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.

/pdf/hazards-of-heavy-metal-contamination-ytc24a1l2a.pdf

Hazards of heavy metal contamination.

https://stacks.cdc.gov/view/cdc/37676/cdc_37676_DS1.pdf

Toxicological Profile for Lead

Health risk assessment of heavy metals and their source apportionment in drinking water of Kohistan region, northern Pakistan

https://www.biologicaldiversity.org/campaigns/get_the_lead_out/pdfs/health/Ekong_et_al_2006.pdf

Lead-related nephrotoxicity: A review of the epidemiologic evidence

Chronic Kidney Disease Associated With Environmental Toxins and Exposures

Reference intervals of cadmium, lead, and mercury in blood, urine, hair, and nails among residents in Mansoura city, Nile delta, Egypt.

Background: Traffic policemen are the most exposed population to lead (Pb) from automobile exhaust. There has been increasing concern about the possible harmful effects of Pb from a

Study of lead exposure from automobile exhaust as a risk for nephrotoxicity among traffic policemen.

Background
Glutathione peroxidase (GPx) protects cells from oxidative damage by catalyzing the reduction of both organic and hydrogen peroxides, using glutathione as a reducing agent. Both plasma GPx (P-GPx) and erythrocyte GPx (E-GPx) have been identified in human blood. Kidney proximal tubular cells are the main source of GPx activity in the plasma. Oxidative damage has been reported to participate in the progression and complications of renal diseases.

Glutathione peroxidase activity in patients with renal disorders.

In this section authors from Egypt describe the use of urinary TGFβ1 and epidermal growth factor in PUJ obstruction. In another paper, authors from London herald what they consider to be a new era in the management of end-stage renal disease in children, presenting the technique of bilateral synchronous posterior prone retroperitoneoscopic nephrectomy with simultaneous peritoneal dialysis.



OBJECTIVES

To investigate the role of transforming growth factor β1 (TGF-β1) and epidermal growth factor (EGF) in voided urine for the diagnosis and follow-up of children with pelvi-ureteric junction obstruction (PUJO).



PATIENTS, SUBJECTS AND METHODS

The study included 35 children with unilateral PUJO who had a pyeloplasty, and 30 healthy control children. Urine samples were obtained from the bladders of patients before surgery, and as voided samples at 1, 2, 3, 6, 9 and 12 months after surgery. Bladder urine samples were also collected from all 30 children in the control group. TGF-β1 and EGF were then measured in all the urine samples.



RESULTS

The level of bladder TGF-β1 before surgery in the patients was significantly higher than that in the healthy control group. A threshold of 190 pg/mg creatinine gave a sensitivity of 100%, a specificity of 80%, a positive predictive value of 85.4%, negative predictive value of 100% and an overall accuracy of 90.8%. Compared with the value before surgery, urinary TGF-β1 was significantly lower at 1 year after pyeloplasty. There was no significant difference between the level of EGF before surgery in the patients and that in the control group, and no significant difference in the level of EGF before and after surgery over the follow-up.



CONCLUSION

We do not recommend using EGF levels in voided urine in the routine diagnosis of children with hydronephrosis. The urinary level of TGF-β1 is a useful noninvasive tool for the long-term follow-up of children with PUJO treated by pyeloplasty. Further studies with various controls are required to confirm the diagnostic accuracy of TGF-β1 in children with PUJO.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1464-410X.2006.06641.x

Pelvi‐ureteric junction obstruction in children: the role of urinary transforming growth factor‐β1 and epidermal growth factor

BACKGROUND Concern has been voiced about exposure to mercury (Hg) from dental amalgam fillings, and there is a need to assess whether this leads to signs of nephrotoxicity. METHODS A total of 101 healthy adults (80 males and 21 females) were included in this study. The population as grouped into those having amalgam fillings (39 males and 10 females) and those without (41 males and 11 females). Hg was determined in blood, urine, hair and nails to assess exposure. Urinary excretion of beta2-microglobulin (beta2M), N-acetyl-beta-D-glucosaminidase (NAG), gamma-glutamyltransferase (gammaGT) and alkaline phosphatase (ALP) were determined as markers of tubular damage. Albuminuria was assayed as an early indicator of glomerular dysfunction. Serum creatinine, beta2M and blood urea nitrogen (BUN) were determined to assess glomerular filtration. RESULTS Hg levels in blood and urine were significantly higher in persons with dental amalgam than those without; in the dental amalgam group, blood and urine levels of Hg significantly correlated with the number of amalgams. Urinary excretion of NAG, gammaGT and albumin was significantly higher in persons with dental amalgam than those without. In the amalgam group, urinary excretion of NAG and albumin significantly correlated with the number of fillings. Albuminuria significantly correlated with blood and urine Hg. CONCLUSION From the nephrotoxicity point of view, dental amalgam is an unsuitable filling material, as it may give rise to Hg toxicity. Hg levels in blood and urine are good markers of such toxicity. In these exposure conditions, renal damage is possible and may be assessed by urinary excretions of albumin, NAG, and gamma-GT.

Sami E. Farahat

Papers

Reference intervals of cadmium, lead, and mercury in blood, urine, hair, and nails among residents in Mansoura city, Nile delta, Egypt.

Study of lead exposure from automobile exhaust as a risk for nephrotoxicity among traffic policemen.

Glutathione peroxidase activity in patients with renal disorders.

Pelvi‐ureteric junction obstruction in children: the role of urinary transforming growth factor‐β1 and epidermal growth factor

Mercury in dental restoration: is there a risk of nephrotoxicity?