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PubMed2002

Lead sources, behaviors, and socioeconomic factors in relation to blood lead of native american and white children: a community-based assessment of a former mining area.

Lead poisoning prevention requires knowledge of lead sources and of appropriate residential lead standards. Data are severely lacking on lead sources for Native American children, many of whom live in rural areas. Further, the relation of mining waste to blood lead concentrations (BPbs) of rural children is controversial. In collaboration with the eight tribes of northeastern Oklahoma, we assessed lead sources and their effects on BPbs for rural Native American and White children living in a former mining region. Venous blood lead, residential environmental (soil, dust, paint, water), and caregiver interview (e.g., hand-to-mouth behaviors, socioeconomic conditions) data were obtained from a representative sample of 245 children 1-6 years of age. BPbs ranged from 1 to 24 microg/dL. There were no ethnic differences in BPbs (p= 0.48) nor any patterns of excess lead sources for Native American or White children. Multiple linear regression analyses indicated that mean soil lead, mean floor lead loading, mouthing behaviors, caregivers' education, and residence in former mining towns were all strongly associated with BPbs. Logistic regression results showed mean floor dust lead loading greater than or equal to 10.1 microg/ft(2) (odds ratio [OR], 11.4; 95% confidence interval [CI], 3.5-37.3), and yard soil lead >165.3 mg/kg (OR, 4.1; CI, 1.3-12.4) were independently associated with BPbs greater than or equal to 10 microg/dL. We also found strong interactions between soil lead and poverty (p= 0.005), and dust and soil sources (p= 0.02). Our findings indicate that soil and dust lead derived largely from mining waste pose a health hazard to Native American and White children, and that current residential dust lead standards are insufficient to adequately protect children. Moreover, our finding that poor children are especially vulnerable to lead exposures suggests that residential standards should consider interactions among socioeconomic conditions and lead sources if environmental justice is to be achieved.

Child↗
PubMed1997

In vivo measurements of lead in fingerbone in active and retired lead smelters.

OBJECT: The aim of this study was to determine the bone lead concentration in lead smelters and reference subjects, relate them to the lead concentration in blood (B-Pb) and urine (U-Pb), and to use the measured bone lead to calculate a biological half-life for lead in bone. METHOD AND DESIGN: The lead concentration in the second phalanx of the left index finger (bone-Pb) was determined in vivo using an X-ray fluorescence technique. The study population comprised 89 smelters with a history of long-term exposure to lead (71 active and 18 retired) and 35 reference subjects (27 active and 8 retired) with no known occupational exposure to lead. Bone-Pb was related to the previous lead exposure, estimated as a time-integrated B-Pb (CBLI). RESULTS: The retired smelters had the highest bone-Pb (median value 55 micrograms/g wet weight, as against 23 micrograms/g in active smelters) and 3 micrograms/g in the reference subjects. A strong positive correlation was observed between the bone-Pb and the CBLI among both active (rs = 0.73; P < 0.001) and retired (rs = 0.71; P = 0.001) smelters. The corresponding correlations between the bone-Pb and the period of employment were of the same magnitude. For retired workers, there were positive correlations between the bone-Pb and the B-Pb (rs = 0.58; P = 0.011) and U-Pb. (rs = 0.56; P = 0.02). Multiple regression analyses showed that bone-Pb was best described by the CBLI, which explained 29% of the observed variance (multiple r2) in bone-Pb in active workers and about 39% in retired workers. The estimated biological half-life of bone-Pb among active lead workers was 5.2 years (95% confidence interval 3.3-13.0 years). CONCLUSIONS: The high bone-Pb seen in retired workers can be explained by the long exposure periods, the higher exposure levels in earlier decades, and the slow excretion of lead accumulated in bone. The importance of the skeletal lead pool as an endogenous source of lead exposure in retired smelters was indicated by the associations between the B-Pb or U-Pb, on the one hand, and the bone-Pb, on the other. In active workers, the ongoing occupational exposure was dominant. The in vivo X-ray fluorescence technique is still mainly a research tool, and more work has to be done before it can be used more widely in clinical practice. However, over the next decade we can anticipate retrospective, prospective and cross-sectional epidemiological studies in which bone lead determinations reflecting the previous lead exposure in both occupationally and nonoccupationally lead exposed populations are related to various types of adverse health outcomes. Such studies will improve our knowledge of dose-response patterns and provide data that will have an impact on hygienic threshold limit values and prevention of lead-induced diseases.

