Cadmium Content In Rice Research Articles

Spatial autocorrelation analysis of monitoring data of heavy metals in rice in China

The aim of this study was to analyze the spatial distribution of heavy metal monitoring data in paddy rice to provide a scientific basis for food safety risk assessment and suggestions for possible risk management. In this study, the spatial distribution data of heavy metals (cadmium, lead, total arsenic, total chromium, and total mercury) in rice collected in the main production provinces of China were analyzed by multidimensional visualization and aggregation analysis. The spatial correlation of elemental contamination was also identified. Monitoring data of cadmium, lead, and arsenic content in different varieties of rice was compared with their mean confidence intervals. Results showed that cadmium content in rice was higher than the limit value in some areas of Hunan, Sichuan, Guangxi and Anhui Provinces in China. With respect to other heavy metals, a small area of Sichuan Province experienced lead levels in rice higher than the limit value. Also, the arsenic level in rice was higher than the limit value in Jiangxi Province, a northern area of Liaoning Province and most parts of Guangzhou and its surrounding areas. In contrast, chromium was only detected at excessive levels in southern Sichuan Province. In addition, a small part of the eastern Sichuan Province was found to have excessive levels of arsenic. Moran's I index of cadmium, arsenic, chromium, lead, and mercury in rice was 0.50, 0.55, 0.21, 0.09, and 0.05, respectively, which revealed a spatial autocorrelation. Overall, there was moderate aggregation of cadmium and arsenic in the monitoring areas, while lead, chromium and mercury showed low aggregation. Geographically for the provinces, the high aggregation of cadmium in rice was evident in Hunan and Jiangxi Provinces and Guangdong border areas. The arsenic in Jiangxi Province and border areas of Jiangxi and Guangdong Provinces also showed high level of aggregation. Meanwhile, the parameter testing of the samples showed that the concentration of cadmium and lead were significantly higher in late Indica rice compared to early Indica rice, while the arsenic and chromium showed the opposite effect. In view of the high levels of certain heavy metals in rice in some provinces, more refined dietary intake assessments of rice as consumed are necessary to determine if populations are exposed to levels that exceed the health-based guidance levels.

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 26year 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 (+0.1ppm) 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.

Analyzing the role of soil and rice cadmium pollution on human renal dysfunction by correlation and path analysis.

The aim of this study was to investigate the role of soil and rice pollution on human renal dysfunction. The participants were 97 inhabitants (46 men and 51 women) who are aged 50 to 60years old and have been living in Xiaogan (Hubei, China) from birth. We collected samples of soil, rice, and urinary correspondingly. Urinary N-acetyl-β-D-glucosaminidase (NAG) and β-2-microglobulin (β2MG) were used as indicators of renal dysfunction, and urinary cadmium (U-Cd) was used as indicator of total internal cadmium exposure. We made a hypothesis that soil cadmium concentration (S-Cd) and rice cadmium concentration (R-Cd) could be used as indicators of environmental cadmium exposure. Correlation and path analysis were used to estimate the relationships among the levels of rice cadmium (R-Cd), soil cadmium (S-Cd), urinary cadmium (U-Cd), and renal damage indicators (NAG and β2MG). Our results showed that there was positive significant relationship between S-Cd (R-Cd, U-Cd), and U-NAG (U-β2MG). The standard multiple regression describing the relationship between S-Cd (R-Cd, U-Cd) and U-NAG was Y1=1.26X1-6.53X2+9.32, where Y is U-NAG, X1 is U-Cd, X2 is S-Cd. The equation of U-β2MG was Y=49.32X1+3085.99X2+143.42, where Y is U-β2MG, X1 is U-Cd, X2 is R-Cd. It is obvious that the effect of S-Cd and R-Cd on NAG or U-β2MG cannot be ignored. Through our study, we can find that the effects of S-Cd on renal health even as significant as R-Cd. To protect people from the damage of cadmium pollution, it is vital to monitor the situation of soil and rice cadmium pollution.

