Occupational exposure to lead, kidney function tests, and blood pressure

Association between chronic lead exposure and markers of kidney injury: A systematic review and meta-analysis

In view of inconsistent reports on the association between chronic lead (Pb) exposure and renal injury markers (potential site of injury), the present systematic review explored their association by reviewing studies that investigated chronic Pb-exposed and those without obvious Pb exposure. Studies reporting blood Pb levels(BLL) and biomarkers of kidney injury [i.e. N-acetyl-β-D-glucosaminidase (NAG), Micro-Globulin(μG) and others] among chronic Pb-exposed and unexposed individuals were systematically searched from digital databases available until February 26, 2024. Preferred Reporting Items of Systematic Reviews and Meta-Analysis Guidelines were adhered to during the execution. Pooled effect size and heterogeneity were estimated using the random effect model and I2Studies reporting blood Pb levels(BLL) and biomarkers of kidney injury [i.e. N-acetyl-β-D-glucosaminidase (NAG), Micro-Globulin(μG) and others] among chronic Pb-exposed and unexposed individuals were systematically searched from digital databases available until February 26, 2024. Preferred Reporting Items of Systematic Reviews and Meta-Analysis Guidelines were adhered to during the execution. Pooled effect size and heterogeneity were estimated using the random effect model and I2. Pooled quantitative analysis revealed elevated BLL [25.64 (21.59-29.70) µg/dL] Pb-exposed group. The pooled analysis confirmed significantly higher urinary NAG [0.68(0.26-1.10) units], α1μG [3.82(0.96-6.68) mg/g creatinine] β2μG [1.5(0.86-2.14) units and serum creatinine [0.03(0.00-0.05) mg/dL] levels in Pb-exposed group, with high heterogeneity. Current observations indicate the proximal tubular injury as the early and potential site of Pb-induced renal injury. Pb-exposed individuals experience proximal tubular injury (KIM-1, NAG) and dysfunction (β2μG, α1μG, Cystatin-C) prior to obvious clinical renal failure. Present observations should caution the policymakers towards drafting regulations for periodic screening with markers of renal injury and / or dysfunction among those chronically exposed to lead despite the certainty of evidence is very low.

The Relationships Between Blood Pb Levels and Blood Pressure Among Lead-Exposed Workers in China: A Repeated-Measure Study

OBJECTIVES

To explore the differences in the increase of systolic blood pressure (SBP) and diastolic blood pressure (DBP) in 3 consecutive years among lead (Pb) workers.

METHODS

Four hundred forty-eight Pb workers were enrolled in this repeated-measure study. Blood Pb, SBP, and DBP were measured in 2015 to 2017. Repeated measure of analysis of variance was used to compare the differences in the increase of SBP and DBP.

RESULTS

The mean SBP values were 124.0/125.5/126.9 mm Hg, and the mean DBP values were 75.4/77.4/77.8 mm Hg from 2015 to 2017. The differences in the increase of SBP and DBP were 2.94/2.42 mm Hg during the 3-year period. The average annual increase of SBP or DBP showed an upward trend in different Pb dose groups ( F = 4.904, P = 0.002; F = 3.612, P = 0.013).

CONCLUSIONS

Lead exposure caused average annual increases in SBP and DBP with 0.98 and 0.81 mm Hg, which provided basic data for health surveillance.

Nephrotoxic Biomarkers with Specific Indications for Metallic Pollutants: Implications for Environmental Health

Environmental and occupational exposure to heavy metals and metalloids is a major global health risk. The kidney is often a site of early damage. Nephrotoxicity is both a major consequence of heavy metal exposure and potentially an early warning of greater damage. A paradigm shift occurred at the beginning of the 21st century in the field of renal medicine. The medical model of kidney failure and treatment began to give way to a social model of risk factors and prevention with important implications for environmental health. This development threw into focus the need for better biomarkers: markers of exposure to known nephrotoxins; markers of early damage for diagnosis and prevention; markers of disease development for intervention and choice of therapy. Constituents of electronic waste, e-waste or e-pollution, such as cadmium (Cd), lead (Pb), mercury (HG), arsenic (As) and silica (SiO₂) are all potential nephrotoxins; they target the renal proximal tubules through distinct pathways. Different nephrotoxic biomarkers offer the possibility of identifying exposure to individual pollutants. In this review, a selection of prominent urinary markers of tubule damage is considered as potential tools for identifying environmental exposure to some key metallic pollutants.

