Health Effects Of Exposure To Cadmium Research Articles

DNA microarray analysis of gene expression profiles in Caenorhabditis elegans exposed to cadmium

The human population exposed to cadmium from air, food and water sources may exhibit abnormalities in multiple organs including the kidneys and the liver, and in the cardiovascular, immune and reproductive systems. In addition, the recognition of cadmium biomarkers which may increase cancer susceptibility are of prime importance. The investigation of the effects of cadmium exposure and the determination of its uptake using animal models are vital efforts that can be made towards identifying the health effects of cadmium exposure on humans. Caenorhabditis elegans (C. elegans) is a nematode commonly used as an animal model for genetic studies and a living biomonitor and which is useful for investigating basic biological processes such as mRNA expression in response to heavy metal exposure. In the present study, we investigated gene expression changes in C. elegans in response to cadmium chloride exposure using microarrays consisting of 22,000 nematode-oligonucleotide probes expressed (>2 fold) following a 24 hour exposure to cadmium chloride. Several categories of genes have been detected from the microarray study and GO analysis. Based on their functions, they have been mapped according to cadmium ion responsive, we identified 958 genes, many of which are novel cadmium responsive genes, that were differentially angiogenesis and defense response to fungus. In conclusion, our investigation suggests importantecotoxociological biomarkers to be investigated in response to cadmium chloride exposure.

Health effects of cadmium exposure in the general environment in Japan with special reference to the lower limit of the benchmark dose as the threshold level of urinary cadmium

This study investigates renal dysfunction in areas without known environmental cadmium pollution and calculates the threshold level of urinary cadmium. Urinary total protein, beta2-microglobulin (beta2-MG), and N-acetyl-beta-D-glucosaminidase (NAG), used as indicators of renal dysfunction, and urinary cadmium concentration, used as an indicator of cadmium exposure, were measured in two sets of 24-hour urine samples from each of 828 participants (410 men, 418 women), aged 40-59 years and living in three areas without any known environmental cadmium pollution. In multiple regression and logistic regression analyses the association between indicators of cadmium exposure and indicators of renal dysfunction were studied. The lower 95% confidence limit of the dose (benchmark dose) corresponding to a 5% (BMDL5) or 10% (BMDL10) level of each indicator of renal dysfunction above the background level) was calculated as the threshold level of urinary cadmium. With all the expressed units [g creatinine(-1) and day(-1)] in the multiple regression analysis, the partial regression coefficients showed a significant association between urinary cadmium concentration and total protein, beta2-MG, and NAG for both genders, except for total protein for women (g creatinine(-1) and day(-1). The same results were obtained for both genders in the logistic regression analysis. The BMDL10 was 0.6-1.2 microg/g creatinine and 0.8-1.6 microg/day for the men and 1.2-3.6 microg/g creatinine, and 0.5-4.7 microg/day for the women. Cadmium exposure and the levels of the indicators of renal dysfunction were associated among the men and women aged 40-59 years in areas without any known environmental cadmium pollution. The threshold level of urinary cadmium in Japan seems to be almost the same as in Belgium and Sweden.

Hazards of heavy metal contamination.

The main threats to human health from heavy metals are associated with exposure to lead, cadmium, mercury and arsenic. These metals have been extensively studied and their effects on human health regularly reviewed by international bodies such as the WHO. Heavy metals have been used by humans for thousands of years. Although several adverse health effects of heavy metals have been known for a long time, exposure to heavy metals continues, and is even increasing in some parts of the world, in particular in less developed countries, though emissions have declined in most developed countries over the last 100 years. Cadmium compounds are currently mainly used in re-chargeable nickel-cadmium batteries. Cadmium emissions have increased dramatically during the 20th century, one reason being that cadmium-containing products are rarely re-cycled, but often dumped together with household waste. Cigarette smoking is a major source of cadmium exposure. In non-smokers, food is the most important source of cadmium exposure. Recent data indicate that adverse health effects of cadmium exposure may occur at lower exposure levels than previously anticipated, primarily in the form of kidney damage but possibly also bone effects and fractures. Many individuals in Europe already exceed these exposure levels and the margin is very narrow for large groups. Therefore, measures should be taken to reduce cadmium exposure in the general population in order to minimize the risk of adverse health effects. The general population is primarily exposed to mercury via food, fish being a major source of methyl mercury exposure, and dental amalgam. The general population does not face a significant health risk from methyl mercury, although certain groups with high fish consumption may attain blood levels associated with a low risk of neurological damage to adults. Since there is a risk to the fetus in particular, pregnant women should avoid a high intake of certain fish, such as shark, swordfish and tuna; fish (such as pike, walleye and bass) taken from polluted fresh waters should especially be avoided. There has been a debate on the safety of dental amalgams and claims have been made that mercury from amalgam may cause a variety of diseases. However, there are no studies so far that have been able to show any associations between amalgam fillings and ill health. The general population is exposed to lead from air and food in roughly equal proportions. During the last century, lead emissions to ambient air have caused considerable pollution, mainly due to lead emissions from petrol. Children are particularly susceptible to lead exposure due to high gastrointestinal uptake and the permeable blood-brain barrier. Blood levels in children should be reduced below the levels so far considered acceptable, recent data indicating that there may be neurotoxic effects of lead at lower levels of exposure than previously anticipated. Although lead in petrol has dramatically decreased over the last decades, thereby reducing environmental exposure, phasing out any remaining uses of lead additives in motor fuels should be encouraged. The use of lead-based paints should be abandoned, and lead should not be used in food containers. In particular, the public should be aware of glazed food containers, which may leach lead into food. Exposure to arsenic is mainly via intake of food and drinking water, food being the most important source in most populations. Long-term exposure to arsenic in drinking-water is mainly related to increased risks of skin cancer, but also some other cancers, as well as other skin lesions such as hyperkeratosis and pigmentation changes. Occupational exposure to arsenic, primarily by inhalation, is causally associated with lung cancer. Clear exposure-response relationships and high risks have been observed.

