Effects of variations in cadmium and lead levels in river sediments on local foods and body burden of local residents in non-polluted areas in Japan

Synthesis and Characterization of Porous MnCo2O4 for Electrochemical Determination of Cadmium ions in Water Samples

To utilize the maximum activity of nanomaterials, it was specifically synthesized by appropriate physicochemical properties. In that aspect, we have described the synthesis of porous MnCo2O4 by simple chemical route and applied for the selective detection of cadmium (Cd (II)). The as-prepared porous MnCo2O4 was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) adsorption isotherm, X-ray diffraction pattern analysis (XRD), Fourier transform infra-red spectroscopy (FT-IR), energy dispersive X-ray (EDX) and electrochemical techniques. The porous MnCo2O4 exhibited an excellent electrochemical behaviour and good analytical response towards the determination of Cd (II). Those analytical factors such as pH, deposition potential and deposition time are optimized by using differential pulse anodic stripping voltammetry (DPASV). A wide linear concentration range from 2.3 to 120 µg L-1, limit of detection (LOD) of 0.72 µg L-1 and the limit of quantification (LOQ) of 0.91 µg L-1 were achieved for determination of Cd (II). The selectivity of the developed sensor was explored in the presence of co-interfering ions. Also our sensor exhibits a good stability, reproducibility and repeatability. In addition, the practicability of proposed sensor was evaluated for the detection of Cd (II) in real water samples.

Increasing CACNA1C expression in placenta containing high Cd level: an implication of Cd toxicity

Cadmium (Cd) has known to produce many adverse effects on organs including placenta. Many essential transporters are involved in Cd transport pathways such as DMT-1, ZIP as well as L-VDCC. Fourteen pregnant women participated and were divided into two groups: high and low Cd-exposed (H-Cd, L-Cd) groups on the basis of their residential areas, Cd concentrations in the blood (B-Cd), urine (U-Cd), and placenta (P-Cd). The results showed that the B-Cd and U-Cd were significantly increased in H-Cd group (p < 0.05). Interestingly, the P-Cd in H-Cd group was elevated (p < 0.05) and positively related to their B-Cd and U-Cd values (p < 0.05). However, the mean cord blood Cd (C-Cd) concentration in H-Cd group was not significantly increased about 2.5-fold when comparing to L-Cd group. To determine the Cd accumulation in placental tissues, metallothionein-1A (MT-1A) and metallothionein-2A (MT-2A) expressions were used as biomarkers. The results revealed that mean MT-1A and MT-2A mRNAs and MT-1/2 proteins were up-regulated in H-Cd group (p < 0.05). In addition, the Ca channel alpha 1C (CACNA1C) mRNA and protein expressions were noticeably elevated in H-Cd group (p < 0.05). From these findings, we suggested that CACNA1C might be implicated in Cd transport in human placenta.

The cadmium and lead content of the grain produced by leading Chinese rice cultivars

The cadmium (Cd) and lead (Pb) content in both white and wholemeal flour milled from 110 leading rice cultivars was assessed. The white flour Cd content ranged from <0.0025 to 0.2530mg/kg (geometric mean (GM)=0.0150mg/kg), while its Pb content ranged from <0.0250 to 0.3830mg/kg (GM=0.0210mg/kg). The indica types took up higher amounts of Cd and Pb than did the japonica types. Although the heavy metal content of wholemeal flour tended to higher than that of white flour, nevertheless 84.5% (Cd) and 95.4% (Pb) of the entries were compliant with the national maximum allowable concentration of 0.2000mg/kg of each contaminant. An analysis of the Cd content in the white flour of three indica type cultivars grown in two consecutive years at two locations indicated that Cd content may be significantly affected by the conditions prevailing in the growing season.

Selection and characterization of DNA aptamers for the development of light-up biosensor to detect Cd(II)

In order to develop a facile, cost-effective and quick-testing light-up biosensor with excellent specificity for cadmium ions (Cd(II)) detection, a modified selection method based on target-induced release of strands was used to isolate aptamers of Cd (II) with high specificity. Circular Dichroism (CD) data confirmed that one of the selected aptamers underwent a distinct conformational change on addition of Cd (II). A biosensor for Cd(II) was developed based on the Cd(II)-induced release of fluorescence-labeled aptamer from complex with a quencher-labeled short complementary sequence. The sensing platform displayed a Cd(II) concentration-dependent increase of fluorescence intensity in the low micromolar range and had an excellent selectivity in the presence of various interfering metal ions. Such biosensor could potentially be used for the detection of Cd(II) in environmental samples.

