铅作业工人肾损伤某些生化指标的变化

目的　探索铅致肾损伤生化指标的变化。方法　观察了某蓄电池厂 10 3名铅作业工人尿总蛋白(TP)、尿β2 微球蛋白 (β2 MG)、尿N 乙酰 β D 氨基葡萄糖苷酶 (NAG)的变化 ,同时分析尿铅含量、接触工龄与三指标的关系。结果　接触组尿TP(5 9 73± 6 84 )mg gCr、尿 β2 MG(12 2 0 1± 1 2 5 ) μg gCr、尿NAG(13 70±1 6 2 )U gCr水平显著高于对照组 ,且随尿铅含量的增高而升高。尿NAG的活性在接触铅 1～ 3年明显高于对照组 ,先于尿TP、尿 β2 MG出现异常。结论　尿NAG活性升高可能反映肾小管细胞损伤。尿NAG活性变化 ,结合尿β2 MG或尿TP的变化 ,可能反映肾受损情况。     

Associations among lead dose biomarkers, uric acid, and renal function in Korean lead workers

Recent research suggests that both uric acid and lead may be nephrotoxic at lower levels than previously recognized. We analyzed data from 803 current and former lead workers to determine whether lead biomarkers were associated with uric acid and whether previously reported associations between lead dose and renal outcomes were altered after adjustment for uric acid. Outcomes included uric acid, blood urea nitrogen, serum creatinine, measured and calculated creatinine clearances, and urinary N-acetyl-ss-d-glucosaminidase (NAG) and retinol-binding protein. Mean (+/- SD) uric acid, tibia lead, and blood lead levels were 4.8 +/- 1.2 mg/dL, 37.2 +/- 40.4 microg/g bone mineral, and 32.0 +/- 15.0 microg/dL, respectively. None of the lead measures (tibia, blood, and dimercaptosuccinic-acid-chelatable lead) was associated with uric acid, after adjustment for age, sex, body mass index, and alcohol use. However, when we examined effect modification by age on these relations, both blood and tibia lead were significantly associated (ss = 0.0111, p < 0.01 and ss = 0.0036, p = 0.04, respectively) in participants in the oldest age tertile. These associations decreased after adjustment for blood pressure and renal function, although blood lead remained significantly associated with uric acid (ss = 0.0156, p = 0.01) when the population was restricted to the oldest tertile of workers with serum creatinine greater than the median (0.86 mg/dL). Next, in models of renal function in all workers, uric acid was significantly (p < 0.05) associated with all renal outcomes except NAG. Finally, in the oldest tertile of workers, associations between lead dose and NAG were unchanged, but fewer associations between the lead biomarkers and the clinical renal outcomes remained significant (p less than or equal to 0.05) after adjustment for uric acid. In conclusion, our data suggest that older workers comprise a susceptible population for increased uric acid due to lead. Uric acid may be one, but not the only, mechanism for lead-related nephrotoxicity.     

Associations of patella lead and other lead biomarkers with renal function in lead workers

OBJECTIVE: We sought to compare associations of patella lead, which may represent a unique cumulative and bioavailable lead pool, with other lead measures in models of renal function. METHODS: Renal function measures included blood urea nitrogen, serum creatinine, measured and calculated creatinine clearances, and urinary N-acetyl-beta-D-glucosaminidase (NAG) and retinol-binding protein. RESULTS: In 652 lead workers, mean (SD) blood, patella, and tibia lead were 30.9 (16.7) microg/dL, 75.1 (101.1) and 33.6 (43.4) microg Pb/g bone mineral, respectively, and were correlated (Spearman's r = 0.51-0.74). Patella lead was associated (P < 0.05) with NAG in all lead workers. In models of effect modification by age, higher patella lead also was associated with higher serum creatinine in older participants. Similar associations were observed for blood and tibia lead. CONCLUSIONS: Associations between patella lead and adverse renal outcomes were not unique; this may be due, in part, to high correlations among the lead biomarkers in this study.     

