Occupational lead exposure

Summary Quantitative measures of saccadic eye movements were examined in 52 lead exposed autobody shop workers and 52 age matched controls with no history of occupational lead exposure. Three characteristics of saccadic eye movements were studied: 1) saccade accuracy; 2) number of overshoots; and 3) maximum velocity. The results indicated that workers exposed to inorganic lead showed a decrease in saccade accuracy and an increase in overshoots compared with controls. Saccade maximum velocity was lower in lead exposed workers than in controls but the difference was just short of statistical significance. Correlations between measures of saccadic eye movements and indicators of lead absorption—blood lead (Pb-B) and zinc protoporphyrin (ZPP) levels-were analyzed in the lead exposed workers. Saccade accuracy was negatively correlated with both Pb-B and ZPP levels. The number of overshoots was not correlated with either Pb-B or ZPP levels. Saccade maximum velocity was not correlated with Pb-B, however, there was a significant negative correlation with ZPP. Age effects observed in the control group were disrupted in lead exposed workers. In addition, saccadic eye movements in younger workers (below 30 years old) were more affected by exposure to inorganic lead than were saccadic eye movements in older workers (50 years and older). It is proposed that these findings are consistent with a relatively rapid buildup of metabolically active lead burden observed in the study group. The data suggest that quantitative assessment of eye movements may be an important tool for studying subclinical central nervous system (CNS) dysfunction due to inorganic lead exposure.Part of this study was presented at the XX International Congress on Occupational Medicine, Cairo, Egypt, Sept. 26–29 (1981)This study was supported in part by NIEHS grant ES00928 of the National Institute of Health, US Department of Health and Human Services     

Occupational and environmental human lead exposure in Brazil

The purpose of this paper is to present a review of data on assessment of exposure and adverse effects due to environmental and occupational lead exposure in Brazil. Epidemiological investigations on children lead exposure around industrial and mining areas have shown that lead contamination is an actual source of concern. Lead in gasoline has been phasing out since the 1980s, and it is now completely discontinued. The last lead mining and lead refining plant was closed in 1995, leaving residual environmental lead contamination which has recently been investigated using a multidisciplinary approach. Moreover, there are hundreds of small battery recycling plants and secondary smelting facilities all over the country, which produce focal urban areas of lead contamination. Current regulatory limits for workplace lead exposure have shown to be inadequate as safety limits according to a few studies carried out lately.     

慢性铅接触者胸腺输出近期功能的研究

目的分析铅接触者外周血T细胞受体删除DNA环(TRECs)的含量,了解其初始T细胞含量和胸腺近期输出功能,从而研究其免疫功能的情况。方法采用实时定量PCR方法检测10例铅接触者外周血TRECs含量,与11例非铅接触者进行比较;采用双变量相关分析法和偏相关分析法分析铅接触组TRECs水平与年龄、工龄、血铅、尿铅、血锌原卟啉(ZPP)和尿δ-氨基-γ-酮戊酸(δ-ALA)浓度的关系。结果10例铅接触者TRECs水平[(2.44±1.87)/1000]明显低于非铅接触者[(5.60±3.96) /1000];TRECs水平与尿δ-ALA浓度呈负相关,有统计学意义(r=-0.754,P<0.05),但控制血铅或尿铅因素后,TRECs水平与尿δ-ALA浓度则无相关性(P>0.05)。结论铅对胸腺输出功能可能造成一定程度的损伤,且TRECs与血铅和尿铅存在相关性,提示低水平的铅接触早已损伤人体的免疫功能。     

Occupational lead exposure and women

The toxicity of lead has been known for approximately 2000 years, but the issue of women exposed to lead in the workplace has received relatively little attention until recent years. The major thesis of this paper is that the fetus represents an organism which is sensitive to lead and that the fetus is exposed to lead through the mother by the fact that lead crosses the placental barrier. Fetal exposure to lead is, in the author's opinion, the critical issue involved in assessing occupational exposure to lead among women of childbearing age. Multiple studies have demonstrated that concentrations of lead in the mother's blood are comparable to concentrations of lead in umbilical cord blood at birth. Many investigators consider the demonstrated effects of lead upon the hematopoietic system to be the earliest effect associated with lead exposure. Control strategies which prevent significant alterations in the heme synthetic pathway of the mother should prevent such changes in the fetus and thus protect against the more serious adverse effects of fetal lead exposure.     

