Blood Lead In Workers Research Articles

Genotoxic Effect of Lead and Cadmium on Workers at Wastewater Plant in Iraq.

Heavy metal poisoning is a worldwide problem that is caused by different human industrial activities such as battery and painting manufacturing and occupational exposure of those working at petrol stations. Wastewater is known to contain higher amounts of heavy metals such as lead (Pd) and cadmium (Cd) and might be sources of exposure for workers at the wastewater treatment plant. However, to our best knowledge, no studies were done to evaluate the level of cadmium and lead in blood of workers at wastewater treatment plants and evaluate the subsequent effect of lead and cadmium on delta-aminolevulinic acid dehydratase (δ-ALAD), urinary delta-aminolevulinic acid (Uδ-ALA), and 8-hydroxy-2′-deoxyguanosine (8-OHdG) as markers of lead and cadmium toxicity. In this case-control study, 79 workers at the Al-Rustumiya wastewater plant in Baghdad, Iraq, and 40 control subjects were included. The levels of lead and cadmium were measured in blood of the study subjects using the atomic absorption spectroscopy (AAS) method. 8-OHdG was analysed using enzyme-linked immunosorbent assay (ELISA) technique. δ-ALAD and Uδ-ALA were estimated using spectrophotometry-based methods. Our work showed that workers had a significantly higher level of lead and cadmium when compared with the control group (P < 0.05), yet, still within the World Health Organization permissible limit. The level of both metals was positively associated with duration of work at the plant (P < 0.01). The activity of δ-ALAD was inversely associated with the lead level, while both Uδ-ALA and 8-OHdG were positively correlated with the lead level (P < 0.05). These three markers lacked any statistically significant association with the cadmium level (P > 0.05). To sum up, working at the wastewater treatment plant was associated with a higher blood level of lead and cadmium and their possible health hazard. Health and occupational safety authorities are required to set up tighter regulations and protocols to minimize these hazards and ensure a safe working environment.

Assessment of lead exposure controls on bridge painting projects using worker blood lead levels

A retrospective analysis of worker blood lead levels (BLL) was conducted using blood lead data collected by four bridge painting contractors before and after lead exposure. The objective of the study was to evaluate the effectiveness of exposure controls in preventing elevated blood lead levels (>25 μg/dl) during bridge painting projects. The contractors selected for the study submitted BLL data for 289 workers representing ten work tasks and 11 bridge painting projects. In total, 713 blood lead levels results were evaluated.The mean blood lead level for all work classifications combined was 10.9 μg/dl at baseline compared with 14.9 μg/dl after two months of exposure and 15.0 μg/dl after four months of exposure. Two months after initial exposure, 29% of the painters and 35% of the laborers had a 10 μg/dl incremental increase or greater in blood lead level. Likewise, 18% of the painters and 26% of the laborers had a blood lead level greater than 25 μg/dl during the same time. The blood lead levels that exceeded the 25 μg/dL threshold ranged from 30μg/dL-63 μg/dL for painters and 26 μg–56 μg/dL for laborers.All work tasks with high-intensity exposure (abrasive blaster/painter, abrasive blaster, painter & laborer) experienced an average blood lead level increase that ranged from 0.2 μg/dl to 8.9 μg/dl two months after initial exposure. Blood lead testing conducted after modified exposure controls (two months after the initial follow-up blood testing) were implemented showed a decrease in average blood lead levels (range −0.14 μg/dl to −2.7 μg/dl) for two high-intensity exposure work tasks. In comparison, the other two high-intensity work tasks had moderate increases (range 1 μg/dl to 2.4 μg/dl). The modified exposure controls included an increase in the air velocity inside of the work containment and an administrative control in the form of additional worker training on lead exposure prevention. The reduction in the 95th percentile (point estimate) BLL exposure profile for each exposure group at the 4-month follow-up blood testing period is associated with modified exposure controls.Ineffective exposure controls were identified through the analysis of worker BLLs. We found two exposure groups (laborer and painter) whose 95th percentile (point estimate) exposure profile was greater than the OSHA construction lead standard's targeted BLL goal (25 μg/dl) during the first two months of exposure. Our research findings provide support for monthly blood lead testing after baseline until blood lead levels are controlled to an acceptable concentration.

