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PubMed1997

Log-additive versus log-linear analysis of lead-contaminated house dust and children's blood-lead levels. Implications for residential dust-lead standards.

The Environmental Protection Agency has been mandated to develop a health-based standard for lead in residential dwellings in the United States. Prior estimates of the relationship between residential dust-lead levels and children's blood-lead concentrations have usually been obtained by using a log-linear regression of blood-lead concentration on levels of lead-contaminated house dust. It remains unknown, however, whether the log-linear model or a frequently cited alternative, the log-additive model, is the preferable regression method for analyzing these data. Secondary analysis of the Lead-in-Dust Study data was undertaken to compare log-additive with log-linear regression analysis for the purpose of developing a health-based dust lead standard. Specifically, we were interested in comparing the log-additive and log-linear analyses in their ability to characterize adequately the relationship of dust-lead loading on various surfaces with blood-lead concentrations among urban children and to develop a predictive model to estimate the risk that a child will develop an elevated blood-lead level on the basis of a known level of dust lead. We used two dust sampling methods, the Baltimore Repair and Maintenance (BRM) vacuum method and the wipe method, to compare the log-linear and log-additive models. The log-linear model was consistently superior to the log-additive model in its ability to explain the variability in the observed blood-lead concentrations of the studied children, for both the wipe sampler and the BRM sampler. In addition, the log-additive model often predicted only a limited increase in the probability of blood-lead concentrations exceeding 10 micrograms/dl as a result of doubling the dust-lead loading exposure, whereas the log-linear model consistently demonstrated a significant increase in the probability of blood-lead concentrations exceeding 10 micrograms/dl. BRM lead loading explained additional variability in blood lead above and beyond that explained by wipe loading for both carpeted and uncarpeted floors. In contrast, wipe-lead loading explained significant additional variability after adjustment for BRM loading for both uncarpeted floors and interior window sills. Although BRM loading better predicted children's blood-lead concentrations than did wipe loading, these differences were not statistically significant. We conclude that the log-linear model explained a greater percentage of the variability in blood-lead concentrations than did the log-additive model, indicating that the log-linear model should be the default model of choice for developing a dust-lead standard.

Air Pollution, Indoor↗
PubMed1996

Plasma and blood lead concentrations, lead absorption, and lead excretion in nonhuman primates.

In order to assess the comparability of lead disposition in the cynomolgus monkey to that in the human, we determined the relationships among blood lead concentration, plasma lead concentration, and lead excretion in monkeys. Six adult (3-5 kg) female cynomolgus monkeys (Macaca fascicularis) without previous experimental lead exposure were given single intravenous injections of from 750 to 3300 micrograms lead as lead nitrate, labeled with 210Pb, per kilogram body weight. Four additional monkeys, fasted overnight, were administered single oral doses of either 750 or 1500 micrograms lead as lead nitrate, labeled with 210 Pb, per kilogram for the assessment of fractional absorption. Blood and plasma lead concentrations (10 monkeys) and urinary and fecal excretion of lead (2 monkeys) were followed up for up to 16 days after lead administration. Fractional absorption from an oral dose was 44% at the lower of the two doses and 22-28% at the higher dose. The relationship between plasma and blood lead concentrations was found to be similar to that in humans, with plasma lead concentration at most a few percent of total blood lead concentration at low concentrations. Partitioning of lead across the red cell membrane in the 2 monkeys given exceptionally high doses (3300 micrograms/kg) intravenously was distinctly lower than that in the 4 monkeys given lower intravenous doses. Urinary clearance of lead in these 2 monkeys was 19% of the estimated glomerular filtration rate, within the range of efficiencies reported for humans. Fecal clearance, however, was anomalous and appeared to be an artifact of the very high dose. Examination of published data for urinary and fecal lead excretion in three adult baboons showed that both functions in the baboons were quantitatively similar to those in humans. Urinary clearance in the baboons was 14-24% of the estimated glomerular filtration rate, and fecal clearance was 78-85% of the urinary clearance. We conclude that nonhuman and human primates are comparable with respect to the relationship of plasma lead concentration to blood lead concentration and the relative efficiency of lead excretion in urine and feces.