Chronic Environmental and Occupational Lead Exposure and Kidney Function among African Americans: Dallas Lead Project II

Background: We examined the effects of lead on kidney function in occupationally and environmentally exposed adults from a Dallas lead smelter community that was the site of an Environmental Protection Agency (EPA) Superfund clean-up. All subjects were African Americans—a racial group that bears a disproportionate burden of kidney disease. Methods: A two-phase health screening was conducted. Phase II included a physical examination and laboratory tests. Study subjects were African Americans residents, aged ≥19 years to ≤89 years. Of 778 subjects, 726 were environmentally exposed and 52 were both occupationally and environmentally exposed. The effects of lead exposure on estimated glomerular filtration rate (eGFR) were examined in three groups: male and female smelter-community residents, as well as males with both occupational and environmental exposure. Multiple linear regression was used to analyze the dependence of eGFR on log (blood lead level), duration of residence in the community, type 2 diabetes, and hypertension. Results: There was a statistically significant negative effect on kidney function for all three groups. Comparison of female and male residents showed a slightly larger negative effect of blood lead level on eGFR in females versus males, with the largest effect seen in male smelter-working residents. For each unit increase (log₁₀ 10 µg/dL = 1) in blood lead level, age-adjusted eGFR was reduced 21.2 mL/min/1.73 m² in male residents, 25.3 mL/min/1.73 m² in female residents and 59.2 mL/min/1.73 m² in male smelter-working residents. Conclusions: Chronic lead exposure is associated with worsening kidney function in both African American male and female residents, as well as male workers in Dallas smelter communities. This effect is slightly, but not statistically significantly, worse in female residents than male residents, and significantly worse in males that both worked and resided in the smelter community.

The effect of environmental lead exposure on human health and the contribution of inflammatory mechanisms, a review

Lead (Pb) pollution has been considered as a major threat for human health due to induction of inflammatory cascades in various tissues. The aim of present review is to summarize the literature on the effects of lead exposure on respiratory, neurologic, digestive, cardiovascular and urinary disorders and the role of inflammation as an underlying mechanism for these effects. Various databases such as ISI Web of Knowledge, Medline, PubMed, Scopus, Google Scholar and Iran Medex, were searched from 1970 to November 2017 to gather the required articles using appropriate keywords such as lead, respiratory disorders, neurologic disorders, digestive disorders, cardiovascular disorders, urinary disorders and inflammation. Disorders of various body systems and the role of inflammation due to lead exposure has been proven by various studies. These studies indicate that lead exposure may cause respiratory, neurologic, digestive, cardiovascular and urinary diseases. The results were also indicated the increased inflammatory cells and mediators due to lead exposure including cytokines and chemokines due to lead exposure which suggested to be the cause various organ disorders.

High-field modulated ion-selective field-effect-transistor (FET) sensors with sensitivity higher than the ideal Nernst sensitivity

Lead ion selective membrane (Pb-ISM) coated AlGaN/GaN high electron mobility transistors (HEMT) was used to demonstrate a whole new methodology for ion-selective FET sensors, which can create ultra-high sensitivity (−36 mV/log [Pb²⁺]) surpassing the limit of ideal sensitivity (−29.58 mV/log [Pb²⁺]) in a typical Nernst equation for lead ion. The largely improved sensitivity has tremendously reduced the detection limit (10⁻¹⁰ M) for several orders of magnitude of lead ion concentration compared to typical ion-selective electrode (ISE) (10⁻⁷ M). The high sensitivity was obtained by creating a strong filed between the gate electrode and the HEMT channel. Systematical investigation was done by measuring different design of the sensor and gate bias, indicating ultra-high sensitivity and ultra-low detection limit obtained only in sufficiently strong field. Theoretical study in the sensitivity consistently agrees with the experimental finding and predicts the maximum and minimum sensitivity. The detection limit of our sensor is comparable to that of Inductively-Coupled-Plasma Mass Spectrum (ICP-MS), which also has detection limit near 10⁻¹⁰ M.

Lead (Pb2+) sorptive removal using chitosan-modified biochar: batch and fixed-bed studies

Chitosan-Modified fast pyrolysis BioChar (CMBC) was used to remove Pb²⁺ from water. CMBC was made by mixing pine wood biochar with a 2% aqueous acetic acid chitosan (85% deacylated chitin) solution followed by treatment with NaOH. The characterizations of both CMBC and Non-Modified BioChar (NMBC) were done using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), scanning electron microscopy (SEM), surface area measurements (S_BET), elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and ζ-potential measurements. Elemental analysis indicated that chitosan accounts for about 25% weight of the CMBC. The Langmuir maximum adsorption capacity of CMBC at pH 5 was 134 mg g⁻¹versus 48.2 mg g⁻¹ for NMBC at 318 K. CMBC column adsorption studies resulted in a capacity of 5.8 mg g⁻¹ (Pb²⁺ conc. 150 mg L⁻¹; pH 5; column dia 1.0 cm; column length 20 cm; bed height 5.0 cm; flow rate 2.5 mL min⁻¹). CMBC removed more Pb²⁺ than NMBC suggesting that modification with chitosan generates amine groups on the biochar surface which enhance Pb²⁺ adsorption. The modes of Pb²⁺ adsorption on CMBC were studied by comparing DRIFTS and X-ray photoelectron spectroscopy spectra before and after Pb²⁺ adsorption.

