 123 μg/Kg, shows the absence of horizontal contamination. During sludges addition, the total PAHs levels in amended soils increased from 232 to 402 μg/Kg. Seven years after sludges addition, it decreased to 275 μg/Kg, which is still more than twice –the levels of control soils. This finding shows that sludges PAHs are preserved in crop soils for long periods of time, on a human scale.     

Cadmium levels in Europe: implications for human health

In this study we used the Forum of European Geological Surveys geochemical baseline data to examine the distribution of cadmium (Cd) in Europe, with a particular reference to the international soil and water guideline values. The highest cadmium levels were found to occur in topsoil and to follow closely the distribution of P₂O₅, suggesting that the contamination was from the use of rock phosphate fertilizer in intensive arable agriculture. In terms of human health impacts, food (up to several hundred μg/day) was found as the only major route of exposure to Cd for the non-smoking general population. It appeared that low levels of chronic exposure to Cd resulted in completely different human health impacts than those high levels that had caused the ‘itai–itai’ disease. Some correlations were suggested between cadmium levels and the age-adjusted prostate or breast cancer rates distributed in the European countries under study.     

Lead in a residential environment in Jamaica

The background levels of lead in Jamaica in soils and sediments, estimated at 37 mg kg^–1, are relatively high compared with world averages. Several areas have values in excess of this due to mineralisation and pollution. One such is the residential Hope Flats/Kintyre area in which levels of lead up to 2.5% are found in the soils and up to 8 g kg^–1 in the water of the nearby Hope River. The blood lead levels of a sample of children were in the range 5.7–57 g dl^–1. The high lead levels suggest a potential health risk, particularly for the children. This can be minimised by programmes which include community education, case management and abatement to reduce the lead exposure.     

Influence of industry on the geochemical urban environment of Mieres (Spain) and associated health risk

This study is concerned with the elemental composition of soils and street dust collected in an historical industrial city of approximately 27 000 inhabitants, where old Hg mining and metallurgical activities strongly affected the load of heavy metals in the urban environment. For the purpose of the study, representative samples of soils and street dust were collected at different locations in the whole urban area (3 km²). Elevated mean concentrations of As in soils and street dust (69 and 135 g g^–1, respectively), and Hg (3.07 and 4.24 g g^–1, respectively), compared to background levels and to those found in other cities, reflect the anomalous geochemical nature of these materials and the strong influence exerted by the old mining sites.     

Exposure of the urban population to mercury in Changchun city, Northeast China

An assessment of exposure to mercury in Changchun city has been undertaken. We estimated Hg exposure to members of the general population based on currently available information and our research. We also studied the Hg concentrations in scalp hair of adults. Adults have an estimated intake of all Hg species via all routes of 6.780 μg day⁻¹ (excluding dental amalgam), which equates to an absorbed dose of 1.718 μg day⁻¹. Fish consumption was the most important exposure route (12% of intake, 43% of absorbed dose). Furthermore, air, cereals and vegetables were important exposure routes, and these exposure were estimated for absorbed dosed at 0.296, 0.209 and 0.318 μg day⁻¹, respectively. The mean Hg concentration in hair was 0.448 μg g⁻¹ (range 0.092–10.463 μg g⁻¹). Hg concentration in the hair of males was 0.422 μg g⁻¹ (0.105–2.665 μg g⁻¹), and was 0.474 μg g⁻¹(0.092–10.463 μg g⁻1) in the hair of females. Neither place of residence nor age had any significant effect on hair Hg concentrations.     

Heavy metal contamination of paddy soils and rice (<Emphasis Type="Italic">Oryza sativa</Emphasis> L.) from Kočani Field (Macedonia)

This research focuses on the heavy metal contamination of the paddy soils and rice from Kočani Field (eastern Macedonia) resulting from irrigation by riverine water impacted by past and present base-metal mining activities and acid mine drainage. Very high concentrations of As, Cd, Cu, Pb and Zn were found in the paddy soils (47.6, 6.4, 99, 983 and 1,245 μg g⁻¹) and the rice (0.53, 0.31, 5.8, 0.5 and 67 μg g⁻¹) in the western part of Kočani Field, close to the Zletovska River, which drains the mining facilities of the Pb–Zn mine in Zletovo. In terms of health risk, the observed highest concentrations of these elements in the rice could have an effect on human health and should be the subject of further investigations.     

