Effects of smoking and lead exposure on proximal tubular integrity among Egyptian industrial workers.

BACKGROUND: The hazards of occupational lead exposure are well documented. Tissue damage produced by lead is slow and progressive. The renal system is one of the systems primarily affected by lead. The present study aimed to evaluate renal proximal tubular functional and structural integrity among lead-exposed and cigarette-smoking male Egyptian workers. This study was extended to investigate the effect of lead exposure and cigarette smoking on urinary excretion of copper (Cu) and zinc (Zn). METHODS: Participants included in the present study were 156 male workers grouped as follows: i) 75 lead non-exposed workers subgrouped into G1 that consisted of 36 non-smokers (age, 39.08+/-6.65 years) and G2, which included 39 smokers (age, 43.87+/-9.93 years); ii) 45 lead-exposed workers (work duration <20 years) subgrouped into G3 that consisted of 25 non-smokers (age, 37.40+/-3.76 years) and G4, which included 20 smokers (age, 38.40+/-4.95 years), and iii) 36 lead-exposed workers (work duration > or =20 years) subgrouped into G5 that consisted of 16 non-smokers (age, 45.94+/-4.19 years) and G6 which included 20 smokers (age, 45.70+/-2.25 years). Functional integrity of proximal tubules was studied by determining urinary level of low-molecular-weight protein alpha1-microglobulin (alpha1M), and structural integrity was investigated by measuring urinary activities of the lysosomal enzyme N-acetyl-beta-D-glucosaminidase (NAG) and the cytoplasmic enzyme glutathione S-transferase (GST). Urinary concentrations of Pb, Cu, Zn, and creatinine were also determined. RESULTS: Data of the present investigation showed increased urinary excretion of all measured urinary parameters among lead-exposed workers in comparison with non-exposed workers whether they were non-smokers or smokers (G3 vs. G1, G5 vs. G1, G4 vs. G2, and G6 vs. G2), with greater elevation among lead-exposed smokers than among lead-exposed non-smokers (G4 vs. G3, G6 vs. G5). In addition, there was a greater increase in levels of all urinary parameters among workers with work duration > or =20 years than in those with <20 years' work duration (G6 vs. G4, G5 vs. G3). CONCLUSIONS: Lead exposure in Egyptian workers causes damage to renal proximal tubules and results in its dysfunction. Cigarette smoking has a nephrotoxic effect and also is synergistic to lead nephrotoxicity on urinary excretion of GST and NAG, as well as Pb.

Subclinical nephrotoxicity caused by smoking and occupational silica exposure among Egyptian industrial workers.

BACKGROUND: The aim of the present work was to investigate early signs of subclinical renal alterations due to silica exposure and smoking among non-silicotics and silicotics by measuring urinary indicators of nephrotoxicity. METHODS: The subjects comprised 29 non-silicotics (9 non-smokers, 20 smokers), 24 silicotics (9 non-smokers, 15 smokers), and 28 referents (9 non-smokers, 19 smokers). Measured urinary parameters were concentrations of total protein, microalbumin, retinol-binding protein, and activities of N-acetyl-beta-D-glucosaminidase and glutathione S-transferase. In addition, we measured levels of urinary silicon and creatinine. RESULTS: Compared with referents, both non-silicotics and silicotics excreted significant high levels of all measured parameters. Smokers in each investigated group also showed increased levels (although not significant) of renal parameters in comparison to corresponding non-smokers. Among non-silicotics, the present results showed that elevation of measured urinary parameters was significantly associated with work duration, while only urinary excretion of glutathione S-transferase was associated with work duration among silicotics. CONCLUSIONS: The study confirms that silica may lead to subclinical signs of nephrotoxicity, and that smoking also has a nephrotoxic effect on kidney and is synergistic to nephrotoxicity of silica exposure. Additionally, the study suggests that renal alterations may occur prior to pulmonary involvement.

Effect of silica exposure on urinary excretion of copper and zinc.