Batch and fixed-bed column studies for the removal of lead (Pb²⁺) from aqueous solution by chitosan-modified pinewood biochar.

Non-occupational Lead and Cadmium Exposure and Blood Pressure in Thai Men

In this study, the effects of low level exposure to lead and cadmium on blood pressure among 212 men have been examined. The mean age was 41 years (range 34-53). The means of systolic and diastolic blood pressure were 126 (range 94-159) and 78 (range 58-117) mmHg, respectively. Blood lead concentration ranged from 144.31 to 779.34 ηmol/L with a geometric mean (GM) of 363.11 ηmol/L. Blood cadmium levels ranged from 1.33-37.81ηmol/L with GM of 8.09 ηmol/L. For stepwise regression analysis, an increase in systolic blood pressure was significantly predictive by an increasing blood lead ( p<0.001) whereas blood cadmium showed no significant correlation with blood pressure. Body mass index and alcohol consumption also contributed to both systolic and diastolic blood pressure. These findings also supported our proposal concerning the association between blood lead and blood pressure. Asia Pac J Public Health 2004; 16(2): 133-137.

Blood pressure and occupational exposure to noise and lead (Pb): A cross-sectional study

Several studies have explored the hypothesis that low blood lead (PbB) and high noise levels may be associated with an increased risk of hypertension. To assess the possible relationship between occupational exposure to lead (Pb) and noise and elevated blood pressure, we studied 105 workers (age: 41.27 ± 6.25 years and length of employment: 4.12 ± 5.33 years) employed in a Pb battery recycling plant by measuring A-weighted equivalent sound level, PbB, δ-aminolevulinic acid dehydratase (ALAD) activity and zinc protoporphyrin (ZPP) levels and systolic and diastolic blood pressure (SBP and DBP). Results showed that occupational exposure to higher ambient Pb and noise levels was related to slightly increased SBP and DBP. PbB values correlated significantly with SBP and DBP, whereas noise levels correlated neither with SBP nor with DBP. Furthermore, workers exposed to higher ambient Pb had higher PbB and ZPP and showed more decreased ALAD activity. Blood pressure does not correlate with noise exposure but only with PbB concentration.

Lead Nephropathy: Revisiting an Overlooked Cause of Kidney Disease

Despite the recognition of lead nephropathy as a consequence of environmental and occupational lead exposure, lead nephropathy still appears to be underrecognized by physicians as a cause and promoter of chronic kidney disease (CKD), especially in people with more apparent causative factors such as diabetes and hypertension. This review focuses on the clinical, pathophysiological and epidemiological perspectives of lead nephropathy with the objective of promoting the awareness of this important but overlooked cause of CKD among physicians. Literature was reviewed using available medical journals and online literature search through Google, Pubmed, Medline, Medscape and HINARI databases. The key words employed were: Lead Nephropathy, Environmental and Occupational lead exposure and chronic kidney disease. Lead nephropathy which is a tubulointerstitial nephritis, may present acutely or chronically in association with hypertension. The clinical diagnosis of lead nephropathy is complex, because the symptoms are varied and non-specific especially with subclinical nephrotoxicity. The recognition of lead nephropathy can be enhanced if physicians have a high index of suspicion in the assessment of patients with renal disease. It is recommended that the evaluation of environmental and occupational nephrotoxins like lead be incorporated into programs for the prevention of CKD, especially in developing countries where lead exposure and toxicity still remain largely unchecked and the prevalence and burden of CKD is increasing.

Symmetric dimethyl arginine and N-acetyl-β-D-glucosaminidase lysozimuria of proximal renal tubules as a target for nephrotoxicity in patients with rheumatoid arthritis treated with disease modifying antirheumatic drugs

BACKGROUND

The aim of this study was to determine the effect of initial therapy with some disease modifying antirheumatic drugs (DMARDs) (Methotrexate and Ketoprofen) on glomerular and tubular integrity in patients with Rheumatoid arthritis (RA).

