Chronic lead exposure: a problem for minority workers

1. Despite regulatory and case identification efforts, lead exposure continues to pose a major health problem for minority workers. 2. Minority workers are overrepresented in lead industries such as lead smelting, lead storage batteries, lead pigment production and pottery. 3. Preliminary data from recently instituted lead registries in California and Texas suggest that minority workers continue to be overexposed to lead. 4. A federal policy that strengthens enforcement of the OSHA lead standard is needed to reduce lead exposure among minority workers.     

Effects of a Thin-Sized Lead Body of a Transvenous Single Coil Defibrillation Lead on ICD Implantation

SCHUCHERT, A., et al. : Effects of a Thin‐Sized Lead Body of a Transvenous Single Coil Defibrillation Lead on ICD Implantation. In the interest of patients receiving implantable cardioverter defibrillators (ICDs), the clinical benefits of newer and thinner transvenous defibrillation leads have to be determined. The aims of this study were to evaluate the ICD procedure duration and the frequency of lead dislocation at the 3‐month follow‐up of a new defibrillation lead with a thin‐sized lead body and its conventionalsized predecessor. The thin‐sized single coil defibrillation lead (Kainox RV, Biotronik; lead body 6.7 Fr) was implanted in 61 patients and the conventional‐sized defibrillation lead (SPS, Biotronik; lead body 7.8 Fr) in 60 patients. Both leads were connected to a left‐sided, prepectorally implanted Phylax ICD (Biotronik) with active housing. The lead implantation time and total procedure duration were determined. Lead implantation time was defined as the time from lead insertion to the end of the pacing measurements. The total procedure duration spanned skin incision to closure. The incidence of lead repositioning during the lead implantation time and during ventricular fibrillation conversion testing was also assessed. The frequency of lead dislocations was recorded at the 3‐month follow‐up. Mean lead implantation time and total procedure duration of the thin‐sized lead (23 ± 22 minutes 76 ± 37 minutes ) were not statistically different from the time needed for the conventional‐sized lead (22 ± 20 minutes 81 ± 34 minutes ). The number of lead repositionings during the lead implantation time was similar (thin‐sized lead: 1.4 ± 2.4 ; conventional‐sized lead: 1.1 ± 1.9 ). An additional lead repositioning was not necessary during ventricular fibrillation conversion testing in 93.4% of the patients with thin‐sized and in 94.4% with conventional‐sized leads (not significant). At the 3‐month follow‐up, there were four (6.6%) lead dislocations in the thin‐sized and four (6.7%) in the conventional‐sized lead group. In conclusion, the downsized lead body of the new defibrillation lead influenced neither ICD procedure duration nor the incidence of lead dislocation during follow‐up.     

环境铅污染与难治性佝偻病

近年来 ,环境铅污染对儿童健康的危害已引起了人们的广泛关注。现介绍环境铅污染的来源、儿童铅代谢的特点以及我国儿童目前的血铅水平 ,从铅对维生素D、钙磷代谢及成骨细胞的影响等方面阐明铅对儿童骨代谢的作用机制 ,指出了环境铅污染可能是我国儿童佝偻病高发病率及常规治疗效果不佳的原因之一 ,并提出了儿童铅危害的主要防治措施。     

Removal of Endocardial Defibrillation Leads

Two patients, each with an endocardial defibrillation lead system (Endotak O62), required lead removal; one because of chronic lead infection and the second because of spurious shocks caused by lead insulation damage. Neither lead could be removed by simple traction. The defective lead was removed by a combination of catheterization techniques including a steerable ablation catheter and traction, both under general anesthesia. The lead with the insulation defect was rapidly removed with a locking stylet, suggesting that endocardial lead defibrillating leads can be removed similarly to pacemaker leads, thus avoid thoracotomy.     

Effectiveness of Action to Reduce Exposure of Free-Ranging California Condors in Arizona and Utah to Lead from Spent Ammunition