Cadmium burden and renal dysfunction among residents in cadmium-polluted areas: A 3-year follow-up study

To investigate dynamic change of cadmium body burden and renal dysfunction among residents living in cadmium-polluted areas. From April to July of 2011, the cadmium-polluted areas of northern Guangdong province in China was chosen as the study site. Based on the levels of cadmium pollution in soil and rice, the survey areas were divided into low exposed group (average concentration of cadmium was 0.15-0.40 mg/kg, 0.5-1.0 mg/kg in rice and soil, respectively) and high exposed group (average concentration of cadmium was >0.40 mg/kg, >1.0 mg/kg in rice and soil, respectively). Stratified random sampling and cluster sampling method of epidemiological investigations were carried out among 414 local residents who lived in cadmium exposure areas for more than 15 years, aged above 40, and without occupational cadmium exposure, including 168 and 246 residents in low and high exposed group, respectively. From March to June of 2014, 305 respondents of those who participated in 2011 were successfully traced, including 116 and 189 respondents in low and high exposed group, respectively. We used health questionnaires to acquire their health status. Home-harvested rice and vegetable samples were collected using quartering method for detection of cadmium level, including 190 rice samples, 161 vegetable samples in 2011 and 190 rice samples, 153 vegetable samples in 2014. Urine specimens of residents were collected for the detection of urinary cadmium and creatinine as well as renal dysfunction biomarkers, namely, N-acetyl-beta-D-glucosamidase (NAG) and β2-microglobulin (β2-MG), respectively. In 2011 and 2014, Chi-square test was used to investigate the differences of abnormality of cadmium concentration in rice, vegetables and urinary cadmium, β2-MG, and NAG that were expressed as odds ratio(OR) and 95% confidence intervals (95%CI). In 2011 and 2014, cadmium concentration P50 (P25-P75) in rice was 0.43 (0.17-1.10) mg/kg, and 0.42 (0.20-1.14) mg/kg, respectively (Z=-0.77,P=0.440). In 2011 and 2014, cadmium concentrations P50 (P25-P75) in vegetables were 0.13 (0.07-0.34) mg/kg, and 0.25(0.12-0.59) mg/kg, respectively, with abnormal rates of 38.5%(62/161) and 60.8%(93/153), respectively. In 2014, both average concentration and abnormal rate of cadmium in vegetables were higher than those in 2011 (Z=-4.69, P<0.001 and χ(2)=15.58,P<0.001). Concentrations of urinary cadmium P50 (P25-P75) in high exposed group were 7.90 (3.96-14.91) μg/g creatinine, 8.64 (4.56-17.60) μg/g creatinine in 2011 and 2014, respectively. Contrary to that in 2011, urinary cadmium of high exposed group was significantly increased in 2014 (Z=-2.80, P=0.005). In 2011 and 2014, concentrations of β2-MG, NAG P50 (P25-P75) were 0.15(0.07-0.29) μg/g creatinine, 0.15 (0.07-0.45) μg/g creatinine, and 7.12 (5.05-10.65) U/g creatinine, 13.55(9.1-19.84) U/g creatinine, respectively, with abnormal rates of 7.5% (23/305), 15.1% (46/305), 8.2% (25/305) , and 33.8% (103/305), respectively. Compared with baseline in 2011, average concentrations of β2-MG, NAG significantly increased in 2014 (Z=-2.263, P=0.024 and Z=-12.52, P<0.001), and abnormal rates of β2-MG, NAG were also higher in 2014 (χ(2)=15.61 , P<0.001 and χ(2)=64.72, P<0.001), with odds ratio(OR) of 2.00 (95%CI:1.23-3.24) and 4.12 (95%CI:2.87-5.92). Environmental cadmium pollution of crops such as rice and vegetables in survey areas continued to remain high. Body burden of cadmium might kept at sustainably high levels and renal dysfunction was worsened after continuous, long-term cadmium exposure. Our results suggested that NAG might be more sensitive than β2-MG to serve as an indicator for an individual's future tubular function.

Effects of alkaline fertilizer on cadmium content in rice and paddy soil.