OBJECTIVES

OBJECTIVES

To determine whether there is a change in clinical and laboratory indicators of renal function in course of the follow up of treatment and whether that change correlates with the dynamics of the quantity of enzymes excreted in urine and reactants of the acute phase.

MATERIALS AND METHODS

Using colorimetric method for determination of NAG, samples of 70 participants were examined (35 RA patients treated with Ketoprofen only, 35 RA patients treated with combined use of Methotrexate and Ketoprofen). The follow up was 5 time-intervals in the course of 24 weeks.

RESULTS

There was moderate correlation between NAG and microalbuminuria (r=0,34) in the group of patients treated with Ketoprofen only, while statistically significant correlation (r=0,21) was seen in group of patients with combined use of Methotrexate and Ketoprofen. NAG enzymuria in size, number of patients registered, and time of appearance were greater and appears earlier in the group with the combined use of Methotrexate and Ketoprofen compared with the mono-therapy with Ketoprofen. Mean urinary NAG induction was increasing with the concomitant use of Methotrexate and Ketoprofen.

CONCLUSIONS

Methotrexate is more potent NAG inductor than Ketoprofen and provokes greater tubular enzymuria than Ketoprofen.

Biochemical effects of lead exposure on battery manufacture workers with reference to blood pressure, calcium metabolism and bone mineral density

Lead is one of the most widely scattered toxic metals in the environment and used by mankind for over 9,000 years. Lead in the environment may be derived from natural or anthropogenic sources. In humans, lead can cause a wide range of biological effects depending upon the level and duration of exposure. The purpose of this study was to find out the effect of lead exposure on systolic and diastolic blood pressure, serum calcium, ionized calcium, phosphorus, parathyroid hormone and vitamin D and examine the overall effect of all these parameters on the bone mineral density of battery manufacture workers. For this study ninety battery manufacture workers were selected and divided in three groups depending upon duration of lead exposure. Group I-workers with duration of lead exposure 1-5 years, Group II-workers with duration of lead exposure 6-10 years and Group III-workers with duration of lead exposure more than 10 years. Each group consisted of thirty workers. Thirty age matched healthy control subjects were taken for comparison. Demographic, occupational and clinical data were collected by using questionnaire and interview. The venous blood samples were collected from the study groups and normal healthy control group. At the time of blood collection random urine samples were collected in amber coloured bottles. The biochemical parameters were estimated by using standard assay procedures. Statistical analysis of the data was done using independent student't' test for parametric variables. Values were expressed as mean ± standard deviation (SD). P values of 0.05 or less were considered to be statistically significant. The blood lead levels and urinary lead levels of all workers were significantly increased (P < 0.001) in proportion to the duration of lead exposure as compared to controls. Systolic and diastolic blood pressure were significantly raised (P < 0.001) in all three study groups of battery manufacture workers as compared to controls. Serum Calcium, Ionized calcium, phosphorus were significantly decreased (P < 0.001) in all the three study groups. Serum vitamin D levels were lowered (P < 0.01) and serum PTH was increased (P < 0.01) in workers as compared to controls. The results of this study clearly indicate that the absorption of lead is more in these workers which adversely affects blood pressure, disturbs calcium and phosphorus metabolism which further impairs mineralization of bone resulting in decreased bone mineral density observed in these workers. Lead toxicity is still persistent in battery manufacture workers though they are using sophisticated techniques in these industries. There is a need to protect the workers from the health hazards of occupational lead exposure.

Review: Lead exposure in battery manufacturing and recycling in developing countries and among children in nearby communities

The battery industry is the largest consumer of lead, using an estimated 80% of the global lead production. The industry is also rapidly expanding in emerging market countries. A review of published literature on exposures from lead-acid battery manufacturing and recycling plants in developing countries was conducted. The review included studies from 37 countries published from 1993 to 2010 and excluded facilities in developed countries, such as the United States and those in Western Europe, except for providing comparisons to reported findings. The average worker blood lead level (BLL) in developing countries was 47 μg/dL in battery manufacturing plants and 64 μg/dL in recycling facilities. Airborne lead concentrations reported in battery plants in developing countries averaged 367 μg/m3, which is 7-fold greater than the U.S. Occupational Safety and Health Administration's 50 μg/m3 permissible exposure limit. The geometric mean BLL of children residing near battery plants in developing countries was 19 μg/dL, which is about 13-fold greater than the levels observed among children in the United States. The blood lead and airborne lead exposure concentrations for battery workers were substantially higher in developing countries than in the United States. This disparity may worsen due to rapid growth in lead-acid battery manufacturing and recycling operations worldwide. Given the lack of regulatory and enforcement capacity in most developing countries, third-party certification programs may be the only viable option to improve conditions.