California condors (Gymnogyps californianus) released into the wild in Arizona ranged widely in Arizona and Utah. Previous studies have shown that the blood lead concentrations of many of the birds rise because of ingestion of spent lead ammunition. Condors were routinely recaptured and treated to reduce their lead levels as necessary but, even so, several died from lead poisoning. We used tracking data from VHF and satellite tags, together with the results of routine testing of blood lead concentrations, to estimate daily changes in blood lead level in relation to the location of each bird. The mean daily increment in blood lead concentration depended upon both the location of the bird and the time of year. Birds that spent time during the deer hunting season in two areas in which deer were shot with lead ammunition (Kaibab Plateau (Arizona) and Zion (Utah)) were especially likely to have high blood lead levels. The influence upon blood lead level of presence in a particular area declined with time elapsed since the bird was last there. We estimated the daily blood lead level for each bird and its influence upon daily mortality rate from lead poisoning. Condors with high blood lead over a protracted period were much more likely to die than birds with low blood lead or short-term elevation. We simulated the effect of ending the existing lead exposure reduction measures at Kaibab Plateau, which encourage the voluntary use of non-lead ammunition and removal of gut piles of deer and elk killed using lead ammunition. The estimated mortality rate due to lead in the absence of this program was sufficiently high that the condor population would be expected to decline rapidly. The extension of the existing lead reduction program to cover Zion (Utah), as well as the Kaibab plateau, would be expected to reduce mortality caused by lead substantially and allow the condor population to increase.     

某蓄电池厂铅作业工人尿铅检测分析

[目的]了解某蓄电池厂职业性铅危害情况，探索职业卫生预防模式。[方法]收集481名铅作业工人晨尿，按照WS／T17—1996方法进行尿铅检测。参照GBZ37—2002（（职业性慢性铅中毒诊断标准》，尿铅〉10．07mg／L为超标（即观察对象限值），比较不同车间、性别的尿铅超标率差异。[结果]481名铅作业工人尿铅均数为（0．077±0．099）mg／L，超标人数92人，超标率为19．13％。外销组、成品车间的工人尿铅超标率分别为6．78％、23．14％，其超标率差异有统计学意义（t〈0．05）。男女工人尿铅超标率分别为21．00％和14．49％，但差异无统计学意义（t〉0．05）。[结论]某蓄电池厂铅作业工人尿铅超标明显，男性工人尿铅超标率高于女性。该厂铅作业工人受铅危害影响情况较重，工作场所中高浓度的铅烟、铅尘是造成铅作业工人血铅、尿铅含量增加的重要因素，该厂应进行工艺改革，采取有效措施控制铅污染，定期进行职业健康检杏，以及时发现问题，预防铅中毒的发生。     

新疆乌鲁木齐市儿童血铅水平及相关因素分析

目的调查乌鲁木齐市儿童血铅水平,分析儿童血铅含量及铅中毒的原因,寻找预防和降低铅中毒的方法和途径,为制定积极有效的干预措施提供科学依据。方法用原子吸收光谱分析仪检测儿童末梢血中铅的含量。结果 5 268例儿童中血铅浓度平均值为(40.55±22.23)μg/L,铅中毒儿童共133例,总检出率为2.52%;男童血铅水平明显高于女童(P<0.01);0～7岁儿童血铅浓度随年龄增长而增高,差异有统计学意义(P<0.01)。结论乌鲁木齐市儿童血铅水平低于中国其他城市,但高于西方发达国家。寻找污染来源,治理环境污染及注意家庭卫生,营养平衡,加大宣传力度,是减少儿童铅中毒最经济和最有效的方法。     

Modeling the effect of succimer (DMSA; dimercaptosuccinic acid) chelation therapy in patients poisoned by lead

Context: Kinetic models could assist clinicians potentially in managing cases of lead poisoning. Several models exist that can simulate lead kinetics but none of them can predict the effect of chelation in lead poisoning. Our aim was to devise a model to predict the effect of succimer (dimercaptosuccinic acid; DMSA) chelation therapy on blood lead concentrations.

Materials and methods: We integrated a two-compartment kinetic succimer model into an existing PBPK lead model and produced a Chelation Lead Therapy (CLT) model. The accuracy of the model’s predictions was assessed by simulating clinical observations in patients poisoned by lead and treated with succimer. The CLT model calculates blood lead concentrations as the sum of the background exposure and the acute or chronic lead poisoning. The latter was due either to ingestion of traditional remedies or occupational exposure to lead-polluted ambient air. The exposure duration was known. The blood lead concentrations predicted by the CLT model were compared to the measured blood lead concentrations.

Results: Pre-chelation blood lead concentrations ranged between 99 and 150?μg/dL. The model was able to simulate accurately the blood lead concentrations during and after succimer treatment. The pattern of urine lead excretion was successfully predicted in some patients, while poorly predicted in others.

Conclusions: Our model is able to predict blood lead concentrations after succimer therapy, at least, in situations where the duration of lead exposure is known.     