PIG-A gene mutation as a genotoxicity biomarker in human population studies: An investigation in lead-exposed workers.

The rodent Pig-a gene mutation assay has demonstrated remarkable sensitivity in identifying in vivo mutagens, while much less is known about the value of the human PIG-A assay for risk assessment. To obtain more evidence of its potential as a predictive biomarker for carcinogen exposure, we investigated PIG-A mutant frequencies (MFs), along with performing the Comet assay and micronucleus (MN) test, in 267 workers occupationally exposed to lead. Multivariate Poisson regression showed that total red blood cell PIG-A MFs were significantly higher in lead-exposed workers (10.90 ± 10.7 × 10-6 ) than in a general population that we studied previously (5.25 ± 3.6 × 10-6 ) (p < .0001). In contrast, there was no increase in lymphocyte MN frequency or in DNA damage as measured by percentage comet tail intensity in whole blood cells. Current year worker blood lead levels (BLL), an exposure biomarker, were elevated (232.6 ± 104.6 μg/L, median: 225.4 μg/L); a cumulative blood lead index (CBLI) also was calculated based on a combination of current and historical worker BLL data. Chi-square testing indicated that PIG-A MFs were significantly related to CBLI (p = .0249), but independent of current year BLL (p = .4276). However, % comet tail intensity and MN frequencies were better associated with current year BLL than CBLI. This study indicates that the PIG-A assay could serve as biomarker to detect the genotoxic effects of lead exposure and demonstrates that a battery of genotoxicity biomarkers having mechanistic complementarity may be useful for comprehensively monitoring human carcinogenic risk.

Association of office and ambulatory blood pressure with blood lead in workers before occupational exposure

In view of decreasing lead exposure and guidelines endorsing ambulatory above office blood pressure (BP) measurement, we reassessed association of BP with blood lead (BL) in 236 newly employed men (mean age, 28.6 years) without previous lead exposure not treated for hypertension. Office BP was the mean of five auscultatory readings at one visit. Twenty-four-hour BP was recorded at 15- and 30-minute intervals during wakefulness and sleep. BL was determined by inductively coupled plasma mass spectrometry. Systolic/diastolic office BP averaged 120.0/80.7 mm Hg, and the 24-hour, awake, and asleep BP 125.5/73.6, 129.3/77.9, and 117.6/65.0 mm Hg, respectively. The geometric mean of blood lead was 4.5 μg/dL (interquartile range, 2.60–9.15 μg/dL). In multivariable-adjusted analyses, effect sizes associated with BL doubling were 0.79/0.87 mm Hg (P = .11/.043) for office BP and 0.29/−0.25, 0.60/−0.10, and −0.40/−0.43 mm Hg for 24-hour, awake, and asleep BP (P ≥ .33). Neither office nor 24-hour ambulatory hypertension was related to BL (P ≥ .14). A clinically relevant white coat effect (WCE; office minus awake BP, ≥20/≥10 mm Hg) was attributable to exceeding the systolic or diastolic threshold in 1 and 45 workers, respectively. With BL doubling, the systolic/diastolic WCE increased by 0.20/0.97 mm Hg (P = .57/.046). Accounting for the presence of a diastolic WCE, reduced the association size of office diastolic BP with BL to 0.39 mm Hg (95% confidence interval, −0.20 to 1.33; P = .15). In conclusion, a cross-sectional analysis of newly hired workers before lead exposure identified the WCE as confounder of the association between office BP and BL and did not reveal any association between ambulatory BP and BL.

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.

Prevention of lead poisoning in construction workers: a new public health approach.