Reduction of lead oxide (PbO2) and release of Pb(II) in mixtures of natural organic matter, free chlorine and monochloramine

The primary focus of this paper is to elucidate the influence of mixtures of natural organic matter (NOM) and free chlorine and NOM and monochloramine on the reduction of PbO2 in drinking water. Parallel experiments using PbO2 particles of two different sizes (approximately 20 and approximately 200 nm) were conducted to explore the effects of particle size on this process. In the absence of NOM, reduction of PbO2 was observed in monochloramine solutions but not in free chlorine solutions. In the presence of NOM, significant Pb(II) formation was observed in disinfectant-free solutions. The release of Pb(II) was suppressed by the additional presence of free chlorine until the point in time when free chlorine was exhausted. Monochloramine also repressed Pb(II) formation in the presence of NOM but not as significantly as free chlorine. The presence of NOM and monochloramine does not necessarily act additively or synergistically due to complex interactions including reduction of PbO2 by NOM, monochloramine mediated reduction of PbO2, and oxidation of NOM by monochloramine. Higher surface area-normalized Pb(ll) formation was found in experiments using larger PbO2 particles. The high reactivity generally associated with nanoparticles was not observed in our study.

Activation profiles of HSPA5 during the glomerular mesangial cell stress response to chemical injury

Environmental injury has been associated with endoplasmic reticulum (ER) stress, a response characterized by activation of the unfolded protein response, proteasomal degradation of proteins, and induction of HSPA5, also known as GRP78 or BiP. Although HSPA5 has been implicated in the stress response to environmental injury in several cell types, its role in the glomerular ER stress response is unknown. In this study, we evaluated HSPA5 activation profiles in rat glomerular mesangial cells (rGMCs) challenged with heavy metals (HgCl2 or Pb2+ acetate) or polycyclic aromatic hydrocarbons (PAHs, ie, benzo(a)pyrene [BaP]). Challenge of rGMCs with 1 or 10 microM HgCl2 or Pb2+ acetate increased HSPA5 mRNA and protein levels. The induction response was sensitive to transcriptional and translational inhibition by actinomycin D (AD) and cyclohexamide, respectively. HSPA5 mRNA was induced by 3 microM BaP in an AD-sensitive manner, but this response was unaffected by the presence of heavy metals. A promoter construct containing sequences that mediate thapsigargin (TH) inducibility of the HSPA5 promoter was refractory to both heavy metals and BaP. The HSPA5 induction response in rGMCs is conserved because it was reproduced with fidelity in immunolocalization experiments of HSPA5 protein in M15 and HEK293 cells in embryonic lines of murine and human origin, respectively. Collectively, these findings identify HSPA5 in the stress response of rGMCs and implicate regulatory mechanisms that are distinct from those involved in TH inducibility.

Occupational and environmental human lead exposure in Brazil

The purpose of this paper is to present a review of data on assessment of exposure and adverse effects due to environmental and occupational lead exposure in Brazil. Epidemiological investigations on children lead exposure around industrial and mining areas have shown that lead contamination is an actual source of concern. Lead in gasoline has been phasing out since the 1980s, and it is now completely discontinued. The last lead mining and lead refining plant was closed in 1995, leaving residual environmental lead contamination which has recently been investigated using a multidisciplinary approach. Moreover, there are hundreds of small battery recycling plants and secondary smelting facilities all over the country, which produce focal urban areas of lead contamination. Current regulatory limits for workplace lead exposure have shown to be inadequate as safety limits according to a few studies carried out lately.

Lead-related nephrotoxicity: a review of the epidemiologic evidence

Chronic kidney disease (CKD) represents a major global public health concern. Efforts to prevent and/or slow progression of CKD are essential. Lead nephropathy, characterized by chronic tubulointerstitial nephritis, is a well-known risk of chronic, high-level lead exposure. However, in recent years, lead exposure has declined sharply, particularly in developed countries. We reviewed epidemiologic research in general, occupational, and patient populations to assess whether lead, at current exposure levels, still contributes to nephrotoxicity. Other pertinent topics, such as risk in children, genetic susceptibility, and co-exposure to cadmium, are also considered. The data reviewed indicate that lead contributes to nephrotoxicity, even at blood lead levels below 5 microg/dl. This is particularly true in susceptible populations, such as those with hypertension (HTN), diabetes, and/or CKD. Low socioeconomic status is a risk factor for both lead exposure and diseases that increase susceptibility. Future public health risk for lead-related nephrotoxicity may be most significant in those rapidly developing countries where risk factors for CKD, including obesity and secondary HTN and diabetes mellitus, are increasing more rapidly than lead exposure is declining. Global efforts to reduce lead exposure remain important. Research is also needed to determine whether specific therapies, such as chelation, are beneficial in susceptible populations.