Absorption↗
PubMed2000

Study of the relationships between bone lead levels and its variation with time and the cumulative blood lead index, in a repeated bone lead survey.

The study aims were to: (i) investigate long term human lead metabolism by measuring the change of lead concentration in the tibia and calcaneus; and (ii) assess whether improved industrial hygiene was resulting in a slow accumulation of lead in an exposed workforce. 109Cd excited K X-ray fluorescence was used to measure tibia lead and calcaneus lead concentrations in 101 workers in a secondary lead smelter. 51 subjects had had similar bone lead measurements 5 years previously. Most of the other subjects had been hired since the first survey. Measurements of whole blood lead were available for the large majority of subjects. Tibia lead concentrations fell significantly (p<0.001) in the 51 subjects with repeated bone lead measurements, from a mean of 39 microg Pb (g bone mineral)(-1) to 33 microg Pb (g bone mineral)(-1). The change correlated negatively with the initial tibia lead concentration, producing an estimate for an overall half-life of 15 years, with a 95% confidence interval of 9 to 55 years. Adding continuing lead exposure and recirculation of bone lead stores to the regression models produced half-life estimates of 12 and 9 years, respectively, for release of lead from the tibia. The repeat subjects showed no net change in calcaneus lead (64 microg Pb (g bone mineral)(-1) initially, 65 microg Pb (g bone mineral)(-1) 5 years later). Subjects not measured previously had average lead concentrations of 15 microg Pb (g bone mincral)(-1) in the tibia and 13 microg Pb (g bone mineral)(-1) in the calcaneus. The rate of clearance of lead from the tibia (9 to 15 years) is towards the more rapid end of previous estimates. The lack of a significant fall in the calcaneus lead was surprising. Attempts should be made to repeat this observation. If confirmed, it would have implications for models of lead metabolism. The relatively low lead concentrations in the non-repeat subjects are reassuring. However, observation after a longer period of employment would be desirable.

Adult↗
PubMed1976

Diagnostic criteria for computer-aided electrocardiographic 15-lead system. Evaluation using 12 leads and Frank orthogonal leads with vector display.

The criteria for the diagnosis of myocardial infarction and ischaemic heart disease by an automated 15-lead computer-aided electrocardiographic system were examined using electrocardiograms of 543 patients. Errors in the electrocardiographic diagnosis were evaluated for each lead system (Frank orthogonal 3-lead, 12-lead, and hybrid 15-lead) using clinical and catheterization data for definitive diagnosis before review of the electrocardiograms and their reports. The effects of combinations of these diagnoses and additional ventricular conduction defects were also studied. Myocardial infarction and left ventricular hypertrophy were more reliably diagnosed using 3-lead and 12-lead systems together than with either system alone. The most sensitive criteria for anterior infarction were a Q/R ratio in Z less than 0-1 and loss of the first 20 ms of anterior forces in the horizontal and sagittal planes of the vectorcardiogram. However, false positive results were frequent, particularly in association with left ventricular hypertrophy, non-specific intraventricular conduction defects, and left bundle branch system block. Our V lead criteria were more specific whether or not these associated conditions were present. No single criterion with an acceptable false positive rate could be found to be sensitive for inferior infarction in all situations. Our most sensitive criteria were those based on the limb leads, and the presence of superior forces for the first 30 ms in the frontal plane of the vectorcardiogram, but these were better in combination. Limb lead criteria were the most specific. False positive results for inferior infarction were more frequent in the presence of left ventricular hypertrophy or ventricular conduction defects other than left anterior hemiblock. ST and T wave abnormalities were more apparent in the 12 leads than in the orthogonal leads. Specificity and sensitivity of criteria were poor, and specificity was decreased and sensitivity was not significantly improved by combining 3-lead with 12-lead criteria. Because of frequent measurement errors of ST, T, and also Q waves by the computer programme, in practice we have achieved increased sensitivity in the diagnosis of ischaemia and infarction with the combination of 3-lead and 12-lead systems. It is concluded that errors of diagnosis by a computer-aided system can be reduced by using multiple leads and that both 12-lead and orthogonal 3-lead systems are necessary for optimal computer diagnosis of left ventricular hypertrophy, myocardial infarction, and ischaemia.