Subjective symptoms and exposure to lead

Summary In a group of men representing the general population and workers occupationally exposed to lead, we measured Pb-B concentrations of 1,828 men and the erythrocyte ALAD activities of 1,327 men and compared them with subjective symptoms as assessed by the Cornell Medical Index (CMI). No statistically significant association between symptoms and either Pb-B concentrations or ALAD activities was found up to levels of 70g/100 ml. At higher Pb-B levels the data were insufficient to allow for conclusions. The specificity of the CMI with regard to classical lead-related symptoms is low, and thus the results should be interpreted with caution, perhaps only as an evidence against the suitability of the CMI for this kind of study.     

Occupational lead exposure and renin release

Hypertension may result from chronic lead exposure. Lead poisoning arising from "moonshine whiskey" drinking has been associated with a rise in plasma renin activity. In the present study, plasma renin concentration following intravenous administration of frusemide was measured in eleven subjects with moderate or severe lead poisoning of industrial origin. The results were compared with those obtained for seven normal, control subjects. There was no significant difference in response obtained in the two groups. Industrial lead poisoning does not appear to affect renin release. The combined insult of lead and alcohol may explain the findings in the previous study.     

Occupational lead exposure and blood pressure

Recent community studies have suggested that low level lead exposure is significantly associated with blood pressure in the general population. This finding is inconsistent with the results of recent occupational studies of lead exposed workers, although the occupational studies contained serious methodological weaknesses. The present study examined the relation between occupational lead exposure and diastolic and systolic blood pressure in randomly selected samples of 270 exposed and 158 non-exposed workers. Four exposure indicators were examined: employment at a lead battery plant nu a control plant, current blood lead value, current zinc protoporphyrin value, and time weighted average blood lead value. After controlling for other known risk factors such as age, education, income, cigarette usage, alcohol consumption, and exercise, the associations between exposure and blood pressure were small and non-significant. In the absence of a biologically feasible hypothesis regarding the mechanism by which low level lead exposure would influence blood pressure the present findings challenge the validity of the general population association.     

Quantitative modeling of lead exposure from glazed ceramic pottery in childhood lead poisoning cases

The US EPA's Integrated Exposure Uptake Biokinetic (IEUBK) Model is a physiologically-based, multicompartment model which simulates lead uptake, distribution within the body, and elimination in order to predict children's blood lead levels. This study used the IEUBK to quantify the relative importance of dietary lead exposure from ceramic bean pots (as opposed to other environmental sources including soil, water, air and indoor dust) in children from San Diego County, CA, the majority of whom had been identified (by actual measurements) to have elevated blood lead levels. The EUBK modeling suggested that dietary lead exposure from beans prepared in Mexican pottery may account for a major fraction of the blood lead burden in children (all of Hispanic ethnicity) whose families used such ceramic ware. The IEUBK model tended to be overpredictive of actual values for blood lead levels, but this was most probably due to uncertainties in the exposure variables in the risk assessment. The results of this model simulation emphasize the need, in a geographic and ethnic setting such as San Diego County, for specific interventions including education and outreach programs for those at risk.     

幼儿园环境中铅含量对儿童血铅值的影响

目的探讨幼儿园环境是否对儿童铅暴露产生影响。方法采集、测定幼儿园环境样品中铅含量,同时采集、测定儿童的手尘铅和血铅浓度,分析环境铅和血铅的相关关系。铅测定方法为原子吸收法。结果19所幼儿园室内地面尘、脱落漆皮。室内降尘、室外地面尘、土壤和自来水铅含量的几何均数分别为86．5μg/m2、235.5μg/g、445．9μg/g、172．4μg/m2、70．1μg/g及12.5μg／L。儿童双手尘铅的平均值为3．4μg。相关分析结果提示血铅与室外地面尘铅、儿童手尘铅呈正相关。多因素分析显示手尘铅被引入血铅的回归方程,而且其标准化回归系数最大,达0.3842,其偏回归系数为0．2018。结论幼儿园的环境卫生状况直接影响着儿童铅的摄入水平。因此有必要对儿童进行健康教育,使其养成勤洗手的卫生习惯,克服吮吸手指的不良行为。     

