Occupational exposure to lead and blood pressure: a study in 105 workers

Low-level Eexposure to lead dust in unusual work schedules and hematologic, renal, and hepatic parameters

BACKGROUND

Many workers are exposed to lead dust in lead-‑zinc mines. Exposure to this heavy toxic metal and its compounds can cause irreversible adverse health effects.

OBJECTIVE

To assess possible hematotoxic, nephrotoxic, and hepatotoxic potentials of low levels of lead in a group of mine workers exposed to this heavy metal in an unusual work schedule.

METHODS

A total of 73 exposed and 70 non-exposed employees were interviewed. Demographic data, and occupational and medical history of the employees were obtained by questionnaires. Air monitoring was performed to determine the workers' time-weighted average (TWA) exposure to lead dust. The threshold limit value (TLV) for lead was adjusted for unusual work schedules according to the model developed by the University of Montreal and the Institute de Recherche en Sante et en Securite du Travail (IRSST). Blood samples were collected for complete blood count, liver and kidney function tests. Data were analyzed using version 21.0 of the SPSS software.

RESULTS

The TWA exposure of workers was 24 μg/m³. On average, the worker's exposure to lead dust did not exceed the 8-h OSHA and ACGIH TLV-TWA of 50 μg/m³. Significant associations were found only between exposure to lead and platelet count, red cell distribution width, total protein, and albumin.

CONCLUSIONS

Exposure to low levels of lead dust in unusual work schedules was not associated with overt hematotoxicity, hepatotoxicity or nephrotoxicity. However, mild, sub-clinical, pre-pathologic significant changes were noted in some blood parameters of the exposed employees as compared with their referent counterparts.

Cadmium and hypertension in exposed workers: A meta-analysis

OBJECTIVES

In the general population, cadmium seems to be responsible for hypertension, atherosclerosis and an increase in acute coronary events. Therefore, the purpose of this meta-analysis was to analyze controlled studies conducted on cadmium and arterial pressure in occupationally-exposed workers.

MATERIALS AND METHODS

After analyzing all the relevant articles found in the literature, 6 publications were selected.

RESULTS

A higher prevalence of hypertension and higher values of systolic and diastolic blood pressure were recorded in the exposed subjects.

CONCLUSIONS

Cadmium in occupationally-exposed individuals appears to induce an increase in systolic and diastolic blood pressure and an increase in the prevalence of hypertension.

Chronic renal failure from lead: myth or evidence-based fact?

In this mini review, we would like to challenge the well-established 'fact' that lead exposure causes chronic renal failure (CRF). Even though only scarce evidence exists of the relationship between lead and renal failure, a World Health Organization Environmental Health Criteria document summarizes that 'Lead has been a very common cause of acute or chronic renal failure'. It is also written and cited in textbooks and numerous publications that chronic lead nephropathy causes a slowly progressive interstitial nephritis manifested by a reduced glomerular filtration rate, and that there is a growing consensus that lead contributes to hypertension in the general population. We will argue that, when published reports are carefully scrutinized, such statements on lead and CRF are not evidence based but are rather founded on a few narrative reports on lead-exposed individuals and statistical associations between lead and serum creatinine (or urea) in a few population studies. We will, however, not argue that lead is not toxic and that lead does not cause other types of severe health effects where the evidence is unquestionable, but we do not believe that the kidneys are an early victim after lead exposure.

Association between a polymorphism of aminolevulinate dehydrogenase (ALAD) gene and blood lead levels in Japanese subjects

This cross-sectional study investigated the relationship between the aminolevulinate dehydrogenase (ALAD) genotype and blood lead levels among 101 Japanese workers. Blood lead concentration measurement, biomarkers, and genotyping were performed. The minor allele frequency (MAF) for ALAD (ALAD2) was 0.08. Although the blood lead level in the subjects with heterozygous GC genotype was significantly higher than those with homozygous GG genotype, there were no significant differences for hemoglobin, hematocrit, serum and urinary ALA levels among genotypes. ALAD2 genotype was significantly associated with the blood lead concentration, even in the environmental lead exposed subjects. Further confirmation with a large sample size is needed.