A field plot trial was conducted at Songbai Village, Chenzhou, Hunan Province to exa-mine the effects of alkaline fertilizer with and without combination application of bacterial regent on cadmium accumulation in rice and paddy soil. Compared with the conventional fertilizer, the alkaline fertilizer reduced the available cadmium content in soil at the tillering, filling and the harvest stages by 8.3%, 6.7% and 16.4% respectively. Compared with the Cd content in soil before transplanting, it was reduced by 7.2% at harvest time in alkaline fertilizer treatment, while increased by 11.0% in the conventional fertilizer treatment. The available cadmium content in soil was increased by 1.2% to 23.3% by bacterial regent. Compared with the conventional fertilizer, the cadmium content of root, stem sheath, leaf, grain and brown rice of the alkaline fertilizer treatment reduced by 54.9%, 56.6%, 41.8%, 62.7% and 67.6% respectively. The alkaline fertilizer treatment combined with bacterial regent increased the cadmium content of brown rice by 63.2%. It was concluded that the alkaline fertilizer could significantly reduce the available cadmium content in both soil and the different organs of the rice, however, when it was combined with bacterial regent together, the effect of alkaline fertilizer to reduce Cd content of brown rice would be declined.

Sudy on Determination of Cadmium Content in Rice

Wavelet function using a variety of experimental spectral decomposition of the image area, the results show that the spectral fractal dimension db series db5 wavelet decomposition of the third layer is the most stable and reliable signal. And cadmium contamination levels in two different areas of Changchun area, for example, on the Hyperion image wavelet decomposition to obtain details of the signal spectrum fractal dimension map, identifying the extent of a wide range of rice cadmium pollution stress. This method is rapid, macro, accurate monitoring of cadmium contamination of rice provides a convenient way.

Benchmark dose of cadmium concentration in rice for renal effects in a cadmium‐polluted area in Japan

The aim of this study was to estimate the reference level of cadmium in rice as the benchmark doses (BMD) and their 95% lower confidence limits (BMDL) for various renal effects by applying an updated hybrid approach. The participants were 1120 men and 1274 women aged 50 years or older who lived in the environmentally exposed Kakehashi river basin for at least 30 years. As indicators of renal dysfunction, glucose, protein, aminonitrogen, metallothionein and β(2) -microgrobulin in urine were measured. Cadmium concentration was determined for rice samples stored in warehouses of the farmers in all of the polluted hamlets. The BMD and BMDL that corresponded to an additional risk of 5% were calculated with background risk at a zero exposure set at 5%. The obtained BMDLs were 0.39 (aminonitrogen), 0.26 (metallothionein), 0.25 (β(2) -microgrobulin) mg kg(-1) in men and 0.44 (glucose), 0.32 (protein), 0.33 (aminonitrogen), 0.28 (metallothionein) and 0.24 (β(2) -microgrobulin) mg kg(-1) in women. The lowest BMDL was 0.25 and 0.24 mg kg(-1) (β(2) -microgrobulin) in men and women respectively. These values were lower than the maximum level (0.4 mg kg(-1)) determined by the Codex Alimentarius Commission, indicating that these BMDLs may contribute to further discussion on the health risk assessment of cadmium exposure.

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

BackgroundDayu 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 19years. AimTo observe cadmium (Cd) exposure levels and its health risks among residents living in contaminated areas that have been exposed to environmental cadmium pollution for 45years. MethodsSubjects 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. ResultOf 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±0.41mg/kg in 2006, the average concentration of U-Cd, U-β2-M and U-NAG from cadmium-exposed areas was 25.82±0.20μg/g Cr, 6525.71±0.93μg/g Cr and 13.65±0.24μmol/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 19years (p<0.05). The levels of U-Cd and U-NAG did not significantly change over time. ConclusionThe concentration of Cd in polluted areas in 2006 is higher than it was in 1987. Renal dysfunction has worsened after 45years of continuous exposure. Thus, environmental protection and special procedures to remove cadmium in these areas require urgent consideration.

