Different association of cigarette smoking with GFR estimated from serum creatinine and that from serum cystatin C in the general population.

BACKGROUND: Previous studies have shown that GFR estimated from serum creatinine (eGFRcr) is higher in smokers although the implications remain unclear. We aimed to clarify the associations of smoking with eGFRcys (GFR estimated from serum cystatin C) and eGFRcr, cys (the surmised most precise GFR estimate based on serum creatinine and cystatin C) in a working population. METHODS: Cross-sectional observation in 1,587 male workers aged 25-64 years. For eGFRcr, JEQcr proposed by the Japanese Society of Nephrology (JSN) and jEPIcr by the Chronic Kidney Disease Epidemiological Collaboration (CKD-EPI) modified for Japanese, and for eGFRcys, JEQcys proposed by JSN and EPIcys by CKD-EPI were calculated together with eGFRcr,cys of JEQaver (the average of JEQcr and JEQcys) and jEPIcr,cys by CKD-EPI modified for Japanese. RESULTS: Mean JEQcys was 95.1 mL/min/1.73 m(2) in contrast to 80.9 in JEQcr, with this difference considerable. Serum cystatin C was higher in smokers and obese subjects while serum creatinine was lower in smokers and slender subjects. JEQcys and EPIcys were lower in smokers while JEQcr and jEPIcr were higher in smokers adjusting for body mass index (BMI). eGFRcr,cys (JEQaver and jEPIcr,cys) did not differ between the never smokers and current smokers. eGFRcr,cys predicted by the equations composed of eGFRcr, BMI, and smoking habits showed a good accordance with calculated eGFRcr,cys. CONCLUSIONS: Either eGFRcr, eGFRcys or both were not reliable indicators of renal function in workers who smoked. The possibly more precise estimate of eGFRcr,cys could be predicted by eGFRcr, BMI and smoking in such a generally healthy population.

Dioxin exposure in breast milk and infant neurodevelopment in Vietnam.

OBJECTIVES: Dioxin levels in the breast milk of mothers residing near hot spots of dioxin contamination areas in South Vietnam remain much higher than in unsprayed areas, suggesting that fetuses and breast-fed infants may be exposed to high levels of dioxins. The present study investigated the association of infant neurodevelopment in early infancy and dioxin exposure during the perinatal period. METHODS: The study involved 216 mother-infant pairs living near the Da Nang airbase, a dioxin contaminated area in Vietnam. Mothers and infants were followed from birth until infants were 4 months old. Dioxin levels in breast milk were measured to estimate the perinatal dioxin exposure, including the infant daily dioxin intake (DDI) via breastfeeding. Infant neurodevelopmental parameters, including cognitive, language and motor domains were assessed at approximately 4 months using the Bayley Scales of Infant and Toddler Development, third edition (Bayley-III). RESULTS: The level of 2,3,7,8-tetrachlorodibenzo-p-dioxin and polychlorinated dibenzo-p-dioxins/furans-toxic equivalents in breast milk and the infant DDI showed significant inverse correlations with neurodevelopmental scores. When the subjects were divided into four groups according to dioxin levels in breast milk, the moderate and high DDI groups had significantly lower cognitive, composite motor and fine motor scores, and the high polychlorinated dibenzo-p-dioxins/furans-toxic equivalents group had significantly lower fine motor score than the low exposure group. For all domains, neurodevelopmental scores were decreased with increase in the level of 2,3,7,8-tetrachlorodibenzo-p-dioxin. CONCLUSION: The present study demonstrates a considerable impact of perinatal dioxin exposure on neurodevelopment in 4-month-old infants living in contaminated areas in Vietnam.

The effects of continuing and discontinuing smoking on the development of chronic kidney disease (CKD) in the healthy middle-aged working population in Japan.

OBJECTIVES: 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. METHODS: 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. RESULTS: 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 m(2), 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. CONCLUSIONS: 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.

Distribution of and factors contributing to chronic kidney disease in a middle-aged working population.