Determination of Cd, Co, Ni and Pb in biological samples by microcolumn packed with black stone (Pierre noire) online coupled with ICP-OES

A simple and sensitive method using microcolumn (20-mm length x 2.0-mm i.d.) packed with black stone (Pierre noire) for the separation/preconcentration of Cd, Co, Ni and Pb in biological samples prior to their online determination by inductively coupled plasma optical emission spectrometry (ICP-OES) has been developed. Optimal experimental conditions including pH, eluent concentration and volume, sample volume and sample flow rate were investigated and established. The adsorption capacity of black stone for Cd, Co, Ni and Pb were found to be 23.4, 21.2, 18.1 and 22.2 mg g(-1), respectively. With a preconcentration time of 72 s and an elution time of 4s, an enrichment factor of 20 and a sampling frequency of 25 h(-1) were obtained. The detection limits corresponding to three times the standard deviations of the blank for Cd, Co, Ni and Pb were found to be 0.3, 0.4, 0.4 and 1.1 ng mL(-1). The precision for seven replicate determinations of Cd, Co, Ni and Pb gave relative standard deviations (RSDs) of 5.9, 4.8, 2.7 and 1.1%, respectively (n=7, C=10 ng mL(-1)). The method was validated with certified reference material GBW09103 human urine and the results obtained were in good agreement with the certified values. The method was also applied to the determination of the target analytes in biological samples with satisfactory results.

The effect of chelation on blood pressure in lead-exposed children: a randomized study

Studies in children suggest a weak association between blood lead concentration and blood pressure. To understand this better, we tested the strength of the association in children with elevated blood lead concentrations and whether succimer chelation changed blood pressure as it did blood lead. In a randomized clinical trial of 780 children with blood lead concentrations of 20-44 microg/dL at 12-33 months of age, we compared the systolic and diastolic blood pressure in the succimer-treated group and placebo group for up to 5 years of follow-up. We also analyzed the relation of blood lead to blood pressure. Children in the succimer group had lower blood lead concentrations for 9-10 months during and after treatment, but their blood pressure did not differ from those in the placebo group during this period. During 1-5 years of follow-up, children in the succimer group had systolic blood pressure 1.09 (95% confidence interval, 0.27-1.90) mmHg higher than did untreated children in a model with repeated measurements, but the difference in diastolic blood pressure was not statistically significant. No association between blood lead and blood pressure was found. Overall, there is no association between blood lead and blood pressure in these children with moderately high lead exposure, nor does chelation with succimer change blood pressure.

Association of blood lead and tibia lead with blood pressure and hypertension in a community sample of older adults

Few studies have compared associations of blood lead and tibia lead with blood pressure and hypertension, and associations have differed in samples with occupational exposure compared with those with mainly environmental lead exposure. African Americans have been underrepresented in prior studies. The authors performed a cross-sectional analysis of 2001-2002 data from a community-based cohort in Baltimore, Maryland, of 964 men and women aged 50-70 years (40% African American, 55% White, 5% other race/ethnicity) to evaluate associations of blood lead and tibia lead with systolic and diastolic blood pressure and hypertension while adjusting for a large set of potential confounding variables. Blood lead was a strong and consistent predictor of both systolic and diastolic blood pressure in models adjusted and not adjusted for race/ethnicity and socioeconomic status. Tibia lead was associated with hypertension status before adjustment for race/ethnicity and socioeconomic status (p = 0.01); after such adjustment, the association was borderline significant (p = 0.09). Propensity score analysis suggested that standard regression analysis may have exaggerated the attenuation. These findings are discussed in the context of complex causal pathways. The data suggest that lead has an acute effect on blood pressure via recent dose and a chronic effect on hypertension risk via cumulative dose.