Current Status of Cadmium Exposure among Japanese, Especially Regarding the Safety Standard for Cadmium Concentration in Rice and Adverse Effects on Proximal Renal Tubular Function Observed in Farmers Exposed to Cadmium through Consumption of Self-Grown Rice

Because the staple food in Japan is rice, which absorbs cadmium (Cd) from the soil efficiently, rice is the main source of exposure to Cd in the Japanese population. In addition, there have been many Cd-contaminated farming areas in Japan. Therefore, a safety standard for the Cd concentration in rice was set as 0.4 ppm by the Japanese government. This safety standard has been followed for decades without any appropriate scientific or legal basis. However, recent epidemiological studies of female Japanese farmers exposed to Cd through self-grown rice, that is, a series of Japanese Multi-centered Environmental Toxicant Study (JMETS), showed evidence that the safety standard is appropriate. Therefore, general Japanese consumers are unlikely exposed to Cd excessively with the application of this safety standard, considering the trend of decreasing amount of rice consumed among the Japanese population. On the other hand, Japanese farmers were found to be at risk of Cd exposure through the consumption of self-grown rice with a high Cd concentration. Actually, the JMETS showed that female farmers at 70 years of age or older had a decreased proximal renal tubular function due to the high renal accumulation of Cd. On the basis of these findings, "medical examinations for Cd exposure" have recently been implemented for farmers residing in Cd-polluted areas in northern Japan. Because it has been estimated that such Cd-polluted areas are actually larger, it is necessary to implement medical examinations of more farmers there, particularly the elderly.

Estimation of cadmium concentrations in rice grown in soils with low levels of cadmium and the risk simulation of Cd contamination

Estimation of cadmium concentrations in rice grown in soils with low levels of cadmium and the risk simulation of Cd contamination

Cadmium availability and accumulation by lettuce and rice

Among the toxic elements, Cd has received considerable attention in view of its association with a number of human health problems. The objectives of this study were to evaluate the Cd availability and accumulation in soil, transfer rate and toxicity in lettuce and rice plants grown in a Cd-contaminated Typic Hapludox. Two simultaneous greenhouse experiments with lettuce and rice test plants were conducted in a randomized complete block design with four replications. The treatments consisted of four Cd rates (CdCl2), 0.0; 1.3; 3.0 and 6.0 mg kg-1, based on the guidelines recommended by the Environmental Agency of the State of São Paulo, Brazil (Cetesb). Higher Cd rates increased extractable Cd (using Mehlich-3, Mehlich-1 and DTPA chemical extractants) and decreased lettuce and rice dry matter yields. However, no visual toxicity symptoms were observed in plants. Mehlich-1, Mehlich-3 and DTPA extractants were effective in predicting soil Cd availability as well as the Cd concentration and accumulation in plant parts. Cadmium concentration in rice remained below the threshold for human consumption established by Brazilian legislation. On the other hand, lettuce Cd concentration in edible parts exceeded the acceptable limit.

Relationship between environmental exposure to cadmium and bone metabolism in a non-polluted area of Japan.

The purpose of this study was to investigate the effects of environmental low-grade cadmium exposure on bone in the population of a non-polluted area. We investigated the relationship between environmental cadmium exposure (via rice intake) and bone metabolism in middle-aged and elderly women living in a non-polluted area in Japan. Four hundred and twenty-nine women over the age of 39years (54.6±9.1years; arithmetic mean±SD) participated in this study in 2003. We investigated blood and urine, and rice intake, and performed ultrasonic bone evaluation, and obtained individual information about the subjects' health. Multiple regression analysis was performed in the statistical analysis. The arithmetic mean of cadmium content in rice was 70.8±44.7μg/kg (AM±SD). The geometric mean of daily cadmium intake (Cd intake) from rice calculated based on food consumption data was 9.12μg/day (GSD 2.33). The geometric means of serum and urine cadmium concentrations were 1.57μg/l (GSD 2.11) and 1.93μg/g creatinine (cr.) (GSD 2.05), respectively. Multiple regression analysis showed positive correlations between (1) urinary free deoxypyridinoline (FDPD-U) and Cd intake (p<0.05), (2) urinary cross-linked N-telopeptides of type I collagen (NTx-U) and Cd intake (p<0.05), and (3) FDPD-U or NTx-U and cadmium concentration in urine (p<0.01). No significant correlation between the parameters of ultrasonic bone evaluation and cadmium associated biomarkers was observed. The results of the present study suggest the possibility of bone metabolic disorder induced by environmental low-grade cadmium exposure. With respect to osteoporosis, a long-term follow-up survey is required to assess the tolerable intake of cadmium in environmental exposure.