Adult↗
PubMed1992

Stable isotopic tracers of lead mobilized by DMSA chelation in low lead-exposed rats.

The ability of DMSA to mobilize skeletal lead or effect a redistribution of endogenous lead to other target organs in low lead-exposed organisms is unclear. Discrepant results of past studies of DMSA and other lead chelators (e.g., CaNa2EDTA) may be due, in part, to experimental differences and difficulties in distinguishing mobilized skeletal lead from other endogenous or exogenous lead sources. Therefore, the influence of DMSA on the mobilization and redistribution of lead in skeletal and soft tissue compartments of low lead-exposed female Wistar (115-125 g) rats was investigated using ultraclean stable lead isotope tracer techniques. Rats that had been reared on a low lead-level diet (lead intake approximately 80 ng Pb/g body/day) were fed 206Pb-enriched drinking water (210 ng Pb/ml) for 1.5 days and then were chelated with a single ip injection of a 0.11 mmol/kg dose of DMSA. Blood, kidney, brain, tibia, urine and feces were collected 24 hr after chelation and analyzed for lead concentrations by graphite furnace atomic absorption spectrometry and for lead isotopic compositions by thermal ionization mass spectrometry. These analyses demonstrated that DMSA chelation significantly increased (15-fold) the diuresis of labile soft tissue lead, but not skeletal lead. DMSA also appeared to effect a redistribution and input of a comparable amount of lead to the skeleton and smaller relative amounts of lead to the soft tissues (blood, kidney) of the chelated animals. The clinical significance of these latter observations beyond the context of this preliminary study is not clear.

Animals↗
PubMedDate not supplied

Lead-glazed ceramic ware and blood lead levels of children in the city of Oaxaca, Mexico.

Although Mexico substantially reduced use of leaded gasoline during the 1990s, lead-glazed pottery remains a significant source of population exposure. Most previous studies of lead in nonoccupationally exposed groups in Mexico have been conducted in the Mexico City metropolitan area. Oaxaca, a poor southern state of Mexico, has a centuries-old tradition of use of low temperature lead-glazed ceramic ware manufactured mainly by small family businesses. We measured blood lead levels in 220 8-10-y-old children (i.e., not from pottery-making families) who were students in the innercity of Oaxaca and in the mothers of all children. The geometric mean blood lead level of the children was 10.5 microg/dl (+7.0/-4.3 microg/dl standard deviation; range = 1.3-35.5 microg/dl). The corresponding mean value for the mothers was 13.4 (+9.0/-5.4 microg/dl standard deviation; range = 2.8-45.3 microg/dl). We used cutoffs that were greater than or equal to 10 microg/dl, 20 microg/dl, and 30 microg/dl, and we determined that 54.9%, 10.3%, and 3.0% of the children were at or above the respective criteria. We accounted for 25.2% of the variance in blood lead levels of the children, using maternal responses to a questionnaire that assessed possible lead sources in a linear multiple-regression model. The most important factors related to lead levels were family use of lead-glazed pottery, use of animal fat in cooking, and family income. The addition of maternal blood lead level to the model increased accounted variance in blood lead to 48.0%. In logistic-regression modeling of children's blood lead levels, we used a cutoff of greater than or equal to 10 microg/dl, and we found that use of lead-glazed pottery was the most important of all questionnaire items that were predictive of blood lead levels (odds ratio = 2.98). In Oaxaca, as is the case elsewhere in Mexico, lead-glazed ceramic ware remains a significant risk factor for elevated blood lead levels in children.

Ceramics↗
PubMedDate not supplied

Effects of lead on the endocrine system in lead smelter workers.