Maternal cadmium exposure during pregnancy and size at birth: a prospective cohort study

BACKGROUND

Cadmium (Cd) is an embryotoxic and teratogenic metal in a variety of animal species, but data from humans are limited.

OBJECTIVES

The aim of the present study was to assess the effects of maternal Cd exposure in pregnancy on size at birth.

METHODS

This prospective cohort study was nested in a population-based nutritional supplementation trial in pregnancy conducted in rural Bangladesh. We selected women recruited from February 2002 through January 2003 who had a singleton birth with measurements of size at birth and had donated a urine sample in early pregnancy for Cd analyses (n = 1,616). Urinary Cd was measured with inductively coupled plasma mass spectrometry and adjusted for specific gravity.

RESULTS

Multiple linear regression analyses adjusted for sex and other potential confounders showed that maternal urinary Cd (median, 0.63 μg/L) was significantly negatively associated with birth weight [unstandardized regression coefficient B = -31.0; 95% confidence interval (CI): -59, -2.8] and head circumference (B = -0.15; 95% CI: -0.27, -0.026). However, associations appeared to be limited to girls, with little evidence of effects in boys. A 1-μg/L increase in Cd in maternal urine was associated with a 0.26-cm (95% CI: -0.43, -0.088 cm) and 0.24-cm (95% CI: -0.44, -0.030 cm) decrease in girls' head and chest circumferences, respectively, and a 45-g (95% CI: -82.5, 7.3 g) decrease in birth weight. Quantile regression analyses indicated that associations with maternal Cd were similar for girls of smaller (25th percentile) and larger (50th and 75th percentiles) sizes at birth.

CONCLUSION

We found evidence of a sex difference in the association between maternal Cd exposure and birth size, which was apparent only in girls. Results add support for the need to reduce Cd pollution to improve public health.

Low cadmium levels in urine of residents in two prefectures where cadmium levels in locally harvested brown rice are higher than in other prefectures in Japan

Recent publications in Japan suggest that Cd in river beds and locally harvested rice tend to be higher in seven prefectures in the north-eastern part on the coast of the Sea of Japan (the high-Cd zone). The present study was initiated to investigate the current level of exposure to Cd and possible health effects among local populations in the zone. Thus, levels of Cd and three tubular dysfunction markers [i.e., α(1)-MG, β(2)-MG, and N-acetyl-β-D-glucosaminidase (NAG)] were examined in urine of local residents (700 and 704 adult women, respectively) in two prefectures (prefecture 1 and prefecture 7), which were located in the north-east (prefecture 1) and south-west ends (prefecture 7) of the high-Cd zone. Urinary Cd levels [e.g., 0.99 and 0.78 μg/l as geometric mean (GM) for observed (non-corrected) values, respectively] in prefecture 1 and prefecture 7 were comparable to the levels in other parts of Japan (All Japan-A; 0.99 μg/l). Correspondingly, GM values for α(1)-MG (2.29 and 1.99 mg/l vs. 2.17 mg/l for All Japan-A) and for β(2)-MG (87 and 80 μg/l vs. 99 μg/l for All Japan-A) were not elevated, and NAG also stayed unchanged (2.89 and 2.87 units/l for prefecture 1 and prefecture 7, respectively). Evaluation in combination with the findings in other five prefectures in the zone suggests that Cd exposure is equal to the national average both in prefecture 1 and in prefecture 7, whereas Cd exposure appeared to be elevated in the central part of the zone. The observation appears to be on line with geographical location of the two prefectures that they are on the two ends of the zone of high natural Cd background.

Burden of cadmium in early childhood: longitudinal assessment of urinary cadmium in rural Bangladesh

Chronic cadmium exposure is associated with many adverse health effects in adults, but little is known about the scenario early in life. This study assessed cadmium exposure and body burden in young children, born to women with known cadmium exposure via rice. As part of our ongoing population-based, longitudinal study of health effects of early-life toxicants exposure in rural Bangladesh, we measured cadmium in urine of about 350 children at 1.5 and 5 years of age, and in 92 children at 3 months of age. Median cadmium concentrations in urine were 0.30, 0.16 and 0.30 microg/L at 3 months, 1.5 and 5 years of age, respectively (0.6 microg/L in mothers). Cadmium concentrations in infant's urine correlated with concentrations in maternal breast milk, saliva, and urine. As expected, concentrations in urine increased from 1.5 to 5 years of age. Rice (median 47 microgCd/kg) is most likely the main source of exposure. In conclusion, we found unexpectedly high cadmium exposure among children in rural Bangladesh. Urinary cadmium concentrations were particularly elevated at 3 months of age, indicating limited reabsorption and accumulation of cadmium in the kidneys, known to be the main site of cadmium burden in older children and adults.

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.