Analysis of QTL for lowering cadmium concentration in rice grains from 'LAC23'

Quantitative trait loci (QTLs) for low cadmium concentration in brown rice were analyzed in 2008 and 2009 using 126 RIL (F6 and F7 plants) grown in a paddy field with high Cd concentration, which were derived from a cross between a high yielding Japanese rice cultivar ‘Fukuhibiki’ and an African upland rice cultivar ‘LAC23’ with the lowest cadmium concentration in rice grains. Totally two QTLs controlling low cadmium concentration in grains were identified in both 2008 and 2009, i.e., one on chromosome 3 (qLCdG3) and one on chromosome 11 (qLCdG11), which had opposite additive effects. In qLCdG11, ‘LAC23’ alleles had the effect of reducing cadmium concentration, but qLCdG3 had the opposite effect. The explained phenotypic variances of qLCdG11 were 9.4% in 2008 and 12.9% in 2009, and those of qLCdG3 were 13.9% in 2008 and 8.3% in 2009. Cadmium concentrations in brown rice showed positive correlations with grain length and grain weight. QTLs for grain length and grain weight were detected on chromosomes 3 and 11, but their positions differed from those for cadmium concentrations. These results suggest a possibility of successful marker-assisted selection of low cadmium trait derived from ‘LAC23’.

Latest status of cadmium accumulation and its effects on kidneys, bone, and erythropoiesis in inhabitants of the formerly cadmium-polluted Jinzu River Basin in Toyama, Japan, after restoration of rice paddies

The cadmium-polluted Jinzu River Basin in Toyama, Japan, where nephropathy and itai-itai disease were endemic among resident farmers decades ago, has been almost completely restored. The aim of this study is to investigate whether inhabitants there would still exhibit cadmium accumulation and its effects on kidneys, bones, and erythropoiesis. We performed a cross-sectional study of 150 subjects from the polluted area and 144 controls from the same prefecture. Participants included female inhabitants from 34 to 74years of age who underwent examinations to gather anthropometrical and medical information, obtain rice, blood and urine samples, and measure bone mineral density. Cadmium concentration in rice from the polluted area was lower than the level in the control area. Blood and urinary cadmium and urinary β(2)-microglobulin levels were higher in subjects from the polluted area than controls, and the urinary β(2)-microglobulin was independently affected by urinary cadmium. Bone mineral density did not differ between the two areas, but it was affected by renal tubular function in subjects from the polluted area. Serum bone alkaline phosphatase was lower in subjects from the polluted area compared to controls. We detected three cases of cadmium nephropathy among the subjects. One of them suffered from a renal anemia type of itai-itai disease. Inhabitants in the formerly polluted area still had high cadmium accumulations and showed a characteristic natural history of chronic cadmium toxicity, indicating that the risk remains for developing nephropathy or itai-itai disease in the future.

Phytoextraction by Rice Capable of Accumulating Cd at High Levels: Reduction of Cd Content of Rice Grain

In accordance with a new international standard set by the Codex Alimentarius Commission for cadmium (Cd) contentin rice grain, Japan must perform large-scale remediation of paddy fields polluted with lowto moderate levels of Cd. Phytoextraction using hyperaccumulating wild plants has been proposed as a low-cost, environmentally friendly restoration technology. However, because of difficulties with sowing, weed and disease control, and harvesting, hyperaccumulators may not be suitable for large-scale phytoextraction in polluted paddy fields. Here, we demonstrated phytoextraction using Indica-type rice cultivars capable of accumulating Cd at high levels. Phytoextraction with the Indica rice Chokoukoku grown for 2 years without irrigation after drainage removed 883 g Cd ha(-1), reduced the total soil Cd content by 38%, and reduced the grain Cd content in subsequently grown Japonica food rice by 47% without decreasing yield. The results suggest that phytoextraction with Chokoukoku can remove Cd from paddy fields polluted with low to moderate levels of Cd and reduce the grain Cd concentration of Japonica food rice cultivars to below the Codex standard within a reasonable time frame. This approach will help reduce the risk of Cd contamination of rice from paddy fields.

