Association between cadmium concentration in rice and mortality in the Jinzu River basin, Japan

Renal tubular dysfunction and cancer mortality in the Japanese general population living in cadmium non-contaminated areas

The relationship between cadmium exposure, exposure-related renal tubular dysfunction, and mortality have been reported, mainly in the residents of Cd contaminated areas in Japan. The aim of this study was to establish the cause-effect relationship between renal tubular dysfunction and cancer mortality in the general population in non-contaminated areas. A 19-year cohort study was conducted in 1110 men and 1703 women in 1993 or 1994, who lived in three cadmium non-contaminated areas. Mortality risk ratios of urinary β2-microglobulin (β2MG) and N-acetyl-β-glucosaminidase (NAG) for all malignant neoplasms and specific cancers were estimated using the Fine and Gray competing risks regression model. Significant HRs for liver and pancreas cancer were observed for NAG (liver: HR corresponding to an increase of 1IU/g cr, 1.10, 95%CI, 1.02-1.19, pancreas: HR, 1.10, 95%CI, 1.02-1.19) in men. In women, a negative HR was observed for NAG (lung cancer: HR 0.80, 95% CI, 0.67-0.96) and for β2MG (all malignant neoplasms: HR, 0.97, 95% CI, 0.93-1.00). The present study indicated that renal tubular dysfunction was significantly related to mortality in the general population of cadmium non-contaminated areas in Japan.

Functionalization of Shirasu-balloons Surface for Removal of Cadmium Ions from Contaminated Soil

Microspheres of aluminosilicate glass from volcanic sediment, whose surfaces were modified with functional groups, Shirasu-balloons (SB), were investigated as an adsorbent to remove cadmium ions from contaminated soil. The introduction of thiol groups (-SH) on the surface of SB enabled it to adsorb cadmium ions. Meanwhile, the introduction of an alkyl group (-ODS) made the surface of SB hydrophobic, and consequently increased the mechanical strength of SB. Those adsorbents could float up on the water surface after the adsorption process. The prepared adsorbent was characterized by FTIR spectrophotometry, elemental analysis and optical microscopy for making photographic images. The adsorption of cadmium ions on the adsorbent was investigated by comparing the results by a plain SB with those by thiol-functionalized SB. The adsorption maximum for cadmium ions was 3.75 mg/g for SH-SB and 2.62 mg/g for SH-ODS-SB, respectively. The adsorption of cadmium ions on functionalized SH-SB and SH-ODS-SB fitted well to the Langmuir isotherm equation. After a shaking time of 24 h, the recovering ratios of the absorbents from soil were 73 wt% for SH-SB and 98 wt% for SH-ODS-SB absorbents. In addition, the kinetic and adsorption-desorption properties of the adsorbent were also considered.

Gibbsite (100) and Kaolinite (100) Sorption of Cadmium(II): A Density Functional Theory and XANES Study of Structures and Energies

Due to the potential toxicity of cadmium (Cd²⁺) and its presence in various waste products found in the environment, it is necessary to develop methods to attenuate and remediate Cd²⁺ waste. Sorption of Cd²⁺ to mineral surfaces is a potential route to accomplish this goal. This work focused on improving our molecular-scale understanding of the chemistry of Cd²⁺ interactions with gibbsite and kaolinite mineral surfaces. Plane-wave density functional theory (DFT) energy minimization calculations and molecular dynamics simulations were used to study the adsorption energies and the nature of the bonds between Cd²⁺ and the mineral surfaces for possible inner- and outer-sphere surface complexes. Models resulting from the DFT calculations were used to calculate theoretical XANES spectra that were compared with experimental Cd L_III XANES of aqueous Cd²⁺ as a proxy for outer-sphere Cd²⁺ hydrated complexes associated with the mineral surfaces. These studies suggest that Cd²⁺ would favorably bond to the (100) surfaces of both kaolinite and gibbsite through a bidentate mononuclear interaction. However, the results indicate that mixtures of surface complexes on these minerals are likely.

Increase of lifetime cadmium intake dose-dependently increased all cause of mortality in female inhabitants of the cadmium-polluted Jinzu River basin, Toyama, Japan

BACKGROUND

Exposure to cadmium (Cd) via food is supposed to affect life prognosis of inhabitants of Cd-polluted area in Japan. However, there have been few reports demonstrating a significant relationship between the amount of Cd intake and mortality. We aimed to investigate the relationship between mortality and individual lifetime Cd intake (LCd) in inhabitants of the polluted Jinzu River basin, Toyama, Japan.