A pilot study on iodine in soils of Greater Kabul and Nangarhar provinces of Afghanistan

A robust and rapid methodology for the determination of iodine by inductively coupled plasma mass spectrometry in environmental samples is presented. Data were initially obtained for the validation of the analytical measurements, using 17 commercially available soil reference materials. The methodology was then tested on soil and water samples collected in Afghanistan where iodine deficiency and its effects are reportedly prevalent. Sample collections were conducted in Greater Kabul; the iodine in agricultural soils was determined to be in the range of 1.6–4.2 mg/kg and that in water drawn for drinking and irrigation was found to range from 9.9 to 22.7 μg/L. Samples were also collected in a second region, Nangarhar province, which is located to the east of Kabul, where goitres in the local population had been reported. The iodine content in soils and water at this location was 0.5–1.9 mg/kg and 5.4–9.4 μg/L, respectively. The organic content of soils in Kabul was found to be in the range of 1.9–4.2%; in Nangarhar, organic content ranged from 1.7 to 4.5%. All of the Afghan soils were slightly alkaline at pH 7.6–8.2.     

Sequential extraction of cadmium in different soil phases and plant parts from a former industrialized area

Cd concentrations in mobile phases of soil are more representative than total Cd concentration for estimating Cd bioavailability, physicochemical reactivity and mobility. In this study, selective sequential extraction procedures were used to determine Cd in different soil phases. Soil samples and plants grown in these soils were collected from a serpentine and copper-mining area in Maden-Elazig-Turkey. The extracted fractions were exchangeable/carbonate, reducible-iron/manganese oxides, oxidizable-organic matter and sulfides, and residual phases except silicates. Concentrations of Cd in soils and plant samples were determined by flame atomic absorption spectrometry and inductively coupled plasma-mass spectrometry. We found that Cd concentrations in the EDTA and NH₂OH·HCl extracts are higher in most soil samples compared to the other extracts. We conclude that Cd levels in mobile phases are unexpectedly high. The observed Cd concentrations are in ranges of 0.03–3.4 mg kg⁻¹ for soil and 0.02–2.5 mg kg⁻¹ for plant parts. The percentages of cadmium up to 56% in exchangeable and carbonates fractions were observed to be significantly higher than in those values less than 2% reported in literature. This study has shown that the modified extraction method can be usefully applied to determine Cd concentrations in potentially mobile phase of soil. Furthermore, it was concluded that Brassicasea and Rumex leaves can be used as hyperaccumulator plants because their translocation factor and/or enrichment coefficient values were found to be higher than 1.0.     

Historical trends of trace metals in a sediment core from a contaminated tidal salt marsh in San Francisco Bay

Sedimentation of metals preserves historical records of contaminant input from local and regional sources, and measurement of metals in sediment cores can provide information for reconstruction of historical changes in regional water and sediment quality. Sediment core was collected from Stege Marsh located in central San Francisco Bay (California, USA) to investigate the historical input of trace metals. Aluminum-normalized enrichment factors indicate that inputs from anthropogenic sources were predominant over natural input for Ag, Cu, Pb, and Zn. Among these, lead was the most anthropogenically impacted metal with enrichment factors ranging from 32 to 108. Depth profiles and coefficients of variation show that As, Cd, and Se were also influenced by anthropogenic input. The levels of these anthropogenically impacted metals decline gradually towards the surface due to regulation of the use of leaded gasoline, municipal and industrial wastewater discharge control, and closure of point sources on the upland of Stege Marsh. Although trace metal contamination is expected to be continuously declining, the rates of decline have slowed down. For lead, it is estimated to take 44, 82, and 153 years to decrease to probable effects level (112 μg/g), the San Francisco Bay ambient surface sediment level (43.2 μg/g), and the local baseline levels (5 μg/g), respectively. Some metals in surface sediments (0–6 cm) are still higher than sediment quality guidelines such as the probable effects level. To further facilitate the recovery of sediment quality, more efficient management plans need to be developed and implemented to control trace metals from non-point sources such as stormwater runoff.     