Correlation between lead in plasma and other indicators of lead exposure among lead-exposed workers

In order to clarify the bioavailability of lead in plasma (PbP), we performed a study on five workers in a Japanese factory manufacturing lead glass-based paints. Blood and urine samples were obtained over a period of 15 months, during which time the workers took it in turns to perform sifting work (with the highest level of lead exposure) for 1-month periods. A total of 75 sets of blood and urine samples were thus obtained. We determined whole blood lead (PbB), PbP, Urinary coproporphyrin (CPU), urinary -aminolevulinic acid (ALAU), urinary lead (PbU) and ALA in plasma (ALAP). In the 15 sets of samples obtained at the end of the period with a high level of lead exposure, PbP correlated significantly with ALAU, CPU, PbU and ALAP, but PbB correlated significantly only with PbU. In the 60 sets of samples obtained following a low level of lead exposure, correlation coefficients between the concentrations of PbP and of ALAU, CPU and PbU exceeded those between the concentrations of PbB and of ALAU, CPU and PbU. These findings indicate that PbP is a better dose indicator of lead biochemically available for heme synthesis and that PbU has a closer correlation with PbP than with PbB.     

Occupational lead exposure and blood pressure.

Recent community studies have suggested that low level lead exposure is significantly associated with blood pressure in the general population. This finding is inconsistent with the results of recent occupational studies of lead exposed workers, although the occupational studies contained serious methodological weaknesses. The present study examined the relation between occupational lead exposure and diastolic and systolic blood pressure in randomly selected samples of 270 exposed and 158 non-exposed workers. Four exposure indicators were examined: employment at a lead battery plant nu a control plant, current blood lead value, current zinc protoporphyrin value, and time weighted average blood lead value. After controlling for other known risk factors such as age, education, income, cigarette usage, alcohol consumption, and exercise, the associations between exposure and blood pressure were small and non-significant. In the absence of a biologically feasible hypothesis regarding the mechanism by which low level lead exposure would influence blood pressure the present findings challenge the validity of the general population association.     

Occupational exposure to lead and neuropsychological dysfunction

OBJECTIVE: To evaluate the neuropsychological effects of current low level and previous higher levels of exposure to lead and evaluate the relation between effects of lead and bone lead. METHODS: A neuropsychological test battery was given to 54 storage battery workers with well documented long term exposure to lead. The effect was studied in two subgroups: those whose blood lead had never exceeded 2.4 mmol/l (the low BPbmax group, n = 26), and those with higher exposure about 10 years earlier (the high BPbmax group, n = 28). In both groups, the recent exposure had been low. Correlations between the test scores and the indices of both long term and recent exposure--including the content of lead in the tibial and calcaneal bone--and covariance analyses were used to assess the exposure-effect relation. Age, sex, and education were controlled in these analyses. RESULTS: Analyses within the low BPbmax group showed a decrement in visuospatial and visuomotor function (block design, memory for design, Santa Ana dexterity), attention (digit symbol, digit span), and verbal comprehension (similarities) associated with exposure to lead and also an increased reporting of subjective symptoms. The performance of the high BPbmax group was worse than that of the low BPbmax group for digit symbol, memory for design, and embedded figures, but there was no reporting of symptoms related to exposure, probably due to selection in this group. No relation was found between the output variables and the tibial lead concentration. The calcaneal lead concentrations were related to the symptoms in the low BPbmax group. CONCLUSIONS: Neuropsychological decrements found in subjects with high past and low present exposure indicate that blood lead concentrations rising to 2.5- 4.9 mmol/l cause a risk of long lasting or even permanent impairment of central nervous system function. Milder and narrower effects are associated with lower exposures; their reversibility and time course remain to be investigated. History of blood lead gives a more accurate prediction of the neuropsychological effects of lead than do measurements of bone lead.

