Cadmium (Cd) has been found as an environmental pollutant in Mae Sot district, Tak province, Thailand. Prolong exposure to high levels of Cd of the resident increases high risk of Cd toxicity especially to kidney which is the primary target of Cd. In order to investigate the early effect of Cd induced renal dysfunction, a kidney injury molecule-1 (KIM-1), a novel biomarker of renal tubular dysfunction, was measured using an enzyme linked immunosorbent assay (ELISA). The method was validated and used to quantify the KIM-1 concentrations in the urine of 700 subjects (260 men, 440 women) who lived in the Cd contaminated area. The KIM-1 concentrations were compared to the concentrations of two conventional renal tubular dysfunction biomarkers, N-acetyl-β-D-glucosaminidase (NAG) and β2-microglobulin (β2-MG). Urinary KIM-1 was correlated with urinary and blood Cd as well as NAG. After adjustment of age and smoking, urinary KIM-1 was correlated with blood Cd more than urinary NAG did. Clear dose response relationships of urinary KIM-1 with urinary Cd were shown in both men and women. These results indicate that the urinary KIM-1 might be more sensitive biomarker than urinary NAG and β2-MG for an early detection of renal tubular dysfunction. It is useful as a tool to detect renal effect of toxicity due to chronic Cd exposure at high level.
Flow-volume, spirometric parameters and chest X-ray examinations were obtained in 162 workers exposed to diatomaceous earth dust and in a group of 81 healthy subjects for comparison.The dust contained from 66.5 to 74.1% of SiO2. Smokers were found in 74.5% of the workers and in 77.3% of the control subjects.Pneumoconiosis were found in 18% (27 cases) of the workers by chest X-ray examinations. The grade of their pneumoconiosis were all mild (25 cases of PR1 and 2 cases of PR2).Eight workers were obstructive (FEV1%<70%), one case was constrictive (%VC<80%) and one case showed mixed disorder in spirometry. The mean value of FEV1% in male workers of age-group 50-55 years was lower than that of the control subjects.In flow-volume test, the mean values of V50 in male workers of age-group 50-55 years and in female of age-groups 30-39 and 40-49 years, were lower than those of the control subjects. Furthermore, the mean values of V25 in male and female workers of age-group 40-49 years, were lower than those of the control subjects. Those differences were statistically significant.Nevertheless, mean values of ratios V50/V25 of workers were not different from those of the control subjects by each sex and by age-group.Comparison of pneumoconiosis group (20 cases) and no-finding group (69 cases) in respiratory function tests were not different in male workers of age-group 40-55 years.On the basis of our observations, we recommend the use of the flow-volume parameters (V50 and V25) in respiratory examinations in workers exposed to diatomaceous earth dust.
The effect of blood cadmium (Cd), which reflects not only Cd body burden but also recent Cd exposure and communicates with fetal blood in the placenta, on newborn size at birth was investigated. Blood Cd of 55 mothers from Toyama, Japan, at 30-32 gestational weeks was measured using a flameless atomic absorption spectrophotometer. The relationship between blood Cd and newborn size was analyzed after adjustment for gestational age and maternal build. A significant inverse correlation was found between infant height and maternal blood Cd. After adjustment for gestational age and maternal weight at 30-32 gestational weeks, the significant inverse relationship between maternal blood Cd and infant height was shown using the multiple regression analysis. Newborn size might be influenced by maternal blood Cd levels to which infants may be exposed during gestation.
The strength of the association between smoking and the development of chronic kidney disease (CKD) in the healthy middle-aged working age population has not been established. This was a retrospective 6-year observational study involving 4,121 male and 2,877 female workers who were free of primary kidney disease, diabetes mellitus, severe hypertension, and the signs and symptoms of CKD. Proteinuria was detected by a dipstick method, and glomerular filtration rate (GFR) was estimated by the equation of the Japan Society of Nephrology. Sixty men (1.5 %) and 21 women (0.7 %) developed proteinuria over the 6 years of the study. Irrespective of sex, in comparison with non-smokers, those who continued smoking showed an odds ratio (OR) of 2.52 with a 95 % confidence interval (CI) of 1.50–4.25 for developing proteinuria while those who quit smoking showed an OR of 1.29 (95 % CI 0.48–3.42), following adjustment for confounders. Among the study population, 443 men (10.7 %) and 356 women (12.4 %) developed a GFR of <60 mL/min/1.73 m2, corresponding to stage III CKD. Continuing smokers had a low OR (0.74, 95 % CI 0.60–0.90) for developing a low GFR, as well as a higher mean GFR than non-smokers. The reduction in GFR during the 6-year study period was not different between smokers and non-smokers, but it was larger in those who developed proteinuria than in those who did not, irrespective of smoking. Continuing smokers showed a twofold or more higher risk of developing proteinuria. Discontinuation of smoking substantially reduced the risk. A longer observational period may be required to detect the smoking-induced risk of developing stage III CKD in the middle-aged working population.
We investigated the biological half-life of the urinary cadmium concentration (U-Cd) based on a 24-year follow-up study after cessation of cadmium exposure in a cadmium-polluted area. Spot urine samples were obtained from all inhabitants in this area in 1979, 1986, 1991, 1999 and 2003. Biological half-life was calculated in the inhabitants whose U-Cd was more than 5 microg l(-1) (9 men and 12 women) or 5 microg g(-1) creatinine (9 men and 19 women) using a one-compartment model. The estimated half-life and 95% confidence intervals were 13.6 years (9.0-28.2 years) and 13.9 years (9.6-25.6 years) for unadjusted U-Cd in men and women, respectively. For creatinine-adjusted U-Cd, they were 14.2 years (11.2-19.4 years) and 23.5 years (17.7-35.0 years) in men and women, respectively. The biological half-lives of U-Cd obtained in this study were identical with the values of total body burden determined by a different method.
The study coverd 45 Itai-itai disease patients, 71 suspected patients and 81 inhabitants in three cadmium-polluted areas.These people were considered to be heavily damaged by cadmium.The reference group was comprised of 82 inhabitants in nonpolluted areas.Spot urine samples were collected and analysed for specific gravity, creatinine, amino-N, proline, total protein, glucose, calcium, phosphorous, cadmium, β2-microglobulin, retinol binding, protein and lysozyme.Itai-itai disease patients had high excretions of total protein, glucose, amino-N, proline, calcium, cadmium and low-molecular weight protein (β2-m., R.B.P. and lysozyme). The Ca/P ratio in urine was highest in patients with Itai-itai disease.There were no significant differences in the urinary findings between Itai-itai disease patients and suspected patients.The inhabitants in the three cadmium-polluted areas showed the same abnormal tendency for urinary findings as did the patients with Itai-itai disease.We concluded that the abnormal urinary findings of Itai-itai disease patients are common among the inhabitants of cadmium-polluted areas and give an advanced picture of chronic cadmium poisoning.