In this study of the effects of lead on the endocrine system, 77 secondary lead-smelter workers (i.e., 62 active and 15 retired) were compared with 26 referents. Lead concentrations were determined in plasma with inductively coupled plasma mass spectrometry (i.e., index of recent exposure), in blood with atomic absorption spectrophotometry, and in fingerbone with K x-ray fluorescence technique (i.e., index of long-term exposure). In addition, pituitary hormones were determined in serum by fluoroimmunoassay, and thyroid hormones and testosterone in serum were determined with radioimmunoassay. Nine lead workers and 11 referents were challenged with gonadotrophin-releasing hormone and thyrotrophin-releasing hormone, followed by measurements of stimulated pituitary hormone levels in serum. Median levels of lead in plasma were 0.14 microg/dl (range = 0.04-3.7 microg/dl) in active lead workers, 0.08 microg/dl (range = 0.05-0.4 microg/dl) in retired lead workers, and 0.03 microg/dl (range = 0.02-0.04 microg/dl) in referents (1 microg/dl = 48.3 nmol/l). Corresponding blood lead concentrations were 33.2 microg/dl (range = 8.3-93.2 microg/dl), 18.6 microg/dl (range = 10.4-49.7 microg/dl), and 4.1 microg/dl (range 0.8-6.2 microg/dl), respectively. Respective bone lead levels were 21 microg/gm (range = -13 to 99 microg/gm), 55 microg/gm (range = 3-88 microg/gm), and 2 microg/gm (range = -21 to 14 microg/gm). Concentrations of basal serum hormone (i.e., free thyroid hormones, thyrotrophin, sex hormone binding globulin, and testosterone) were similar in the 3 groups. There were no significant associations between the hormones mentioned herein and blood plasma, blood lead, and bone lead levels. In the challenge test, stimulated follicle-stimulating hormone levels were significantly lower in lead workers (p = .014) than in referents, indicating an effect of lead at the pituitary level. Also, there was a tendency toward lower basal stimulated follicle-stimulating hormone concentrations in lead workers (p = .08). This effect, however, was not associated with blood plasma level, blood lead level, or bone lead level. In conclusion, a moderate exposure to lead was associated with only minor changes in the male endocrine function, particularly affecting the hypothalamic-pituitary axis. Given that sperm parameters were not studied, the authors could not draw conclusions about fertility consequences.

Adult↗
PubMed1985

Increased lead levels in brain after long-term treatment with lead and dithiocarbamate or thiuram derivatives in rats.

Lead concentrations in blood and brain were measured in rats exposed to lead via drinking water, 0.25% Pb (12 mM), and dithiocarbamate/thiuram derivatives administered by gavage singly or in combination for 6 weeks. Sodium salts of diethyldithiocarbamate (DEDTC) and dimethyldithiocarbamate (DMDTC) were given in doses of 0.2 mmol/kg and tetramethylthiuram disulfide (thiram) and tetraethylthiuram disulfide (disulfiram) in doses of 0.1 mmol/kg twice a week. In rats that received lead plus dithiocarbamate/thiuram derivatives lead concentrations in blood and brain were significantly increased; disulfiram being most effective in increasing lead levels, followed by thiram, DMDTC and DEDTC. In blood, lead levels were increased 3-fold and in brain almost 4-fold after treatment with lead plus disulfiram compared to treatment with lead alone. When rats were given DEDTC or thiram by gavage (0.1 mmol/kg/day 5 days a week for 2 weeks) after cessation of the lead treatment, there was no increase in blood lead levels but in thiram-treated rats brain lead concentration was increased 2.7-fold. In rats treated with DEDTC intraperitoneally after cessation of lead treatment, both blood and brain concentrations of lead were increased. This study suggests that combined exposure of lead and dithiocarbamate/thiuram derivatives causes a substantial increase in brain levels of lead which are not always reflected in increases of blood lead levels. This interaction effect ought to be taken into consideration when evaluating the health effects of environmental and occupational lead exposure.

