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PubMed1982

Lead exposure patterns and parameters for monitoring lead absorption among workers in Singapore.

A study was carried out among 1414 workers in 14 industries in Singapore to determine the extent of their exposure to lead and their lead absorption. High-level exposure situations found included secondary lead smelting, followed by mixing of lead salt stabilizers and lead storage battery manufacture. Other exposure situations included those relating to lead welding, print shop, wire splicing, leaded paint manufacture, fire-fighting and soldering. Early cases of lead absorption could not be detected by clinical signs alone. Other parameters such as blood lead and delta-aminolaevulinic acid dehydratase had to be used. There was good correlation between a rise in blood lead and a fall in delta-aminolaevulinic acid dehydratase levels.

Air Pollutants, Occupational↗
PubMed1981

[Excretion of lead in the gastric and duodenal juice of persons with occupational lead poisoning and normal subjects].

Lead was measured in the gastric and duodenal juice of three patients with lead poisoning (blood concentrations of lead: 4.30; 5.16; 5.50 mumol/l). The lead excretion into the gastric juice was 94.6; 29.9 and 18.3 nmol Pb X h-1 for the poisoned persons and 57.9 +/- 38.1 nmol Pb X h-1 for healthy persons (n = 20). Pentagastrin (6 microgram/kg, i.m.) stimulated lead excretion in both groups (normal + 109%, lead poisoned persons: + 180%; + 187%; + 311%). The lead excretion was correlated with an increase of HCl-secretion and volume in healthy persons. The lead excretion into the duodenal juice after secretion (1 unit/kg) amounted to 14.2 +/- 8.8 nmol Ph X h-1 in healthy persons, whereas after secretion plus caerulein 18.8 +/- 7.2 nmol Pb X h-1 were found. In the duodenal juice of the lead poisoned persons 27.5 and 474.9 nmol Ph X h-1 respec. were found after secretion and 58.9 and 491.8 nmol Pb X h-1 respec. after secretion plus caerulein. Lead excretion was correlated with enzyme secretion (trypsin and chymotrypsin).

Ceruletide↗
PubMed1986

Lead in teeth: the influence of the tooth type and the sample within a tooth on lead levels.

Different sections of permanent teeth have been sampled and the lead levels estimated using carbon furnace AAS. Very high levels of lead (500-3400 micrograms g-1) and other trace metals (Cd, Cu, Fe and Zn) occur on the surface of the teeth, falling off rapidly a few micrometers into the teeth. Lead levels in the bulk enamel of incisors vary depending on the position within the tooth, the highest values occur on the lingual side near the gums and the lowest levels on the labial side near the tooth top. The ratio of the concentration of lead in enamel to dentine and to circumpulpal dentine was found to be 1:2:6, and within the dentine the lead levels were highest in the root dentine. The root dentine in the permanent teeth of eight, near complete or representative, sets of teeth was analysed for lead. The ratio ([Pb]tooth/[Pb]total set) decreased in the order: first molars greater than central incisors greater than lateral incisors greater than canines greater than premolars greater than second molars greater than third molars. This order inversely correlates with the age of formation or eruption of the teeth, i.e. the older teeth have the highest levels of lead in the dentine. Dentine appears to be the best material to use to estimate lead, particularly in relation to the integrated lead intake of a person. Dentine lead was determined in a small sample of deciduous teeth obtained from children living in rural areas. The levels were found to be slightly less than for children living in new housing urban areas and significantly less than for children living in older houses of urban areas.

Bicuspid↗
PubMed1987

Chelatable lead versus lead in human trabecular and compact bone.

In active and retired lead workers there was a close correlation between urinary excretion of lead during 6 h after intake of a single oral dose of 0.5 g penicillamine, and the excretion during 24 h. In chelation tests it is thus sufficient to collect urine for only a few hours. There was a close correlation between the amount of chelatable lead and the blood-lead level, as well as the lead level in biopsies of trabecular bone from vertebrae, but there was no association with lead in compact bone, as measured in finger-bone by in vivo X-ray fluorescence. The chelatable lead probably mainly reflects the soft tissue lead pool and a fraction of the trabecular bone lead pool, which has a relatively rapid turnover. It is not a valid indicator of the pool of lead which has slowly accumulated in the compact bone, and it is thus not useful as a time-integrated index of the exposure over a long period of time.