Adult↗
PubMed1997

A study of the relationship between ambient lead and blood lead among lead battery workers.

OBJECTIVE: To examine the relationship between ambient lead levels and blood lead levels and to explore the modifiers of the relationship between ambient lead and blood lead. METHOD: A cross-sectional study was conducted in two lead battery factories. Blood lead level and ambient lead concentration were measured for each participant concurrently. A structured questionnaire was administered to collect sociodemographic characteristics and occupational history. DESIGN: Biological and personal environmental measurements of 219 lead-exposed workers were analyzed by both simple and multiple linear regression. A regression model was selected for interpretation. RESULTS: A high correlation (r = 0.62) between ambient lead (PbA) and blood lead (PbB) was observed. In addition, numerous factors, including age, sex, alcohol consumption, personal hygiene practice and type of lead exposure, were also found to influence blood lead levels. Although PbB was highly correlated with PbA, blood lead level may not be effectively lowered by reducing ambient lead level. Based on the regression coefficients, improvement of hygienic practice was more effective at lowering PbB than reducing ambient lead level. Good hygienic practice may be the preferential way to reduce lead exposure in current conditions. CONCLUSION: Education of correct work practice may be more important than engineering control in the developing countries to lower blood lead levels in lead battery factories.

Adult↗
PubMed1999

Comparison of 18-lead ECG and selected body surface potential mapping leads in determining maximally deviated ST lead and efficacy in detecting acute myocardial ischemia during coronary occlusion.

Kornreich identified 6 body surface potential mapping (BSPM) leads outside the standard 12-lead electrocardiographic (ECG) sites for optimal recognition of ST segment elevation (+) and depression (-) during acute ischemia in anterior, inferior, and posterior myocardial zones (A+, A-, I+, I-, P+, P-). No comparison has been made between the 6 selected BSPM leads and 18-lead ECG (12 + V3-5R + V7-9) in detecting acute myocardial ischemia during coronary occlusion. Continuous 18-lead ECG and 6 selected BSPM leads were recorded in 68 patients (77 vessels) undergoing coronary angioplasty during balloon occlusion. Ischemia was defined as ST segment deviation (deltaST) > or = 100 microV > or = 1 lead from the preinflation baseline. The 18-lead ECG was a more frequent source of the maximal deltaST lead during left anterior descending artery, right coronary artery, and left circumflex artery occlusion (71 [92%]) than the 6 selected BSPM leads (5 [7%]). The 18-lead ECG was more efficacious than the 6 selected BSPM leads for detecting acute myocardial ischemia in the group as whole. The 18-lead ECG was also more efficacious for detecting right ventricular ischemia associated with proximal right coronary artery occlusion and for detecting ST segment elevation during left circumflex artery occlusion. Our findings indicate that the 18-lead ECG is the most frequent source of maximally deviated lead and is more efficacious in detecting myocardial ischemia during balloon occlusion than the 6 selected BSPM leads. The 6 selected BSPM leads do not add information above and beyond the 12- or 18-lead ECG, and thus cannot be recommended as optimal sites for continuous ST segment monitoring of patients with acute coronary syndromes.

Aged↗
PubMed2000

Thoracic location of the lead with maximal ST-segment deviation during posterior and right ventricular ischemia: comparison of 18-lead ECG with 192 estimated body surface leads.