Animals↗
PubMed2000

109Cd K x ray fluorescence measurements of tibial lead content in young adults exposed to lead in early childhood.

OBJECTIVES: Tibia lead measurements were performed in a population of 19-29 year old people who had been highly exposed to lead in childhood to find whether lead had persisted in the bone matrix until adulthood. METHODS: (109)Cd K x ray fluorescence was used to measure the tibia lead concentrations of 262 exposed subjects and 268 age and sex matched controls. Questionnaire data allowed a years of residence index to be calculated for exposed subjects. A cumulative blood lead index was calculated from the time weighted integration of available data of blood lead. RESULTS: The mean (SEM) difference between exposed and control men was 4.51 (0.35) micrograms Pb/g bone mineral, and between exposed and control women was 3.94 (0. 61) micrograms Pb/g bone mineral. Grouped mean bone lead concentrations of exposed subjects were predicted best by age. When exposed and control subjects' data were combined, grouped mean bone lead concentrations were predicted best by cumulative blood lead index. The years of residence index was neither a good predictor of bone lead concentrations for exposed subjects nor for exposed and control subjects combined. Finally, exposed subjects had increased current blood lead concentrations that correlated significantly with bone lead values. CONCLUSION: Bone lead concentrations of exposed subjects were significantly increased compared with those of control subjects. Lead from exposure in early childhood had persisted in the bone matrix until adulthood. Exposed subjects had increased blood lead concentrations compared with controls. Some of this exposure could be related to ongoing exposure. However, some of the increase in blood lead concentration in adult exposed subjects seemed to be a result of endogenous exposure from increased bone lead stores. The endogenous exposure relation found for men was consistent with reported data, but the relation found for women was significantly lower. Further research is needed to find whether the observed differences are due to sex, or pregnancy and lactation.

Adult↗
PubMed2000

Lead isotopes as a supplementary tool in the routine evaluation of household lead hazards.

The advent of magnetic sector inductively coupled plasma-mass spectrometry (ICP-MS) allows rapid, accurate, and precise measurement of lead isotopes in environmental and biological samples at a lower cost than traditional methods. This may increase the feasibility of including lead isotope measurements as a routine tool to identify household sources of lead exposure to children. Here, we present three household case studies to illustrate how lead hazard evaluations by an environmental specialist could be supplemented with routine lead isotope analyses of potential lead sources and blood. Sampling for lead isotopes was undertaken following the U.S. Department of Housing and Urban Development regulatory guidelines for the evaluation of lead hazards in housing, and with the consideration of minimizing the additional costs associated with lead isotope measurements. The range of isotopic ratios within a single residence was large enough to allow the characterization of different lead sources, particularly when both major (e.g., (207)Pb/(206)Pb) and minor (e.g., (206)Pb/(204)Pb) isotope ratios were considered. These cases illustrate the utility of the lead isotope method to identify main source(s) of lead exposure to the child; discard unlikely sources of exposure to the child; point to sources of lead to dust; and substantiate or refine the environmental assessment based exclusively on lead concentrations and loadings. Thus, a more effective evaluation of household lead hazards would likely benefit from considering a) lead concentrations and loadings in and around the household environment; b) all isotopic ratios of potential lead sources within that environment; and c) information about behavioral habits, as well as an evaluation of viable pathways of exposure to the child.

Blood Chemical Analysis↗
PubMed2000

Effects of lead exposure before pregnancy and dietary calcium during pregnancy on fetal development and lead accumulation.

