Renal dysfunctions of inhabitants in a cadmium-polluted area

Highly Sensitive Detection of Iron Ions in Aqueous Solutions Using Fluorescent Chitosan Nanoparticles Functionalized by Rhodamine B

Detection of iron ions in aqueous solutions is of significant importance because of their important role in the environment and the human body. Herein, a fluorescent rhodamine B-functionalized chitosan nanoparticles probe is reported for the efficient detection of iron ions. The chitosan nanospheres-rhodamine B (CREN) was prepared by grafting rhodamine B onto the surface of chitosan nanospheres through an amidation reaction. The as-prepared CREN fluorescent probes exhibit high fluorescence intensity under ultraviolet light. When iron ions are added to the CREN solution, they can be coordinated with weak-field ligands such as N and O on the surface of chitosan nanoparticles (CSNP) by a high-spin method. The self-assembly of Fe³⁺ on the surface of the CREN led to the generation of single electrons and the presence of high paramagnetism, resulting in fluorescence quenching. The quenching effect of Fe³⁺ on the CREN fluorescent probe can achieve the efficient detection of Fe³⁺, and the detection limit reaches 10^-5 mol/mL. Moreover, this fluorescence quenching effect of Fe³⁺ on the CREN fluorescent probe is specific, which could not be disturbed by other metal ions and counteranions.

Chronic kidney disease of unknown origin is associated with environmental urbanisation in Belfast, UK

Chronic kidney disease (CKD), a collective term for many causes of progressive renal failure, is increasing worldwide due to ageing, obesity and diabetes. However, these factors cannot explain the many environmental clusters of renal disease that are known to occur globally. This study uses data from the UK Renal Registry (UKRR) including CKD of uncertain aetiology (CKDu) to investigate environmental factors in Belfast, UK. Urbanisation has been reported to have an increasing impact on soils. Using an urban soil geochemistry database of elemental concentrations of potentially toxic elements (PTEs), we investigated the association of the standardised incidence rates (SIRs) of both CKD and CKD of uncertain aetiology (CKDu) with environmental factors (PTEs), controlling for social deprivation. A compositional data analysis approach was used through balances (a special class of log contrasts) to identify elemental balances associated with CKDu. A statistically significant relationship was observed between CKD with the social deprivation measures of employment, income and education (significance levels of 0.001, 0.01 and 0.001, respectively), which have been used as a proxy for socio-economic factors such as smoking. Using three alternative regression methods (linear, generalised linear and Tweedie models), the elemental balances of Cr/Ni and As/Mo were found to produce the largest correlation with CKDu. Geogenic and atmospheric pollution deposition, traffic and brake wear emissions have been cited as sources for these PTEs which have been linked to kidney damage. This research, thus, sheds light on the increasing global burden of CKD and, in particular, the environmental and anthropogenic factors that may be linked to CKDu, particularly environmental PTEs linked to urbanisation.

Is Urinary Cadmium a Biomarker of Long-term Exposure in Humans? A Review

Cadmium is a naturally-occurring element, and humans are exposed from cigarettes, food, and industrial sources. Following exposure, cadmium accumulates in the kidney and is slowly released into the urine, usually proportionally to the levels found in the kidneys. Cadmium levels in a single spot urine sample have been considered indicative of long-term exposure to cadmium; however, such a potentially exceptional biomarker requires careful scrutiny. In this review, we report good to excellent temporal stability of urinary cadmium (intraclass correlation coefficient 0.66-0.81) regardless of spot urine or first morning void sampling. Factors such as changes in smoking habits and diseases characterized by increased excretion of proteins may produce short-term changes in urinary cadmium levels. We recommend that epidemiologists use this powerful biomarker in prospective studies stratified by smoking status, along with thoughtful consideration of additional factors that can influence renal physiology and cadmium excretion.

A biomarker found in cadmium exposed residents of Thailand by metabolome analysis

First, the urinary metabolic profiling by gas chromatography-mass spectrometry (GC-MS), was performed to compare ten cadmium (Cd) toxicosis cases from a Cd-polluted area in Mae Sot (Thailand) with gender-matched healthy controls. Orthogonal partial list square-discrimination analysis was used to identify new biomarker candidates in highly Cd exposed toxicosis cases with remarkable renal tubular dysfunction. The results of the first step of this study showed that urinary citrate was a negative marker and myo-inositol was a positive marker for Cd toxicosis in Thailand. In the second step, we measured urinary citrate in the residents (168 Cd-exposed subjects and 100 controls) and found significantly lower levels of urinary citrate and higher ratios of calcium/citrate and magnesium/citrate, which are risk factors for nephrolithiasis, in highly Cd-exposed residents. Additionally, this inverse association of urinary citrate with urinary Cd was observed after adjustment for age, smoking and renal tubular dysfunction, suggesting a direct effect of Cd on citrate metabolism. These results indicate that urinary citrate is a useful biomarker for the adverse health effects of Cd exposure in a Thai population with a high prevalence of nephrolithiasis.