Thresholds and Complications with Right Ventricular Septal Pacing Compared to Apical Pacing

Background: Right ventricular septal pacing has been proposed as an alternative to apical pacing. However, data concerning thresholds and requirement for lead repositioning with this technique are scant.
Methods: We reviewed data at implantation and follow-up of 362 consecutive recipients of the same model of active fixation lead (Medtronic 5076-58, Minneapolis, MN, USA) to avoid differences due to lead characteristics. Patients were divided into two groups according to whether the lead was positioned on the interventricular septum (n = 157) or at the right ventricular apex (n = 205). Thresholds, lead impedance, and requirement for lead repositioning were compared between groups at implantation and follow-up.
Results: There were no differences between the septal and apical groups in sensing and pacing thresholds or lead impedance, either at implantation or during a 24-month follow-up. In the septal group, the lead had to be repositioned in four patients (2.5%) due to lead dislodgement in two patients, acute threshold rise in one patient, and pericardial effusion in another patient (the lead had unintentionally been positioned on the anterior free wall in these last two patients). In the apical group, the lead had to be repositioned in eight patients (3.9%, P = 0.56) due to lead dislodgement in three patients and acute threshold rise in five patients.
Conclusions: Acute and chronic thresholds associated with septal pacing are similar to those observed with apical pacing, and risk of lead dislodgement is low. However, multiple radioscopic views must be used to avoid inadvertent positioning of the lead on the anterior free wall .     

厦门市婴儿至学龄前儿童血铅检测结果与分析

目的了解厦门市儿童血铅水平分布状况,为预防儿童铅中毒提供依据。方法随机选择厦门妇幼保健院门诊就诊的儿童,年龄0～10岁,采用原子吸收石墨炉法测定全血血铅值。结果 2010～2013年间共有11 271例儿童检测全血血铅水平,血铅均值为51.0μg/L。不同年龄组的男童铅中毒率高于女童,差异有统计学意义(P0.05)。在1～6岁期间,随着年龄增加血铅均值逐渐上升,并在学龄前期达到高峰,之后的学龄期儿童均值不再增高,但血铅中毒率始终呈现逐渐下降的趋势。结论厦门市儿童铅中毒率接近国内其他城市平均水平,但学龄前儿童血铅的均值水平随年龄增长而增加,铅污染对儿童身体健康危害应引起重视。     

Lead levels in dentine and circumpulpal dentine of deciduous teeth of normal and lead poisoned children

A method for the preparation of circumpulpal dentine for lead analysis is described. The technique consists of cutting 600-μ-thin sections of deciduous teeth, and, utilizing a vice, fracturing off the circumpulpal dentine from the coronal dentine. Both dentine and circumpulpal dentine of teeth of normal American children and previously identified lead-poisoned children were prepared in this fashion and analyzed for lead. Comparing the lead-poisoned teeth with normal teeth, the results indicate that a 6-fold difference in the mean lead content existed between the two groups. The uptake of lead by the two dentine zones at low levels of lead intake was also examined. Thus, comparing tooth lead levels of normal American and Icelandic children, 2–3 times less lead was found in the teeth of Icelandic children. The sensitivity of the dentinal zones for lead, the simplicity of the preparative method and the ease of collection of the teeth supports the use of teeth as useful indicators of previous lead exposure.     

The contribution of drinking water lead to maternal blood lead concentrations

The association between domestic water lead concentrations and blood lead concentrations has been examined in 232 mothers at delivery. The blood lead was found to vary significantly with the cube root of the water lead. This association was stronger for first flush water lead rather than for running water lead. This study emphasises the danger to mothers and to their children of environmental lead over-exposure in areas of soft acid plumbosolvent water.     

Blood lead levels in the United States “Oldest-Old” population

Context. Previous studies have suggested significant endogenous lead release from bony stores in the elderly raising the concern for elevated blood lead levels in that population. Objective. We undertook to determine the range of blood lead levels in the “oldest-old” population, a demographic category that includes persons aged 80 years and older. Materials and methods. We analyzed blood lead level data from the National Health and Nutrition Examination Survey (NHANES) for the years 1999–2010 for persons aged 80 years and older. We also screened an inner-city population of patients aged 80 years of age and older presenting to an emergency department. Results. Among persons aged 80 years and older sampled in the NHANES surveys, the geometric mean blood lead level each year varied from 1.98 to 2.66 mcg/dL. Of the 2,168 measured blood lead levels, only 15 samples (0.69%) exceeded our a priori definition of an elevated blood lead level (greater than 10 mcg/dL). Of those 15 samples, the highest blood lead level was 15.3 mcg/dL. For our screening of an inner-city oldest-old population, we enrolled 76 subjects and found a geometric mean blood lead level of 1.72 mcg/dL. Discussion. Several considerations place elderly persons at a theoretically increased risk of elevated blood lead level, including previously documented birth cohort effect for blood lead levels with older cohorts having higher mean blood lead levels and concern for endogenous lead exposure due to release of lead from bony stores. However, our statistical analysis of NHANES data and screening of an inner-city oldest-old population suggests that elevated blood lead levels in this population are rare. Conclusion. Routine blood lead level screening in the elderly is not indicated.     

