Sweat lead levels in persons with high blood lead levels: lead in sweat of lead workers in the tropics

Samples of blood, sweat and urine were collected from eight control subjects and 19 lead workers in a battery manufacturing factory in the tropics. Sweat samples were collected while workers cycled on a bicycle ergometer at room temperature (27-31 degrees C). All samples were analysed by atomic absorption spectrophotometry. Workers with blood lead levels of 13-36 micrograms dl-1 had sweat levels of 72-256 micrograms l-1 and urinary levels of 28-288 micrograms/g creatinine, while controls had levels of 9-12.2 micrograms dl-1, 9-30 micrograms l-1 and 9-19.6 microgram/g creatinine, respectively. Estimations of sweat lead in lead workers can be masked by skin contamination.     

Blood lead and associated risk factors in Ontario children

The purpose of this study was to determine blood levels in Ontario children and to identify those risk factors associated with higher blood lead levels. A random sample of 1315 children aged 7 and younger from urban, suburban and rural Ontario was selected. Blood lead concentration was determined in finger prick blood samples by graphite furnace atomic absorption spectrophotometry. Measurements of lead in air, tap water, soil, and gasoline were also established. Traffic pattern were determined in each area. A questionnaire was administered to a random sample of 800 families of the children tested to assess the presence of other risk factors. Urban children had higher geometric mean blood lead levels (12.02, S.D. = 4.4 micrograms/dl) than suburban children (9.95, S.D. = 3.5 micrograms/dl), and they, in turn, had higher blood lead levels than rural children (8.91, S.D. = 3.9 micrograms/dl). Each of these differences is statistically significant (p less than 0.001). Fifty four (4.3%) of all children were at or above the alert level of 20 micrograms/dl. The proportion above the alert level did not differ significantly between urban, suburban and rural children. Blood lead levels were slightly higher for males than females and for pre-schoolers aged 3 and 4, compared to school age children aged 5 and 6. The blood lead levels of these children were significantly lower than that of children surveyed near a point source of industrial emissions. Multivariate statistical modelling resulted in a set of characteristics which best explained the differences in children's blood lead levels.(ABSTRACT TRUNCATED AT 250 WORDS)     

Studies of blood lead levels in children by proton-induced X-ray emission (PIXE)

Blood lead levels of children admitted to Sion Hospital, Bombay (India), from the adjoining Dharavi slum areas have been determined by proton-induced X-ray emission (PIXE). Blood samples were collected from 36 children with suspected lead poisoning and from 20 control children. The analysis showed that the lead concentration of the patients varied from 0.1 to 6.0 micrograms ml-1. In addition to lead, K, Ca, Fe, Cu, Zn, Se, Br and Rb were also detected simultaneously, of which the concentrations of Fe, Cu, Zn, Se, Rb and Pb were determined. The high blood lead levels of the children from this area may be ascribed to environmental pollution due to heavy vehicular traffic and industrial sources.     

Lead poisoning in cattle--transfer of lead to milk.

The transfer of lead to milk in cattle in relation to blood lead levels and the uptake of lead in edible tissues was studied for an accidental exposure over 1 or 2 days to lead in excessive amounts from the licking of burnt storage batteries. The degree of exposure was monitored by determination of blood lead levels. Milk and blood samples were taken from eight cows, without acute symptoms of lead poisoning, during a period of 18 weeks. Two weeks after the accidental exposure, lead levels (mean +/- SD) in milk were 0.08 +/- 0.04 mg kg-1 and in blood 0.36 +/- 0.04 mg kg-1 in six of the cows. The relationship between lead concentration in blood and those in milk was found to be exponential and could be expressed by the equation: log y = 3.19x - 2.36 (r = 0.85, p less than 0.001), where y and x are the lead concentrations in milk and blood, respectively. The lead level in milk was relatively constant up to a blood lead level of 0.2-0.3 mg kg-1, and increased sharply at higher blood levels. The biological half-life of lead in blood was shown to be approximately 9 weeks. In eight acutely sick cows, which were emergency slaughtered, the range of lead levels in edible muscle tissue was 0.23-0.50 mg kg-1 wet weight. Very high concentrations were found in the kidneys, with a range of 70-330 mg kg-1, and in the livers, with a range of 10-55 mg kg-1. Four of the cows were pregnant, in the first or second month of gestation, during the episode of exposure. The lead exposure was not found to disturb the gestation or development of the fetuses.     