Blood translation elongation factor-1δ is a novel marker for cadmium exposure

Translation elongation factor-1δ (TEF-1δ) has been identified as a novel cadmium-responsive proto-oncogene. However, it is still unclear whether TEF-1δ could be a potential biomarker of cadmium exposure. Rats were treated with CdCl₂ at different concentrations (high dose 1.225, mid-dose 0.612 and low dose 0.306 mg/kg body weight, respectively) for 14 weeks, and the cadmium levels, weight coefficients, serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), blood urea nitrogen (BUN), serum creatinine (SCR), 24-h urine protein (24hPro), urinary creatinine (Cr) and pathological features were determined. The TEF-1δ expression in white blood cells and multiple organs were examined by reverse transcription polymerase chain reaction (PCR) and were also confirmed with fluorescence quantitative PCR. A cadmium dose-dependent increase (p < 0.05) of cadmium levels in blood, urine, liver, kidney, heart and lung, and the weight coefficients was observed. The liver and renal function indictors including AST, ALT, SCR, BUN and 24hPro, were elevated in a cadmium dose-dependent manner (p < 0.05). Significant pathological changes in liver, kidney, heart and lung were indicated. The TEF-1δ expression was up-regulated in both blood and organs (p < 0.05). Moreover, the expression level of blood TEF-1δ was positively correlated to TEF-1δ expression level, cadmium level and toxicity in the organs (p < 0.01). This study indicates that blood TEF-1δ is a novel valuable biomarker for cadmium exposure and its organ toxicity.

Mechanism of cadmium-induced cytotoxicity on the ZFL zebrafish liver cell line

The cadmium ion (Cd²⁺) is a highly toxic metal ion; however, its hepatic toxic effects are not very well characterized in a systematic manner. In this study, a zebrafish liver cell line, ZFL was used as a model to investigate the mechanism of Cd²⁺-induced cytotoxicity on hepatocytes. The intracellular level of reactive oxygen species decreased following the administration of Cd²⁺; antioxidant levels and related enzyme activities and gene expression were detected, showing that the toxic effects of Cd²⁺ might not be coupled to oxidative stress. To understand the cytotoxic effects of Cd²⁺ on ZFL cells after Cd²⁺ exposure, a total of 77 differentially expressed proteins were detected by two-dimensional gel electrophoresis; 43 of them were further identified by MALDI-TOF-MS. The proteins that responded to Cd²⁺ in ZFL cells were related to stress response, transporters, regulation of transcription, redox homeostasis, or different signaling pathways, with half of these proteins having metal ion binding capabilities.

Changes in renal tubular and glomerular functions and biological Acid-base balance after soil replacement in Cd-polluted rice paddies calculated with a general linear mixed model

Using a general linear mixed model, we conducted a 10-year follow-up investigation of 29 persons requiring observation in the cadmium (Cd)-polluted Kakehashi River basin to determine serial changes in biological parameters after removal of Cd-polluted soil present in rice paddies. In particular, we investigated changes in urinary Cd, urinary total protein, biological acid-base balance based on arterial blood pH, carbon dioxide tension (Pa(CO2)), base excess (BE), serum chloride ion (SCl(-)), and renal glomerular function based on serum creatinine (SCr) and creatinine clearance (C(Cr)). In both sexes, urinary Cd concentrations decreased and total protein concentrations increased with increasing number of years elapsed, with the partial regression coefficients statistically significant in the women. Partial regression coefficients showed positive values for SCl(-), with statistical significance in both sexes. The value for Pa(CO2) was significantly negative in men. Given the serial changes in arterial blood pH, Pa(CO2), BE, SCl(-), it is suggested that the biological acid-base balance will progress to metabolic acidosis with hyperchloremia. Moreover, glomerular dysfunction as indicated by an increase in SCr and a decrease in C(Cr) will continue to progress even after soil replacement. Interventions such as soil replacement appear to be too late to prevent progressive renal failure in Cd-exposed populations.