Relationship of blood lead levels to blood pressure in exhaust battery storage workers

Several researches has focused the hypothesis that low blood lead levels could be associated with an increased risk of hypertension. To assess the relation between occupational lead exposure and elevated blood pressure a group of 27 workers, age range from 27 to 62 years, mean (SD) 36.52 (+/- 8.16) yr; length of employment mean (DS) 2.97 (+/- 1.67) yr, were recruited as study subjects. The following variables were measured: blood lead concentration (BPb), delta-Aminolevulinic Acid Dehydratase (ALAD) activity, Zinc Protoporphirin (ZPP), creatinine, hematocrit, Body Mass Index (BMI) and Systolic Blood Pressure (SBP) and Diastolic Blood (DBP) Pressure. The results showed that long term occupational exposure was related to a slight increase of systolic and diastolic blood pressure among workers who had been exposed to higher level of lead with respect to workers exposed to lower level of lead. Furthermore, blood lead concentration (BPb) and ZPP resulted higher among workers exposed to higher level of ambient lead, while in the same group of workers ALAD activity resulted more inhibited. The authors concluded long term cumulative lead exposure can significantly increase blood pressure in low level Pb exposed workers.

Environmental and Biological Monitoring in a Lead Acid Battery Manufacturing Unit in India

An environmental and biological monitoring of a lead acid battery manufacturing unit was carried out to measure the respirable particulate matter, lead content in working atmosphere and blood lead levels of workers employed in different sections. The results showed high mean air lead concentration in buffing (1444.45 microg/m(3)), plate cutting (430.14 microg/m(3)) and pasting (277.48 microg/m(3)) sections. The mean blood lead levels of employees in these sections were also higher than the values prescribed by ACGIH.

The G894-T894 Polymorphism in the Gene for Endothelial Nitric Oxide Synthase and Blood Pressure in Lead-Exposed Workers From Korea

We evaluated whether the G -T polymorphism in exon 7 of the endothelial nitric oxide synthase (eNOS) gene is associated with blood pressure or modifies the relation between lead dose and blood pressure in 803 lead workers in Korea. A total of 84.9% of individuals were homozygous GG, 14.4% heterozygous GT, and 0.8% homozygous TT. The T allele was not significantly associated with systolic or diastolic blood pressure. The prevalence of hypertension did not differ by T status (OR = 0.82; 95% CI = 0.50-1.37). There was no evidence of effect modification by eNOS genotype on relations of lead dose with blood pressure. These data provide no evidence that the T allele is associated with higher blood pressure or modifies the association of lead dose with blood pressure.

Estimating the global burden of disease of mild mental retardation and cardiovascular diseases from environmental lead exposure

The disease burden from exposure to lead resulting in mild mental retardation (due to IQ point decreases) and cardiovascular outcomes (due to increases in blood pressure) was estimated at a global level. Blood lead levels were compiled from the literature for 14 geographical regions defined by the World Health Organization according to location and adult and child mortality rates. Adjustments were applied to these levels, where appropriate, to account for recent changes relating to the implementation of lead-reduction programs and the lower levels seen in rural populations. It is estimated that mild mental retardation and cardiovascular outcomes resulting from exposure to lead amount to almost 1% of the global burden of disease, with the highest burden in developing regions. This estimate can be used to assess the magnitude of the benefits that could be accrued by increasing the global coverage of lead-reduction programs.

Associations of lead biomarkers with renal function in Korean lead workers

AIMS

To compare associations of lead biomarkers with renal function in current and former lead workers.

METHODS

Cross sectional analysis of first year results from a longitudinal study of 803 lead workers and 135 controls in South Korea. Clinical renal function was assessed by blood urea nitrogen (BUN), serum creatinine, and measured and calculated creatinine clearance. Urinary N-acetyl-beta-D-glucosaminidase (NAG) and retinol-binding protein were also measured.

RESULTS

Mean (SD) tibia lead, blood lead, and DMSA chelatable lead levels in lead workers were 37.2 (40.4) micro g/g bone mineral, 32.0 (15.0) micro g/dl, and 767.8 (862.1) micro g/g creatinine, respectively. Higher lead measures were associated with worse renal function in 16/42 models. When influential outliers were removed, higher lead measures remained associated with worse renal function in nine models. An additional five associations were in the opposite direction. Effect modification by age was observed. In 3/16 models, associations between higher lead measures and worse clinical renal function in participants in the oldest age tertile were significantly different from associations in those in the youngest age tertile which were in the opposite direction. Mean urinary cadmium (CdU) was 1.1 micro g/g creatinine (n = 191). Higher CdU levels were associated with higher NAG.