Lead absorption and renal dysfunction in a South African battery factory

OBJECTIVES: To test the association between inorganic lead (Pb) exposure, blood pressure, and renal function in South African battery factory workers, with both conventional and newer measures of renal function and integrity. METHODS: Renal function measures included serum creatinine, urea, and urate (n = 382). Urinary markers (n = 199) included urinary N-acetyl-beta-D-glucosaminidase (NAG), retinol binding protein, intestinal alkaline phosphatase, tissue non-specific alkaline phosphatase, Tamm-Horsfall glycoprotein, epidermal growth factor, and microalbuminuria. RESULTS: Mean current blood Pb was 53.5 micrograms/dl (range 23 to 110), median zinc protoporphyrin 10.9 micrograms/g haemoglobin (range 1.9 to 104), and mean exposure duration 11.6 years (range 0.5 to 44.5). Mean historical blood Pb, available on 246 workers, was 57.3 micrograms/dl (range 14 to 96.3). After adjustment for age, weight and height, positive exposure response relations were found between current blood Pb, historical blood Pb, zinc protoporphyrin (ZPP), and serum creatinine and urate. Blood pressure was not associated with Pb exposure. Among the urinary markers, only NAG showed a positive association with current and historical blood Pb. CONCLUSION: An exposure-response relation between Pb and renal dysfunction across the range from < 40 to > 70 micrograms/dl blood Pb was found in this workforce, with conventional measures of short and long term Pb exposure and of renal function. This could not be explained by an effect on blood pressure, which was not associated with Pb exposure. The findings probably reflect a higher cumulative renal burden of Pb absorption in this workforce in comparison with those in recent negative studies. The results also confirm the need for strategies to reduce Pb exposure among industrial workers in South Africa.

 

     

Lead exposure among small-scale battery recyclers, automobile radiator mechanics, and their children in Manila, the Philippines

Blood lead (PbB) and hemoglobin levels (Hb) were determined in 40 battery repair/recycling shop workers, 16 radiator repair shop workers, and 20 children living in the immediate vicinity of these shops. Unexposed residents with similar socioeconomic status were also investigated. Mean PbB level was significantly higher for battery workers (54.23 microg/dL) when compared to radiator workers (20.04 microg/dL) and unexposed adults (12.56 microg/dL) (P<0.001). Among battery workers, 94% had PbB levels above the WHO permissible exposure limit of 40 microg/dL for males and 30 microg/dL for females. There was no demarcation between workplace and living quarters; therefore, workers' families were similarly exposed to hazards. Children living in the immediate vicinity of battery shops also had significantly higher mean PbB levels (49.88 microg/dL) compared to radiator shop children (11.84 microg/dL) and unexposed children (9.92 microg/dL). For workers with PbB > 40 microg/dL, 90% were anemic (Hb < 13 g/dL for males and <11.5 g/dL for females). Linear regression showed a correlation (r=-0.214; P=0.03) between Hb level and log(10)PbB. There was no significant relationship between anemia and blood lead in children (r=-0.146). We conclude that radiator repair activities appeared to increase the body burden of lead, although not up to a level significantly different from unexposed counterparts. Battery recycling/repair activities, however, significantly increased blood lead levels in workers and their children.     

Associations of renal function with polymorphisms in the delta-aminolevulinic acid dehydratase, vitamin D receptor, and nitric oxide synthase genes in Korean lead workers

We analyzed data from 798 lead workers to determine whether polymorphisms in the genes encoding delta-aminolevulinic acid dehydratase (ALAD), endothelial nitric oxide synthase (eNOS), and the vitamin D receptor (VDR) were associated with or modified relations of lead exposure and dose measures with renal outcomes. Lead exposure was assessed with job duration, blood lead, dimercaptosuccinic acid (DMSA)-chelatable lead, and tibia lead. Renal function was assessed with blood urea nitrogen (BUN), serum creatinine, measured creatinine clearance, calculated creatinine clearance and urinary N-acetyl-beta-D-glucosaminidase (NAG), and retinol-binding protein. Mean (+/- SD) tibia lead, blood lead, and DMSA-chelatable lead levels were 37.2 +/- 40.4 microg/g bone mineral, 32.0 +/- 15.0 microg/dL, and 767.8 +/- 862.1 microg/g creatinine, respectively. After adjustment, participants with the ALAD(2) allele had lower mean serum creatinine and higher calculated creatinine clearance. We observed effect modification by ALAD on associations between blood lead and/or DMSA-chelatable lead and three renal outcomes. Among those with the ALAD(1-2) genotype, higher lead measures were associated with lower BUN and serum creatinine and higher calculated creatinine clearance. Participants with the eNOS variant allele were found to have higher measured creatinine clearance and BUN. In participants with the Asp allele, longer duration working with lead was associated with higher serum creatinine and lower calculated creatinine clearance and NAG; all were significantly different from relations in those with the Glu/Glu genotype except NAG (p = 0.08). No significant differences were seen in renal outcomes by VDR genotype, nor was consistent effect modification observed. The ALAD findings could be explained by lead-induced hyperfiltration.     

