An in-vivo study of renal cadmium and hypertension

Correlations of urinary cadmium with hypertension and diabetes in persons living in cadmium-contaminated villages in northwestern Thailand: A population study

Risk for hypertension and diabetes has not been conclusively found to be a result of cadmium exposure. A population-based study was conducted in 2009 to examine the correlations of urinary cadmium, a good biomarker of long-term cadmium exposure, with hypertension and diabetes in persons aged 35 years and older who lived in the 12 cadmium-contaminated rural villages in northwestern Thailand. A total of 5273 persons were interviewed and screened for urinary cadmium, hypertension, and diabetes. The geometric mean level of urinary cadmium for women (2.4+/-2.3 microg/g creatinine) was significantly greater than that for men (2.0+/-2.2 microg/g creatinine). Hypertension was presented in 29.8% of the study population and diabetes was detected in 6.6%. The prevalence of hypertension significantly increased from 25.0% among persons in the lowest tertile of urinary cadmium to 35.0% in the highest tertile. In women, the rate of hypertension significantly increased with increasing urinary cadmium levels in both ever and never smokers, after adjusting for age, alcohol consumption, body mass index, and diabetes. In men, such association was less significantly found in never smokers. The study revealed no significant association between urinary cadmium and diabetes in either gender. Our study supports the hypothesis that environmental exposure to cadmium may increase the risk of hypertension. Risk for diabetes in relation to cadmium exposure remains uncertain in this exposed population.

Monte Carlo simulation of neutron irradiation facility developed for accelerator based in vivo neutron activation measurements in human hand bones

The neutron irradiation facility developed at the McMaster University 3 MV Van de Graaff accelerator was employed to assess in vivo elemental content of aluminum and manganese in human hands. These measurements were carried out to monitor the long-term exposure of these potentially toxic trace elements through hand bone levels. The dose equivalent delivered to a patient during irradiation procedure is the limiting factor for IVNAA measurements. This article describes a method to estimate the average radiation dose equivalent delivered to the patient's hand during irradiation. The computational method described in this work augments the dose measurements carried out earlier [Arnold et al., 2002. Med. Phys. 29(11), 2718-2724]. This method employs the Monte Carlo simulation of hand irradiation facility using MCNP4B. Based on the estimated dose equivalents received by the patient hand, the proposed irradiation procedure for the IVNAA measurement of manganese in human hands [Arnold et al., 2002. Med. Phys. 29(11), 2718-2724] with normal (1 ppm) and elevated manganese content can be carried out with a reasonably low dose of 31 mSv to the hand. Sixty-three percent of the total dose equivalent is delivered by non-useful fast group (> 10 keV); the filtration of this neutron group from the beam will further decrease the dose equivalent to the patient's hand.

In vivo neutron activation analysis of organ cadmium burdens. Referent levels in liver and kidney and the impact of smoking

In vivo neutron activation measurements of liver and kidney cadmium have been made in 77 exposed workers and 101 referents. Cadmium levels were higher in exposed workers than in referents; both in liver, 25.7 cf. 0.6 micrograms/g, and kidney, 17.9 cf. 2.7 mg. The 19 referents who never smoked had lower mean organ cadmium burdens than the other referents, the difference achieving statistical significance in the kidney, p less than .01. Cigarette smoking was estimated to increase cadmium body burden by 370 +/- 140 micrograms/pack year. These referent cadmium levels are similar to, although slightly below, previous in vivo and autopsy data.

In vivo measurements of cadmium and lead in occupationally-exposed workers and an urban population

This paper reports the preliminary findings of a survey of lead and cadmium body burdens in a nonoccupationally exposed population in Swansea, Wales, using the techniques of in vivo neutron activation and X-ray fluorescence analysis. Some measurements on an occupationally cadmium-exposed group are also included. The results confirm the association between cadmium and smoking and bone lead and age. The in vivo measurements demonstrate a degree of comparability with other data, which supports the further detailed analysis of the relationships between body burden and exposure, on the one hand, and possible health effects on the other.

Cadmium concentrations in human kidneys from the UK

The concentration of cadmium in the cortex and medulla of nearly 1000 kidneys obtained at autopsy was determined by atomic absorption spectrophotometry. Particular care was taken over the analytical procedures to ensure the accuracy and precision of the results; intrakidney variability was examined and found to be small. The frequency distributions of cadmium concentrations were approximately lognormal. There was much variability in cadmium concentrations between individuals, with geometric coefficients of variation for both cortex and medulla of around 100%. Cadmium concentrations varied with age and smoking habits, but not sex. Values were successively higher than those in the previous age-group up to 50-59 years (geometric mean 19 micrograms/g), after which they were successively lower; on average, heavy smokers had cadmium concentrations some 15-20% higher than those in light smokers who in turn had values some 15-20% higher than those in non-smokers. No definite conclusions could be reached on the variation of cadmium concentrations with either cause of death or location, or over time. The present study, the first of its kind in the UK, has provided benchmark data; its results are broadly in line with those from previous but smaller studies in other countries.