Ambulatory (24 Hour) Blood Pressure Monitoring in Police Officers

The aim of the study is to evaluate, by ambulatory (24 h) blood pressure monitoring (ABPM), whether police officers exposed to urban pollutants and possible psycho-social stressors could be at risk of changes in ambulatory systolic blood pressure (SBP), and ambulatory diastolic blood pressure (DBP) compared to controls. After excluding the principal confounding factors, police officers and controls have been subdivided into non-smoker and smoker subjects. Police officers were compared by sex, age, length of service, family history of cardiovascular disease, serum total cholesterol, serum HDL cholesterol, serum LDL cholesterol, plasma triglyceride, body mass index (BMI kg/m (2)) and drinking habits with controls. Smoker police officers were compared with controls also by the smoking habit. In the non smoker group 77 police officers with outdoor activity (38 men and 39 women) and 87 controls with indoor activity (43 men and 44 women) were studied. In the smoker group 43 police officers (21 men and 22 women) and 29 controls (15 men and 14 women) were studied. In non smoker male police officers ambulatory SBP mean values during 24 h, during day-time and during night-time were significantly higher than controls. In the same group ambulatory DBP values during 24 h and between 6 AM and 11 AM and between 10 PM and 6 AM were significantly higher in police officers than controls. The results suggest that occupational exposure to urban pollutants and possible psycho-social stressors could cause changes in ABPM values in male police officers compared to controls.

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.

Blood lead level is associated with elevated blood pressure in blacks

Chronic lead exposure has been associated with elevated blood pressure in epidemiological studies. It is not known whether the previously observed relation between blood lead and hypertension persists after significant reductions have been made in environmental lead contamination. We examined the relation between blood lead levels and blood pressure in a representative sample of 14 952 whites and blacks aged 18 years or older who participated in the Third National Health and Nutrition Examination Survey. Blood lead was measured by atomic absorption spectrophotometry and blood pressure by standard sphygmomanometry. Mean blood lead levels were significantly higher for black men and women (5.4 and 3.4 microg/dL, respectively) compared with white men and women (4.4 and 3.0 microg/dL, respectively). After multivariate adjustment for important covariables, each standard deviation higher blood lead (3.3 microg/dL) was associated with a 0.82 (95% confidence interval [CI], 0.19 to 1.44) mm Hg and a 1.55 (95% CI, 0.47 to 2.64) mm Hg higher systolic blood pressure among black men and women, respectively. In contrast, blood lead level was not associated with blood pressure among white men or women. The multivariate-adjusted odds ratio (95% CI) of hypertension associated with a 1-SD higher level of blood lead was 1.08 (95% CI, 0.99 to 1.19) for black men and 1.39 (95% CI, 1.21 to 1.61) for black women. These findings suggest that increased levels of blood lead remain an important environmental risk factor for elevated blood pressure in blacks.

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.

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.

Heavy metal toxicity, part II: lead and metal fume fever

This review is the second of a two-part review of heavy metal toxicity. This part will identify the salient features of the toxicopathophysiology, clinical presentation, and emergency department management of lead toxicity and metal fume fever.

Relationship of blood lead levels to blood pressure in battery workers

The effect of lead exposure on blood pressure in the modern industrial setting is controversial. In this study, we followed 67 workers in a lead-battery plant for 6-10 y, and blood pressure and blood lead levels were measured every 6 mo. Weight, height, alcohol intake, cigarette smoking, and age were recorded. Partial correlation coefficients showed that initial systolic blood pressure, age, and body mass index (i.e., weight/height squared) accounted for 25%, 30.9%, and 20.2%, respectively, of the variance in systolic blood pressure (p < .001 in all cases). Conversely, average blood lead levels (13 +/- 3 tests/worker) accounted for only 0.4% of the variance (not significant). Repeated-measures analysis of variance showed a small--but significant--association between blood lead levels and systolic blood pressure. There was a negative correlation between blood lead levels and diastolic blood pressure. There were 18 men with average blood lead levels that were less than 30 micrograms/dl (average = 25 +/- 3 micrograms/dl), and 32 men had levels of 40 micrograms/dl or more (average = 47 +/- 6 micrograms/dl). The mean final systolic blood pressure, adjusted for age, and initial systolic blood pressure were 117 +/- 13 mm Hg and 114 +/- 11 mm Hg, respectively. We concluded that blood lead levels had no clinically significant effect on blood pressure in lead-battery workers. The main predictors of the follow-up systolic blood pressure were age, body mass index, and initial systolic blood-pressure measurements.