In 1990, Yale University, the Connecticut Departments of Health Services and of Transportation, the Connecticut Construction Industries Association, and the state's construction trade unions created the Connecticut Road Industry Surveillance Project (CRISP). Data from 90 bridge projects from 1991 to 1995 and approximately 2,000 workers were evaluated. The distribution of peak lead concentrations in the blood for CRISP workers classified into five groups were compared to that from workers outside of Connecticut. This demonstration project was instrumental in lowering bridge worker blood lead levels. After 1992, only the painting contract employees experienced peak blood lead levels with < or = 2% exceeding 50 microg/dl. Compared to similar workers in other states, Connecticut workers had significantly lower peak blood lead levels. Two thousand workers and over 120 contractors benefited directly from CRISP. Two key features of the CRISP model differed from the 1993 OSHA standard: a contract-specified lead health protection program and a centralized system of medical monitoring. These differences may account for the improved protection observed between the CRISP and non-Connecticut cohorts.

Effect of personal hygiene on blood lead levels of workers at a lead processing facility.

The relationship between personal hygiene and blood lead levels was tested at a lead processing facility. During the workers' semiannual respirator fit test, when they were confident their hands were clean, the amount of lead on their right hands was measured. Samples were obtained by cleaning one entire hand with a wiping towel treated with a proprietary mixture of alcohol, surfactants, and ethylenediaminetetraacetic acid. Wipe samples were analyzed for total lead and then compared with the worker's blood lead level. Each worker's personal habits at rest were also observed. Workers with more than 1 year's experience had a significantly positive correlation between lead on the hand tested and their blood level. The study strongly suggests that lead on the skin ultimately enters the bloodstream. The route of entry was not investigated. Personal habits of the workers with high blood lead levels were observed to include actions that would quickly contaminate their hands shortly after washing.

Effect of Personal Hygiene on Blood Lead Levels of Workers at a Lead Processing Facility

The relationship between personal hygiene and blood lead levels was tested at a lead processing facility. During the workers semiannual respirator fit test, when they were confident their hands were clean, the amount of lead on their right hands was measured. Samples were obtained by cleaning one entire hand with a wiping towel treated with a proprietary mixture of alcohol, surfactants, and ethylenediaminetetraacetic acid. Wipe samples were analyzed for total lead and then compared with the worker's blood lead level. Each worker's personal habits at rest were also observed. Workers with more than 1 year's experience had a significantly positive correlation between lead on the hand tested and their blood level. The study strongly suggests that lead on the skin ultimately enters the bloodstream. The route of entry was not investigated. Personal habits of the workers with high blood lead levels were observed to include actions that would quickly contaminate their hands shortly after washing.

Effects of chromium on lymphocyte subsets and immunoglobulins from normal population and exposed workers.

Blood lymphocyte subsets and serum immunoglobulins were studied in 15 men (mean age: 35 years), not exposed to toxic agents, and in 15 healthy men, exposed to dust containing several compounds (including lead chromate), working in a factory producing plastic materials. Worker blood lead and urine chromium (Cr) levels were significantly higher than controls, while serum Cr concentration was unchanged. In the worker blood, CD4+ helper-inducer (mainly CD4+-CD45RO- "virgin"), CD5--CD19+ B, CD3--CD25+ activated B and CD3--HLA-DR+ activated B and natural killer (NK) lymphocytes were significantly reduced (about 30-50 %). The investigated workers were exposed to hexavalent Cr, as lead chromate, whereas normal population (control group) was mainly exposed to trivalent Cr. In the control group, urinary Cr showed a significant positive correlation with CD16+-56+ NK, CD5+-CD19+ B and HLA-DR+ activated T, B and NK lymphocytes and a negative correlation with serum IgA immunoglobulins; moreover, serum Cr was significantly correlated with all blood lymphocytes and HLA-DR+, CD3--HLA--DR+ and CD3--CD25+ lymphocyte subsets. These data suggest that trivalent Cr may be involved in mechanisms regulating the immune response in humans.