 

     

The effect of long-term low-dose lead exposure on thyroid function in adolescents

This study investigated blood lead (Pb-B) levels and Pb-B effects on thyroid functions in long-term low-level-lead-exposed male adolescents who work as auto repairers. Pb-B and ALAD index (logarithm of activated delta-aminolaevulinic acid dehydratase/nonactivated delta-aminolaevulinic acid dehydratase) were measured as indicators of exposure to lead. Thyroid function tests including free thyroxine (FT4), free triiodothyronine (FT3), and thyrotrophin (TSH) were conducted and thyroid ultrasounds were performed in 42 lead-exposed adolescents and 55 healthy control subjects. Mean Pb-B levels and ALAD index were found significantly higher in the study group than in the normal control group (7.3+/-2.92 microg/dl vs. 2.08+/-1.24 microg/dl, P < 0.001 and 0.44+/-0.26 vs. 0.29+/-0.23, P < 0.05, respectively). FT4 levels were found significantly lower in the study group (1.02+/-0.18 mI/mL and 1.12+/-0.14 mIU/mL, P < 0.05). No subject in the control group had an abnormal FT4 level, but FT4 levels were found under normal limits in 11 subjects (26%) in the study group. FT3 and TSH levels in the study and control groups did not differ (P > 0.05). Thyroid volumes in the study and control groups did not exhibit any significant differences (P > 0.05). Pb-B was found to be negatively correlated to FT4 levels (r = -0.20, P = 0.044). This study revealed that long-term low-level lead exposure may lead to reduced FT4 level without significant changes in TSH and T3 levels in adolescents even at low Pb-B levels.     

万州区262名铅作业工人职业健康调查

目的:了解重庆万州区铅作业工人的健康状况。方法:对万州区262名铅作业工人进行职业健康检查和血铅含量测定。结果:262名铅作业工人中血铅含量超过≥600μg/L诊断值达到铅中毒水平有8人,含量在400μg/L～599μg/L铅中毒观察对象30人。年龄越大工龄越长的工人血铅异常率越高。女性神经衰弱症状、血常规、尿常规、心电图异常率均高于男性。结论:铅作业工人存在职业危害,企业应采取有效的职业病防治措施,对劳动者进行职业健康监护,血铅超标者驱铅治疗,预防控制铅中毒发生。     

Indicators of internal dose in current and past exposure to lead

Summary Chelatable lead (PbU-EDTA) is the best indicator of lead concentration at the critical organ level (indicator of dose). However, since this test is not easily applicable for the biological monitoring of lead-exposed subjects, the current practice is to determine lead in blood (PbB) and/or in urine (PbU). But these tests are indicators of exposure and not of dose. To analyze the reliability of PbB and PbU in estimating lead dose, the relationships between PbU-EDTA and PbB and between PbU-EDTA and PbU were studied in two groups of male lead workers: 48 currently exposed and 45 with past exposure to lead.In currently exposed workers the correlation between PbU-EDTA and PbB and between PbU-EDTA and PbU was very close (r = 0.85, r = 0.74, respectively); in past exposed workers the correlation with PbU-EDTA was decidedly lower for PbB (r = 0.54) and not significant for PbU (r = 0.29). In both cases the relationship between the variables was linear. In the previously exposed men, PbB displayed lower values than those found in currently exposed men.These results indicate that both PbB and PbU allow an indirect estimation to be made of the internal dose in currently exposed subjects, whereas the tests cannot be used for this purpose in subjects who have long since ceased to be exposed. In these cases chelatable lead must be determined.     

Occupational lead exposure and amino acid profiles and liver function tests in industrial workers

The aim of the present study is to determine the effect of blood lead on the plasma levels of amino acids and serum liver enzymes in industrial workers in United Arab Emirates (UAE). This comparison study consisted of 100 industrial workers (exposed) and 100 non-industrial workers (non-exposed), matched for age, sex and nationality selected from Al-Ain, Abu-Dhabi Emirates. Industrial workers had higher proportion (19%) of smokers than non-industrial workers (11%) which was not considered to be statistically significantly different. Industrial workers had significantly higher mean of blood lead level (77.5 +/- 42.8 miccrog x dl(-1)) than non-industrial workers (19.8 +/- 12.3 microg x dl(-1)). The amino acid analysis showed higher values among industrial than non-industrial workers for histidine, isoleucine, leucine, threonine, lysine, valine, methionine and arginine (essential amino acids, (p<0.0001). Ornithine, taurine, glutamic acid, serine, glycine, proline and alanine (non-essential amino acids) showed significantly higher values in industrial when compared with the non-industrial workers (p<0.0001). Plasma liver function test, cardiac enzymes and renal function test were carried out on industrial and non-industrial workers. The results revealed alkaline phosphatase (p=0.012) and lactate dehydrogenase (p=0.029) were significantly higher in industrial than in non-industrial workers. On the basis of this study, it can be concluded that a substantial difference in amino acid profiles, blood lead and LFT between exposed and non-exposed was found. These results might be related to lead exposure and might have affects on the kidneys or liver.     