清酒製造工程中の白米，清酒および酒粕中のカドミウム含量の変化

清酒製造工程中の白米，清酒および酒粕中のカドミウム含量の変化

Cadmium content in rice and its daily intake in Ghaemshahr region of Iran

This investigation surveyed Cadmium (Cd) content of Iranian rice (oryza saliva) which is predominant rice culture in north of Iran. A total of 60 samples were collected from Ghaemshahr region in Mazandaran province (North of Iran). The samples were collected in during harvesting of rice in field. The first step, grains of raw rice were digested by acid digestion method and then were analyzed for Cadmium by atomic absorption spectrometer. To assess the daily intake of Cd by rice, from daily consumption of rice was calculated. The results showed that average concentration of Cd in rice was 0.40± 0.16µg/g dry wt and ranged from 0.12 to 0.83 ig/g dry wt. The Cd content in the rice samples was found to be upper the FAO/WHO Guidelines. Also average weekly intake of Cd from rice was 7.7µg/kg body weight/week that it was approximately 10% more than to the maximum weekly intake recommended by WHO/FAO.

Amelioration of Cadmium Polluted Paddy Soils by Porous Hydrated Calcium Silicate

Porous hydrated calcium silicate (PS) is a by-product of autoclave light weight concrete and is being used as a silicon fertilizer in Japan. The impacts of this amendment on the yield and cadmium content of rice (Orzya sativa L. var. Kokoromachi), soil pH and the extractability of soil cadmium assessed by 1 M NH4OAc were compared with those of silica gel and CaCO3 by pot experiments. The application of PS at the rate of 2.0% and silica gel at the rate of 1.0% in Andosol and PS at the rate of 0.75% in Alluvial soil significantly increased the grain weight of rice. PS and CaCO3 treatment significantly increased soil pH, decreased the 1 M NH4OAc extractability of cadmium and reduced cadmium content in straw and brown rice in the two soils. However, cadmium content of rice of PS treatments was not significantly different from that of CaCO3 treatments in Andosol, while was significantly lower than that of CaCO3 treatments in Alluvial soil. Soil analysis showed that it was less effective in increasing soil pH and decreasing the extractability of cadmium by 1 M NH4OAc than CaCO3 at the same application rate in Andosol. Soil pH and 1 M NH4OAc extractability of cadmium were not significantly different between 2.0% of PS and CaCO3 treatments in Alluvial soil. The application of silica gel did not improve soil pH nor decrease the extractability of soil cadmium, but resulted in a significant decline of cadmium content in brown rice. These results demonstrate that the supply of silicon together with an increase in soil pH, as obtained by PS application, shows potential to reduce the cadmium content of rice.

Genotypic Variation in Shoot Cadmium Concentration in Rice and Soybean in Soils with Different Levels of Cadmium Contamination

A pot experiment was conducted to investigate whether the shoot cadmium (Cd) concentration in 11 rice and 10 soybean cultivars varied among 4 soils with different levels of Cd contamination. Significant differences in shoot Cd concentration were found among rice or soybean cultivars grown in the 4 soils. The ranking of the rice cultivars for the shoot Cd concentration varied considerably among the soils. On the other hand, the soybean cultivars were ranked similarly in terms of shoot Cd concentration in the 4 soils. Significant and positive correlations were found between the Cd and Zn concentrations and between the Cd and Mn concentrations in the shoot of rice cultivars, when they were grown in 2 soils with relatively moderate levels of Cd contamination. The shoot Cd concentration in the soybean cultivars, however, was not correlated with the concentrations determined for any of the metals (Zn, Mn, Cu, and Fe) across the 4 soils. Significant and positive correlations between the concentrations of Cd in younger shoots and mature seeds were detected among the soybean cultivars in 2 soils used, unlike among the rice cultivars, indicating that it may be difficult to evaluate the genotypic variation in seed Cd concentration using relatively younger shoots in the case of rice. These results revealed that genotypic differences in shoot Cd concentration in rice or soybean are variable or invariable among soils, respectively.

II. Cadmium Concentration in Rice Produced in Unpolluted Paddy Field and Cadmium Concentration in Volcanic Ash Soils(On the Japanese Comment for Maximum Levels in Foods by CCFAC.)

II. Cadmium Concentration in Rice Produced in Unpolluted Paddy Field and Cadmium Concentration in Volcanic Ash Soils(On the Japanese Comment for Maximum Levels in Foods by CCFAC.)