Organochlorine pesticides in soils around Guanting Reservoir,China

Fifty-six representative samples of topsoil were collected around Guanting Reservoir, which is an important water source for Beijing. Concentrations of the insecticides HCH, DDT, and their metabolites were quantified by use of gas chromatography (GC) with electron capture detection (ECD). Organochlorine pesticides (OCPs) are still present in surface soils in the Guanting area. DDT accounts for about 93% of the total OCP content. Concentrations of α/γ, β/γ, and DDT/DDE are the result not only of historical use, but also of more recent depositions. Statistical analyses, including principal component analysis (PCA) and cluster analysis (CA), revealed associations between concentrations of OCPs and major soil characteristics. Geographical information system (GIS) technology was used to develop maps of the distributions of OCP concentrations. The areas of greatest contamination were primarily in the central part of the study area and were correlated with greater population density, heavier traffic, and more industrial activity.     

Human hair mercury levels in the Wanshan mercury mining area,Guizhou Province,China

The total mercury (T-Hg) and methyl mercury (Me-Hg) concentrations in the hair were measured to evaluate mercury (Hg) exposure for the residents in Da-shui-xi Village (DSX) and Xia-chang-xi Village (XCX) in the Wanshan Hg mining area, Guizhou Province, Southwestern China. The mean concentrations in the hair of DSX residents were 5.5 ± 2.7 μg/g and 1.9 ± 0.9 μg/g for T-Hg and Me-Hg, respectively. The concentrations in the hair of XCX residents were 3.3 ± 1.4 μg/g and 1.2 ± 0.5 μg/g for T-Hg and Me-Hg, respectively. Hair Me-Hg concentrations were significantly correlated to T-Hg (r = 0.42, P < 0.01) in the two sites; on average, hair Me-Hg concentration accounted for 40 and 44% of T-Hg for DSX and XCX residents, respectively. Age has no obvious correlation with hair Hg and the hair Hg levels showed a significant gender difference, with higher T-Hg and Me-Hg concentrations in the hair from males than females. The rice collected from the two sites showed high levels of T-Hg and Me-Hg concentration. The results indicated a certain Hg exposure for the residents in DSX and XCX in the Wanshan Hg mining area.     

Assessment of toxicity of heavy metal contaminated soils by the toxicity characteristic leaching procedure

The concentrations of Cu, Zn, Pb and Cd in soils near a lead–zinc mine located in Shangyu, Zhejiang Province, China, were determined and their toxicity was assessed using the toxicity characteristic leaching procedure (TCLP) developed by the United States Environmental Protection Agency. The TCLP method is a currently recognized international method for evaluation of heavy metal pollution in soils. The available levels of Cu, Zn, Pb and Cd were 8.2–36, 23–143, 6.4–1367 and 0.41–2.2 mg kg⁻¹, respectively, while the international standards were 15, 25, 5 and 0.5 mg kg⁻¹, respectively. Soils around the mine were more polluted with Zn and Pb, followed by Cd and Cu. Moreover, the levels of heavy metals in the soils extracted by TCLP indicated that extraction fluid 2 was more effective than extraction fluid 1 in extracting the heavy metals from the polluted soils and there was a positive correlation between fluids 1 and 2. Available heavy metal contents determined by TCLP were correlated with soil total heavy metal contents.     