Effects of calcium on the absorption and retention of lead.

An inverse relationship between lead retention and dietary calcium content has been known to exist for many years, but the reasons for this association remained unknown. In rats, the manipulation of dietary calcium had no significant effect upon the absorption of lead, but calcium-deprived animals had decreased excretion and thus increased body retention of lead. Intraluminal calcium decreased the absorption of test doses of lead from the small intestine in a dose-related manner. We postulated that this occurred because the two metals competed for similar binding sites on intestinal mucosal proteins which were important in the absorptive process. In vivo, lead bound to two heat-stable intestinal mucosal fractions which have been shown to bind calcium. Although more lead bound to the higher molecular weight fraction and more calcium bound to the lower molecular weight vitamin D-induced CaBP, substantial amounts of lead and calcium were found in both fractions. Further, the addition of calcium to test doses of lead markedly diminished the amount of lead bound by both fractions. Shared binding sites on absorptive proteins would explain why dietary calcium decreases lead absorption.     

Indicators of Possible Lead Exposure Among Children Attending Public Lead Screening Clinics: Implications for Primary Prevention

Abstract Because lead exposure is a health-related condition that precedes elevated blood lead levels, the aims of this study were to examine the prevalence of lead exposure among children attending lead screening clinics in two Wisconsin counties and to explore its relationship to demographic variables. Based on data obtained from parents, significant relationships were found between the history of possible exposure and the demographic variables of rural or urban home location, rented or owned dwelling, and family income. About 90% of the children were being exposed to at least one possible lead source. The rationale for intensive study of lead exposure's demographic context was validated, and the need for primary prevention of lead exposure was affirmed.     

Effect of a Single Element Subcutaneous Array Electrode Added to a Transvenous Electrode Configuration on the Defibrillation Field and the Defibrillation Threshold

Even with the use of biphasic shocks, up to 5% of patients need an additional subcutaneous lead to obtain a defibrillation safety margin of at least 10 J. The number of patients requiring additional subcutaneous leads may even increase, because recent generation devices have a < 34 J maximum output in order to decrease their size. In 20 consecutive patients, a single element subcutaneous array lead was implanted in addition to a transvenous lead system consisting of a right ventricular (RV) and a vena cava superior lead using a single infraclavicular incision. The RV lead acted as the cathode; the subcutaneous lead and the lead in the subclavian vein acted as the anode. The biphasic defibrillation threshold was determined using a binary search protocol. Patients were randomized as to whether to start them with the transvenous lead configuration or the combination of the transvenous lead and the subcutaneous lead. In addition, a simplified assessment of the defibrillation field was performed by determining the interelectrode area for the transvenous lead only and the transvenous lead in combination with the subcutaneous lead from a biplane chest X ray. The intraoperative defibrillation threshold was reconfirmed after 1 week, after 3 months, and after 12 months. The mean defibrillation threshold with the additional subcutaneous lead was significantly (P = 0.0001) lower (5.7 ± 2.9 J) than for the transvenous lead system (9.5 ± 4.6 J). With the subcutaneous lead, the impedance of the high voltage circuit decreased from 48.9 ± 7.4 Ω to 39.2 ± 5.0 Ω. In the frontal plane, the interelectrode area increased by 11.3%± 5.5% (P < 0.0001) and in the lateral plane by 29.5%± 12.4% (P < 0.0001). The defibrillation threshold did not increase during follow-up. Complications with the subcutaneous electrode were not observed during a follow-up of 15.8 ± 2 months. The single finger array lead is useful in order to lower the defibrillation threshold and can be used in order to lower the defibrillation threshold.     

Kinetic analysis of lead metabolism in healthy humans.