Sample collection guidelines for trace elements in blood and urine. IUPAC Commission of Toxicology

This paper presents an organized system for element-specific sample collection and handling of human blood (whole blood, serum or plasma, packed cells or erythrocytes) and urine also indicating a proper definition of the subject and sample. Harmonized procedures for collection, preparation, analysis and quality control are suggested. The aim is to assist scientists worldwide to produce comparable data which will be useful on a regional, national and international scale. The guidelines are directed to the elements aluminium, arsenic, cadmium, chromium, cobalt, copper, lead, lithium, manganese, mercury, nickel, selenium and zinc. These include the most important elements measured for their occupational or clinical significance, and serve as examples of principles that will guide development of methods for other elements in the future.

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

In the present study we examined sensitive biochemical markers of kidney function and damage in 166 workers exposed to lead and in 60 control workers. The objective was to investigate the chronic renal toxicity of lead and its possible correlation with arterial pressure. Diastolic arterial pressure was higher in the exposed group (p < 0.05), but the two groups did not differ in systolic pressure. Median activity of urinary N-acetyl-beta-D-glucosaminidase was higher in the exposed group (p < 0.001), and correlated with blood lead levels (p < 0.001) and duration of exposure (p < 0.001), but not with arterial pressure. The other indicators studied, gamma-glutamyl-transpeptidase and alanine-aminopeptidase activity, urine albumin, and total urine protein, were not higher than in the control group and were not correlated with blood lead, duration of exposure, or arterial pressure.

Perspectives on lead toxicity

Lead toxicity causes hematological, gastrointestinal, and neurological dysfunction in adults and children. Symptoms are usually noted with blood lead greater than 1.93 mumol/L. Severe or prolonged exposure may also cause chronic nephropathy, hypertension, and reproductive impairment. Lead inhibits enzymes; alters cellular calcium metabolism; stimulates synthesis of binding proteins in kidney, brain, and bone; and slows nerve conduction. Less severe exposure to lead, designated by blood lead levels of 0.48-0.96 mumol/L, has been implicated in poor pregnancy outcome, impaired neurobehavioral development, reduced stature in young children, and higher blood pressure in adults. Biochemical and systemic effects of high and low level lead toxicity are described. Dust, water, and paint chips are still major sources of lead but lead from folk remedies, cosmetics, food supplements, food preparation utensils, and improperly prepared infant formula has caused epidemic and sporadic severe lead toxicity. Screening for pediatric low level lead exposure requires measurement of blood lead.

The correspondence between U.K. 'action levels' for lead in blood and in water

This paper considers whether the Department of the Environment's water lead concentration criterion for lead pipe replacement and action in individual cases, i.e. 50 micrograms/l in any sample, is too high when set against the Department of Health's advisory action limit for blood lead concentration of 25 micrograms/100 ml. The relationships between blood lead and water lead concentrations found in the Glasgow and Ayr duplicate diet studies, together with unpublished data from Glasgow and Liverpool, indicate that over 10% of people exposed to an average water lead concentration of 100 micrograms/l (the earlier action level) would have blood lead concentrations above 25 micrograms/100 ml, as would about 4% of those exposed to 50 micrograms/l (the Maximum Admissible Concentration in an EEC Directive). For adults, average water lead concentrations should not exceed 30 micrograms/l to ensure compliance with the limit for blood lead, i.e. so that not more than 2% exceed 25 micrograms/100 ml. However, for one of the critical groups, bottle-fed infants (whose diet is 90% water), average water lead concentrations should not exceed 10-15 micrograms/l. The WHO's Provisional Tolerable Weekly Intake (PTWI) for children (25 micrograms/kg body weight) also implies that their water lead concentrations should not exceed 10-15 micrograms/l.