OBJECTIVES: To clarify the distribution of chronic kidney disease (CKD) and the factors contributing to its development and progression in middle-aged Japanese workers/employees. METHODS: This was a retrospective study involving 3,964 men and 2,698 women aged 35-64 years in 2009 who had been followed-up until 2003. Data on proteinuria determined with a dipstick and glomerular filtration rate estimated from serum creatinine concentration (eGFR) were collected in the annual health check-ups. RESULTS: Proteinuria was detected in 2.9 and 1.1 % of the men and women, respectively, and total CKD was detected in 16.0 and 16.1 % of the men and women respectively. Moderate or severe CKD associated a high risk of cardiovascular diseases and end-stage kidney disease was found mostly in the male subjects [2.0 (men) vs. 0.6 % (women)]. High-risk CKD was found in 3.3 % of the men aged 55-64 years. A body mass index (BMI) of ≥30, hypertension, diabetes mellitus (DM), current smoking and some job types were independently related to the development of proteinuria, while age, BMI, hypertriglyceridemia, and job types were related to total CKD. The development of high-risk CKD was related to preceding mild CKD signs of reduced eGFR and proteinuria as well as to hypertension, DM, smoking, and job type. CONCLUSIONS: Chronic kidney disease was found in 16 % of middle-aged workers with an equal prevalence in both sexes, while high-risk CKD was found mostly in men, of whom 3.3 % were aged 55-64 years. Obesity, hypertension, DM, smoking and some job types were related to the development and progression of CKD.

Cigarette smoking, proteinuria, and renal function in middle-aged Japanese men from an occupational population.

OBJECTIVES: To clarify the renal effects of cigarette smoking in a middle-aged occupational population because the effects have previously been demonstrated mainly in community populations that included many elderly people who are thought to be vulnerable to such effects. METHODS: In 990 middle-aged men recruited from a chemical plant, proteinuria was measured by a dipstick method and the glomerular filtration rate was estimated (eGFR) using a formula proposed by the Japanese Society of Nephrology. RESULTS: Proteinuria was found in 4.6% of the current smokers and 1.5% of the never-smokers. It was found in 4.8% of the subjects having a Brinkman index (BI) of 400-599 and 6.3% of those having a BI of 600 or above. The odds ratio for proteinuria in them was 2.94 (CI: 1.01-8.55) and 3.61 (CI: 1.29-10.1), respectively, adjusting for possible confounders. The mean eGFR was higher in smokers than in nonsmokers throughout middle age up to 64 years. Normal but high eGFR was found in 6.7% of the current heavy smokers and subnormal eGFR in 5.7% of the largest cumulative cigarette consumers in contrast to 3.0% or less of the never-smokers. Proteinuria was found in 13.3% of the subjects showing subnormal eGFR, specifically in 16.7% of the smokers and 8.3% of the nonsmokers. CONCLUSIONS: Smoking causes proteinuria in working middle-aged men. Smokers tend to have a high eGFR, but those with subnormal eGFR showed proteinuria most frequently. Whether the high eGFR in smokers will eventually decrease and cause proteinuria remains an important focus for further studies.

Seventeen-year observation on urinary cadmium and beta2-microglobulin in inhabitants after cessation of cadmium-exposure in Japan.

The purpose of this study was to clarify the change and relationship of urinary cadmium (Cd) and beta(2)-microglobulin (beta(2)-MG) concentrations of inhabitants in Cd-polluted areas after soil restoration. The urinary Cd and beta(2)-MG concentrations of 25 males and 28 females did not show a significant change, 22 years after the Cd-polluted soil was restored. Once exposed to Cd, it was found to remain in the body, 22 years after the Cd -polluted soil was restored. However, this did not influence renal tubular dysfunction in most of the younger generation compared with elders heavily exposed to Cd.

Cadmium-exposed population in Mae Sot District, Tak Province: 4 bone mineral density in persons with high cadmium exposure.