Millions of women of child-bearing age have substantial bone lead stores due to lead exposure as children. Dietary calcium ingested simultaneously with lead exposure can reduce lead absorption and accumulation. However, the effects of dietary calcium on previously accumulated maternal lead stores and transfer to the fetus have not been investigated. We studied the effects of lead exposure of female rats at an early age on fetal development during a subsequent pregnancy. We gave 5-week-old female Sprague-Dawley rats lead as the acetate in their drinking water for 5 weeks; controls received equimolar sodium acetate. This was followed by a 1-month period without lead exposure before mating. We randomly assigned pregnant rats (n = 39) to diets with a deficient (0.1%) or normal (0.5%) calcium content during pregnancy. A total of 345 pups were delivered alive. Lead-exposed dams and their pups had significantly higher blood lead concentrations than controls, but the concentrations were in the range of those found in many pregnant women. Pups born to dams fed the calcium-deficient diet during pregnancy had higher blood and organ lead concentrations than pups born to dams fed the 0. 5% calcium diet. Pups born to lead-exposed dams had significantly (p<0.0001) lower mean birth weights and birth lengths than controls. There were significant inverse univariate associations between dam or pup organ lead concentrations and birth weight or length. The 0.5% calcium diet did not increase in utero growth. Stepwise regression analysis demonstrated that greater litter size and female sex were significantly associated with reduced pup birth weight and length. However, lead exposure that ended well before pregnancy was significantly (p<0.0001) associated with reduced birth weight and length, even after litter size, pup sex, and dam weight gain during pregnancy were included in the regression analysis. The data demonstrate that an increase in dietary calcium during pregnancy can reduce fetal lead accumulation but cannot prevent lead-induced decreases in birth weight and length. The results provide evidence that dietary nutrients can influence the transfer of toxins to the fetus during pregnancy. If these results are applicable to women, an increase in diet calcium during pregnancy could reduce the transfer of lead from prepregnancy maternal exposures to the fetus.

Animals↗
PubMed1996

Use of endogenous, stable lead isotopes to determine release of lead from the skeleton.

The stable lead isotope methodology can be used to study the release of lead from bone into the circulation because of its potential to distinguish circulatory lead from "older" and isotopically different skeletal lead that may have been accumulated years or decades earlier. Here we report the initial results from a larger ongoing study that evaluates the skeleton as a source of lead to the circulation in environmentally exposed human subjects. Lead concentrations and stable lead isotopic compositions were measured in blood and trabecular bone samples obtained from five patients who underwent total hip or knee joint replacement. All subjects contained low blood (1-6 micrograms/dl) and bone (0.6-7 micrograms/g dry weight) lead concentrations typical of environmentally exposed individuals. There were relatively large differences in the lead isotopic compositions between the paired blood and bone samples from each subject. These isotopic differences are attributed to differences in the lead isotopic compositions of past versus current lead exposures and to the long elimination half-life of lead in the skeleton compared to lead in the circulation. Based on these data, we determined that the skeleton contributed 40-70% of the lead in the blood of these subjects. This initial study demonstrates the utility of the stable lead isotope methodology for investigating the release of lead from the skeleton. It also shows that the skeleton can be an important endogenous source of lead exposure in environmentally exposed humans.

Aged↗
PubMed1998

Relationships of lead in breast milk to lead in blood, urine, and diet of the infant and mother.

We have obtained stable lead isotope and lead concentration data from a longitudinal study of mobilization of lead from the maternal skeleton during pregnancy and lactation and in which the newly born infants were monitored for 6 months postpartum to evaluate the effects of the local environment on lead body burden of the infant. Samples of maternal and infant blood, urine, and diet and especially breast milk were measured for 21 mothers and 24 infants. Blood lead concentrations were less than 5 microg/dl in all except one subject. The mean lead concentration in breast milk +/- standard deviation was 0.73 +/- 0.70 microg/kg. In seven subjects for whom serial breast milk sampling was possible, the lead concentration varied by factors of from 2 to 4, and for three subjects there was an increase at or after 90 days postpartum. For the first 60-90 days postpartum, the contribution from breast milk to blood lead in the infants varied from 36 to 80%. Multiple linear regression analyses indicated statistically significant relationships for some of the variables of isotope ratios and lead concentrations between breast milk, blood, urine, and diet for infants and mothers. For example, the analyses revealed that both a mother's breast milk 207Pb/206Pb and 206Pb/204Pb ratios and lead concentration provide information to predict her infant's blood 207Pb/206Pb and 206Pb/204Pb ratios. The major sources of lead in breast milk are from the maternal bone and diet. An evaluation of breast milk lead concentrations published over the last 15 years indicates that studies in which the ratio of lead concentrations in breast milk to lead concentrations in whole maternal blood (Multiple>100) were greater than 15 should be viewed with caution because of potential contamination during sampling and/or laboratory analyses. Selected studies also appear to show a linear relationship between breast milk and maternal whole blood, with the percentage of lead in breast milk compared with whole blood of <3% in subjects with blood lead levels ranging from 2 to 34 microgram/dl. The levels of lead in breast milk are thus similar to those in plasma. Breast-fed infants are only at risk if the mother is exposed to high concentrations of contaminants either from endogenous sources such as the skeleton or exogenous sources.