Health risks related to residential exposure to cadmium in Zhenhe County, China

In this study, the authors examined the health risks to 1234 residents (15-80 yr of age) who lived near a lead-zinc mine and to 801 controls (15-80 yr of age) who lived 40 km from the mine. Subjects had higher levels of urinary cadmium, urinary beta2-microglobulin, and N-acetyl-beta-glucosaminidase (NAG) than controls (p < 0.0001), but subjects' urinary beta2-microglobulin and NAG were within normal ranges. Standardized death rates for cancer in the contaminated and control areas were 116.7/100,000 and 90.28/100,000, respectively, and for neonatal disease the respective rates were 89.83/100,000 and 16.74/100,000. Young girls residing in the contaminated areas had higher menstrual abnormalities than did controls (p = 0.002). The prevalence of difficulties in becoming pregnant and the proportion of premature births and stillbirths were higher among those in the contaminated areas (p < 0.0001). Individuals who lived around the lead-zinc mine had different health problems than those who lived far from the mine in Zhenhe County, Republic of China.

Urinary cadmium and serum levels of estrogens and androgens in postmenopausal Japanese women

BACKGROUND

Recent laboratory studies have suggested that cadmium is an estrogenic compound and may be a potential risk factor for breast cancer.

METHODS

We investigated the relationship between urinary cadmium concentrations and serum concentrations of estrone, testosterone, and dehydroepiandrosterone sulfate in 164 postmenopausal Japanese women.

RESULTS

There was a significant positive association between the urinary cadmium and serum testosterone levels after controlling for age and body mass index. The mean testosterone level was 28% higher in women with high urinary cadmium (> or = 3.00 microg/g creatinine) than in those with low urinary cadmium (< 2.00 microg/g creatinine). Urinary cadmium was not significantly associated with serum estrone and dehydroepiandrosterone sulfate levels. Additional adjustment for smoking, alcohol and reproductive factors including known risk factors for breast cancer did not substantially alter the results.

CONCLUSION

Data suggested that cadmium exposure is associated with increased testosterone levels. As high testosterone levels have been associated with the risk of breast cancer, the involvement of cadmium exposure in breast cancer risk should be evaluated in future studies.

Total cadmium intake and mortality among residents in the Jinzu River Basin, Japan

This study investigated the relationship between total cadmium intake and mortality among rural inhabitants of the Jinzu River Basin, Japan. A follow-up survey was conducted for 6,128 days on 3,236 inhabitants. The rural communities were divided into 2 groups, one with a total cadmium intake of < 2.0 gm and the other > or = 2.0 gm. Standardized mortality ratios and a Cox's proportional hazard model indicated mortality risk was greater in the > or = 2.0 gm group, compared with the < 2.0 gm group. In the Jinzu River Basin, a total cadmium intake > or = 2.0 gm exerts an adverse influence on life prognosis.

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 renal dysfunction and mortality among inhabitants in the region around the Jinzu River basin polluted by cadmium

A follow-up study was conducted on 5725 inhabitants (men 2858, women 2867) in and around the Jinzu River basin to determine the influence of environmental Cd exposure on mortality. In the Jinzu River basin, standardized mortality ratios (SMRs) investigated according to urinary findings (protein, glucose, and protein+glucose) were significantly low in the urinary protein-, glucose-, and protein+glucose-negative groups. SMRs calculated after dividing urinary protein- and glucose-positive status into two levels were lowest in the proteinuria- and glycosuria-negative groups and tended to be high in the higher positive groups. In the Jinzu River basin, Cox's hazard ratios were significantly higher for men and women in the urinary protein, glucose and protein+glucose-positive-groups. In the same analysis where the urinary protein- and glucose-positive subjects were divided into two levels, mortality was demonstrated to be higher in the groups with the greater degrees of proteinuria and glycosuria. In the Jinzu River water system almost all SMRs and Cox's hazard ratios showed statistical significance. This was not the case in the other water systems. Mortality of inhabitants with Cd-induced renal injury is increased in the Jinzu River basin.