Occupational lead exposure and screening of glucose-6-phosphate dehydrogenase polymorphism: useful prevention or nonvoluntary discrimination?

Objective: To discuss regulatory guidelines excluding subjects with erythrocyte glucose-6-phosphate dehydrogenase (G6PD) deficiency from lead-exposed jobs in the light of epidemiology findings on the mortality of these subjects. Methods: Two mortality follow-up studies were conducted. The first comprised 1979 male subjects newly identified as G6PD-deficient during a 1981 screening of the G6PD polymorphism among the general population in Sardinia, Italy. The second comprised 1080 male workers employed in maintenance and production departments of a lead smelting plant, who were divided into two subcohorts by erythrocyte G6PD phenotype. Results: As compared with the general male population, G6PD-deficient subjects had significantly fewer deaths than expected from ischemic heart disease (standardized mortality ratio (SMR)=28; 95% CI 10–62), cerebrovascular diseases (SMR=22; 95% CI 6–55), and liver cirrhosis (SMR = 12; 95% CI 0–66). Among lead smelters the standardized mortality rates from cardiovascular diseases and all cancers observed among the G6PD-deficient subcohort were lower than those seen among subjects with the wild-type G6PD. No death from disease of the blood and hematopoietic system was observed among G6PD-deficient subjects in these two follow-up studies. Conclusions: These studies did not provide evidence of hypersensitivity to lead hematotoxicity among G6PD-deficient individuals at exposure levels within the current standards. Provided that workplace exposure complies with current standards, the hypothetical benefit of excluding G6PD-deficient individuals from lead-exposed jobs should be weighted against the loss of personal abilities and the economic damage in a social environment with diffuse unemployment. Received: 14 July 1997 / Accepted: 17 October 1997     

铜冶炼铅暴露工人599名尿铅水平

目的探讨铜冶炼业铅危害程度,评价健康损害与危害因素的关系,为目标干预提供依据。方法对两个生产工艺相同的铜冶炼厂的599人涉铅作业人员进行职业健康检查,按照《职业健康监护技术规范》要求,599人均检测了尿铅。结果两铜冶炼厂工人尿铅超标率为36.39%,其中甲厂工人超标率为45.34%,乙厂工人超标率为30.11%,两厂工人比较,差异有统计学意义(P0.05)。结论铜冶炼业铅职业危害严重,不同铜冶炼业工人尿铅超标率不同。     

Body burdens of mercury, lead, selenium and copper among Baltimore newborns

Umbilical cord blood or serum concentrations of mercury, lead, selenium and copper were measured with inductively coupled plasma mass spectrometry in a population of 300 infants born in Baltimore, Maryland. Geometric mean values were 1.37 μg/L (95% confidence interval: 1.27, 1.48) for mercury; 0.66 μg/dL (95% CI: 0.61, 0.71) for lead; and 38.62 μg/dL (95% CI: 36.73, 40.61) for copper. Mean selenium was 70.10 μg/L (95% CI: 68.69, 70.52). Mercury, selenium and copper levels were within exposure ranges reported among similar populations, whereas the distribution of lead levels was lower than prior reports; only one infant had a cord blood lead above 10 μg/dL. Levels of selenium were significantly correlated with concentrations of lead (Spearman's ρ=0.20) and copper (Spearman's ρ=0.51). Multivariable analyses identified a number of factors associated with one of more of these exposures. These included: increase in maternal age (increased lead); Asian mothers (increased mercury and lead, decreased selenium and copper); higher umbilical cord serum n−3 fatty acids (increased mercury, selenium and copper), mothers using Medicaid (increased lead); increasing gestational age (increased copper); increasing birthweight (increased selenium); older neighborhood housing stock (increased lead and selenium); and maternal smoking (increased lead). This work provides additional information about contemporary prenatal element exposures and can help identify groups at risk of atypical exposures.