Adult↗
PubMed2005

[Influence of soil lead upon children blood lead in Shenyang City].

The dynamic correlation coefficients between soil lead and blood lead, the children blood lead arose from soil lead and the length of time over which the blood lead concentration can fall to be at or below the threshold value (10 microg x dL(-1)) are analyzed. If the aggregated soil lead and blood lead are stratified by the seven geographic regions studied, an elevated R of 0.9200 could be calculated, and the lead exposure assessment may require knowledge of geographic dimension of the exposure topology components. The children blood lead levels calculated based on the soil lead in the unit of geographic region show that the blood lead levels of about 90% of children exceed the threshold value in the west industrial area, while they are all below the threshold value in the east area. The children, whose blood lead level exceed the threshold value, are in the range of 3.48% - 31.81% in the other areas. The length of time over which the blood lead concentration can fall to be at or below the threshold value is highest, and average 26.68months, in the west area, and the order is the west > the north > the northeast > the southwest > the northwest > central area > the east, it is zero in the east area, and the maximum recovery time follow the same order. The blood lead levels and the recovery time are controlled by the environmental lead contamination, and the lead hazard intervention would contribute to the fall of blood lead levels.

Child↗
PubMed1988

Calcium-lead interactions involving earthworms. Part 2: the effect of accumulated lead on endogenous calcium in Lumbricus rubellus.

The calcium and lead burdens of tissue fractions of Lumbricus rubellus were quantified in 'native' animals from acidic and calcareous disused lead mines, and from control ('naive') animals exposed to lead-polluted soils under laboratory conditions. Most of the body burden of lead was accumulated within the posterior alimentary canal, and significant positive correlations were generally found between the calcium and lead burdens in this tissue fraction, which were evident in both the naturally and laboratory lead-exposed animals. The calcium:lead correlation is probably due to a proliferation of the calcium-rich, lead-sequestering chloragosome granules, and may thus be regarded as a specific tissue response to cellular lead incursion. No calcium-lead relationship was recorded in the rest (largely composed of the body wall) fraction of earthworms inhabiting the lead-polluted sites. However, a concomitant increase in calcium and lead in this tissue fraction of the laboratory lead-exposed control animals was noted. It is concluded that in naturally lead-exposed earthworms, the cells of this tissue fraction may be relatively resistant to the toxic effects of the metal. By contrast, it is apparent that a non-specific cytotoxic response by the cells of the rest of 'naive' animals occurs, as demonstrated by the concurrent increase in its calcium and lead burdens. These results suggest that a tolerance mechanism to lead, perhaps with a genetic basis, may exist in earthworms naturally exposed to lead.

Journal Article↗
PubMed2005

Surgical epicardial left ventricular lead versus coronary sinus lead placement in biventricular pacing.