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

A follow-up survey on 2101 inhabitants (1566 men, 535 women), who participated in a 1967 health survey and had resided in their present rural community since birth was conducted to determine the influence of environmental cadmium exposure on the mortality of the general population in the Jinzu River basin. The survey was conducted over 6128 days from August 1, 1967 to May 10, 1984. The rural communities were divided into two groups, one with a cadmium concentration in rice of < 0.30 ppm and the other > or = 0.30 ppm. The influence of cadmium concentration in rice on mortality was analyzed using SMRs and a Cox's proportional hazards model. In both sexes, SMRs tended to be greater in the > or = 0.3 ppm group as compared to < 0.3 ppm group. The Cox hazard ratios for males and females in the > or = 0.30 ppm group, to those in the < 0.30 ppm group, were 1.42 and 1.10, respectively (significant in the men). Since the mean cadmium concentration in rice in each rural community was closely related to the development of renal injury, in regions with high cadmium concentrations in rice, the development of renal injury induced by cadmium is believed to be the factor underlying the increased mortality observed.

Dose-response relationship between urinary cadmium concentration and beta2-microglobulinuria using logistic regression analysis

Logistic regression analysis was used to investigate the dose-response relationship for environmental cadmium exposure and to consider the effect age had on this association. The target population comprised 3178 inhabitants of Japan who were more than 50 y of age and who lived in a cadmium-polluted area and 1134 inhabitants who lived in nonpolluted areas of Japan. Logistic regression analysis was completed on the dose-response relationship between urinary cadmium concentration (i.e., an indicator of cadmium body burden) and beta2-microglobulinuria (i.e., an index of renal tubular dysfunction caused by exposure to cadmium). Both age and urinary cadmium concentration were associated significantly with beta2-microglobulinuria. Based on the relationship that was determined, we calculated, by age and sex, the values of urinary cadmium concentration that corresponded to the prevalence rates of beta2-microglobulinuria in the nonpolluted population. The resulting values were 1.6-3.0 micrograms/g creatinine for men and 2.3-4.6 micrograms/g creatinine for women.

Urinary beta 2-microglobulin concentration and mortality in a cadmium-polluted area

A 9-y follow-up study of 3,178 persons who lived in a cadmium-polluted area was conducted to assess the influence of environmental cadmium exposure on long-term outcome. The standardized mortality ratios of the urinary beta 2-microglobulin-positive subjects (> 1,000 micrograms/g creatinine) of both sexes were higher than those of the general Japanese population, whereas the cumulative survival curves were lower than those of the urinary beta 2-microglobulin-negative group. A significant association was also found between urinary beta 2-microglobulin and mortality, using a Cox's proportional hazards model. Moreover, mortality rates increased in proportion to increases in the amount of urinary beta 2-microglobulin excreted. These results suggest that the prognosis for cadmium-exposed subjects with proximal tubular dysfunction is unfavorable. The mortality rate tended to become higher as the severity of renal dysfunction progressed.

Impairment of vitamin D metabolism due to environmental cadmium exposure, and possible relevance to sex-related differences in vulnerability to the bone damage

To determine whether depleted serum 1 alpha,25-dihydroxyvitamin D (VD) concentrations are associated with cadmium (Cd)-induced renal damage, the relationships between four indices of renal function and two indicators of bone metabolism, that is, serum VD and parathyroid hormone (PTH) concentrations, were analyzed in 30 male and 44 female subjects exposed to environmental Cd. Also, these associations were compared in male and female subjects to evaluate sex-related differences in vulnerability to the bone damage observed in Cd-exposed persons. Serum VD decreased significantly with declines in creatinine clearance and percentage tubular reabsorption of phosphate, and with increases in serum creatinine and serum beta 2-microglobulin (beta 2m) concentrations in the female subjects exposed to Cd, but not in the male subjects. The correlation between serum VD and PTH levels was also significant only in the females. Correlation coefficients between serum beta 2m and VD and those between serum PTH and VD in both sexes were significantly different. These results suggest that renal damage due to Cd exposure leads to the decreases in the serum VD level and increases in serum PTH level, and that the more marked changes in serum VD and PTH in the women may play a role in the development of sex-related differences in Cd-induced bone injury.