METHODS

We conducted a 26-year follow-up survey in 2407 inhabitants (1208 men and 1199 women) who participated in health examinations for screening of renal dysfunction from 1979 to 1984. The calculation of LCd in each inhabitant was based on the formula of Nogawa (Nogawa et al., 1989): (mean Cd concentration in rice of the present hamlet × 333.5 g/day + 34 μg/day) × 365 days/year × number of years of residence in the present hamlet + 50 μg/day × 365 days/year × number of years living in Cd non-polluted regions. In this formula, 333.5 g/day is the 1970 average daily intake of rice in this area, 34 µg/day is the Cd intake from foods other than rice in this area, and 50 μg/day is the average intake of Cd in non-polluted areas in Japan. Mortality risk ratios of LCd for all and specific causes were estimated after adjustments for age at baseline, smoking status, and history of hypertension using a Cox hazard model or Fine and Gray competing risks regression model.

RESULTS

The mortality risk ratios of LCd (+ 1 g) for all causes in women were significantly dose-dependently increased (risk ratio: 1.08). Relative risk of LCd for kidney and urinal tract disease, renal diseases, renal failure and toxic effects of cadmium were significantly higher in women.

CONCLUSIONS

The present study documents that individual LCd dose-dependently decreased life prognosis over long-term observation in women. LCd was significantly related to the increased mortality for renal disease and toxic effect of Cd in women. The result provides clear evidence that life prognosis was adversely affected by Cd-exposure, especially in women.

Reduction of cadmium uptake in rice endophytically colonized with the cadmium-tolerant bacterium Cupriavidus taiwanensis KKU2500-3

The effects of the cadmium (Cd)-tolerant bacterium Cupriavidus taiwanensis KKU2500-3 on the growth, yield, and Cd concentration in rice grains were investigated in the rice variety Phitsanulok 2 (PL2), which was cultivated in a hydroponic greenhouse. The numbers of Cd-tolerant bacteria isolated from the roots and shoots of plants under the RB (rice with bacteria) and RBC (rice with bacteria and Cd) treatments ranged from 2.60 to 9.03 and from 3.99 to 9.60 log cfu·g−1 of PL2, respectively. This KKU2500-3 strain was successfully colonized in rice, indicating that it was not only nontoxic to the plants but also became distributed and reproduced throughout the plants. Scanning electron microscopy analysis revealed attachment of the bacterium to the root surface, whereas the internally colonized bacteria were located in the vascular tissue, cell wall, and intercellular space. Although the Cd contents found in PL2 were very high (189.10 and 79.49 mg·kg−1 in the RC (rice with Cd) and RBC roots, respectively), the Cd accumulated inside the rice seeds at densities of only 3.10 and 1.31 mg·kg−1, respectively; thus, the bacteria reduced the Cd content to 57.74% of the control content. Therefore, the colonizing bacteria likely acted as an inhibitor of Cd translocation in PL2.

Relationship between mortality and rice cadmium concentration in inhabitants of the polluted Jinzu River basin, Toyama, Japan: A 26 year follow-up

The aim of this study was to investigate the relationship between mortality and rice cadmium (Cd) concentration in inhabitants of a polluted area in Japan. The target subjects were inhabitants of the Jinzu River basin who participated in health examinations for screening of renal dysfunction from 1979 to 1984. The mean rice Cd concentration in each hamlet was used as an index of the Cd exposure. We conducted a 26 year follow-up survey in 3281 inhabitants (1544 men and 1737 women) whose data regarding the rice Cd concentration were available. Mortality risk ratios for all and specific causes were estimated after adjustments for age at baseline, smoking status and history of hypertension using a Cox hazard model or Fine and Gray competing risks regression model. The mortality risk ratios of rice Cd concentration (+0.1 ppm) for all causes in women were significantly increased (risk ratio: 1.04). Furthermore, the relative risks of rice Cd concentration for kidney and urinary tract disease, renal diseases, renal failure and toxic effects of cadmium were significantly increased in both sexes. These findings indicated that increased rice Cd concentration decreased the prognosis for life over a long-term observation in women. This result provides important information for determining the worldwide standard for allowable rice Cd concentration.

Geographic distribution of cadmium and its interaction with the microbial community in the Longjiang River: risk evaluation after a shocking pollution accident

A shocking Longjiang River cadmium pollution accident occurred in 2012, the effects of which on microbial communities remain unclear. Alkaline precipitation technology was applied for remediation, but concerns rose about the stability of this technology. To understand the geographic distribution of cadmium and its correlation with microbes, in this study, 39 water samples and 39 sludge samples from this river and 2 soil samples from the nearby farmland were collected for chemical and microbial analyses. The Cd concentrations of all water samples were lower than 0.005 mg/L and reached the quality standards for Chinese surface water. A ranking of sludge samples based on Cd contents showed sewage outfall > dosing sites > farmland, all of which were higher than the quality standard for soil. Alkaline precipitation technology was effective for Cd precipitation. Cd was unstable; it was constantly dissolving and being released from the sludge. The Cd content of each phase was mainly influenced by the total Cd content. Over 40,000 effective sequences were detected in each sample, and a total of 59,833 OTUs and 1,273 genera were found using Illumina MiSeq sequencing. Two phyla and 39 genera were notably positively correlated with the Cd distribution, while the cases of 10 phyla and 6 genera were the opposite.