By using our database of continuous 18-lead electrocardiographic (ECG) recordings (standard + V3-5R + V7-9) during coronary angioplasty, we selected 68 patients with left circumflex balloon occlusions (posterior ischemia model) or proximal right coronary artery balloon occlusions (right ventricular IRV] ischemia model). ST-segment amplitudes (J + 60 ms) at preangioplasty baseline were subtracted from maximal ST amplitudes during balloon inflation to create a positive or negative change score (deltaST) for each of the 18 leads. DeltaST elevation was used to describe a change in the ST level in the positive direction from baseline, whether or not actual ST elevation from the isoelectric line was present. DeltaST depression was used to describe a change in the ST level in the negative direction from baseline, whether or not actual ST depression from the isoelectric line was present. ST amplitudes from 8 of the 12 standard leads were then used to estimate ST amplitudes at 192 body surface sites spanning the entire anterior and posterior thorax using the transformation technique of Lux. Thoracic distributions of the DeltaST values were displayed on a torso figure, including locations of the 18 lead locations and points of maximal ST elevation and depression. The 192 estimated body surface unipolar leads were compared with 18-lead ECGs (bipolar and unipolar). During 53 left circumflex occlusions, the maximal deltaST elevation was always located in the 18-lead ECG, with the most frequent locations at leads III, II (41%), V7-8 (34%), and V5-6 (25%). The maximal deltaST depression was located outside the 18-lead ECG (89%), with the most frequent locations above standard lead V2 (67%) and V3 (14%). During 16 proximal right coronary artery occlusions, the maximal deltaST elevation was always located in the 18-lead ECG, with the most frequent locations at leads III (81%) and V2-3R (13%). The maximal deltaST depression was located outside the 18-lead ECG (93%), with the most frequent locations above standard lead V2 (50%), V3 (14%), and V4 (14%). We conclude that maximal deltaST elevation is always located in the 18-lead ECG and maximal deltaST depression is frequently located outside of 18-lead ECG during left circumflex and proximal right coronary artery occlusions. Future studies are required to determine the bipolar leads for the 192 estimated body surface potential mapping leads.

Angina, Unstable↗
PubMed2003

A comparison of 2-lead, 6-lead, and 12-lead ECGs in patients with changing edematous states: implications for the employment of quantitative electrocardiography in research and clinical applications.

OBJECTIVE: Precordial ECGs reveal significant intrasubject variability due to the inexact employment of the recommended V(1)-V(6) chest landmarks. Also, as per the Einthoven law, the six limb leads can be derived from leads 1 and 2. The purpose of this study was to evaluate whether the 12-lead ECG could be substituted by ECG sets with a limited number of leads. MATERIALS AND METHODS: The performance of three ECG systems (ie, the 12-lead ECG, a 6-lead ECG comprising the limb leads, and a 2-lead ECG comprising exclusively leads 1 and 2) was evaluated in data from 28 patients with anasarca (AN), 28 control patients, 10 patients who had undergone hemodialysis, and 3 patients with idiopathic dilated cardiomyopathy. RESULTS: Linear regression analyses of changes in ECG data with the weight gain of patients with AN and the intercorrelations of the three ECG systems in the various patient subgroups were found to be statistically significant at p = 0.0005 and r values ranging from 0.61 to 0.99, which are suggestive of good/excellent correlations. However, regression analyses of peak weight (PW) gain with changes in the 2-lead ECG (r = 0.43; p = 0.02) and 6-lead ECG (r = 0.48; p = 0.01), and half of PW gain and 12-lead ECG (r = 0.41; p = 0.03), 6-lead ECG (r= 0.18; p = 0.35), and 2-lead ECG (r = 0.43; p = 0.02) revealed poor correlations. CONCLUSION: ECG systems, comprising 2 or 6 leads, can be substituted for the 12-lead ECG for certain clinical and research applications (pertaining to the amplitude of QRS complexes), attesting to the inherent redundancy of the information from the 12-lead ECG.

Cardiomyopathy, Dilated↗
PubMedDate not supplied

Relationship between soil and dust lead in a lead mining area and blood lead levels.