CONCLUSIONS

These data suggest that lead has an adverse effect on renal function in the moderate dose range, particularly in older workers. Associations between higher lead measures and lower BUN and serum creatinine and higher creatinine clearances may represent lead induced hyperfiltration. Environmental cadmium may also have an adverse renal impact, at least on NAG.

Lead exposure and urinary N-acetyl beta D glucosaminidase activity in adolescent workers in auto repair workshops

PURPOSE

To investigate levels of lead (Pb) exposure and renal tubular damage among adolescent workers in auto repair workshops in Turkey.

METHODS

The study was conducted on 39 adolescent workers (mean age: 16.18 +/- 3.19 years) in auto repair workshops (8 autoelectrician, 10 motor repairman, 8 auto painter, 5 turner, 8 bonnet straighter). Thirteen adult employees of battery production in the workshops (mean age: 32.08 +/- 10.94 years) and 29 healthy rural adolescent (mean age: 14.78 +/- 2.68 years) constituted the control groups. The level of blood Pb was investigated by an atomic absorption spectrophotometer and urinary N-acetyl beta- D glucosaminidase (NAG) activity was measured by a colorimetric method. Mann-Whitney U test was performed to examine group differences.

RESULTS

All subjects and controls had normal blood urea, creatinine, uric acid, sodium, potassium levels, normal routine urine examination and tubular phosphorus reabsorption. Blood Pb levels in auto repair workers (8.13 +/- 7.41 mug/dL) were significantly higher than the rural control group (3.49 +/- 1.39 mug/dL) but lower than the battery workers (25.27 +/- 9.82 mug/dL). Urinary NAG (U/gr creatinine) (4.71 +/- 2.11) was lower than the battery workers (7.39 +/- 4.37), however significantly higher than the normal control group (3.07 +/- 1.20). In addition, auto painters had higher levels of Pb exposure and urinary NAG activity than the other workers (p <.05).

CONCLUSION

Chronic low dose Pb exposure was found to cause renal tubular injury in children workers of auto repair workshops.

An epidemiological re-appraisal of the association between blood pressure and blood lead: a meta-analysis

Studies on the possible association between blood pressure and blood lead have reached divergent conclusions. In a previous meta-analysis, a doubling of the blood lead concentration was associated with a 1.0/0.6 mm Hg increase in systolic and diastolic blood pressure (BP). This meta-analysis updates the analysis originally performed in 1994. Articles on the association between BP and blood lead were identified from computer searches from January 1980 to February 2001 using the Medical Literature Analysis and Retrieval System. Of the studies reviewed, 31 provided sufficient details to be considered. The meta-analysis included 58518 subjects recruited from the general population in 19 surveys and from occupationally exposed groups in 12 studies. In all but four studies, the results were adjusted for age, and most studies took into account additional confounding factors such as body mass index and the use of alcohol and medication. Weighted joint P-values were calculated using Stouffer's procedure. The association between BP and blood lead was similar in both men and women. In the combined studies, a two-fold increase in blood lead concentration was associated with a 1.0 mm Hg rise in the systolic pressure (95% CI +0.5 to +1.4 mm Hg; P < 0.001) and with a 0.6 mm Hg increase in the diastolic pressure (95% CI +0.4 to +0.8 mm Hg; P < 0.001). On balance, this meta-analysis suggests that there can only be a weak association between BP and blood lead.

Blood pressure, left ventricular mass, and lead exposure in battery manufacturing workers

BACKGROUND

Although debate about the relationship between lead and blood pressure has focused on low environmental lead levels, industrial exposure remains a concern.

METHODS

We measured blood pressure and left ventricular mass (LVM) in 108 battery manufacturing workers, and calculated cumulative and historic average measures of blood lead.

RESULTS

Diastolic pressure increased with increasing lead levels, with a significant (P = 0.04) 5 mmHg difference in mean pressure between the highest and lowest cumulative exposure levels. Diastolic pressure increased with the log of cumulative lead (P = 0.06). Both hypertension (defined as currently medicated or systolic > 160 mmHg or diastolic > 95 mmHg) and LVM increased nonsignificantly with increasing lead exposure (P-values > or = 0.17 for hypertension and > or = 0.20 for LVM).

CONCLUSIONS

We found a small effect of blood lead on diastolic blood pressure, particularly for a cumulative measure of exposure, but no convincing evidence of associations between lead and other blood-pressure-related outcomes. Published 2001 Wiley-Liss, Inc.