Identification of low-Cd cultivars of sweet potato (Ipomoea batatas (L.) Lam.) after growing on Cd-contaminated soil: uptake and partitioning to the edible roots

Cadmium (Cd) contamination in agricultural products presents a threat to humans when consumed. Sweet potato is the world's seventh most important food crop. The aims of this study were to screen for low-Cd sweet potato cultivars and clarify the mechanisms of low-Cd accumulation in edible roots. A pot experiment was conducted to investigate the variation of Cd uptake and translocation among 30 sweet potato cultivars grown in contaminated soils with three different Cd concentrations. Cadmium concentrations in edible roots were significantly different among cultivars and were significantly affected by Cd treatment, and the interaction between cultivar and Cd treatment. High-Cd cultivars have higher ratios of edible root/shoot Cd concentration and edible root/feeder root Cd concentration than low-Cd cultivars; however, the ratio of shoot/feeder root Cd concentration seems unrelated to the ability of Cd accumulation in edible roots. Four sweet potato cultivars, Nan88 (No. 10), Xiang20 (No. 12), Ji78-066 (No. 15), and Ji73-427 (No. 16), were identified as low-Cd cultivars. Cadmium translocation from feeder roots to edible roots via the xylem, and from shoots to edible roots via the phloem, controls Cd accumulation in edible roots of sweet potato cultivars.

Renal tubular dysfunction increases mortality in the Japanese general population living in cadmium non-polluted areas

The aim of this study was to establish the cause-effect relationship between renal tubular dysfunction and mortality. A 19-year cohort study was conducted in 900 men and 1313 women in 1993 or 1994 who lived in two cadmium non-polluted areas in Japan. Hazard ratio (HR) and 95% confidence interval (95% CI) of urinary β2-microglobulin (β2-MG) and N-acetyl-β-glucosaminidase (NAG) for mortality were calculated using a proportional hazard regression. Forward stepwise model selection was applied to the potential covariates such as age, body mass index, mean arterial pressure, various lifestyle factors and present illness. Simultaneously, the dose-effect relationship between renal tubular markers and urinary cadmium at baseline was evaluated using multiple regression analyses. In men, HR was significant for β2-MG (HR corresponding to an increase of 100 μg/g cre: 1.02) and NAG (HR corresponding to an increase of 1 IU/g cre: 1.05). In women, a significant HR was observed for β2-MG (HR corresponding to an increase of 100 μg/g cre: 1.01) and NAG (HR corresponding to an increase of 1 IU/g cre: 1.02). Dose-effect relationships were significant for urinary cadmium and all renal tubular markers in men and women. The present study indicated that renal tubular dysfunction was significantly related to mortality in the general population of cadmium non-polluted areas in Japan.

Cadmium exposure and clinical cardiovascular disease: a systematic review

Mounting evidence supports that cadmium, a toxic metal found in tobacco, air and food, is a cardiovascular risk factor. Our objective was to conduct a systematic review of epidemiologic studies evaluating the association between cadmium exposure and cardiovascular disease. Twelve studies were identified. Overall, the pooled relative risks (95% confidence interval) for cardiovascular disease, coronary heart disease, stroke, and peripheral arterial disease were: 1.36 (95% CI: 1.11, 1.66), 1.30 (95% CI: 1.12, 1.52), 1.18 (95% CI: 0.86, 1.59), and 1.49 (95% CI: 1.15, 1.92), respectively. The pooled relative risks for cardiovascular disease in men, women and never smokers were 1.29 (1.12, 1.48), 1.20 (0.92, 1.56) and 1.27 (0.97, 1.67), respectively. Together with experimental evidence, our review supports the association between cadmium exposure and cardiovascular disease, especially for coronary heart disease. The number of studies with stroke, heart failure (HF) and peripheral arterial disease (PAD) endpoints was small. More studies, especially studies evaluating incident endpoints, are needed.

Cadmium exposure and its health effects: a 19-year follow-up study of a polluted area in China

BACKGROUND

Dayu County, which is located in southwestern Jiangxi Province in China, has been a cadmium (Cd)-contaminated area since the 1960s. A series of studies about Cd pollution were carried out in the 1980s. However, no further studies of the area were conducted during the following 19 years.