UNLABELLED: The relationship between lead mining waste and childhood lead poisoning is poorly understood. This study evaluates the contribution of soil lead to blood lead levels. METHODS: 125 children between 6 and 71 months of age living in a lead mining area of southwestern Missouri were evaluated for blood lead and their homes tested for lead in soil, dust, and paint. These results were compared to 26 control children. RESULTS: Homes in the lead mining area had significantly increased soil and dust lead levels and significantly higher blood lead levels. The primary source of dust lead was soil lead. There was a strong relationship between blood lead levels and dust, soil, and paint lead. CONCLUSION: Soil lead related to mining operations plays a significant role in contributing to blood lead levels in children.

Child, Preschool↗
PubMed2006

Lead exposure, lead poisoning, and lead regulatory standards in China, 1990-2005.

This article presents a summary of lead exposure levels and lead poisoning at workplaces in China reported in the Chinese medical literature between 1990 and 2005. A comprehensive literature search identified 618 papers reporting lead exposure and lead poisoning data. The data were analyzed in terms of time period, type of industry, size of factory, and task or process. In 2002 the new Occupational Diseases Prevention and Control Act was passed in China, with new provisions specifically for regulatory enforcement. Therefore, a comparison of lead exposure levels and lead poisoning rates before and after the 2002 Act will shed some light on the effectiveness of the new regulation. The reported lead exposure levels covered a wide range; some measurements were in excess of 250 mg/m(3), which was orders-of-magnitude higher than the occupational exposure levels (OELs) for lead in China. The overall arithmetic mean, median, and geometric mean were 0.92, 0.25, and 0.24 mg/m(3), respectively. Approximately 53.7% of the averages reported in the papers were above the national OELs. The data demonstrated that many facilities in the lead industries reported in the literature were not in compliance with the OELs. Similarly, there appeared to be only a minor impact of the 2002 Act on the reduction of occupational lead poisoning in China. The lead poisoning rates reported in the literature were well above 30%. Judging by the lead exposure levels and the lead poisoning rates, the current overall occupational health monitoring system appears inadequate, lacking the necessary enforcement. The 2002 Act, without the necessary enforcement, did not appear to have a major impact on either lead exposures or lead poisoning in China. Much work in enforcing the 2002 Act remains to be done.

China↗
PubMed1997

Measurement error and its impact on the estimated relationship between dust lead and children's blood lead: Members of the Rochester Lead-in-Dust Study Group.

OBJECTIVE: Lead-contaminated house dust is a major contributor to lead intake among urban children, but the reliabilities of various dust lead measurement methods and their impact on the estimated correlations between dust lead and children's blood lead levels are unknown. METHODS: Repeated field measurements of lead-contaminated dust from children's homes were taken from 16 housing units using five dust lead measurement methods. Estimates of measurement error were used to obtain reliability ratios for the dust lead measurements, which were then used to correct estimated correlations between lead-contaminated dust and children's blood lead. RESULTS: Reliability varied over methods and surface types (from 0.0 to 0.8), but wipe loading and the BRM vacuum loading methods generally had greater reliability. Technician effects, inadvertent field exposure to lead, contamination of collection equipment, and laboratory instrument error were found to contribute little to total measurement error. Corrected correlations between blood lead and wipe loading measurements were 7 to 104% higher than uncorrected correlations. The multiple R2 and partial R2 for a wipe composite measurement in a multivariate regression model increased from 0.43 to 0.64 and from 0.053 to 0.26, respectively, after correction for measurement error bias. CONCLUSIONS: Variation in lead deposition within small areas and variations in collection inherent to the devices are major contributors to measurement error. Measurement error causes dramatic underestimation of correlation between lead-contaminated house dust and children's blood lead.

Air Pollution, Indoor↗
PubMed1986

Increased lead concentration in brain and potentiation of lead-induced neuronal depression in rats after combined treatment with lead and disulfiram.