Bone and Bones↗
PubMed1986

Lead retention in blood and brain after preweaning low-level lead exposure in the rat.

Newborn rats of the albino Wistar strain were exposed to lead from birth to 20 days of age through mothers milk, from dams which were fed diets containing 0, 0.25, 0.5 or 1.0% powdered lead. Subsequent determination of tissue lead revealed a direct relationship between the lead levels in both blood and brain of the pups and the lead dosage to which they were indirectly exposed via the dams' milk. Lead retention in both tissues was still evident at 100 days of age, with the relative elevation of lead levels being an order of magnitude higher in brain than in blood. There were no obvious signs of lead intoxication in the pups, apart from mild growth retardation in the group with the highest lead burden. However there was a significant retardation in behavioral development observed on two of four measures which were employed. It was concluded that brief exposure to low lead levels in infancy can have long lasting consequences in the brain and in behavior.

Animals↗
PubMed1995

Relationship between bone lead and other indices of lead exposure in smelter workers.

The relationship between blood lead (B-Pb) indices and bone lead was determined in 81 smelter workers. Lead exposure had changed dramatically since the smelter opened 27 years ago; therefore, workers were stratified by years employed. Seventy workers, hired prior to 1979 (Group 1), had a mean (range) age of 46 years (35-64), mean years of employment 23 (16-27), mean years of education 8 (0-13), mean B-Pb 26 micrograms dl-1 (13-43), mean time-weighted average (TWA) B-Pb 44 micrograms dl-1 (23-57) and mean integrated blood lead index (IBL), 983 micrograms Pb year dl-1 (537-1437). Eleven workers, hired after 1978 (Group 2), had a mean age of 34 years (24-55), mean years of employment 11 (5-14), mean years of education 11 (8-12), mean B-Pb 26 micrograms dl-1 (8-13), mean TWA 33 micrograms dl-1 (17-44) and mean IBL 378 micrograms year dl-1 (81-555). Bone lead measured in the mid-tibia used K-X-ray fluorescence. Mean bone lead in Group 1 and Group 2 was 45 (-7-90) and 11 (-12-33) micrograms Pb (g bone mineral)-1, respectively. Linear regression analysis demonstrated a significant relationship between bone lead and B-Pb indices. B-Pb accounted for 10.8%, years employed 12.7%, TWA 31.4% and IBL 36% of the bone lead variance. Using a previously established relationship, the mean bone lead predicted a mean B-Pb content of approximately 8 micrograms dl-1 in Group 1 as compared to 2 micrograms dl-1 in Group 2. The mean B-Pb was 26 micrograms dl-1 in both groups despite differences in contribution from bone stores. Differential contribution of ambient air lead to B-Pb in the two groups of current workers with similar job titles may reflect use of personal protective equipment.

Adult↗
PubMed1992

Stable isotope labeling of lead compartments in rats with ultralow lead concentrations.

The role of the mammalian skeleton as an endogenous lead source is unclear. This is due in part to difficulties in distinguishing mobilized skeletal lead from other endogenous and exogenous lead sources. Therefore, we have applied ultraclean stable lead isotope techniques to label skeletal and soft tissue lead compartments within the rat with distinguishable lead isotopic signatures. Female Wistar (defined flora) rats were fed 206Pb-enriched drinking water ([Pb] = 110 ng/ml) and sacrificed after durations of 2, 4, 7, and 14 days. Blood, kidney, vertebra, and tibia tissues were analyzed for lead concentrations and stable isotopic compositions. The resulting isotopic ratios in soft (blood and kidney) and skeletal (vertebrae and tibia) tissues differed by approximately 40% after 2 days exposure to the 206Pb tracer. More than 90% of the tracer isotopic signature was contained in the soft tissues after 10 days exposure, while skeletal tissues acquired only approximately 50% of the tracer by the end of the study. Because these animals were maintained under trace metal-clean conditions, they contained lead concentrations in whole blood (0.3-3 ng/g), kidney (11-27 ng/g dry wt), and bone (35-70 ng/g dry wt) tissues that are the lowest known reported for contemporary terrestrial mammals, and they (in bone) are comparable to levels in preindustrial mammals. The elevated concentrations of lead in kidney (fresh weight) relative to levels in blood are consistent with the presence of specific lead-binding sites in the kidney at very low levels of exposure.