AIM

To observe cadmium (Cd) exposure levels and its health risks among residents living in contaminated areas that have been exposed to environmental cadmium pollution for 45 years.

METHODS

Subjects involved in the survey in 1987 were interviewed again in 2006. Rice and urine samples from surviving subjects were collected to assess the level of cadmium exposure. Urinary Cd (U-Cd), urinary β2-microglobulin (U-β2-M) and urinary N-acetyl-β-d-glucosaminidase (U-NAG) were used as biomarkers to evaluate renal function. A medical examination was also performed on all subjects to diagnose clinical symptoms of Cd-exposure.

RESULT

Of the 96 subjects of the 1987 study who were alive in 2006, a total of 76 subjects were successfully recruited to this study. The average cadmium concentration in rice from the exposed areas was 0.59 ± 0.41 mg/kg in 2006, the average concentration of U-Cd, U-β2-M and U-NAG from cadmium-exposed areas was 25.82 ± 0.20 μg/g Cr, 6525.71 ± 0.93 μg/g Cr and 13.65 ± 0.24 μmol/g Cr, respectively, in 2006. Compared with the 1987 results, the 2006 results showed that the U-β2-M level in the exposed areas increased significantly after 19 years (p<0.05). The levels of U-Cd and U-NAG did not significantly change over time.

CONCLUSION

The concentration of Cd in polluted areas in 2006 is higher than it was in 1987. Renal dysfunction has worsened after 45 years of continuous exposure. Thus, environmental protection and special procedures to remove cadmium in these areas require urgent consideration.

Cadmium contamination of agricultural soils and crops resulting from sphalerite weathering

The biogeochemistry and bioavailability of cadmium, released during sphalerite weathering in soils, were investigated under contrasting agricultural scenarios to assess health risks associated with sphalerite dust transport to productive soils from mining. Laboratory experiments (365 d) on temperate and sub-tropical soils amended with sphalerite (<63 μm, 0.92 wt.% Cd) showed continuous, slow dissolution (0.6-1.2% y(-1)). Wheat grown in spiked temperate soil accumulated ≈38% (29 μmol kg(-1)) of the liberated Cd, exceeding food safety limits. In contrast, rice grown in flooded sub-tropical soil accumulated far less Cd (0.60 μmol kg(-1)) due to neutral soil pH and Cd bioavailability was possibly also controlled by secondary sulfide formation. The results demonstrate long-term release of Cd to soil porewaters during sphalerite weathering. Under oxic conditions, Cd may be sufficiently bioavailable to contaminate crops destined for human consumption; however flooded rice production limits the impact of sphalerite contamination.

Cadmium(II) complex formation with cysteine and penicillamine

The complex formation between cadmium(II) and the ligands cysteine (H(2)Cys) and penicillamine (H(2)Pen = 3,3'-dimethylcysteine) in aqueous solutions, having C(Cd(II)) approximately 0.1 mol dm(-3) and C(H(2)L) = 0.2-2 mol dm(-3), was studied at pH = 7.5 and 11.0 by means of (113)Cd NMR and Cd K- and L(3)-edge X-ray absorption spectroscopy. For all cadmium(II)-cysteine molar ratios, the mean Cd-S and Cd-(N/O) bond distances were found in the ranges 2.52-2.54 and 2.27-2.35 A, respectively. The corresponding cadmium(II)-penicillamine complexes showed slightly shorter Cd-S bonds, 2.50-2.53 A, but with the Cd-(N/O) bond distances in a similar wide range, 2.28-2.33 A. For the molar ratio C(H(2)L)/C(Cd(II)) = 2, the (113)Cd chemical shifts, in the range 509-527 ppm at both pH values, indicated complexes with distorted tetrahedral CdS(2)N(N/O) coordination geometry. With a large excess of cysteine (molar ratios C(H(2)Cys)/C(Cd(II)) >or= 10), complexes with CdS(4) coordination geometry dominate, consistent with the (113)Cd NMR chemical shifts, delta approximately 680 ppm at pH 7.5 and 636-658 ppm at pH 11.0, and their mean Cd-S distances were 2.53 +/- 0.02 A. At pH 7.5, the complexes are almost exclusively sulfur-coordinated as [Cd(S-cysteinate)(4)](n-), while at higher pH, the deprotonation of the amine groups promotes chelate formation. At pH 11.0, a minor amount of the [Cd(Cys)(3)](4-) complex with CdS(3)N coordination is formed. For the corresponding penicillamine solutions with molar ratios C(H(2)Pen)/C(Cd(II)) >or= 10, the (113)Cd NMR chemical shifts, delta approximately 600 ppm at pH 7.5 and 578 ppm at pH 11.0, together with the average bond distances, Cd-S 2.53 +/- 0.02 A and Cd-(N/O) 2.30-2.33 A, indicate that [Cd(penicillaminate)(3)](n-) complexes with chelating CdS(3)(N/O) coordination dominate already at pH 7.5 and become mixed with CdS(2)N(N/O) complexes at pH 11.0. The present study reveals differences between cysteine and penicillamine as ligands to the cadmium(II) ion that can explain why cysteine-rich metallothionines are capable of capturing cadmium(II) ions, while penicillamine, clinically useful for treating the toxic effects of mercury(II) and lead(II) exposure, is not efficient against cadmium(II) poisoning.