Parathyroid hormone-stimulated cadmium accumulation in Madin-Darby canine kidney cells

Although most renal cadmium transport occurs in proximal tubules indirect evidence suggests that distal tubules may also transport this heavy metal. Since the distal nephron is the site at which parathyroid hormone (PTH) regulates calcium absorption, we evaluated the effects of PTH on Cd2+ accumulation in Madin-Darby canine kidney (MDCK) cells. MDCK cells express a distal-like phenotype including PTH-sensitive adenylyl cyclase and stimulation of calcium transport. MDCK cells were grown to confluence in phenol red-free Dulbecco's modified Eagle's medium. PTH increased 109CdCl2 accumulation in a concentration-dependent manner over the range of 10(-11)-10(-9) M bPTH[1-34]. At 10(-9) M, PTH increased Cd2+ accumulation maximally by 205%. The PTH antagonist, bPTH[3-34], failed to augment 109Cd2+ accumulation. The dihydropyridine agonist, Bay k 8644, in the presence of PTH, increased 109Cd2+ uptake by 200% over vehicle-treated controls and by approximately 100% over PTH or Bay k 8644 alone. The apparent Km for Bay k 8644 activation was 1.3 microM. Bay k 8644-augmented 109Cd2+ uptake was competitively inhibited by the calcium channel antagonist nifedipine. No voltage dependence of Bay k 8644-amplified 109Cd2+ uptake could be detected. Based on these observations we conclude: (1) MDCK cells accumulate Cd2+; (2) PTH increases Cd2+ uptake into MDCK cells; and (3) Cd2+ entry in kidney epithelial cells is mediated, at least in part, by dihydropyridine-sensitive calcium channels.

Significant increase of urinary mucoprotein in environmental-cadmium-exposed Japanese subjects

Urinary mucoprotein (U-MP) was determined in 169 Japanese environmental-cadmium-exposed and 81 non-exposed subjects. Urinary total protein, albumin, beta 2-microglobulin (beta 2-MG), cadmium (Cd) and creatinine were also measured. Significant increases in U-MP and other proteins were found in the Cd-exposed subjects. Significant correlations between each protein were seen in the Cd-exposed and the total group of subjects. U-MP was highly correlated with urinary beta 2-MG and their correlation coefficient was the highest in the total group of subjects. beta 2-MG was the most sensitive indicator among them to detect Cd-induced renal dysfunction, although beta 2-MG is degraded in urine with a pH less than 5.5 U-MP is an acid-soluble protein. Therefore, U-MP is also available for studies on renal dysfunction caused by exposure to Cd, in conjunction with beta 2-MG.

Long-term observation of serum creatinine and arterial blood pH in persons with cadmium-induced renal dysfunction

Twenty-one subjects who had cadmium (Cd)-induced renal dysfunction and who lived in a Cd-polluted area in Japan were investigated to determine changes in their renal function. Since 1974, serum creatinine and arterial blood pH were measured annually during the autumn months for 9-14 y. Mean serum creatinine was significantly increased during this period, i.e., from 1.19 +/- 1.28 mg/100 ml to 1.68 +/- 1.56 mg/100 ml. Even after cadmium exposure ceased, significant deterioration of glomerular filtration was found. Eleven subjects showed a greater than 20% serum creatinine increase during this period. The most severe case had a serum creatinine value of 4.4 mg/100 ml at the most recent examination and experienced generalized edema, which suggests a clinical diagnosis of renal failure. The mean arterial blood pH values decreased significantly in all subjects, i.e., from 7.400 +/- 0.023 to 7.361 +/- 0.034. The 11 subjects cited above also showed a significant decrease and progression of tubular dysfunction after Cd exposure ceased. Our findings suggest that Cd-induced renal tubular dysfunction and decreased glomerular filtration are aggravated even after cessation of environmental Cd exposure, and in some cases this renal dysfunction may progress to renal failure.

Elevation of urinary trehalase activity in patients of itai-itai disease

The elevation of urinary trehalase activity in patients of itai-itai disease was examined. Urinary trehalase was correlated with tubular reabsorption of phosphorus (%TRP): the lower the trehalase activity, the worse was %TRP. Furthermore, this activity was inversely correlated with urinary glucose and urinary total protein. In itai-itai disease, the excretion of beta 2-microglobulin seems to be maximal, and urinary trehalase activity was low in the latter stages of the disease. It is inferred that itai-itai disease produces extremely severe tubular damage as well as glomerular dysfunction.

Urinary trehalase activity and renal brush-border damage in inhabitants of a cadmium-polluted area (Jinzu River basin)

Elevated urinary trehalase activity was observed in the inhabitants of the Jinzu River basin. Urinary trehalase activity was correlated with other urinalysis components, such as beta 2-microglobulin, glucose, amino nitrogen, and cadmium, of which a high level was observed in cadmium-polluted areas as compared with the reference area. Renal trehalase is specifically localized in tubular brush borders [M. Nakano, J. Histochem. Cytochem., 30 (1982) 1243-1248]. From these results it is inferred that tubular brush-border damage occurs in inhabitants of the Jinzu River basin.