BACKGROUND: Occupational exposure to silica could lead to renal histological alterations in the glomeruli and proximal tubules. We investigated urinary excretion of copper and zinc and its possible relationship to renal alterations and work duration among nonsmoking, silica-exposed workers. METHODS: Thirty-six control subjects (age, 39.08 +/- 6.65 years) and 48 silica-exposed workers (age, 36.79 +/- 7.33 years) were included in the present study. The exposed workers were grouped into workers with <10 years' work duration (n = 9; age, 29.0 +/- 1.50 years) and workers with > or =10 years' work duration (n = 39; age, 38.59 +/- 6.94 years). Glomerular function was assessed by measuring urinary level of microalbumin, and proximal tubular reabsorption function was assessed by measuring urinary level of alpha1-microglobulin. Structural integrity of proximal tubules was studied by measuring urinary activity of cytosolic enzyme glutathione S-transferase (GST). Also, urinary levels of copper, zinc, and creatinine were measured. RESULTS: All measured urinary parameters were significantly increased among silica-exposed workers compared with control subjects. A significant correlation was observed between urinary levels of each of copper and zinc with the glomerular and proximal tubular functional and structural urinary parameters as well as work duration. CONCLUSIONS: Occupational silica exposure may lead to increased urinary loss of copper and zinc as protein-metal complex, and the urinary level of these essential trace elements may be a marker for renal dysfunction. The urinary excretion of GST may be a useful marker for proximal tubular injury.

Nephrotoxic effects of mercury exposure and smoking among Egyptian workers in a fluorescent lamp factory.

BACKGROUND: It is known that mercury (Hg) has a nephrotoxic effect in exposed workers. This effect is evident when there is advanced damage of kidney tissue. METHODS: A random morning urine sample was collected from each participant for measuring urinary concentrations of total protein (UTP), retinol-binding protein (URBP), creatinine (UCr), Hg (UHg), and the activities of leucine-aminopeptidase (ULAP) and glutathione S-transferase (UGST) as well as N-acetyl-beta-D-glucosaminidase (UNAG). RESULTS: Urinary excretion of the measured parameters was significantly increased among Hg-exposed workers who were smokers and among Hg-exposed workers with work duration >or=11 years than those with

Effect of mercury vapour exposure on urinary excretion of calcium, zinc and copper: relationship to alterations in functional and structural integrity of the kidney.

BACKGROUND: The kidney has a remarkable capacity to concentrate mercury (Hg) and as such is a primary target organ when exposure to Hg occurs, and it is also an organ for Hg excretion. OBJECTIVE: The present work aims to investigate the effect of occupational Hg vapour exposure on the urinary excretion of calcium (Ca), zinc (Zn) and copper (Cu), and the possible association of this excretion to work duration as well as renal alterations. METHODS: 83 non-smoker participants (36 referents, age: 35.6 +/- 9.5 years; 27 Hg vapour-exposed workers with < or = 10 years work duration, age: 33.0 +/- 5.1 years; and 20 Hg vapour-exposed workers with > or = 11 years work duration, age: 39.50 +/- 8.50 years) were included in the present study. Urinary levels of microalbumin (U-Malb) and retinol-binding protein (U-RBP) as well as cytosolic glutathione S-transferase activity (U-GST) were measured to assess the glomerular and proximal tubular reabsorption functions as well as structural integrity of proximal tubules; respectively. In addition, blood Hg (B-Hg), serum levels of Hg (S-Hg) and Ca (S-Ca), and urinary levels of Hg (U-Hg), Ca (U-Ca), Zn (U-Zn), Cu (U-Cu) and creatinine (U-cr) were estimated. RESULTS: In comparison to referents, all investigated parameters showed significant increase (except S-Ca and U-Zn/U-Cu ratio that significantly decreased among the workers as one group, S-Ca and U-Zn/U-Cu ratio that significantly and nonsignificantly decreased; respectively among workers with < or = 10 years work duration, S-Ca and U-Zn/U-Cu ratio that significantly decreased among workers with > or = 11 years work duration). In addition, B-Hg was nonsignificantly increased and S-Ca was significantly decreased; also, both U-Hg and U-Zn/U-Cu were nonsignificantly decreased among workers with > or = 11 years work duration in comparison to those with < or = 10 years work duration. Also, each of U-Hg, U-Ca, U-Zn and U-Cu was related to one another, while each of U-Ca, U-Zn and U-Cu was related to each of U-Malb, U-RBP and U-GST (except U-Zn was not related to U-GST). CONCLUSION: Hg vapour exposure leads to renal alterations which may parallel the change in proteinuria and enzymuria as well as the increased loss in urine of each of Ca, Zn and Cu. The urinary assessment of these metals may be used as a good indicator for renal dysfunction.