Lack of correlation between cadmium level in local brown rice and renal failure mortality among the residents: a nation-wide analysis in Japan

OBJECTIVES

Cadmium is a ubiquitous hazardous element with nephro-toxicity after long-term exposure. The present study was initiated to examine possible effects of dietary cadmium (Cd) intake on health of local residents across Japan. For this purpose, Cd in locally harvested brown rice (Cd-BR) was taken as the parameter of Cd exposure, and two measures of mortality, i.e., standardized mortality ratio (SMR) and age-adjusted renal insufficiency mortality rate (AARIMR) were employed as parameters of over-all health effects including effects on kidney.

METHODS

Japan consists of 47 prefectures. Data on Cd in 37,250 brown rice samples harvested in 1997-1998 in the 47 prefectures were made available from the Ministry of Agriculture, Forestry and Fisheries, Japan. SMR and AARIMR data (for the year 2000) by two genders in the 47 prefectures were cited from publications of the Ministry of Health, Labour and Welfare, Japan. Possible correlation of Cd in brown rice (Cd-BR) with SMR and AARIMR was examined by Poisson regression analysis.

RESULTS

The geometric mean (GM) Cd-BR for Japan as a whole was 0.040 mg/kg with a geometric standard deviation (GSD) of 2.72. Prefectural GM values varied from a low of <0.01 mg/kg to a high of 0.089 mg/kg. Nevertheless, SMR (in a range of 89.9-119.5 for men and 87.1-111.7 for women) did not correlate with Cd-BR significantly. AARIMR (in a range of 5.3-11.9 and 3.2-8.4 for men and women, respectively) tended to decrease as a function of increasing Cd-BR both in men and women, although the correlation was insignificant in both genders.

CONCLUSIONS

No evidence was obtained in the present analysis to suggest that either mortality as a whole or the mortality due to renal failure is affected by dietary intake of Cd in rice.

Regional assessment of cadmium pollution in agricultural lands and the potential health risk related to intensive mining activities: a case study in Chenzhou City, China

The purpose of this study was to assess the extent of cadmium (Cd) contamination in agricultural soil and its potential risk for people. Soils, rice, and vegetables from Chenzhou City, Southern China were sampled and analyzed. In the surface soils, the 95% confidence interval for the mean concentration of Cd varied between 2.72 and 4.83 mg/kg (P < 0.05) in the survey, with a geometric mean concentration of 1.45 mg/kg. Based on the GIS map, two hot spot areas of Cd in agricultural soils with high Cd concentrations were identified to be located around the Shizhuyuan, Jinshiling, and Yaogangxian mines, and the Baoshan and Huangshaping mines, in the center of the city. About 60% of the total investigated area, where the agricultural soil Cd concentration is above 1 mg/kg, is distributed in a central belt across the region. The critical distances, at which the soil Cd concentration were increased by the mining activities, from the mines of the soils were 23 km for the Baoshan mine, 46 km for the Huangshaping mine, and 63 km for the Shizhuyuan mine, respectively. These are distances calculated from models. The Cd concentrations in rice samples ranged from 0.01 to 4.43 mg/kg and the mean dietary Cd intake from rice for an adult was 191 microg/d. Results of risk indexes showed that soil Cd concentrations possessed risks to local residents whose intake of Cd from rice and vegetables grown in soils in the vicinity of the mine was 596 microg/d.

Sulfur amino acid deprivation in cadmium chloride toxicity in hepatoma cells

The aim of this study was to investigate the effect of individual sulfur amino acid deprivation in cadmium chloride toxicity. HTC cells were deprived of cystine and/or methionine for 12h and then exposed to CdCl(2) for 12h. HepG2 cells were deprived of cystine for 3 and 5h and exposed to CdCl(2) for 3h. In addition HepG2 cells were deprived of methionine for 12h and then exposed to CdCl(2) for 5 and 12h. Our results indicate that only cystine depletion increased cadmium toxicity in HTC cells but not in HepG2 cells as indicated by the neutral red assay. This effect was due to glutathione depletion as indicated by measurement of intracellular glutathione in HTC cells following deprivation of cystine. Methionine depletion had only a slight effect on the viability of HepG2 cells.