Blood lead and its effect on Cd, Cu, Zn, Fe and hemoglobin levels of children

The levels of heavy metals, such as Pb, Cd, Cu, Zn and Fe, in whole blood samples of Mumbai and Hyderabad children have been determined. In the present study, 576 blood samples of children (3-6 years old) were collected during 1996-1998 and analyzed for heavy metal contents by anodic stripping voltammetry and atomic absorption spectrometry. The geometric mean concentrations of Pb, Cd, Cu and Zn in blood of Mumbai children were 8.0, 0.10, 86.5 and 398.9 microg dl(-1), while those for Hyderabad children were 13.3, 0.13, 100.6 and 483.4 microg dl(-1) respectively. The geometric mean concentrations of Fe in the blood of Mumbai and Hyderabad children were 21.9 and 34.5 mg dl(-1), respectively. Of the Mumbai children, 61.8% were found to have a blood lead concentration lcss than 10 microg dl(-1), while the corresponding proportion of Hyderabad children was 27.4%. Higher concentrations of Pb in the children's blood were observed at high traffic areas in both cities. A decreasing trend in the hemoglobin content with increasing blood lead levels was observed for Mumbai children. A good negative correlation (-0.61) between the blood lead and iron has been observed for Mumbai children The hemoglobin content of 85% of the study population was found to vary between 8 and 14 g%.     

Environmental exposure to lead and arsenic among children living near a glassworks

Concentrations of lead (Pb) in blood (B-Pb, geometric mean 34.6 micrograms l-1, n = 127) and inorganic arsenic (As) and its metabolites in urine (U-As, mean 5.1 micrograms/g creatinine, n = 35) did not differ between children living in a village close to a glassworks emitting both Pb and As and children living in a reference area. There was no significant effect on B-Pb and U-As related to parents working at the glassworks or consumption of domestically grown vegetables. Neither was there any significant effect upon B-Pb of sex, age, potentially lead-exposing hobbies, or consumption of canned foods. Boys had higher U-As than girls (5.8 vs 4.2 micrograms/g creatinine, p = 0.005), and there was a decrease with age (range 8.4-10.4 years, 27% per year, p = 0.01). Further, parental smoking habits had a significant effect on both B-Pb and U-As. In children of non-smoking parents the B-Pb was 30 micrograms l-1, in children with one parent who smoked 39 micrograms l-1 (smoking father 37, smoking mother 41 micrograms l-1) and in children with two parents who smoked 47 micrograms l-1 (p less than 0.001). The corresponding values for U-As were 4.2, 5.5, and 13 micrograms/g creatinine, respectively (p = 0.01).     

Determination of lead in blood--an interlaboratory study

An international co-operative blood-Pb interlaboratory study and a Canadian co-operative blood-Pb interlaboratory study were conducted using freeze-dried bovine blood samples with different endogenous Pb levels. The samples were prepared from whole blood of a nonexposed cow and another fed with a single dose of lead acetate. The mean values computed for the two samples analyzed by 25 international participants from 13 countries were 55 and 250 micrograms Pb l-1, respectively. These results showed a positive bias of 10% for the low level and 9% for the high Pb level with respect to the reference values obtained by isotope dilution mass spectrometry. In the case of the Canadian interlaboratory survey the mean values computed for the two samples analyzed by the 12 participants were 40 and 229 micrograms Pb l-1, respectively. These results showed a negative bias of 20 and 0.4% in relation to the target values of 50 and 230 micrograms Pb l-1, respectively. Despite such a bias, the data, on the whole, were of acceptable precision and accuracy when compared with previous interlaboratory blood-Pb surveys.     

Blood lead levels of Jamaican children island-wide

An island-wide survey of 1081 basic school children, mainly in the age group 2-6 years, is reported. The range of blood lead levels (BLLs) was 1.4 to 202 microg/dL with arithmetic and geometric means of 7.3 microg/dL (standard deviation, 13 microg/dL) and 4.35 microg/dL respectively. Two hundred and thirty children were identified with blood lead levels above 10 microg/dL and among these, 80 were provided with medical attention and of eleven who received chelation, six children were desperately ill from acute lead poisoning necessitating repeated sessions of chelation therapy. The higher blood lead values were found mainly in poor areas of the urban Kingston and St. Andrew Corporate Area, and in St. Catherine where there remain observable though reduced effects from a lead-contaminated area. Environmental interventions, including building an increased national awareness, have also been carried out to reduce the immediate and future dangers of lead poisoning. The most important source of the lead exposure is the recovery of lead from old automobile batteries and even a quite small smelter can contaminate a significant area. Further work is in progress to identify and examine historical and active smelter sites, their possible effects on childhood health, and their remediation.     