The effects of disulfiram (tetraethylthiuram disulfide) on blood and brain lead levels and on lead-induced changes in growth and cerebellar Purkinje neuron excitability were assessed in adult Sprague-Dawley rats. Disulfiram is metabolized to diethyldithiocarbamate, which forms a lipophilic complex with lead, and can thereby influence the tissue distribution of lead. Pregnant rats were exposed to 0.25% lead acetate or an equimolar amount of sodium acetate in the drinking water, and these treatments were continued for 4 weeks after birth. Half of the mothers from each group were given 0.1 mmole/kg disulfiram orally twice a week until parturition, after which the treatment was continued for 4 weeks in the respective pups in the form of subcutaneous injections. Although lead exposure markedly increased blood lead levels, the increase in brain lead levels was much more modest. Disulfiram markedly increased brain lead levels while blood lead levels in this group were only slightly elevated as compared to animals receiving lead alone. In addition, the lead + disulfiram group had depressed weight gain during maturation, and Purkinje neuron firing rates were reduced. The lead alone and disulfiram alone groups were not different from controls in these respects. These data suggest that disulfiram potentiates the adverse effects of lead on growth rates and on cerebellar Purkinje neuron function by facilitating the accumulation of lead in brain tissue.

Animals↗
PubMed2006

A comparison of portable XRF and ICP-OES analysis for lead on air filter samples from a lead ore concentrator mill and a lead-acid battery recycler.

Personal and area samples for airborne lead were taken at a lead mine concentrator mill, and at a lead-acid battery recycler. Lead is mined as its sulfidic ore, galena, which is often associated with zinc and silver. The ore typically is concentrated, and partially separated, on site by crushing and differential froth flotation of the ore minerals before being sent to a primary smelter. Besides lead, zinc and iron are also present in the airborne dusts, together with insignificant levels of copper and silver, and, in one area, manganese. The disposal of used lead-acid batteries presents environmental issues, and is also a waste of recoverable materials. Recycling operations allow for the recovery of lead, which can then be sold back to battery manufacturers to form a closed loop. At the recycling facility lead is the chief airborne metal, together with minor antimony and tin, but several other metals are generally present in much smaller quantities, including copper, chromium, manganese and cadmium. Samplers used in these studies included the closed-face 37 mm filter cassette (the current US standard method for lead sampling), the 37 mm GSP or "cone" sampler, the 25 mm Institute of Occupational Medicine (IOM) inhalable sampler, the 25 mm Button sampler, and the open-face 25 mm cassette. Mixed cellulose-ester filters were used in all samplers. The filters were analyzed after sampling for their content of the various metals, particularly lead, that could be analyzed by the specific portable X-ray fluorescence (XRF) analyzer under study, and then were extracted with acid and analyzed by inductively coupled plasma optical emission spectroscopy (ICP-OES). The 25 mm filters were analyzed using a single XRF reading, while three readings on different parts of the filter were taken from the 37 mm filters. For lead at the mine concentrate mill, all five samplers gave good correlations (r2 > 0.96) between the two analytical methods over the entire range of found lead mass, which encompassed the permissible exposure limit of 150 mg m(-3) enforced in the USA by the Mine Safety and Health Administration (MSHA). Linear regression on the results from most samplers gave almost 1 ratio 1 correlations without additional correction, indicating an absence of matrix effects from the presence of iron and zinc in the samples. An approximately 10% negative bias was found for the slope of the Button sampler regression, in line with other studies, but it did not significantly affect the accuracy as all XRF results from this sampler were within 20% of the corresponding ICP values. As in previous studies, the best results were obtained with the GSP sampler using the average of three readings, with all XRF results within 20% of the corresponding ICP values and a slope close to 1 (0.99). Greater than 95% of XRF results were within 20% of the corresponding ICP values for the closed-face 37 mm cassette using the OSHA algorithm, and the IOM sampler using a sample area of 3.46 cm2. As in previous studies, considerable material was found on the interior walls of all samplers that possess an internal surface for deposition, at approximately the same proportion for all samplers. At the lead-acid battery recycler all five samplers in their optimal configurations gave good correlations (r2 > 0.92) between the two analytical methods over the entire range of found lead mass, which included the permissible exposure limit enforced in the USA by the Occupational Safety and Health Administration (OSHA). Linear regression on the results from most samplers gave almost 1 ratio 1 correlations (except for the Button sampler), indicating an absence of matrix effects from the presence of the smaller quantities of the other metals in the samples. A negative bias was found for the slope of the button sampler regression, in line with other studies. Even though very high concentrations of lead were encountered (up to almost 6 mg m(-3)) no saturation of the detector was observed. Most samplers performed well, with >90% of XRF results within +/- 25% of the corresponding ICP results for the optimum configurations. The OSHA algorithm for the CFC worked best without including the back-up pad with the filter.