Cadmium exposure aggravates mortality more in women than in men

This study aimed to examine whether the mortality associated with exposure to cadmium (Cd) differs between the sexes. Target subjects were 14,604 (6,944 men, 7,660 women) from a list of all residents in the Jinzu River basin in 1967 and 1968. Trend of proportion of the population aged 70 years and older was significantly higher in women in the following decreasing order: non-Jinzu River basin, a region receiving a mixed water supply, and the Jinzu River basin. Sex ratios (proportions of population of men to that of women) in those aged 70 years and older became significantly higher in the same order. This tendency was compatible with the geographical distribution of the prevalence of abnormal urinary findings and Cd concentration in rice which was grown and consumed in the area. This study revealed that Cd exposure aggravates mortality more in women than in men.

The early responses of Arabidopsis thaliana cells to cadmium exposure explored by protein and metabolite profiling analyses

To get more insight into plant cell response to cadmium (Cd) stress, both proteomic and metabolomic "differential display" analyses were performed on Arabidopsis thaliana cells exposed to different concentrations of the toxic chemical. After a 24 h treatment, soluble proteins extracted from untreated and treated cells were separated by 2-D-PAGE and image analyses were performed to quantify and compare protein levels. Proteins up- and down-regulated in response to Cd were identified by MS and mapped into specific metabolic pathways and cellular processes, highlighting probable activation of the carbon, nitrogen, and sulfur metabolic pathways. For some of these proteins, Northern blot and RT-PCR analyses were performed to test transcript accumulation in response to Cd. In parallel, metabolite profiling analyses by LC coupled to ESI MS were initiated to better characterize the metabolic adaptation to the chemical stress. This study revealed that the main variation at the metabolite level came from the presence of six different families of phytochelatins, in A. thaliana cells treated with Cd, whose accumulation increases with Cd concentrations. Taken together these data provide an overview of the molecular and cellular changes elicited by Cd exposure.

Urinary cadmium and mortality among inhabitants of a cadmium-polluted area in Japan

The influence of cadmium (Cd) body burden on mortality remains controversial. Excess mortality and the dose-response relationship between mortality and urinary cadmium excretion were investigated in this study among environmentally exposed subjects. A 15-year follow-up study was carried out on 3119 inhabitants (1403 men and 1716 women) of the Cd-polluted Kakehashi River basin, whose urinary Cd concentration was examined in a 1981-1982 health impact survey. The mortality risk of high urinary Cd (> or = 10 microg/g Cr) subjects after adjustment for age using Cox's proportional hazard model was higher than that of moderate urinary Cd (< 10 microg/g Cr) subjects in both sexes. When the subjects were divided into five groups according to the amount of urinary Cd (<3, 3-5, 5-10, 10-20, > or = 20 microg/g Cr), the mortality risk was significantly increased among the subjects with urinary Cd > or = 3 microg/g Cr in proportion to the increases in the amount of urinary Cd concentration after adjustment for age, especially in women. Furthermore, special causes of death among high and moderate urinary Cd were investigated, and mortality risk ratio for heart failure, which is a cause of death often diagnosed in cases with a gradual deterioration culminating in death, was significantly increased in both sexes, compared with the moderate urinary Cd subjects. Also, in women the mortality risk for renal diseases in the high urinary Cd subjects was significantly higher than that in the moderate urinary Cd subjects. These results suggest that a causal association between Cd body burden and mortality exists among inhabitants environmentally exposed to Cd but that no special disease may be induced except renal diseases.

Modulation of cadmium chloride toxicity by sulphur amino acids in hepatoma cells

Cadmium is a toxic metal and no effective antidote exists at present. The aim of this study was to examine whether sulphur amino acids, involved in glutathione synthesis, can modulate cadmium toxicity in vitro. Two hepatoma cell lines (HepG2 and HTC cells) were exposed to cadmium chloride (0-100 microM) for 8h in control media or in media containing 1mM of homocysteine, cysteine or cystathionine. Cell viability was then assessed with the neutral red assay. In order to assess the mechanism by which homocysteine and cysteine modulate cadmium toxicity their ability to scavenge reactive oxygen species was determined as well as the potential to increase intracellular glutathione levels. The ability of the sulphur amino acids to prevent cadmium uptake by HTC and HepG2 cells was also assessed. The results indicate that homocysteine and cysteine protect efficiently both cell lines from cadmium chloride toxicity whereas cystathionine protects efficiently HTC cells but not HepG2 cells. This effect was shown to be dependent on the dose of each amino acid and increased protection from cadmium was observed with increasing concentrations of homocysteine and cysteine. Both amino acids prevented the formation of reactive oxygen species only when they were administered together with cadmium chloride. In addition homocysteine and cysteine did not increase intracellular glutathione levels. The results indicate that the mechanism by which sulphur amino acids protect from cadmium toxicity in vitro is due to the reduced uptake of the metal by the cells possibly by direct binding to the -SH group of the amino acids.