Air and blood lead levels in lead acid battery recycling and manufacturing plants in Kenya

The concentration of airborne and blood lead (Pb) was assessed in a Pb acid battery recycling plant and in a Pb acid battery manufacturing plant in Kenya. In the recycling plant, full-shift area samples taken across 5 days in several production sections showed a mean value ± standard deviation (SD) of 427 ± 124 μg/m(3), while area samples in the office area had a mean ± SD of 59.2 ± 22.7 μg/m(3). In the battery manufacturing plant, full-shift area samples taken across 5 days in several production areas showed a mean value ± SD of 349 ± 107 μg/m(3), while area samples in the office area had a mean ± SD of 55.2 ± 33.2 μg/m(3). All these mean values exceed the U.S. Occupational Safety and Health Administration's permissible exposure limit of 50 μg/m(3) as an 8-hr time-weighted average. In the battery recycling plant, production workers had a mean blood Pb level ± SD of 62.2 ± 12.7 μg/dL, and office workers had a mean blood Pb level ± SD of 43.4 ± 6.6 μg/dL. In the battery manufacturing plant, production workers had a mean blood Pb level ± SD of 59.5 ± 10.1 μg/dL, and office workers had a mean blood Pb level ± SD of 41.6 ± 7.4 μg/dL. All the measured blood Pb levels exceeded 30 μg/dL, which is the maximum blood Pb level recommended by the ACGIH(?). Observations made in these facilities revealed numerous sources of Pb exposure due to inadequacies in engineering controls, work practices, respirator use, and personal hygiene.     

First-year changes in blood lead and zinc protoporphyrin levels within two groups of occupational lead workers

Quarterly changes in blood lead (PbB) and zinc protoporphyrin (ZPP) levels experienced by 30 male lead-acid storage battery workers and 24 auto assembly workers during their initial year of occupational lead exposure are described. The greatest absolute and percentage increases above baseline PbB levels occurred during the first 3 months of continuous exposure when battery and assembly workers' average PbB levels increased by 99% and 134%, respectively. Peak average PbB levels were reached during the second quarter of exposure for battery workers (27.3 micrograms/dL) and during the third quarter for assembly workers (34.3 micrograms/dL). Mean ZPP levels increased steadily through the first 3 quarters of exposure for both groups of workers before declining slightly during the final 3 months. Third-quarter average ZPP levels were 46.6 micrograms/dL for battery workers and 59.4 micrograms/dL for assembly workers. In general, for the assembly workers, the slopes of quarterly dose (PbB)-effect (loge ZPP) regressions increased with increasing exposure duration (up to 0.044 by the third quarter of exposure) and were significant (p less than 0.0001). Similar calculations for the battery workers were not statistically significant (p greater than 0.05) and showed no exposure-related trends. Probit-based dose (PbB)-response (ZPP level greater than two standard deviations above the baseline ZPP) analyses of the assembly worker data resulted in a 30.0 micrograms/dL ED50 estimate (PbB concentration at which 50% of a similarly exposed population would be expected to develop an "elevated" ZPP level).(ABSTRACT TRUNCATED AT 250 WORDS)     

Lead poisoning associated with malaria in children of urban areas of Nigeria

The principal objectives of this study are to (a) investigate the prevalence of elevated blood lead levels (EBLLs) in children of three major cities of Nigeria with different levels of industrial pollution; (b) identify the environmental, social and behavioral risk factors for the EBLLs in the children; and (c) explore the association between malaria (endemic in the study areas) and EBLLs in the pediatric population. The study involved 653 children aged 2-9 years (average, 3.7 years). The mean blood lead level (BLL) for the children was 8.9+/-4.8mug/dL, the median value was 7.8mug/dL, and the range was 1-52mug/dL. About 25% of the children had BLL greater than 10mug/dL. There were important differences in BLLs across the three cities, with the average value in Ibadan (9.9+/-5.2mug/dL) and Nnewi (8.3+/-3.5mug/dL) being higher than that in Port Harcourt (4.7+/-2.2mug/dL). Significant positive associations were found between BLL and a child's town of residence (p<0.001), age of the child (p=0.004), length of time the child played outside (p<0.001), presence of pets in a child's home (p=0.023), but negatively with educational level of caregiver (p<0.001). This study is one of the first to find a significant negative association between BLL and malaria in a pediatric population, and this association remained significant after controlling for confounding diseases and symptoms. The shared environmental and socio-demographic risks factors for lead exposure and Plasmodium (most common malaria parasites) infection in urban areas of Nigeria are discussed along with possible ways that lead exposure may influence the host response to infection with malarial parasites.     