OBJECTIVE: To measure bone mineral density in cadmium-exposed persons aged 40 years and older that lived in the 12 contaminated villages in northwestern Thailand. MATERIAL AND METHOD: Five hundred seventy three persons with urinary cadmium levels > or = 5 microg/g creatinine during the 2004-2006 surveys were screened in 2007 for urinary excretion of cadmium, bone formation and resorption markers, and renalfunction markers. Calcaneus bone density was measured in each person by a dual-energy X-ray absorptiometry bone scanner. RESULTS: The mean age of the study persons was 57 years old. The geometric mean level of urinary cadmium for women was significantly higher than that for men. Women had a lower mean of calcaneus bone density than men. The rate of osteoporosis in women (21.5%) was significantly higher than that for men (14.7%). Calcaneus bone density was negatively correlated with urinary excretion of calcium (in both genders) and crosslinked N-telopeptide of type I collagen (in women), after adjusting for other co-variables. Increasing urinary cadmium levels appeared to correlate with reduced bone density in women, but not in men. In both genders, urinary excretion of beta2-microglobulin and N-acetyl-beta-D-glucosaminidase was higher in persons with osteoporosis than those without. CONCLUSION: Bone mineral loss is correlated with urinary cadmium levels and renal dysfunction in this female population.

Cadmium-exposed population in Mae Sot district, Tak province: 3. Associations between urinary cadmium and renal dysfunction, hypertension, diabetes, and urinary stones.

OBJECTIVE: To study the associations between urinary cadmium and renal dysfunction, hypertension, diabetes, and urinary stones in an adult population living in cadmium-contaminated areas in Mae Sot District, Tak Province, Thailand. MATERIAL AND METHOD: Seven hundred ninety five cadmium-exposed adults were screened for urinary cadmium, renal dysfunction, hypertension, diabetes, and urinary stones in 2005. Six selected markers of renal function in the present study were urinary excretion of beta2-microglobulin (beta2-MG), N-acetyl-beta-D-glucosaminidase (NAG), total protein and calcium, serum creatinine, and glomerular filtration rate (GFR). RESULTS: The mean age of the study persons was 50-years-old. The overall prevalence rates of hypertension, diabetes, and urinary stones were 33.3%, 6.2%, and 8.9% respectively. The prevalence of increased proteinuria was greatest in those with urinary cadmium levels > or = 15 microg/g creatinine. Urinary excretion of beta2-MG, NAG, and total protein significantly increased with increasing urinary cadmium levels, after adjusting for other co-variables by multiple linear regression analysis. However, urinary cadmium was not significantly associated with urinary calcium, serum creatinine, and GFR. The prevalence rates of hypertension, diabetes, and urinary stones did not significantly increase with increasing urinary cadmium levels. Hypertension, diabetes, and urinary stones were also significant predictors of impaired renal function. CONCLUSION: In this population, increasing levels of urinary cadmium are associated with increasing urinary excretion of beta2-MG, NAG, and total protein. Risk for hypertension, diabetes, and urinary stones remains uncertain in relation to cadmium exposure.

Biological half-life of cadmium in the urine of inhabitants after cessation of cadmium exposure.

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.

Association of lifetime cadmium intake or drinking Jinzu River water with the occurrence of renal tubular dysfunction.