OBJECTIVE: Biventricular pacing has demonstrated improvement in cardiac function in treating congestive heart failure (CHF). Two different operative strategies (coronary sinus vs. epicardial stimulation) for left ventricular (LV) pacing were compared. METHODS: Since April 1999, a total of 86 patients (pts, age: 63+/-10 years) with depressed systolic LV function (mean ejection fraction 24+/-9%), left bundle-branch-block (mean QRS 182+/-22 ms) and congestive heart failure NYHA III or higher were enrolled. For biventricular stimulation coronary sinus (CS) leads were placed in 79 pts. Nine of these devices were converted to surgical epicardial LV-leads, because of CS-lead failure. In 7 patients epicardial LV-leads were initially implanted surgically, accounting for a total of 16 pts with surgical placed epicardial steroid-eluting LV-leads. For these, a limited left-lateral thoracotomy (7+/-4 cm) was used. Thirty-three (38%) pts had an indication for a defibrillator. The mean follow-up time was 16.4+/-15.4 months (0.1-45 months), representing 107.1 patient-years. RESULTS: In the biventricular pacing mode, QRS duration decreased to 143+/-16 ms (P<0.001). Threshold capture of the CS-leads increased significantly compared to surgically placed epicardial leads (18 month control: 2.2+/-1.4V/0.5 ms vs. 0.7+/-0.3V/0.5 ms), which had no increase in threshold (P<0.001). At the 18 month follow-up 7 CS-leads had a threshold of >4V/0.5 ms vs. epicardial leads which were under 1.1V/0.5 ms, except for one (1.8V/0.5 ms). After CS-lead implantation 25 LV-lead related complications occurred, (failed implantation, CS-dissection, loss of pacing capture, diaphragm stimulation or lead dislodgment), vs. one dislodgement after surgical epicardial lead placement (P<0.05). Correct lead positioning (obtuse marginal branch area) was achieved in all surgical epicardial placements but only in 70% with CS-leads (P<0.03). In the follow up period, 9 pts died (4 cardiac related). Heart transplantation was necessary in 4 pts due to deterioration of the cardiomyopathy. CONCLUSIONS: Surgical epicardial lead placement revealed excellent long-term results and a lower LV-related complication rate compared to CS-leads. Although, the approach via limited thoracotomy for biventricular pacing is associated with 'more surgery', it is a safe and reliable technique and should be considered as an equal alternative.

Bundle-Branch Block↗
PubMed2002

Extraction of pacemaker and implantable cardioverter defibrillator leads: patient and lead characteristics in relation to the requirement of extraction tools.

Effective tools for extraction of pacemaker and ICD leads have been developed in the past decennium. This study investigated the necessity of using these tools in addition to direct traction in relation to patient and lead characteristics. The study encompasses first attempts at extraction of consecutive pacemaker and ICD leads from the subpectoral area. A stepwise extraction protocol was used with traction first (directly or with a locking stylet) followed by laser sheath extraction if not successful. The indication, patient age, time from implant, fixation mechanism, location, and insertion site of the leads were studied in relation to the outcome of traction. A total of 145 leads in 83 patients were extracted. Leads were implanted for 71 +/- 61 months. Indication for extraction was infection in 96 leads and malfunction in 49 leads. There were 90 ventricular leads including 16 ICD leads. Forty-nine (34%) leads were extracted with traction; in 96 (66%) leads a laser sheath was necessary. All leads implanted for < 6 months could be removed with traction alone. In a multivariate logistic regression model, time from implant was the main factor determining success of traction (P < 0.001), but in case of infection the success rate increased (P = 0.004). In conclusion, time from implant is the decisive factor to judge the potential efficacy of lead extraction with direct traction. If leads are implanted for 6 months, the availability of additional extraction tools is necessary when lead extraction is considered. In addition to time from implant, infected leads have a better chance to be removed with traction although it is a much weaker predictor.

Defibrillators, Implantable↗
PubMed2005

Lead dust in Broken Hill homes: effect of remediation on indoor lead levels.