The effect of occupational exposure to metals on the nervous system function in welders

We explored the relationship between metals exposure and nervous impairment in welders. The metals exposure of 82 welders and 51 operators were evaluated for blood Pb, Cd and Mn by atomic absorption spectrometry, and the nervous system impairment was evaluated with the neurobehavioral core test battery and electromyography. Pb (geometric mean: 117.31 mug/L; range: 0.5-327.6 mug/L) and Cd (geometric mean: 3.54 mug/L; range: 0.2-12.5 mug/L) in welders were significantly higher than those in operators. Welders had higher prevalence of nervous system symptoms and worse standard scores of 8 items such as depression-dejection than operators. Significant difference of nervous performance in welders only existed in different concentration groups of Pb and Mn. The performances of fatigue-inertia and some others had negative correlations with Pb and digit span with Mn. Therefore, the nervous system impairment in welders could be attributed to occupational exposure of Pb and Mn, but not Cd, concomitantly.     

Second-hand smoke exposure and blood lead levels in U.S. children

BACKGROUND: Lead is a component of tobacco and tobacco smoke, and smokers have higher blood lead levels than do nonsmokers. METHODS: We examined the relation between second-hand smoke exposure and blood lead levels in a nationally representative sample of 5592 U.S. children, age 4-16 years, who participated in the Third National Health and Nutrition Examination Survey (1988-1994). Linear and logistic regression modeling was used to adjust for known covariates. RESULTS: Geometric mean blood lead levels were 1.5 mug/dL, 1.9 mug/dL, and 2.6 mug/dL for children with low, intermediate, and high cotinine levels, respectively. The adjusted linear regression model showed that geometric mean blood lead levels were 38% higher (95% confidence interval [CI] = 25-52%) in children with high cotinine levels compared with children who had low cotinine levels. The logistic regression models showed that children with high cotinine levels were more likely to have blood lead levels >/=10 mug/dL than were children with low cotinine levels (odds ratio [OR] = 4.4; CI = 1.9-10.5). CONCLUSIONS: Second-hand smoke could be associated with increased blood lead levels in U.S. children aged 4-16 years.     

Neurocognitive impairment in lead-exposed children of Andean lead-glazing workers

OBJECTIVE: The level of lead (Pb) exposure necessary to induce intellectual impairment has not been firmly established. Some studies using conventional language-based intelligence tests have reported that pediatric blood lead (PbB) levels lower than 10 microg/dL (0.483 micromol/L) are associated with neurocognitive impairment. However, these tests may introduce cultural biases in the assessment of intellectual functioning. The objective of this study was to assess the effects of PbB concentration on nonverbal intelligence in Andean children with chronic environmental Pb exposure using a nonlanguage-based test of cognitive functioning. METHODS: Using Raven Colored Progressive Matrices (RCPM) as a measure of nonverbal intelligence, this study investigated the effects of Pb exposure (biomarker: PbB levels) on intellectual functioning in 188 chronically Pb-exposed children (age range: 5.33-11.67 years) of Ecuadorian Andean Pb-glazing workers. RESULTS: The mean PbB level of the 188 children was 29.3 microg/dL (range: 3.5-94.3 microg/dL). Forty-seven children had PbB levels <10 microg/dL (Centers for Disease Control and Prevention [CDC] I classification), of which 30 had abnormal (ie, < or =25th percentile) RCPM standard scores. Of the 141 children with PbB levels > or =10 microg/dL, 97 had abnormal RCPM scores. A regression analysis revealed a statistically significant negative association (r = -0.331, P < 0.0001) between PbB level and RCPM standard score. Conversion of RCPM standard scores to estimated IQ scores showed an approximate two-point decrease in IQ for each 10-microg/dL increment in PbB level from 10 to >70 microg/dL. CONCLUSIONS: Performance on a test of nonverbal intelligence was inversely associated with chronic Pb exposure in Andean children with PbB levels below and above the CDC risk management level of 10 microg/dL, with the decline in test scores suggesting a dose-response relationship.     