Animals↗
PubMed1988

Lead and osteoporosis: mobilization of lead from bone in postmenopausal women.

Although it has been known that humans accumulate lead in bone, mineralized tissue has been considered primarily as a sequestering compartment and not as a site of toxic action for lead. However, experimental data indicate that bone lead can be released during conditions of demineralization, such as pregnancy and lactation. We have examined lead status in women, before and after menopause, using the NHANES II dataset compiled between 1976 and 1980. In 2981 black and white women there was a highly significant increase in both whole blood and calculated plasma lead concentration after menopause. The results indicate that bone lead is not an inert storage site for absorbed lead. Moreover, lead may interact with other factors in the course of postmenopausal osteoporosis, to aggravate the course of the disease, since lead is known to inhibit activation of vitamin D, uptake of dietary calcium, and several regulatory aspects of bone cell function. The consequences of this mobilization may also be of importance in assessing the risks of maternal lead exposure to fetal and infant health.

Adult↗
PubMed2002

Stable lead isotopes and lake sediments--a useful combination for the study of atmospheric lead pollution history.

Analysis of stable lead isotopes and lead concentrations in lake-sediment deposits, not least in varved (annually-laminated) sediments, is a useful method to study lead pollution history. This paper presents details from a study of 31 lakes in Sweden. Using a strong acid digestion of sediment samples and ICP-MS analyses, we have found that Swedish lake sediments have a high natural (pre-pollution) 206[Pb]207[Pb] ratio (mean 1.52+/-0.18, range 1.28-2.01, n=31 lakes). In contrast, atmospheric lead pollution derived from metal smelting processes, coal burning and from alkyl-lead added to petrol has a lower ratio (< 1.2). Consequently, when pollution lead deposition began approximately 3500 years ago, the lead isotope ratio of the sediments started to decline, and in modern sediments it is typically < 1.2. Using the isotope and concentration values and a mixing model, the relative contribution of pollution and natural lead in sediment samples can be calculated. The pollution lead records of the Swedish lake sediments show a consistent picture of the atmospheric lead pollution history. Some noticeable features are the Roman peak (approx. 0 AD), the large and permanent Medieval increase (approx. 1000 AD), peaks at approximately 1200 and 1530 AD, the rapid increase after World War II, the peak in the 1970s, and the large modern decline.

Air Pollutants↗
PubMed2003

Blood and hair lead levels in boys and girls living in two Sardinian towns at different risks of lead pollution.

This study reports blood and hair lead levels measured in 1998 in 222 children from two Sardinian towns: Portoscuso and Sestu. Portoscuso is in a polluted area of Sardinia due to its vicinity to the industrial zone of Portovesme. As a consequence of its economy and location, Sestu is not exposed to lead pollution. Blood lead (PbB) concentration was determined in heparinized venous blood samples by graphite furnace atomic absorption spectrophotometry (AAS). Hair lead (PbH) concentration was determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). With respect to blood lead levels, the boys of Portoscuso have the highest arithmetic mean value (11.30 microg/dL), followed by the Portoscuso girls (7.39 microg/dL); they are followed, but with much lower values, by the boys (4.09 microg/dL) and girls (3.34 microg/dL) of Setsu. For hair lead levels, the Portoscuso boys have the highest arithmetic mean value (15.51 microg/g), followed by the Portoscuso girls (8.82 microg/g) and the Sestu boys (4.03 microg/g) and girls (2.83 microg/g). Therefore the mean values of PbB and PbH follow similar patterns in the boys and girls of the two Sardinian towns. Two-way ANOVA reveals a significant effect of sex and town on log PbB and log PbH. Moreover, values of the Bravais-Pearson coefficients of correlation between log PbB and log PbH are statistically significant for the total sample (r=0.5086; P<0.001), for males (r=0.4275; P<0.01), and for females (r=0.4859, P<0.001). The sensitivity of the hair lead analysis in identifying lead concentrations above 10 microg/g is 49%. The results support the hypothesis that hair lead levels can be considered an indicator of different relative exposure of populations to lead pollution.

Child↗
PubMed1996

Lead migration from lead crystal wine glasses.