Air Pollutants, Occupational↗
PubMed2002

Relationship between lead levels on painted surfaces and percent lead in the particles aerosolized during lead abatement.

Quantifying airborne lead on lead abatement work sites is critical in assessing worker lead exposures. Airborne lead levels depend on both the concentration of aerosolized particles and the percent lead in those particles. The lead level on the painted surface being abated may affect the percent lead in aerosolized particles. Experiments were performed in the University of Cincinnati Environmental Test Chamber (volume approximately 24.3 m3) using wood doors painted with lead-based paint. Three methods were used for paint removal: dry scraping, wet scraping, and dry machine sanding. Particles aerosolized during lead abatement activities were collected on filters using the Button Personal Inhalable Aerosol Samplers (SKC Inc., Eighty Four, PA) mounted in the workers' breathing zone. The filters were subsequently analyzed for percent lead in the particles. A portable X-ray fluorescence (XRF) instrument (NITON-700, NITON Inc., Bedford, MA) was used to measure surface lead levels of the doors. The accuracy of the XRF instrument was verified by testing standard reference materials prepared by the National Institute of Standards and Technology (NIST) and by Princeton Gamma Tech Inc. It was also verified by relating XRF results from painted door surfaces to laboratory lead analysis data obtained from paint chip samples taken from the same painted surfaces (r2 = 0.81, p < 0.001). A highly significant relationship (r2 = 0.83, p < 0.001) was found between the XRF readings and the percent lead in the particles aerosolized during dry scraping. No significant relationship was found for wet scraping (r2 = 0.09, p = 0.56) or dry machine sanding (r2 = 0.002, p = 0.92). The relationship between surface lead levels and percent lead in particles was found to be dependent on the paint removal method. This variation was attributed to the difference in water absorption property of the paint layers and the different particle aerosolization mechanisms inherent in each paint removal method.

Aerosols↗
PubMed1976

[The human placenta's lead level as a parameter of the ecological lead exposure. Its validity in comparison to the lead level in blood, the activity of the delta-aminolevulinic acid dehydratase and the concentration of the free erythrocyte porphyrins of newborns and their mothers (author's transl)].

In order to estimate the ecological exposure of lead, placenta- and blood-investigations were made at four collectives from variously industrialized regions (Ruhrregion, Middle Frankonia Centre, Bavarian Forest). 148 normal births and 19 premature births (in each case mothers and newborns) were listed as well as twelve abortions. We investigated the lead-level in blood, the activity of delta-aminolaevulinic acid dehydratase (ALA-D) the concentration of free erythrocyte porphyrine (FEP) and the placentas' lead concentration. Though in the Ruhrregion (Dortmund) significantly higher lead levels in blood were found compared to the Bavarian Forest, the results together, were in the normal range, less than 35 mug%. In an average the mothers' lead level in blood was around 1.4 times (ca. 5 mug%) above that of their newborns; analysing this statistically, highly significant correlations were found. However for the ALA-D activity and the FEP-results no direct dependence of the lead levels in blood could be found. In the placentas mean lead concentrations between 1.94 mug and 2.23 mug per gram dry-weight (30.6 mug-38.9 mug/100 g wet-weight) were gained. In the contrary to the measured results of lead in blood the average placentas' lead level of the most and least industrialized regions were almost identical. A correlation between the mothers' respectively their children's lead levels in blood and the placental lead concentrations could not be proved. No relation could be found between the results and the gestation ages. As final results: 1. The placenta is no ideal investigation object concerning the environment's lead exposure. 2. It has no special barriere - or depot - function in lead metabolism. 3. In order to estimate the environment's lead exposure the determination of the lead level in blood will also be in future the optimal method. This investigation is of special value because of its validity of the results and the practicability of winning the samples compared to other parameters and biological materials.