Biological monitoring of dichloropropene: air concentrations, urinary metabolite, and renal enzyme excretion

Fifteen applicators of dichloropropene (DCP) were studied for personal air exposure to DCP, excretion of the metabolite of DCP (3CNAC), and excretion of the renal tubular enzyme, N-acetyl glucosaminidase (NAG). Each was studied for four 6-8 h consecutive intervals following baseline determinations of 3CNAC and NAG excretion. In accord with pilot data, 24-h urinary excretion of 3CNAC (mg) correlated well with exposure product for DCP (min exposed.mg/m3), r = 0.854, p less than .001. A more precise correlation of the air exposure product with urinary excretion of 3CNAC was discerned by using the morning urine after the previous day of exposure (micrograms/mg of creatinine), r = 0.914, p less than .001. Four workers had clinically elevated activity of NAG (greater than 4 mU/mg creatinine) in any of their urine collections after baseline. Nine workers showed greater than 25% increases in NAG excretion when compared to baseline. Dichloropropene air exposure products of greater than 700 mg.min/m3 or excretion of greater than 1.5 mg 3CNAC/d distinguished abnormally high daily excretion of NAG. These data demonstrate a firm positive relationship between air exposure and internal exposure, and a possible subclinical nephrotoxic effect in DCP workers.     

Dose-response relations between urinary cadmium and tubular proteinuria in cadmium-exposed workers

Cadmium in urine reflects the body burden in cadmium-exposed individuals. Urinary β2-microglobulin is frequently used as a marker of tubular proteinuria with an arbitrarily chosen value (34 μg/mmole creatinine) as the cut-off limit. Both this cut-off level and a lower limit (25 μg/mmole creatinine) were used in a study of the relationship between urinary cadmium and β₂-microglobulin in 561 cadmium-exposed battery workers. There was a clear dose-response relation between the urinary cadmium level and the prevalence of tubular proteinuria ranging from 0.8% in the lowest exposure group, excreting less than 1 nmole cadmium/mmole creatinine, to 46.4% (50.0 for the lower cut-off level) in the highest exposure group with a mean urinary cadmium of 15 nmole/mmole creatinine. The relation between urinary cadmium and tubular proteinuria was also assessed using probit analysis. There was a 10% response at a urinary cadmium of 3 nmole/mmole creatinine. The impact of age on the dose-response relation was explored in two age groups with the cut-off point at 60 years of age, showing a 10% prevalence of tubular proteinuria at urinary cadmium levels of 1.5 nmole/mmole creatinine in this older age group and 5.0 nmole/mmole creatinine in the category under 60 years of age. The study thus indicates that the present health-based limit (10 nmole/mmole creatinine) proposed by the World Health Organization (WHO) is too high and it is suggested that a new limit should be set to 3 nmole/mmole creatinine.     

Surveillance of workers exposed to mercury vapour:validation of a previously proposed biological threshold limit value for mercury concentration in urine

A cross-sectional epidemiological study was carried out among subjects exposed to mercury (Hg) vapour, ie, a group of 131 male workers (mean age: 30.9 yr; average duration of exposure, 4.8 yr) and a group of 54 female workers (mean age, 29.9 yr; average duration of exposure 7 yr). The results were compared with those obtained in well-matched control groups comprising 114 and 48 male and female workers, respectively. The intensity of current Hg vapour exposure was rather moderate as reflected by the levels of mercury in urine (HgU) (mean and 95th percentile: males 52 and 147 micrograms/g creatinine; females 37 and 63 micrograms/g creatinine) and of mercury in blood (mean and 95th percentile: males 1.4 and 3.7 micrograms/dl; females 0.9 and 1.4 microgram/dl). Several symptoms mainly related to the central nervous system (memory disturbances, depressive feelings, fatigue, irritability) were more prevalent in the Hg-exposed subjects. They were, however, not related to exposure parameters. In both male and female Hg-exposed workers no significant disturbances were found in short-term memory (audioverbal), simple reaction time (visual), critical flicker fusion, and colour discrimination ability. Only slight renal tubular effects were detected in Hg-exposed males and females, ie, an increased urinary beta-galactosidase activity and an increased urinary excretion of retinol-binding protein. The prevalence of these preclinical renal effects was more related to the current exposure intensity (HgU) than to the duration of exposure and was detected mainly when HgU exceeds 50 micrograms/g creatinine. Changes in hand tremor spectrum recorded with an accelerometer were found in the Hg-exposed males only. The prevalence of abnormal values for some hand tremor parameters (total velocity and total displacement in the 2-50-Hz band) was mainly increased in male workers exposed for more than 10 yr. Unlike the renal tubular effects, the preclinical signs of tremor were more related to the integrated exposure than to the current exposure. Since the female workers, who have been exposed to Hg vapour levels usually insufficient to increase their HgU levels above 50 micrograms/g creatinine, did not exhibit any change in hand tremor pattern, the results of the present study tend to validate our previously proposed biological threshold limit value of a HgU of 50 micrograms/g creatinine for workers chronically exposed to mercury vapour.     