Coordinating Federal and State Lead Control Activities: The Connecticut Model for Integrated Lead Exposure Enforcement

Abstract Activities related to lead exposure control and enforcement occur at various levels of state and federal government. Many states have blood lead surveillance programs requiring laboratories and clinicians to report elevated blood lead levels to state lead registries. In Connecticut, the Adult Blood Lead Registry, operated by the Department of Public Health and Addiction Services, receives reports of blood lead levels in excess of 10 μg/dl from clinical laboratories. Further, the U.S. Department of Labor-Occupational Safety and Health Administration, through the General Industry and Construction Lead Standards, requires biological monitoring of workers. In Connecticut, the Department of Transportation, through the Connecticut Road Industry Surveillance Project, requires monitoring of worker blood lead levels by contract specification. In 1993 these four agencies joined together to form a single integrated enforcement network designed to control lead toxicity in workers throughout Connecticut. Usin...

Interrelation between urinary delta-aminolevulinic acid (ALA), serum ALA, and blood lead in workers exposed to lead.

Using a fluorometric HPLC method, we determined delta-aminolevulinic acid (ALA) in sera and urine samples from 16 lead workers with blood lead levels ranging from 19 to 107 microG/100 ml. The concentration of ALA in serum correlated highly with the urinary ALA concentration (gamma = 0.957 for ALA mg/1; gamma = 0.967 for ALA mg/g creatinine). The ALA concentrations in the serum of lead workers ranged from 11 to 151 micrograms/1 with a mean of 51 micrograms/1. In addition, the concentrations of urinary ALA (mg/g creatinine) and serum ALA micrograms/1) had a strong correlation with blood lead concentrations (gamma = 0.838 and 0.892, respectively). These data indicate that the measurement of serum ALA, as well as urinary ALA, is very useful for the biological monitoring of occupational lead exposure.

The Lead-Exposed Worker

The lead standard established by the federal Occupational Safety and Health Administration in 1978 requires physicians and employers to follow very specific guidelines when treating lead-exposed workers. For example, if a worker's blood lead level is 2.90 mumol/L of whole blood or greater, the worker must be removed from work, with full pay and retention of seniority, until the blood level falls below 1.95 mumol/L. Physicians play a key role in the implementation of the lead standard; the standard specifies frequency of blood lead measurements, frequency and extent of medical monitoring, and medical removal from work. This article reviews the lead standard as it applies to physicians and makes recommendations about managing the worker with lead poisoning.

Elimination kinetics of blood lead in workers with chronic lead intoxication.

Blood lead elimination half-lives were determined for 65 patients with occupational chronic lead intoxication who were removed from exposure, treated with intravenous EDTA, and followed for periods of up to 2,419 days. The median overall blood lead elimination half-life was 619 days in patients with normal renal function and 1,907 days in patients with renal impairment. Slow-phase elimination half-lives in patients followed for longer than 5 years ranged from 1,658 to 7,189 days. Blood lead concentrations declined during periods of chelation with a mean half-life of 7 days and rebounded to near prechelation concentrations following termination of chelation with a mean doubling time of 27 days. The overall blood lead elimination half-life was positively associated with length of follow-up (p less than 0.001), age (p = 0.04), and duration of exposure (p = 0.02), but was not associated with the initial blood lead concentration following cessation of exposure or the total amount of EDTA received.

A multivariate statistical method for the establishment of maximum allowable exposure to toxic materials in the workplace.

A model has been developed for setting standard limiting concentrations for toxic substances in the body fluid or tissues of industrial workers. The method is very flexible, and allows the use of either univariate or multivariate data, and of classification schemes which are either supervised, unsupervised, or partially supervised. An index of subclinical biological damage is derived which is used to determine an optimal limiting exposure level. The model is applied to the particular case of selecting a maximum allowable concentration of blood lead in workers in industrial settings where lead toxicity is a danger.