Blood lead levels and risk factors for lead poisoning among children in Jakarta,Indonesia

The phase-out of leaded gasoline began in Jakarta, Indonesia on July 1, 2001. We evaluated mean blood lead levels (BLLs) and the prevalence of elevated BLLs of Jakarta school children and assessed risk factors for lead exposure in these children before the beginning of the phase-out activities. The study involved a population-based, cross-sectional blood lead survey that included capillary blood lead sampling and a brief questionnaire on risk factors for lead poisoning. A cluster survey design was used. Forty clusters, defined as primary schools in Jakarta, and 15 2nd- and 3rd-grade children in each cluster were randomly selected for participation in the study. The average age of children in this study was 8.6 years (range 6-12) and the geometric mean BLL of the children was 8.6 microg/dl (median: 8.6 microg/dl; range: 2.6-24.1 microg/dl) (n=397). Thirty-five percent of children had BLLs > or =10 microg/dl and 2.4% had BLLs > or =20 microg/dl. Approximately one-fourth of children had BLLs 10-14.9 microg/dl. In multivariate models, level of education of the child's primary caregiver, water collection method, home varnishing and occupational recycling of metals, other than lead, by a family member were predictors of log BLLs after adjustment for age and sex. BLLs of children who lived near a highway or major intersection were significantly higher than those of children who lived near a street with little or no traffic when level of education was not included in the model. Water collection method was a significant predictor of BLLs > or =10 microg/dl after adjustment for age and sex. BLLs in children in this study were moderately high and consistent with BLLs of children in other countries where leaded gasoline is used. With the phase-out of leaded gasoline, BLLs of children in Jakarta are expected to rapidly decline as they have in other countries that have phased lead out of gasoline.     

Dealing with lead in Broken Hill--trends in blood lead levels in young children 1991-2003

The objective of the study was to investigate trends in blood lead concentrations in preschool children between 1991 and 2003, as part of the evaluation strategy of a public health lead management program in Broken Hill, Australia. Since 1991, all Broken Hill children aged 1-4 years have been offered at least annual blood lead screening as part of a community-wide lead management program. Recruitment of children was promoted throughout the period using local media and distribution of promotional material from health care centres and preschool, childcare, and educational facilities around the city. Venous blood samples were collected using standard procedures and analyses were subjected to internal and external quality control programs. Because the frequency distribution of blood lead levels are skewed, geometric rather than arithmetic means were used for comparative purposes. Trend analysis was based on age and sex standardised mean blood lead levels. The number of 1- to 4-year-old children screened ranged between 496 and 948 in any one year and response rates varied between 39% and 73%. The age-sex standardised mean blood lead level decreased from 16.3 microg/dL to 7.1 microg/dL between 1991 and 2003. Overall, blood lead levels declined by 56% over 13 years. These reductions were consistently observed irrespective of age or where a child lived in the town. The rate of decline has slowed since 1997. We conclude that substantial progress has been made in dealing with the lead problem in Broken Hill children, although the rate of decline of blood lead levels has slowed. Continued public health action is still needed to bring the proportion of young children with significantly elevated blood lead levels (>15 microg/dL) down from the 2003 figure of 12% to the NHMRC community-based target for lead in young Australians of 5%.     

Blood lead levels of the general populations of three Chinese cities

Blood samples were obtained from 537 adults (age greater than or equal to 16 years) living in three cities in China; in Hefei in 1985, and in Shenyang and Jinxi in 1987. The samples were subjected to blood lead (Pb-B) analyses. The subjects were factory workers either in solvent-synthesizing or solvent application plants with no known exposure to metals (including lead). Their smoking and drinking habits were confirmed in medical interviews. Blood lead was significantly higher in smokers than in non-smokers, although no dose-dependency was observed. The Pb-B values in non-smokers were log-normally distributed. The Pb-B among non-smokers was significantly higher in men [104.0 micrograms l-1 (1.428) 87] [geometric mean (geometric standard deviation) number of determinations] than in women [75.5 micrograms l-1 (1.358) 225] when the data from the three cities were combined. There was a significant difference in the Pb-B levels of non-smoking men in the three cities studied, suggesting that regional food habits should be considered as a possible contributory factor of a non-occupational nature. The present findings are compared with observations from Korea and Japan from the viewpoint of environmental health.     

Lead in sweat and its relationship to salivary and urinary levels in normal healthy subjects

Sweat was collected from the arms of 24 normal healthy subjects while they sat in a hot chamber. Blood, urine and saliva samples were also collected. These were analyzed for lead by atomic absorption spectrophotometry. Sweat lead levels recorded in this study are lower than those previously reported. Subjects with mean blood lead levels of 8.62 micrograms dl-1 (range 6-13.6) had mean sweat levels of 5.2 micrograms l-1 (range 1.5-13.0), approximately 25% of their urinary levels. Although salivary lead levels with a mean of 4.8 micrograms l-1 (range 2.5-10) are comparable to sweat levels, their relationship to blood lead levels is poor (r = -0.186 compared with r values of 0.7208 and 0.234 for sweat and urinary levels, respectively).     