A comparative evaluation of the biological effects of environmental cadmium-contaminated control diet and laboratory-cadmium supplemented test diet

This study was designed to examine the effects of a diet contaminated by environmental cadmium on organ/body weight ratio and selected toxicological indices. It was also designed to permit a comparative analysis of the effects of the diet contaminated by environmental cadmium and that of cadmium supplemented diet based on the same parameters. Our results show that even though the cadmium content of the environmental cadmium contaminated diet was 300% less than that of the cadmium supplemented diet, the former caused statistically significant changes in Superoxide dismutase (SOD) activity (P < 0.025), Na+/K+ ATPase activity (P < 0.005) and Malondialdehyde (MDA) level (P < 0.025) when values at the end of 1 month exposure were compared to the values at the end of 3 months exposure. These parameters were altered in the same manner by the cadmium content of the supplemented diet in addition to significant reduction in liver/body weight ratio (P < 0.005) within the exposure periods examined. By virtue of the very close nature of the values of these parameters in rats exposed to the two different diets, it appears that the background cadmium (cadmium from the environment) content of the diets is largely responsible for the observed changes, except in the case of liver/body weight ratio.

Cadmium, lung and prostate cancer: a systematic review of recent epidemiological data

Cadmium (Cd) and its compounds were classified as "carcinogenic to humans (Group 1)" by IARC in 1993. The observation of an increased number of lung cancers in a U.S. cohort of cadmium-exposed workers and the finding of tumors in animals exposed to various cadmium compounds apparently played an important role in this assessment. Since this evaluation, several cohorts of cadmium exposed workers have been updated and some additional data regarding environmental exposure to cadmium and cancer risk have been published. The main purpose of this systematic review was to examine whether inclusion of the studies that were not available for the 1993 evaluation might change the overall assessment of the carcinogenic potential of cadmium compounds. A second objective was to examine whether the recent studies are qualitatively better than the older ones and whether they should receive more weight in this assessment. A third issue was to investigate whether a competing effect between nonmalignant respiratory disease (NMRD) and lung cancer may have affected the results for lung cancer in occupationally exposed cohorts. Overall, considering the results of the most recent studies does not suggest that the effect of cadmium on lung cancer increases with improvement of the study design but points to a lower relative risk in the groups exposed to cadmium in the absence of arsenic and nickel. No evidence was found to support the hypothesis that NMRD represents a competing cause of death reducing the mortality from lung cancer. The association between cadmium exposure and prostate cancer was not confirmed in the latest available updates. Studies in environmentally exposed populations do not indicate an increased relative risk of cancer.

Determination of trace cadmium in rice by flow injection on-line filterless precipitation-dissolution preconcentration coupled with flame atomic absorption spectrometry

A simple, environmentally friendly, cost-effective, and sensitive method was developed for the determination of trace cadmium in rice by flow injection (FI) on-line precipitation preconcentration coupled with flame atomic absorption spectrometry (FAAS). The precipitation preconcentration of trace cadmium was achieved by on-line merging of the sample and ammonia solutions. The resultant precipitates were on-line collected by a knotted reactor (KR) without filtration. A solution of 1 mol L(-1) HNO(3) was employed to dissolve the collected precipitates and to deliver the analyte into the FAAS system for on-line detection. Preconcentration at a sample loading flow rate of 3.8 mL min(-1) for 35 s gave an enhancement factor of 44 and a detection limit (3sigma) of 0.002 microg g(-1) for the solid sample with a sample throughput of 72 h(-1). The precision (RSD, n = 11) was 2.0% at the 4.0 microg L(-1) level. The concentration of cadmium in a certified reference material (GBW 08511, rice flour) by the developed method using simple aqueous standards for calibration was in good agreement with the certified value. The proposed method was also successfully applied to the determination of trace cadmium in locally collected rice samples.