The steady state kinetics of lead metabolism were studied in five healthy men with stable isotope tracers. Subjects lived in a metabolic unit and ate constant low lead diets. Their intake was supplemented each day with 79--204 mug of enriched lead-204 as nitrate which was ingested with meals for 1--124 days. The concentration and isotopic composition of lead was determined serially in blood, urine, feces, and diet and less commonly in hair, nails, sweat, bone, and alimentary tract secretions by isotopic dilution, mass spectrometric analysis. The data suggest a three compartmental model for lead metabolism. The first compartment encompasses blood and is 1.5--2.2 times larger than the blood mass. It contains approximately 1.7--2.0 mg of lead and has a mean life of 35 days. This pool is in direct communication with ingested lead, urinary lead, and pools two and three. The second compartment is largely composed of soft tissue, contains about 0.3--0.9 mg of lead, and has a mean life of approximately 40 days. This pool gives rise to lead in hair, nails, sweat, and salivary, gastric, pancreatic, and biliary secretions. Pool three resides primarily in the skeleton, contains the vast quantity of body lead, and has a very slow mean life. Bones appear to differ in their rates of lead turnover. Within the relatively small changes in blood lead observed in the present study, the transfer coefficients between the pools remained constant.     

Predictors of Fracture Risk of a Small Caliber Implantable Cardioverter Defibrillator Lead

Introduction: The Sprint Fidelis 6949 implantable cardioverter defibrillator (ICD; Medtronic Inc., Minneapolis, MN, USA) lead has a high rate of fracture. Identification of predictors of subsequent fracture is useful in decision making about lead replacement and for future lead design. We sought to determine if there are clinical, procedural, or radiological features associated with a greater risk of subsequent lead fracture. Methods: Patients with Sprint Fidelis 6949 lead fractures (Fracture group) were identified from our institutional database. Each patient in the Fracture group was matched to two controls, immediately preceeding and succeeding Sprint Fidelis 6949 implant. Clinical and procedural characteristics were compared. Chest radiographs performed 2 weeks after ICD implant were reviewed by an observer blinded to outcomes. The following features were assessed: ICD tip location, lead slack, kinking of the lead body (≥90°), and presence of lead “crimping” within the anchoring sleeve. Results: Twenty‐six patients with Sprint Fidelis 6949 lead fractures were identified and were matched to 52 control patients. On univariate analysis, a higher left ventricular ejection fraction (LVEF), prior ipsilateral device implant, history of prior ICD lead fracture, and noncephalic venous access were associated with risk of lead fracture. On multivariate analysis, a higher LVEF was the only independent predictor of lead fracture (P = 0.006). Radiological features were similar between the two groups. Conclusions: In this study, a higher LVEF was associated with a greater risk of lead fracture in patients with Sprint Fidelis 6949 ICD leads. Radiographic features did not predict subsequent risk of lead fracture in our population. (PACE 2010; 437–443)     

Failure of Defibrillator Paddle as Mimic for Subcutaneous Patch Lead During Nonthoracotomy Implantable Cardioverter Defibrillator Lead Configuration Assessment

It is a common, although virtually unsubstantiated, practice to assess the efficacy of nonthoracotomy lead systems for implantable cardioverter defibrillators using a defibrillator paddle as mimic for the subcutaneous patch lead. We report a case in which an adequate defibrillation threshold was documented with the nonthoracotomy lead system using a defibrillator paddle but not following implantation of the true subcutaneous patch lead. This case suggests that the substitution of a defibrillator paddle for the subcutaneous patch lead during nonthoracotomy lead system evaluation may have significant limitations in assessing lead configuration efficacy.     

3621例儿童血铅水平调查

目的调查2009年深圳市妇幼保健院门诊儿童血铅水平和铅中毒状况。方法采用钨舟原子吸收光谱法测定3621例0～12岁儿童血铅水平,对各年龄组儿童血铅值应用SPSS15.0软件进行分析。结果 3621例0～12岁儿童血铅水平为43.58μg/L,按年龄分为4组,组间差异有统计学意义,男、女童血铅水平分别为45.61、41.23μg/L,幼儿前期和小学阶段儿童血铅水平存在性别差异。血铅水平大于或等于100μg/L者130例,铅中毒率为3.59%,铅中毒率最低为婴儿组(2.76%),最高是小学阶段(7.05%);男童铅中毒51例,铅中毒率为4.16%,女童铅中毒49例,铅中毒为2.76%,中毒的比例在男女童间差异具有统计学意义(P0.05)。结论儿童血铅水平及中毒率随年龄增长而增加,男童血铅水平及中毒率均高于女童。