Lead release from lead crystal wine glasses was measured at 15 contact times from 1 min to 24 h (1440 min) in 4% acetic acid and wine at room temperature. Lead release at 1 min was equal to approximately 50 and 30% of cumulative lead release measured at 30 and 1440 min, respectively, in both extractants. Lead release at 1440 min was 467 ng/ml in acetic acid and 358 ng/ml in wine. Lead release was less in wine (pH 3.14) than in acetic acid (pH 2.39) because of the increased pH and ethanol content of wine. Lead release was also measured under conditions that simulated consumer use. In experiments with chilled and room temperature wine that was steadily removed from vessels during 1-30 min of contact, results were not significantly less than results of experiments in which wine temperature was 20.0 +/- 2.5 degrees C and contact area was constant. In repeated-leaching experiments, the total micrograms of lead released in 30 min decreased and was a function of 1/L2, where L was leach number. Wine results fit a linear regression model of lead release vs square root of time which was previously proposed to describe corrosion of lead silicate glass by acetic acid. Slopes and intercepts of the square-root-of-time model were used to explain results of repeated-leaching experiments.

Acetic Acid↗
PubMed1999

Achieving dust lead clearance standards after lead hazard control projects: an evaluation of the HUD-recommended cleaning procedure and an abbreviated alternative.

The U.S. Department of Housing and Urban Development's (HUD's) Guidelines for the Evaluation and Control of Lead-Based Paint Hazards in Housing strongly recommend that after lead hazard control interventions all walls, ceilings, floors, and other horizontal surfaces be cleaned using a three-step process to reduce lead-contaminated dust and debris. The three steps are: an initial vacuuming using a machine equipped with a high-efficiency particulate air (HEPA) filter (HEPA vacuum), wet wash with a lead cleaner, and a final HEPA vacuum. This study evaluated the effectiveness of two cleaning protocols: (1) the HUD-recommended three-step procedure, and (2) an abbreviated two-step cleaning procedure that omits the final HEPA vacuum. Cleaning procedures were evaluated in 27 dwelling units that had undergone significant lead hazard control interventions likely to produce lead dust. Dust lead samples were collected on floors and in window sills and troughs prior to the lead control hazard intervention, after the wet wash step of the cleaning procedure, and after completion of the second HEPA vacuuming. The results of the study demonstrate that dust lead surface loading on smooth and cleanable surfaces following the three-step and two-step cleaning procedures can achieve 1995 federal guidance dust clearance levels and levels substantially lower. Although the dust lead clearance rates before and after the second HEPA vacuum were the same, the time saved by omitting the second HEPA is small relative to the other elements of the cleaning process.

Air Pollution, Indoor↗
PubMed1988

Prediction of children's blood lead levels on the basis of household-specific soil lead levels.

To help guide policy decisions about removing lead-contaminated soils, the authors estimated a regression model for predicting a child's blood lead level on the basis of his or her household-specific soil lead level. The data analyzed were blood lead levels (1-45 micrograms/dl) and household-specific soil lead levels (53-20,700 ppm) of 596 children aged 1-5 years who lived in the Helena Valley of Montana and the Silver Valley of Idaho during August 1983. A non-threshold, multiple linear regression model indicated that the estimated mean natural log transformed blood lead level increased by 0.231 micrograms/dl for each unit increase in natural log transformed soil lead level (ppm), after adjusting for the average number of daily outdoor play hours and whether someone in the household smoked. The model predicted that, at a soil lead level of 1,000 ppm, a child who does not play outside and who does not live in a household where someone smokes would be at low risk of lead toxicity (blood lead level between 4 and 24 micrograms/dl).

Child, Preschool↗
PubMed1994

Assessing the relationship between environmental lead concentrations and adult blood lead levels.

This paper presents a model for predicting blood lead levels in adults who are exposed to elevated environmental levels of lead. The model assumes a baseline blood lead level based on average blood lead levels for adults described in two recent U.S. studies. The baseline blood level in adults arises primarily from exposure to lead in diet. Media-specific ingestion and absorption parameters are assessed for the adult population, and a biokinetic slope factor that relates uptake of lead into the body to blood lead levels is estimated. These parameters are applied to predict blood lead levels for adults exposed to a hypothetical site with elevated lead levels in soil, dust and air. Blood lead levels ranging from approximately 3-57 micrograms/dl are predicted, depending on the exposure scenarios and assumptions.