Cadmium biomonitoring and renal dysfunction among a population environmentally exposed to cadmium from smelting in China (ChinaCad).

Cadmium, an environmental pollutant, can have adverse effects on the human body. The kidney is the critical organ. In order to improve the understanding of the dose-response relationship between cadmium exposure and health effects, and especially renal dysfunction, a study on a general population group in China was performed. This study was therefore concerned with cadmium exposure biomarkers, such as the concentrations in blood (BCd) and urine (UCd), and effect biomarkers of renal dysfunction, such as beta2-microglobulin (beta2m), retinol binding protein (RBP) and albumin (ALB). To improve the evaluation of exposure levels in relation to the adverse health effects of cadmium exposure in the general population, a quality control program was conducted to determine analytical quality in the determination of cadmium in blood and urine and for beta2m, creatinine, ALB and RBP. The measurements showed that analytical quality was adequate. The exposure and effect biomarkers were studied in the population groups living in three areas, namely a control area and two Cd polluted areas. In the highly exposed area, most of the BCd values were higher than 5 microg/l and most of the UCd values were higher than 5 microg/g creatinine. Beta2-microglobulin, retinol binding protein, and albumin in urine were all significantly higher in the population living in the heavily polluted area than in that in the control area. Based on data from all three areas, a marked dose-response relationship between UCd or BCd and the prevalence of renal dysfunction was demonstrated. The number of abnormalities in kidney was related to the level of cadmium exposure. Only one index of renal tubular dysfunction was affected in subjects exposed to low levels of cadmium, but more than two indices of renal function were affected in those exposed to high levels.

Studies on health effects of cadmium exposure in the general environment

Effects of exposure to cadmium (Cd) in the general environment on health have been studied in several Cd-polluted areas in Japan. In this paper, results of investigations in the Kakehashi River basin, Ishikawa, a Cd-polluted area, are mainly reviewed as follows. 1. In an epidemiological study, prevalences of beta 2-microglobulinuria (beta 2-MG-uria) were 14. 3 and 18.7% in Cd-exposed men and women over 50 years of age, respectively, when a cutoff level of beta 2-MG of 1000 micrograms/g.cr. was used. These values are significantly high compared with those of nonexposed subjects. 2. Using several urinary indicators of renal function, such as alpha 1-microglobulin, N-acetyl-beta-D-glucosaminidase, human intestinal alkaline phosphatase, mucoprotein and albumin, levels of all indicators were significantly higher in Cd-exposed subjects than in nonexposed subjects. Furthermore, in a 5-year follow-up study, irreversibility of Cd-induced renal damage was shown after the level of beta 2-MG rose above 1000 micrograms/g.cr. 3. Exposure to Cd caused marked osteopenia, in particular in women, as assessed by microdensitometry, and this osteopenia was significantly associated with Cd-induced renal dysfunction. Serum 1 alpha, 25 dihydroxy-vitamin D levels were lower and serum parathyroid hormone (PTH) levels were higher in Cd-exposed subjects with renal damage than in nonexposed subjects. We assume that disturbances in vitamin D and PTH metabolism may be one of the causative factors for Cd-induced bone damage. 4. The dose-response relationships between Cd exposure and renal dysfunction were assessed using several statistical methods such as simple linear regression, probit linear regression, logistic regression analysis and general linear models. The prevalences of beta 2-MG-uria or metallothioneinuria were employed as indices of health effects, while urinary Cd and total Cd intake was used as indicators of Cd exposure. As the biological threshold, urinary Cd concentrations were calculated to be 3.8-4.2 micrograms/g.cr. in men and 3.8-4.8 micrograms/g.cr. in women, and a maximum allowable intake of about 2 g Cd is considered to be a reasonable estimate for preventing Cd-induced renal dysfunction. 5. A significant association was found between urinary beta 2-MG and mortality in a 9-year follow-up study of 3178 Cd-exposed inhabitants, using Cox's proportional hazards model. Moreover, mortality rates increased in proportion to increases in the amount of urinary beta 2-MG excreted. These results suggest that the prognosis for Cd-exposed subjects with renal tubular dysfunction is unfavorable.

A comparison between health effects of cadmium and cadmium concentration in urine among inhabitants of the Itai-itai disease endemic district

The relationship between urinary cadmium concentration (micrograms/g creatinine) and the health effects of cadmium exposure was studied in 406 inhabitants who lived in and around the Jinzu River basin. Cadmium concentration in urine was employed as the index of cadmium exposure. Total protein, glucose, calcium, and phosphorus in urine and calcium, inorganic phosphorus, and alkaline phosphatase in serum served as indices of health effects. On a group basis a close relationship was found between cadmium concentration in urine and health effects. Prevalence rates of indices of health effects increased proportionally with increasing cadmium concentrations in urine. It was concluded that cadmium concentration in urine expressed as micrograms/g creatinine is a useful parameter in estimating the health effects of cadmium exposure from the environment.