Renal function in dry cleaning workers exposed to perchloroethylene

Perchloroethylene (PCE) is a widely used dry cleaning and degreasing solvent. Although there is evidence in animals and humans for renal effects at extremely high doses, there are few studies of its potential renal toxicity at typical occupational concentrations. This study reports on the relationship of PCE in breath and estimates of chronic exposure with the urinary ratios of total urinary protein, albumin, and n-acetyl-glucosaminidase (NAG) to creatinine in dry cleaning workers exposed to PCE. Regression models including one or more exposure variables, demographic variables, mean arterial blood pressure (MAP), and the presence of diseases affecting kidney function were examined. Urine samples, breath samples, exposure histories, and medical histories were obtained from 192 dry cleaning workers. The results failed to demonstrate any consistent relationship between exposure and renal outcome variables. However, protein/creatinine and albumin/creatinine were significantly, although weakly and positively, associated with MAP; NAG/creatinine was weakly but significantly positively associated with age; mean NAG/creatinine was also higher in non-whites. The reasons why an association between exposure and renal outcome was not found are discussed.     

Search for anti-laminin antibodies in the serum of workers exposed to cadmium,mercury vapour or lead

Summary Anti-laminin antibodies were sought for in the serum of workers exposed to mercury vapour (Hg, n = 58), lead (Pb, n = 38) or cadmium (Cd, n = 47). Thirty-one workers removed from Cd exposure for an average of eight years were also examined. Compared with control workers matched for age and socio-economic status, the prevalence of circulating anti-laminin antibodies was not increased in workers exposed to Hg (mean duration of exposure: 7.9 years and mean urinary excretion of Hg: 72 g/g creatinine) nor in those exposed to Pb (mean duration of exposure: 10.6 years and mean Pb levels in blood: 535 g/l). In contrast, anti-laminin antibodies were significantly more prevalent in Cd-exposed workers whose urinary Cd exceeded 20 g/g creatinine. This observation was made in both currently exposed workers and in workers removed from Cd exposure (mean duration of exposure: 9.4 and 24.6 years and mean urinary Cd: 7.8 and 13.4 g/g creatinine respectively). These autoantibodies were found in Cd workers with normal renal function as well as in those with increased proteinuria.     

Change in the iso-enzyme profiles of urinary N-acetyl-beta-D-glucosoaminidase in workers exposed to mercury

The iso-enzyme profiles of urinary N-acetyl-beta-D-glucosoaminidase (NAG) were studied in the workers from a chloro-alkaline electrolysis plant that had been continuously exposed to elemental mercury. The same workers then had a work break of four months and were later re-exposed to mercury for another five months. The activities of urinary NAG in workers exposed to mercury before and after the work break and in the control group were 2.09 +/- 1.03 IU/L; 0.90 +/- 0.52 IU/L and 1.13 +/- 0.35 IU/L, respectively. The fraction of the dominant A form activity in the total activity, in the workers exposed to mercury after a work break (85.31 +/- 5.32%), was almost equal to the fraction of A in the control group (84.64 +/- 2.75%). The percent fraction of A forms (A and A2) during continuous exposure was almost equal to the sum of the fractions A and A2 in the control group and for exposure after the work break. The fraction of the B form activity in the total activity during exposure to elemental mercury for five months after the work break (7.41 +/- 3.45%) was lower (P < 0.1) than the fraction of the B form in the control group (8.62 +/- 2.19%). The decrease in the fraction of the B form compared with the control group was more significant (P < 0.001) in the case of continuously exposed workers (5.25 +/- 2.55%). Beside the major A and B iso-enzymes of NAG, the A2 form was also isolated, and its fraction in the control group (6.73 +/- 2.15%) was not negligible. For workers exposed to mercury for five months, it was 7.28 +/- 3.52%. It is concluded that mercury affected the increased exocytosis of iso-enzyme A and the inhibition of B iso-enzyme of NAG. The increase in activity of urinary NAG in subjects exposed to mercury was a consequence of the increased excretion of A form. It was established also that the four months work break was sufficient for the repair of renal damages that occurred during continuous exposure, and which were monitored by the activity of NAG. Thus, the effects of mercury seem to have been reversible.     