Absorption↗
PubMed1984

Relation between pica and blood lead in areas of differing lead exposure.

Surveys were conducted in four areas in Wales with differing degrees of environmental lead. In two areas the source of the lead was traffic and in one it was spoil from lead mining in the past. The fourth area, which served as a control, was a village remote from heavy traffic, industry, and lead mining. Various environmental samples were taken, and children aged 1-3 years and their mothers were studied. Blood lead concentrations were raised in the lead mining area, and within the areas defined by traffic flow the blood lead concentrations of the mothers showed a gradient. Pica in the children, assessed by a questionnaire, showed no relation with blood lead, but the amount of lead removed from the children's hands with 'wet wipes' was an important contributor to blood lead concentrations.

Adult↗
PubMed1984

Temporal stability of blood lead concentrations in adults exposed only to environmental lead.

The temporal stability of blood lead concentrations of 21 healthy adults (14 men and 7 women) exposed only to environmental lead was assessed by analysis of 253 blood specimens collected serially over periods from 7 to 11 months. Improved analytical sensitivity allowed detection of small (less than 1.0 microgram/100 ml) changes in blood lead concentrations and both within- and between-run analytical errors were minimized by a strict internal quality control protocol. The women had lower blood lead concentrations (mean 8.5, range 7.4-10.8 micrograms/100 ml) than did the men (mean 12.2, range 8.6-15.8 micrograms/100 ml). These are within the expected ranges for non-occupationally exposed persons. Blood lead concentrations in the serial specimens from both men and women changed very little over the study period, with standard deviations of less than 0.5 micrograms/100 ml for the majority of individual mean concentrations: for all except two subjects the standard deviations were less than 0.8 micrograms/100 ml. Two subjects showed significant changes in blood lead concentrations during the study (standard deviations of mean greater than 1.0 micrograms/100 ml). A temporary increase in oral lead intake was identified for one of these subjects. In the absence of substantial changes in lead exposure blood lead levels in adults are remarkably stable and for their environmental monitoring a single blood lead concentration is an excellent biological indicator.

Adult↗
PubMed1983

Contribution of lead in dust to children's blood lead.

The importance of urban dust as a source of lead for young children is still disputed. Although blood-lead data from various population surveys usually show a peak concentration in early childhood, there is evidence that such a peak is small or absent altogether in children without much access to the general environment. An examination of those studies where groups of people in regions of low and high lead contamination have been compared shows that the child/adult blood-lead ratio is almost always enhanced in the more exposed groups. This implies a route of lead uptake which is important for children but less so for adults, and it is likely that this route is the dust-hand-mouth one. There are sufficient data to suggest a quantitative relationship between raised levels of blood lead and lead in dust. There is a strong case for a lead-in-dust standard but some will probably remain unpersuaded unless or until there are reliable data for blood lead and environmental lead involving matched groups of young people from urban and rural areas.

Adolescent↗
PubMed1999

[Effects of environmental lead exposure in kindergartens on children's blood lead level].

OBJECTIVE: To determine if kindergartens' environmental status can influence children's lead exposure. METHODS: Environmental specimens, such as floor dust, peeled-off paint chip, soil and drinking water, as well as children's hand dust and blood samples, were collected and measured for their lead levels in 19 kindergartens, to analyze the relationship between children's blood lead levels and their environmental lead exposure. RESULTS: Geometric means of lead concentrations in indoor floor dust, peeled-off paint chip, dust fallout, outdoor floor dust, soil and drinking water were 86.5 microg/m(2), 235.5 microg/g, 445.9 microg/g, 172.4 microg/m(2), 70.1 microg/g and 12.5 microg/L, respectively. Lead level on children's hands averaged 3.4 microg at both hands. Blood lead levels in children correlated positively with the lead concentrations of outdoor floor dust and their hand dust, with correlation coefficients of 0.5186 and 0.2206, respectively. Multiple regression analysis showed that hand dust lead level in children entered the regression model with a largest standardized partial regression coefficient of 0.3842 and a coefficient of determination of 0.673 for the full equation with F = 6.52 and P < 0.01. CONCLUSION: Status of environmental health in kindergartens plays an important role in children's lead exposure. It is necessary to offer health education for children and make them wash their hands often and overcome unhealthy behavior of sucking their fingers.

Child Day Care Centers↗