A global perspective on cadmium pollution and toxicity in non-occupationally exposed population

Cadmium is a non-essential element that has high rates of soil to plant transference compared with other non-essential elements, and certain plant species accumulate large amounts of cadmium from low cadmium content soils. In this paper, levels of cadmium found in major food groups are highlighted together with cadmium levels found in liver and kidney samples from non-occupationally exposed populations. Data on human kidney cadmium levels identified recently, including the study in our own laboratory, are compared with older studies. Human-tissue cadmium contents showed large variations among individuals, but sources of the variation remain unknown. Exposure levels of 30-50 microg per day have been estimated for adults and these levels have been linked to increased risk of bone fracture, cancer, kidney dysfunction and hypertension. Increased mortality was found among individuals showing signs of cadmium renal toxicity compared with those without such signs, suggesting that renal toxicity may be an early warning of complications, sub-clinical or clinical morbidity.

Influence of years engaged in agriculture and number of pregnancies and deliveries on mortality of inhabitants of the Jinzu River basin area, Japan

BACKGROUND

The occurrence of itai-itai disease is thought to be affected by such factors as pregnancy, lactation, hormonal disorders, aging, and calcium deficiency.

AIMS

To study the influence of years engaged in agriculture and number of pregnancies and deliveries on the mortality of inhabitants of the Jinzu River basin area, which has been an endemic region for itai-itai disease.

METHODS

From 6,667 participants (3,181 men, 3,486 women; participation rate 93.4%) in the 1967 health survey, 3,639 subjects (1,591 men, 2,048 women) whose years engaged in agriculture were established, and 2,559 women/2,410 women with a known number of pregnancies/deliveries were selected as the target population. These data were confirmed on the basis of self reported replies confirmed afterwards by interview. The survival survey was conducted for 6,127 days from 1 August 1967 to 10 May 1984. Subjects were divided according to three water systems: the Jinzu River, non-Jinzu River, and mixed water system; the influence on mortality of the years engaged in agriculture and the number of pregnancies/deliveries was analysed using a Cox's proportional hazards model according to the water systems.

RESULTS

The mean years engaged in agriculture and mean number of pregnancies/deliveries were not different among the three water systems. Cox's hazard ratios of these parameters to mortality were not statistically significant in the any of the water systems.

CONCLUSIONS

Neither the years engaged in agriculture nor the number of pregnancies/deliveries influenced mortality in subjects living not only in the non-Jinzu River basin but also in the Jinzu River basin using a Cox's proportional hazards model.

Association between total cadmium intake calculated from the cadmium concentration in household rice and mortality among inhabitants of the cadmium-polluted Jinzu River basin of Japan

A follow-up survey was conducted to investigate the relationship between total Cd intake and mortality in the Jinzu River basin for 6128 days among 757 inhabitants who ingested household rice. When the subjects were divided into two groups, standardized mortality ratios (SMRs) were 0.94 in men and 1.36 in women for the > or = 2.0 g group and 0.68 in men and 0.29 in women for the <2.0 g group (significant in the women). Cox's hazard ratios for men, women, and men+women for the > or = 2.0 g group relative to those in the <2.0 g group were 1.406, 3.955 and 1.950 (significant in the men+women). Using total Cd intake as a continuous variable, the hazard ratios were 1.045, 1.146 and 1.049 in men, women, and men+women (significant in the women), respectively. In the Jinzu River basin, increased total Cd intake appears to exert an adverse influence on life prognosis.

Metals and women's health

There is a lack of information concerning whether environmental-related health effects are more or less prevalent or manifested differently in women compared to men. Previously, most research in the area of toxicology and environmental and occupational health involved male subjects. The present work aims at reviewing exposure and health effects of cadmium, nickel, lead, mercury, and arsenic manifested differently in women than in men. The gender difference in exposure to nickel results in a much higher prevalence of nickel allergy and hand eczema in women than in men. The internal cadmium dose is generally higher in women than in men, due to a higher gastro-intestinal absorption at low iron stores. This was probably one major reason why Itai-itai disease was mainly a woman's disease. Yet, data are sparse regarding the risk for women relative to men to develop cadmium-induced kidney damage in populations exposed to low levels of cadmium. Lead is accumulated mainly in bone and increased endogenous lead exposure has been demonstrated in women during periods of increased bone turnover, e.g., menopause. Both lead and mercury exposure in pregnant women has to be kept low in order to prevent neurodevelopment effects in the developing fetus and child. Limited data indicate that women are more affected than men following exposure to methylmercury at adult age, while males seem to be more sensitive to exposure during early development. Regarding arsenic, some data indicate gender differences in the biotransformation by methylation, possibly also in susceptibility to certain arsenic-related cancers. Obviously, gender-related differences in exposure and health effects caused by metals are highly neglected research areas, which need considerable focus in the future.