Erythrocytes↗
PubMed1996

The standard 11-lead ECG. Neglect of lead aVR in the classical limb lead display.

This study investigates how the format of limb lead display influences electrocardiographic (ECG) interpretation. The positive aspect of lead aVR (included in the classical display) is directed opposite to that of the other leads. This could lead to an ECG interpreter's disregard of lead aVR, thus providing a "standard 11-lead ECG." It is hypothesized that when using the classical limb lead display, ECG interpreters often ignore lead aVR, even when considering complex ECGs. Thirty-five of the participants attending this International Society of Computerized Electrocardiology meeting were asked to interpret five complex ECGs, displayed in the classical format. Lead aVR had been replaced by lead -aVR on all of these recordings. Second, the participants were asked if they (1) used all 12 leads, (2) used lead aVR, and (3) noticed that lead aVR had been changed. The results indicate that a vast majority of interpreters (80-94%) did not detect when lead aVR had been reversed. This suggests that interpreters only use 11 of the standard leads when presented with the classical display method to evaluate clinical problems.

Arrhythmias, Cardiac↗
PubMed2006

Comparison of patella lead with blood lead and tibia lead and their associations with neurobehavioral test scores.

OBJECTIVE: Lead exposure in adults is associated with worse cognitive function in cross-sectional and longitudinal studies. Previous studies have mainly examined relations with blood lead or cortical bone lead; few have examined trabecular bone lead. METHODS: We performed a cross-sectional analysis of the relations of patella lead and other lead biomarkers with measures of neurobehavioral and peripheral nervous system function in 652 lead workers. RESULTS: Patella lead was found to be associated with worse performance on seven of 19 tests of manual dexterity, sensory vibration threshold, and depressive symptoms. The associations of patella lead with cognitive function were essentially similar to those with blood lead or tibia lead but of somewhat lower magnitude. CONCLUSIONS: In this study, measurement of patella lead did not aid causal inference regarding cognitive effects when compared with blood lead and tibia lead.

Adult↗
PubMed2004

Reductions in blood lead overestimate reductions in brain lead following repeated succimer regimens in a rodent model of childhood lead exposure.

Although many studies have demonstrated the efficacy of succimer chelation in reducing blood and brain lead levels, the relative efficacy of the drug in the two tissues is less well understood. This issue is important because blood lead levels after chelation are used clinically to estimate reductions in the brain, the most critical organ in considering lead-induced neurotoxicity. The present study was designed to further investigate this issue, using multiple chelation regimens. Long-Evans rats were exposed to one of three lead exposure regimens from birth until postnatal day 40, followed by treatment with succimer (one or two 3-week regimens) or vehicle. The results indicated that one succimer regimen was significantly superior to vehicle treatment in lowering lead levels in both blood and brain across the entire 8-week follow-up period. Similarly, a second succimer regimen offered significant additional benefit relative to one regimen for both blood and brain across the 4-week follow-up period. However, several findings revealed that succimer-induced reductions in brain lead lagged behind reductions in blood lead and were generally smaller in magnitude. Furthermore, a rebound was detected in blood, but not brain, lead levels after both succimer regimens. Given the results of this study, we urge caution in using blood lead as a surrogate for brain lead levels, particularly during and immediately after chelation treatment when reductions in blood lead levels overestimate reductions in brain lead levels. The present results suggest that, in clinical use, succimer treatment may need to extend beyond the point at which blood lead levels have dropped to an "acceptable" target value in order to effectively reduce brain lead levels and minimize neurotoxicity.

Animals↗