This study was performed to clarify whether lifetime cadmium (Cd) intake (LCd) calculated from consumption of Cd-polluted rice and other foods, or drinking and/or cooking with Jinzu River water is associated with the occurrence of renal tubular dysfunction and to estimate the threshold level of LCd using a benchmark dose procedure. From participants in the 1967 and 1968 health examinations, the 2607 subjects (1430 men and 1177 women) who were aged 50 years or more, and who had either resided in the current hamlet since birth or moved there from a nonpolluted area and resided for a total of 30 years or longer were chosen as the target population. Based on a multiple logistic regression analysis performed for abnormal urinary findings (proteinuria, glucosuria, or proteinuria with glucosuria) using LCd as the explanatory variable with or without consideration of use of the river water for drinking and/or cooking, it was inferred that both factors of LCd and use of the river water influenced the occurrence of renal tubular dysfunction, with LCd appearing to exert a greater impact compared to drinking/cooking with the river water. Moreover, the threshold values of LCd for proteinuria with glucosuria were estimated to be 2.91 g in men and 1.79 g in women, without adjustment for use of the river water. After adjustment for its use, the values of proteinuria were calculated to be 0.93 g in women. When assuming user/nonuser status of the river water, the threshold level was calculated as 0.75/0.93 g in women. The difference of 0.18 g was interpreted as representing the influence of drinking/cooking with the river water.

Estimation of benchmark rice cadmium doses as threshold values for abnormal urinary findings with adjustment for consumption of Jinzu River water.

We performed this study to determine whether both eating cadmium (Cd)-polluted rice and drinking and/or cooking with Jinzu River water are associated with renal tubular dysfunction. A multiple logistic regression analysis of retrospective data indicated that both factors may contribute to this condition. Estimated threshold values of rice Cd concentration in men were 0.13-0.27 ppm and 0.09-0.18 ppm in women, without adjustment for use of Jinzu River water. The additional influence of drinking and/or cooking with Jinzu River water was estimated to be about 0.008 ppm.

Serial changes in urinary cadmium concentrations and degree of renal tubular injury after soil replacement in cadmium-polluted rice paddies.

Targeting persons requiring observation in the Cd-polluted Kakehashi River basin a serial observation study was conducted. Namely we followed the serial changes in 50 subjects who ingested household rice for 10 years after replacement of Cd-polluted soil in rice paddies. The serial changes in urinary substance levels in individuals were determined adjusting for the potential effect of age using a general linear mixed model. Cd excretions decreased with increasing number of years elapsed, with the partial regression coefficients of the number of years elapsed statistically significant in the women. The ratio of the Cd excretion theoretical values at the completion of soil replacement and 10 years later was 0.60 and the reduction rate was calculated as 5.0% per year in women. However, it was surmised that in practice a decrease to the level of inhabitants of non-polluted districts would not be achievable. The indices of renal tubular injury (beta(2)-microglobulin, retinol binding protein (RBP), total protein, amino-N and glucose) with the exception of amino-N in men showed increased excretion in both sexes with increasing number of years elapsed with statistically significant differences in RBP and total protein in both sexes and glucose in men. In this study using a general linear mixed model, which is an appropriate statistical method to perform a follow-up study, Cd concentrations in rice and urine were found to decrease after Cd exposure was reduced, but the degree of renal tubular injury was not found to improve, leading to the conclusion that the renal tubular injury induced by environmental Cd exposure is irreversible.

Estimation of benchmark doses as threshold levels of urinary cadmium, based on excretion of beta2-microglobulin in cadmium-polluted and non-polluted regions in Japan.

The threshold level of urinary cadmium (Cd) for beta2-microglobulin (MG)-uria was calculated using a benchmark dose (BMD) approach. Total number of subjects was 3103 for Cd-polluted areas and 2929 for non-polluted areas. Multiple logistic regression analysis was employed to fit the dose-response model taking into consideration an age effect. Cut-off values for urinary beta2-MG were defined as those corresponding to the 84th and 97.5th percentile of beta2-MG levels in the controls, and 1000 microg/g creatinine (cr). The BMD low (BMDL) was calculated using the profile likelihood method. When the benchmark response was 5%, the BMD/BMDL of Cd for the 84th percentile of beta2-MG for mean age, 55, 65, and 75 years was 3.0/2.7, 4.6/4.2, 2.8/2.6, and 1.8/1.6 microg/g cr in men and 3.4/3.2, 5.8/5.5, 3.2/3.1, and 1.8/1.7 microg/g cr in women, respectively. The value for the 97.5th percentile for each age was 4.9/4.5, 7.6/7.0, 4.6/4.3, and 2.6/2.4 microg/g cr in men and 5.9/5.6, 9.7/9.2, 5.6/5.3, and 2.8/2.6 microg/g cr in women. Namely it became clear that the margin between the threshold level and average excretion level of urinary Cd was small in the older population in Japan. To prevent the adverse health effects caused by exposure to Cd, it is important to establish the threshold level of Cd exposure at each age.