This study was undertaken to determine whether home remediation effectively reduced indoor lead levels in Broken Hill, a long-established silver-lead-zinc mining town in outback Australia. A before-after study of the effect of home remediation on indoor lead levels was embedded into a randomized controlled trial of the effectiveness of remediation for reducing elevated blood lead levels in young children. Moist towelettes were used to measure lead loading (microg/m2) on internal windowsills and internal and entry floors of 98 homes; samples were collected before, immediately after, and 2, 4, 6, 8, and 10 months after remediation. Data were log(10) transformed for the analysis. Remediation reduced average indoor lead levels by approximately 50%, and lead levels remained low for the duration of the follow-up period (10 months). The greatest gains were made in homes with the highest initial lead levels; homes with low preremediation lead levels showed little or no benefit. Before remediation, homes located in areas with high soil lead levels or with "poor" dust proofing had higher lead levels than those in areas with lower soil lead levels or with "medium" or "good" dust proofing; these relative differences remained after remediation. There was no evidence that lead loading was reduced by an increased opportunity to become aware of lead issues. We conclude that remediation is an effective strategy for reducing the lead exposure of children living in homes with high indoor lead levels.

Air Pollutants↗
PubMed2005

Reversible neurobehavioral performance with reductions in blood lead levels--a prospective study on lead workers.

Lead poisoning remains an occupational hazard in Taiwan. Many studies, based on crossed-section design, have focused on changes in lead-associated neurobehavioral dysfunctions that occur at increased blood lead levels. This study evaluates the changes in neurobehavioral performance of lead workers as blood levels are reduced. We tested 27 lead workers in a lead glaze factory using the computer-based and automated Chinese edition of Neurobehavioral Evaluation System 2 (C-NES II) in 1994, 1996, and 1997. The association of blood lead levels and C-NES II results were analyzed by longitudinal data analysis methods, repeated ANOVA and mixed model analyses after adjustment for potential confounders. Over these 4 years, the mean lead blood levels of workers were reduced from 26.3(SD=12.0) to 8.3(SD=6.9) microg/dL. Based on a mixed model analysis, we found that the negative effects of exposure to lead on neurobehavioral performance can be reversed to some extent with lowering levels of blood lead. During this period, we found significant improvements in 3 subtests: finger tapping, pattern comparison reaction time, and memory. This study tentatively concluded that reversibility of the neurobehavioral performance after reduction of the lead exposure, which encourages industrial hygiene and personal health promotion to reduce their body lead burden. However, though use of NES is more sensitive to detect the changes, the chronic symptoms (using standardized questionnaire) were found to decline slowly when blood lead level is reduced, with no statistically significant difference. The result means that to avoid the lead exposure primarily is essential to prevent chronic symptoms. We conclude that the most important way to prevent and possibly reverse chronic symptoms of lead poisoning remains to be the avoidance of exposure to lead.

Adult↗
PubMed1978

Experimental lead intoxication in dogs: a comparison of blood lead and urinary delta-aminolevulinic acid following intoxication and chelation therapy.

Intravenous lead administration to dogs produced an acute syndrome of lead intoxication charcterized by depression, vomiting, anorexia and weight loss. The effect of chelation therapy with calcium disodium ethylene diamine tetraacetate, penicillamine or both was determined by serially monitoring changes in blood lead and urine delta-aminolevulinic acid. Following therapy, blood lead values were significantly lower in chelated dogs than non-treated lead exposed dogs on days 7 and 10. Urine delta-aminolevulinic acid at day 7 was significantly higher in untreated lead exposed dogs than in other groups. There was no significant difference in blood lead or urine delta-aminolevulinic acid between lead intoxicated dogs which underwent the indicated chelation therapy protocols. There was, however, a trend for higher urinary delta-aminolevulinic acid excretion in those intoxicated dogs undergoing calcium disodium ethylene diamine tetraacetate therapy as opposed to those undergoing penicilamine therapy. There was no significant correlation between blood lead and urinary delta-aminolevulinic acid previous to lead exposure. However, after lead exposure significant correlation was present at days 4, 7, 10 and 14. Certain lead exposed dogs following chelation therapy were noted to have normal blood lead levels but elevated urinary delta-aminolevulinic acid suggesting that blood lead does not always correlate with metabolic effects of lead in the body. Urinary delta-aminolevulinic acid was therefore recommended as an additional laboratory parameter which improved assessment of lead exposure in dogs, particularly in determining adequacy of chelation therapy.

Aminolevulinic Acid↗