Epidemiology and trace elements

Basically, epidemiology is the making of measurements of known reproducibility, in a bias-free manner, on representative samples of subjects drawn from defined communities. Epidemiology has become a relatively precise science and its value in medicine is widely appreciated. So too are its limitations: the difficulties in achieving a high response rate, in identifying and controlling confounding factors in the examination of an association, and the ultimate difficulties in distinguishing causation from association. While the value of community-based studies seems to be recognized by those interested in man and his environment, the need for the strict application of epidemiological procedures, and the limitations imposed on conclusions drawn from studies in which these procedures have been compromised, does not seem to be adequately understood. There are certain known links between trace elements in the environment and disease: for example the level of iodine in soil and water and the prevalence of goitre; the level of fluoride in water and the prevalence of dental caries. The investigation of other possible associations is difficult for a number of reasons, including interrelationships between trace elements, confounding of trace element levels (and disease) with social and dietary factors, and the probability that relationships are generally weak. Two conditions in which associations are likely are cardiovascular disease and cancer. Despite research along a number of lines, the relevance of trace elements to cardiovascular disease is not clear, and certainly the apparent association with hardness of domestic water supply seems unlikely to be causal. The same general conclusion seems reasonable for cancer, and although there are a very few well established associations which are likely to be causal, such as exposure to arsenic and skin cancer, the role of trace elements is obscure, and likely to be very small.

Urinary cadmium and lead concentrations and their relation to blood pressure in a population with low exposure

The 24 hour urinary excretion of cadmium (U-Cd) and lead (U-Pb), and the excretion of beta-2- microglobulins and retinol binding protein concentration in spot urines, were determined in a random 4% sample of the population of a small Belgian town. Blood pressure and body weight were measured on two separate occasions. U-Cd averaged 2.4 nmol/24 h in 46 youths, increased with age, and was significantly higher in 57 adult men as compared with 59 women (9.3 v 7.2 nmol/24 h; p less than 0.01). U-Pb averaged 28 nmol/24 h in youths and similarly increased with age: adult men excreted more lead than women (64 v 40.0 nmol/24 h; p less than 0.001). Among men, manual workers excreted more cadmium (12.6 v 7.5 nmol/24 h; p less than 0.05) but a similar amount of lead (62 v 61 nmol/24 h) compared with office workers. After adjusting for sex and age, U-Cd and U-Pb were not related to body weight and cigarette consumption. In simple regression analysis, U-Cd was positively correlated with both systolic (r = +0.30; p less than 0.05) and diastolic (r = +0.38; p less than 0.01) blood pressure in women. After adjusting for other contributing variables, however, a weak but negative relation became apparent between systolic pressure and U-Cd in women (t = -2.21; p = 0.033) and between diastolic pressure and U-Cd in men (t = -2.04; p = 0.047). In women urinary beta-2-microglobulin was related to diastolic pressure (r-0.44; p<0.01) and after adjusting for age to both systolic (t=2.75; p=0.009) and diastolic (t=-3.07; p=0.004) pressure. In none of the sex-age groups did U-Pb and retinol binding protein contribute to the blood pressure variability.

Renal cadmium content in the West of Scotland

The trace element content of kidneys has been documented in very few international centres. Significant differences can be demonstrated between the cortical and medullary levels of calcium, zinc and cadmium. For the West of Scotland the values for the latter are similar to those found in Scandinavia. There are significantly higher cadmium contents in subjects who smoke and who have evidence of ischaemic heart disease.

Calibration of a 238Pu,Be facility for partial-body measurements of organ cadmium

An improved instrument is described for the measurement of liver and kidney cadmium by in vivo neutron activation analysis in both occupationally and environmentally exposed persons. Detailed calibrations of the instrument used in a study of 83 male workers at a cadmium production plant are give. The importance of accurate organ localisation by ultrasound is stressed, without which errors of 40 and 25% in individual and group kidney measurements, respectively, can occur. The detection limit (2 SD of the background) is 2.2 mg cadmium in the kidney and 1.5 micrograms g-1 (wet weight) in the liver for a local dose of 4.7 mSv. This instrument therefore combines the advantages of portability with high sensitivity of detection of cadmium.

Renal cadmium overload without nephrotoxicity

A redundant nickel/cadmium battery worker was investigated for non-specific fatigue after completing five years in the industry. Sensitive techniques for in-vivo organ cadmium measurement showed a moderate accumulation in the liver but a very large concentration in the kidneys. Despite this, overall glomerular and tubular function were not impaired. It was concluded that the mechanism of proteinuria observed in some cadmium workers is obscure and not clearly related to the degree of kidney saturation with cadmium.

A comparison of 252Cf and 238Pu, Be neutron sources for partial-body in vivo activation analysis

A comparison is made of the isotopic neutron sources 252 Cf and 238 Pu, Be for partial-body in vivo neutron activation analysis. Depth distributions of thermal neutron fluences in a water phantom are very similar for the two sources. The peak depth occurs at 5 cm. This value is approximately 2 cm less than the values obtained with uncollimated neutrons produced in broad-beam irradiations. With respect to the fluence-to-dose ratio, the 252 Cf neutrons have an advantage of approximately 1.4 over the 238 Pu, Be source. The use of 252 Cf offers two additional advantages for the investigator. First, it minimizes the on-line fast-neutron damage in Ge(Li) semiconductor detectors. Secondly, it is subject to much less stringent transport regulations that 238 Pu, Be. The latter feature takes on particular importance in view of the increasing usefulness of transportable instruments for in vivo cadmium measurements at the workplace.