Influence of job strain on changes in body mass index and waist circumference--6-year longitudinal study.

OBJECTIVES: This study examined the effect of changes in psychosocial workplace characteristics on weight gain and abdominal obesity. METHODS: Twice, at an interval of 6 years, the authors conducted examinations of job demand-control-support and measurements of body mass index and waist circumference among 2200 men and 1371 women aged 30-53 years and working in a factory. The scores of the psychosocial work characteristics in each examination were dichotomized at the median values for the men and women separately and then categorized into three groups as follows: group I: low score in both the first and second examinations, group II: low score in the first examination and high score in the second (or high at the first and low at the second), and group III: high in both the first and second examinations. RESULTS: Although there was no statistically significant association between psychosocial work characteristics and the change in body mass index, for both genders, the change in waist circumference increased more in group III than in group I. Similarly, the odds ratios for the change in waist circumference above the 75th percentile for groups II and III increased more than in group I, being 1.13 [95% confidence interval (95% CI) 0.87-1.46 and 1.39 (95% CI 1.07-1.79) for the men in groups II and III, respectively, and 1.27 (95% CI 0.90-1.78) and 1.78 (95% CI 1.26-2.52) for the women in groups II and III, respectively. CONCLUSIONS: The results suggest that high job strain is a risk factor for increased abdominal obesity.

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.

Atmospheric temperature and pressure influence the onset of spontaneous pneumothorax.

BACKGROUND: The aim of the study was to examine the influence of the changes in the atmospheric temperature (ATemp) and the atmospheric pressure (APres) on the occurrence of a spontaneous pneumothorax (SP). PATIENTS AND METHODS: From January 2000 to March 2014, 192 consecutive SP events were examined. The ATemp and APres data at the onset of SP, as well as those data at 12, 24, 36, 48, 60, and 72 h prior to the onset time, were analyzed. RESULTS: The frequencies of SP occurrence were not statistically different according to the months or seasons, but were statistically different according to the time period (P < .01) and SP events occurred most frequently from 12:00 to 18:00. SP events frequently occurred at an ATemp of 25 degrees Celsius or higher. There was a significantly negative correlation between the APres and the ATemp at the SP onset time. The values of change in the APres from 36 to 24 h prior to SP onset were significantly lower than the preceding values. CONCLUSIONS: In this study, we observed that a SP event was likely to occur in the time period from 12:00 to 18:00, at an ATemp of 25 degrees Celsius or higher, and at 24-36 h after a drop of APres.

Effects of cadmium exposure during pregnancy on trace elements in fetal rat liver and kidney.

Female rats were exposed by intragastric administration with a cannula 1mg/kg/day or 10mg/kg/day CdCl2 for the 11 days from the 9th to 19th day of pregnancy, and the effects of Cd exposure on eight elements, Na, K, Ca, Mg, P, Fe, Zn, and Cu in fetal liver, kidney, brain, fetal membrane and placenta then examined. We found that: (1) although Cd was not detected in fetal kidney and brain, significant Cd accumulation was found in fetal liver, fetal membrane and placenta in the 10 mg/kg Cd group, (2) the Zn and Fe concentrations in fetal liver in the 10 mg/kg Cd group were significantly lower than those in the control group, but no difference was found in the placenta, (3) the Cu concentrations in the placenta, fetal membrane and liver in the 10 mg Cd groups were significantly lower than those in the control group, (4) Na/K ratio in the placenta and fetal kidney and the Ca concentration in the placenta in the 10 mg/kg Cd group were lower than those in the controls. These results suggest that Cd exposure inhibits Zn and Fe transportation from the placenta to fetus, as well as Cu, Ca, Na and K uptake and transportation across the placenta, possibly influencing fetal growth and metabolism.