Effect of fire smoke on some biochemical parameters in firefighters of Saudi Arabia

Background

Lead exposure is common in automobile battery manufacture and repair, radiator repair, secondary smelters and welding units. Urinary Aminolevulinic acid has validity as a surrogate measure of blood lead level among workers occupationally exposed to lead. This study had therefore assessed the magnitude of lead exposure in battery repair workers of three transport service enterprises.

Methods

To this effect, a cross-sectional study was carried out on lead exposure among storage battery repair workers between November 2004 and May 2005 from Anbasa, Comet and Walia transport service enterprises, Addis Ababa, Ethiopia. Subjective information from the workers was obtained by making use of structured questionnaire. Other information was obtained from walkthrough evaluation of the repair units. Aminolevulinic acid levels in urine were used as an index of the exposure. This was coupled to measurements of other relevant parameters in blood and urine collected from adult subjects working in the repair units as well as age matched control subjects that were not occupationally exposed to lead. Aminolevulinic acid was determined by spectrophotometry, while creatinine clearance, serum creatinine, urea and uric acid levels were determined using AMS Autolab analyzer.

Results

Urinary aminolevulinic acid levels were found to be significantly higher in exposed group (16 μg/ml ± 2.0) compared to the non-exposed ones (7 μg/ml ± 1.0) (p < 0.001). Alcohol taking exposed subjects exhibited a significant increase in urinary aminolevulinic acid levels than non-alcohol taking ones (p < 0.05). Moreover, urinary aminolevulinic acid levels of exposed subjects increased with age (p < 0.001) as well as duration of employment (p < 0.001). Whereas serum uric acid levels of exposed subjects was significantly higher than non-exposed ones (p < 0.05), no statistically significant difference had been found in renal indices and other measured parameters between exposed and non-exposed subjects. From the questionnaire responses and walkthrough observations, it was also known that all the repair units did not implement effective preventive and control measures for workplace lead exposure.

Conclusion

Taken together, these findings indicated that workers in lead acid battery repair units of the transport service enterprises are not protected from possibly high lead exposure. Thus, strict enforcement of appropriate and cost effective preventive and control measures is required by all the enterprises.     

职业接触汞工人肾脏早期损伤指标的探讨

目的　探讨职业接触汞工人肾损伤的早期监控指标。方法　尿汞 (HgU)采用二硫腙化学法测定 ,尿视黄醇结合蛋白 (RBP)、尿 β2 微球蛋白 (β2 MG)和尿微量白蛋白 (mALB)采用全定量酶免疫法测定 ,尿N 乙酰 β D 氨基葡萄糖苷酶 (NAG)和γ 谷氨酰基转移酶 (γ GT)采用速率法测定 ,尿肌酐(Cr)采用苦味酸法测定。结果　职业接触汞工人尿RBP、β2 MG、NAG、γ GT测定结果分别为 (4 39.7±2 0 1.4 )、(14 1.4± 5 6 .3) μg gCr,(12 .3± 5 .7)、(6 0 .3± 18.5 )U gCr,均高于对照组 [分别为 (2 4 3.2±16 9.1)、(88.6± 4 1.2 ) μg gCr,(8.2± 1.6 )、(4 1.3± 13.2 )U gCr],差异均有显著性 (P <0 .0 5 ,P <0 .0 1)。随尿汞含量增加上述指标有逐渐增高的趋势 ;单项及两项检测RBP、β2 MG、NAG、γ GT的阳性率较低 ,联合其中 3项检测阳性率较高 ,联合 4项检测阳性率可达 85 .5 %。结论　联合检测RBP、β2 MG、NAG、γ GT是诊断职业接触汞工人早期肾损伤的灵敏指标。