Diagnostic value of urinary alanine aminopeptidase and N-acetyl-beta-D-glucosaminidase in comparison to alpha 1-microglobulin as a marker in evaluating tubular dysfunction in glomerulonephritis patients

To estimate the diagnostic value of tubular parameters, the urinary alanine aminopeptidase (AAP), N-acetyl-beta-D-glucosaminidase (NAG) and the alpha(1)-microglobulin (a1M) of 150 patients with histologically proven glomerulonephritis (GN) were determined. In addition, the reabsorption rate of the proximal tubule and the fractional excretion of sodium, the free water clearance and the renal function were assessed by inulin and p-aminohippurate (PAH) clearance. Compared to healthy controls, urinary AAP, NAG and a1M were found significantly elevated in GN patients. Morphological tubular changes were confirmed by significant differences in urinary laboratory parameters. In patients with tubular atrophy, the diagnostic sensitivity and specificity were calculated as follows: AAP (0.94/0.35), NAG (0.75/0.59) and a1M (0.73/0.52). In patients showing tubular protein droplets, the values were 0.90/0.17 for AAP, 0.78/0.76 for NAG and 0.84/0.74 for a1M and in patients with interstitial fibrosis, the values were AAP (0.95/0.35), NAG (0.75/0. 46) and a1M (68/0.38). Urinary AAP, NAG and a1M reflect histologically proven tubulus alteration in GN, although in most cases, the renal function is still intact. AAP indicates very early tubular impairment and, in some cases, AAP is elevated although NAG and a1M are still within normal ranges. We suggest that the enzyme activities are useful in the diagnostics of early stages of the disease.

Clinical evaluation and management of lead-exposed construction workers

An estimated one million construction workers are currently occupationally exposed to lead. Until 1993, construction workers were not offered the protections of OSHA's 1978 standard for lead exposure in industrial activities. Preventing exposure to lead in the construction setting presents many challenges, given the rapidly and frequently changing work environment. This article reviews the adverse effects of lead on human health and presents an approach to the diagnosis, management, and prevention of lead-related illness. The medical aspects of the 1993 OSHA standard for lead in construction are described.

Urinary biomarkers as indicators of renal disease

Using modern technology, minute quantities of LMWP, prostanoids, growth factors, intra-renal and extra-renal enzymes can be measured in urine. Excretory patterns that are characteristic for site and mechanism of renal injury often can be found. It is possible to recognise urinary biomarker patterns that suggest the putative environmental nephrotoxin. Our own studies performed in subjects with low level occupational and environmental exposures in New Jersey confirm the pattern specificity and threshold effects for Cr, Hg and Pb. In addition, we have been able to show that increased NAG and IAP excretion following Pb exposure correlates with current (blood Pb) but not with the cumulative Pb burden (bone Pb). The relatively specific characteristic patterns of biomarker excretion are lost as renal failure progresses. Moreover, renal injury that results in tubular proteinuria may not progress to renal failure. Nevertheless, urine biomarkers can help to establish acceptable levels and identify the need for long term surveillance to ascertain when clinical renal disease may result.

High-affinity renal lead-binding proteins in environmentally-exposed humans

Chronic low level lead (Pb) exposure is associated with decrements in renal function in humans, but the molecular mechanisms underlying toxicity are not understood. We investigated cytosolic Pb-binding proteins (PbBP) in kidney of environmentally-exposed humans to identify molecular targets of Pb and elucidate mechanisms of toxicity. This study is unique in that it localized PbBPs based on physiologic Pb that was bound in vivo. Two Pb-binding polypeptides were identified, thymosin beta 4 (T beta 4, 5 kDa) and acyl-CoA binding protein (ACBP, 9 kDa, also known as diazepam binding inhibitor, DBI). These polypeptides, which have not been previously recognized for their metal-binding capabilities, were shown to bind Pb with high affinity (Kd approximately 14 nM) and to account for an estimated > 35% of the total Pb in kidney cortex tissue. Both T beta 4 and ACBP (DBI) occur across animal species from invertebrates to mammals and in all major tissues, serving multiple possible functions (e.g. regulation of actin polymerization, calmodulin-dependent enzyme activity, acyl-CoA metabolism, GABA-A/benzodiazepine receptor modulation, steroidogenesis, etc.). Thus, these data provide the first evidence of specific molecular targets of Pb in kidney of environmentally-exposed humans, and they suggest that low-level Pb toxicity may occur via alteration of T beta 4 and ACBP (DBI) function in renal and other tissues, including the central nervous system.

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.