Increasing polybrominated diphenyl ether (PBDE) contamination in sediment cores from the inner Clyde Estuary,UK

The concentrations of 16 polybrominated diphenyl ether (PBDE) congeners in six short sediment cores from the Clyde Estuary were determined by gas-chromatography mass-spectrometry. Total PBDE concentrations ranged from 1 to 2,645 μg/kg and the average concentration was 287 μg/kg. BDE-209 was the main congener and varied from 1 to 2,337 μg/kg. Elevated total PBDE concentrations were observed close to the sediment surface in the uppermost 10 cm of four of the six sediment cores. Comparison of the down core PBDE profiles revealed that the increase was driven by the accumulation of deca-BDE. Although the deca-BDE mix was dominant, the presence of lower molecular weight congeners BDE-47, BDE-99, BDE-183 and BDE-153 at most sediment intervals suggested additional sources of penta-BDE and octa-BDE pollution. Changing PBDE source input was the major factor in influencing the proportion of nona-brominated congeners, although other explanations such as post burial photo-debromination of BDE-209 cannot be entirely discounted. A clear cascading to lower hepta-, hexa-, and penta-homologues was not found. The increase in total PBDE concentrations and particularly the deca-BDE may possibly be ascribed to the use and subsequent disposal of electrical appliances such as televisions and computers. In the Clyde sediments, the proportion of nona-brominated congeners was higher than that reported for commercial mixtures. This might be due to changing sources of PBDEs or post burial photo-debromination of BDE-209.     

Cadmium, zinc and copper accumulation in the squid Illex argentinus from the Southwest Atlantic Ocean

 The levels and burdens of Cd, Zn, Cu and Hg were measured in the dorsal mantle, digestive gland and gonads of the squid Illex argentinus, from the Southwest Atlantic Ocean. Mature and immature individuals of both sexes were analysed. Correlations of heavy metal concentrations and burdens with sex and food habits were studied. The highest metal levels were found, particularly for Cd, in the digestive gland, which attained a concentration of up to 270 μg g⁻¹ (wet weight). Dorsal mantle and gonads exhibited the same order of metal enrichment: Zn>Cu>Cd. Zinc and Cu levels were higher in ovaries than in testes and varied with the stage of maturation. The dorsal mantle exhibited the lowest heavy metal concentrations. Mercury levels were below the detection limit of the method in all the tissues analysed. Received: 7 September 1999 / Accepted: 9 March 2000     

Pollution assessment of the lower basin of Lakes Kainji/Jebba, Nigeria: heavy metal status of the waters, sediments and fishes

The objective of this investigation was to examine the heavy metal status of the lower basin of Kainji dam (used for hydroelectricity generation), which includes Lakes Kainji/Jebba, Nigeria, and the potential for human exposure to heavy metals from eating fish caught in the lakes. Water, sediments and fish were sampled from the lakes and evaluated for As, Cu, Co, Cr, Fe, Hg, Mn, Ni, Pb, Sb, Ti, V and Zn using the EDXRF technique. Fe and Mn were found to be present at high mean concentrations in the water (13 and 9 μg L^-1), sediment (7092 and 376 μg g^-1) and fish (11.4 and 4.6 μg g^-1) samples. Sb (3.2 μg L^-1), Ti (4.1 μg L^-1), Cr (2.2 μg L^-1), Co (1.2 μg L^-1), Cu (1.3 μg L^-1) and Pb (1.2 μg L^-1) in the water samples and Sb (29 μg g^-1), Ti (27 μg g^-1), V (27 μg g^-1), Cr (27 μg g^-1), Co (40 μg g^-1), Ni (33 μg g^-1), Cu (25 μg g^-1), Zn (59 μg g^-1) and Pb (19 μg g^-1) in the sediment samples were found to be of medium mean concentrations. The other metals were present at trace levels (<1 μg), including As and Hg in the fish and sediment samples. There was an appreciable increase in␣metal concentrations in going from the water to the sediment samples. The probable source of the pollutants is anthropogenic, arising from agricultural activities, corrosion/abrasion of the ferrous steel material and additives in the lubricants and insulation used for auxiliary services on the turbine floor of the dam constructed on the lakes. However, natural geological sourcing from the underlying lake rock cannot be totally ignored, particularly the high levels of Fe and Mn in the sediment samples. The potential risk for human exposure to these metals emanates from the fish caught in the lakes and subsequently consumed, as there are already significant levels of these metals in the two fish species analysed, Tilapia (Oreochromis niloticus) and Chrysicthys (Chrysicthys auratus).