Estimation of biological half-life of urinary cadmium in inhabitants after cessation of environmental cadmium pollution using a mixed linear model.

We investigated the biological half-life of urinary cadmium concentration (U-Cd) based on a 22-year follow-up study after cessation of environmental Cd pollution. Spot urine samples were obtained from the inhabitants (32 men and 36 women) in the target area in 1986, 1991, 1999, 2003 and 2008. These inhabitants were divided into higher or lower baseline U-Cd group by the cut-off of 5 µg l(-1) or 5 µg g(-1) creatinine. Biological half-life of U-Cd was estimated using a linear mixed model adjusted for the baseline age. In the higher baseline U-Cd groups, the estimated half-life and 95% confidence intervals were 12.4 years (9.3-18.8 years) and 11.4 years (9.3-14.6 years) for unadjusted U-Cd in men and women, respectively. For creatinine-adjusted U-Cd, they were 16.0 years (13.0-20.7 years) and 20.4 years (16.6-26.2 years) in men and women, respectively. In the lower baseline U-Cd groups, biological half-life for unadjusted U-Cd in men was solely significant (23.4 years) and longer than the corresponding half-life in the higher baseline U-Cd group. The biological half-lives of U-Cd obtained in this study were identical with the values for U-Cd or total body burden determined by a different method.

Cadmium exposure and trace elements in human breast milk.

The interrelations of the seven elements, calcium (Ca), magnesium (Mg), sodium (Na), potassium (K), phosphorus (P), copper (Cu), zinc (Zn), and cadmium (Cd) in human breast milk were examined in Japanese mothers to clarify the effects of Cd exposure on these important elements for infant growth. Breast milk and urine samples were obtained from 68 mothers, aged 19-38 years, at 5-8 days postpartum. The concentrations were determined by inductively-coupled plasma atomic emission spectrometry for Ca, Mg, Na, K, P, by flame atomic absorption spectrophotometry for Cu and Zn, and by flameless atomic absorption spectrophotometry for Cd. Geometrical mean Cd concentrations were 0.28 (geometrical standard deviation=1.82) microg/l in breast milk and 1.00 (1.93) microg/g creatinine in urine. Among the above elements only Cd concentration in breast milk was significantly correlated with urinary Cd concentration (r=0.451, P<0.001). Significant positive correlations were found between Cu and Ca (r=0.500, P<0.001), Cu and Mg (r=0.378, P<0.01), and Zn and Mg (r=0.355, P<0.01) in breast milk. Cd concentration in breast milk showed an inverse relationship with Ca concentration in breast milk (r=-0.248, P<0.05). These results indicate that the Cd concentration in breast milk closely reflects Cd body burden, with increased Cd in breast milk possibly affecting Ca secretion in breast milk.

Cadmium and nutritional intake in pregnant Japanese women.

A study to clarify the food composition and nutritional factors that contribute to the levels of blood and urinary cadmium (Cd) was conducted on 50 pregnant Japanese women with mean age of 29 years. The mean iron (Fe) intake of subjects was 9.2 mg, which is much lower than the recommended level of 20 mg for pregnant women. Cd in urine samples collected at 30-32 weeks of gestation were correlated (r = 0.354), but urinary Cd was related to age more than blood Cd. Urinary Cd and blood Cd levels were inversely related to total energy (rpartial = -0.325, and -0.334, respectively) and fat intake (rpartial = -0.419, and -0.379, respectively), even after adjustment for age. Blood Cd was also correlated to protein and iron intake (rpartial = -0.299, and -0.353, respectively). These results indicate that Cd exposure levels of pregnant women with low energy intake, especially less fat intake, were higher than those of women with more energy and fat intake. In particular, blood Cd may be affected by protein and iron intake in pregnant women with increased these nutrients demand.