Parathyroid hormone concentration in the serum of people with cadmium-induced renal damage

Serum parathyroid hormone (PTH) and renal functions were measured in thirty subjects with cadmium-induced renal damage and in the same number of control subjects. The negative correlations between PTH and creatinine clearance (Ccr) and between PTH and percentage renal phosphorus reabsorption (% TRP) were significant in the cadmium (Cd)-exposed group. Serum PTH concentrations were clearly high in two cases of the cadmium-exposed group. Their renal functions decreased severely compared with those of the other Cd-exposed people. The present study indicates that chronic cadmium intoxication could cause increased secretions of PTH, which may be related to cadmium-induced bone damage.

Alpha 1-microglobulin in urine as an indicator of renal tubular damage caused by environmental cadmium exposure

Alpha1-Microglobulin (alpha 1-m) was determined in the urine of both the cadmium-exposed and nonexposed subjects and was compared with those of other urinary parameters such as beta 2-microglobulin (beta 2-m), glucose, total protein or amino acids. Large amounts of alpha 1-m were detected in the urine of cadmium-exposed subjects. There were significant correlations between alpha 1-m and other urinary parameters. The sensitivity and specificity of both alpha 1-m and beta 2-m as indices of tubular dysfunction caused by cadmium was similar. It was concluded that alpha 1-m in urine seemed to be a useful indicator of renal tubular dysfunction caused by cadmium.

Copper and zinc levels in serum and urine of cadmium-exposed people with special reference to renal tubular damage

Urinary copper and zinc concentrations and their serum levels were determined in women environmentally exposed to cadmium, including "itai-itai" disease patients and suspected patients, for evaluating the effect of cadmium exposure on metabolism of such essential metals as copper and zinc in human beings. Copper concentrations in the urine of cadmium-exposed women, especially "itai-itai" patients and suspected patients, were much higher than those of nonexposed women. Zinc concentrations in the urine of cadmium-exposed women, however, were not different from those of nonexposed women. Zinc levels in the serum of the "itai-itai" patients were somewhat lower than those of the nonexposed women. On the other hand, serum copper was almost equal in the cadmium-exposed and the nonexposed women. The correlation coefficient between beta 2-microglobulin amounts and copper concentrations in the urine of all women examined was as high as 0.95. It is concluded that exposure to cadmium will cause an increase in the excretion of copper in urine, which is attributable to renal tubular damage due to the cadmium exposure, and that urinary zinc excretion is not increased by cadmium exposure, even in the patients who suffer from severe renal tubular damage.

Urinary N-acetyl-beta-D-glucosaminidase and beta 2-microglobulin in 'itai-itai' disease

N-acetyl-beta-D-glucosaminidase (NAG) activity in urine was measured in patients with 'itai-itai' disease, from chronically advanced cadmium poisoning. Elevation of NAG activity, however, was not so marked as that of beta 2-microglobulin (beta 2-MG) in the urine of patients and suspected patients. We conclude that the beta 2-MG test is more valuable than the NAG test for evaluating the severity of the renal tubular damage in chronically advanced cadmium (Cd) poisoning.

Urinary metallothionein as a new index of renal dysfunction in "Itai-Itai" disease patients and other Japanese women environmentally exposed to cadmium

The significance of elevated excretion of metallothionein in urine of women living in cadmium-polluted areas of Japan was studied with respect to renal dysfunction. The relationships between the concentrations of metallothionein in urine and those of other non-specific urinary indices of renal dysfunction, i.e., total protein, glucose, beta 2-microglobulin, retinol-binding protein, alpha-amino nitrogen and proline were examined. In addition, the relationships between urinary metallothionein and urinary cadmium and copper were also evaluated. It was found that the logarithm of the metallothionein concentration in urine was significantly correlated with the logarithm of the concentrations of each of the above parameters. When subjects with signs of renal dysfunction, including "itai'itai" disease patients and patients suspected of the disease, were compared with subjects with normal renal functions, as a group, the former excreted significantly higher concentrations of metallothionein in their urine than the latter. The results suggest that the elevated excretion of metallothionein is not only an index of excessive cadmium exposure, but also of renal dysfunction caused by chronic exposure to this metal.