Body burdens of lead in hypertensive nephropathy

Chronic lead exposure resulting in blood lead concentrations that exceed 1.93 mumol/l (40 micrograms/dl) or chelatable urinary lead excretion greater than 3.14 mumol (650 micrograms) per 72 h has been associated with renal disease. A previous study had found greater chelatable urine lead excretion in subjects with hypertension and renal failure than in controls with renal failure due to other causes, although mean blood lead concentrations averaged 0.92 mumol/l (19 micrograms/dl). To determine if chelatable urinary lead, blood lead, or the hematologic effect of lead (zinc protoporphyrin) were greater in hypertensive nephropathy (when hypertension precedes elevation of serum creatinine) than in other forms of mild renal failure, we compared 40 study subjects with hypertensive nephropathy to 24 controls having a similar degree of renal dysfunction due to causes other than hypertension. Lead burdens were similar in both the study and control groups as assessed by 72-h chelatable urinary lead excretion after intramuscular injection of calcium disodium EDTA (0.74 +/- 0.63 vs. 0.61 +/- 0.40 mumol per 72 h, respectively), and by blood lead (0.35 +/- 0.23 vs. 0.35 +/- 0.20 mumol/l). We conclude that subjects from a general population with hypertensive nephropathy do not have greater body burdens of lead than renal failure controls.

Air lead exposures and blood lead levels within a large automobile manufacturing workforce, 1980-1985

Recent (1980-1985) trends in air lead (PbA) exposures and blood lead (PbB) levels experienced by approximately 10,000 workers employed in various stages of the automobile manufacturing process (i.e., auto assembly, lead-acid battery manufacture, foundry work, and "other" manufacturing-related operations) are described. Between 1980-1985, the mean PbB levels of assembly, battery, foundry, and "other" workers decreased by 28, 24, 3, and 27%, respectively, to 16.6, 23.6, 15.9, and 11.8 micrograms Pb/dl. Workers in the following job categories experienced the highest annual mean PbB levels: paste machine operators (battery plants), solder-grinders (assembly plants), and crane operators (foundries). During the same period, median 8-h Time Weighted Average PbA exposures (micrograms Pb/m3) in assembly plants, battery plants, and foundries decreased by 10, 12, and 20%, respectively, to 8.1, 13.6, and 10.9 micrograms/m3.

Environmental lead exposure and the kidney

Lead and its components remain widely distributed in the environment and in some workplaces. Lead serves no useful physiological function, yet is potentially toxic to several organ systems. For many years human health effects have been recognized after heavy lead exposure. Recently more subtle human effects have been suggested invoking nervous system, reproductive and kidney function. Assessing lead body burden and dose-response relationships of this metal by blood lead determination, porphyrin assessments, chelation testing or bone lead studies may be difficult. Quantitative assessment of subtle changes in kidney function by routine BUN, creatinine, or urinalysis also poses problems. There is now mounting evidence that chronic low level environmental lead exposure may subtly effect kidney function. This paper first examines the history of lead and kidney function and then examines critically the evidence associating low-level environmental lead exposure and effects on renal function.

Influence of occupational low-level lead exposure on renal parameters

The influence of lead exposure on renal function was examined. In 155 lead workers and 126 control workers, lead in blood (PbB) and zinc protoporphyrin in blood (ZPP) were measured as indicators of exposure to lead; various proteins in urine were measured as parameters of renal functions. Regression and matched-pair analyses suggest that tubular parameters may be more influenced by lead exposure than glomerular parameters. Changes in renal function parameters may already occur at PbB levels below 3 mumol/liter (600 micrograms/liter). The excretion of N-acetyl-beta-D-glucosaminidase appears to be the most consistent and sensitive parameter of an early effect on the tubular function.