Blood lead levels in primary school children in Trinidad and Tobago

This study is the first national baseline survey of blood lead levels (BLLs) conducted on primary school children (ages 5-7 years) in Trinidad and Tobago. A total of 1,761 students from 61 schools participated in the study over a 3-month period. Measurements of capillary BLLs were assessed as well as responses to a risk assessment questionnaire. BLLs ranged from <1 microg/dL to 28.6 microg/dL with a geometric mean of 2.8 microg/dL, which compared favourably with results from the U.S. 1991-94 National Health and Nutrition Examination Survey. Fifteen (0.9%) children had a BLL>or=10 microg/dL (10.8-28.6 microg/dL) of which three (0.2%) met the U.S. criteria for lead poisoning (BLL>or=20 microg/dL). Further environmental investigations are required to identify source(s) of lead exposure in cases with high BLL.     

Microsampling technique and determination of blood lead by Zeeman atomic absorption spectrophotometry

Quality control materials and participation in proficiency testing programmes were used for assessing the long-term performance of our blood lead analysis. The accuracy and precision of the blood controls, Metals 1 and 2 from the Behring Institute, were evaluated over a 1-year period. The accuracy of the method was also monitored by the Centers for Disease Control (CDC) Blood Lead Proficiency Testing Programme over a 3-year period. Nearly 85% (28 out of 33 samples) of our results were within +/- 5% of the CDC reference values. There were excellent correlations between our results and the target values of several proficiency testing samples, with correlation coefficient values of 0.9959-0.9970. The method was used for the screening of blood lead in children in conjunction with microsampling techniques.     

Reducing the risks of children living near the site of a former lead smeltery

The sources of lead exposure, soil, household dust, diet and ambient air near a former lead smeltery were studied. The blood lead level of small children was also determined. The aim of the study was to define, based primarily on blood lead measurements, whether children living in the contaminated area may be at risk. Within 500 m from the site of the smeltery, there were several areas where the Finnish limit value for soil Pb, i.e. 300 mg/kg, was exceeded. In the recently built areas, the surface soil has been replaced and soil remediation has taken place in schoolyards and the playgrounds of children's day-care centres. Lead content in household dust was clearly elevated in the contaminated areas. In approximately 20 years, after the smeltery was closed in 1984, the lead concentrations of the fruits and berries in local gardens have decreased to one-tenth. In some samples, the limit values are still exceeded. The lead concentration in ambient air is now 50 times lower than in the 1970s. The blood lead level of the children living in the area is slightly but statistically significantly higher than that of the children in the control areas. The critical blood lead level, i.e. 10 microg/100 ml, was not exceeded in any of the children examined. The average and maximum lead concentrations of 63 analysed blood samples were 2.2 and 5 microg/100 ml, respectively. In contrast, the average and maximum blood lead levels of school children in 1981 were 6.7 and 13.0 microg/100 ml, respectively. The risk reduction measures undertaken during the past 20 years are described.     

Assessing remedial effectiveness through the blood lead:soil/dust lead relationship at the Bunker Hill Superfund Site in the Silver Valley of Idaho

The 21 square mile Bunker Hill Superfund Site in northern Idaho includes several thousand acres of contaminated hillsides and floodplain, a 365-acre abandoned lead/zinc smelter and is home to more than 7000 people in 5 residential communities. Childhood lead poisoning was epidemic in the 1970s with >75% of children exceeding 40 microg/dl blood lead. Health response activities have been ongoing for three decades. In 1991, a blood lead goal of 95% of children with levels less than 10 microg/dl was adopted. The cleanup strategy, based on biokinetic pathways models, was to reduce house dust lead exposure through elimination of soil-borne sources. An interim health intervention program, that included monitoring blood lead and exposures levels, was instituted to reduce exposures through parental education during the cleanup. In 1989 and 2001, 56% and 3% of children, respectively, exceeded the blood lead criteria. More than 4000 paired blood lead/environmental exposure observations were collected during this period. Several analyses of these data were accomplished. Slope factors derived for the relationship between blood lead, soil and dust concentrations are age-dependent and similar to literature reported values. Repeat measures analysis assessing year to year changes found that the remediation effort (without intervention) had approximately a 7.5 microg/dl effect in reducing a 2-year-old child's mean blood lead level over the course of the last ten years. Those receiving intervention had an additional 2-15 microg/dl decrease. Structural equations models indicate that from 40 to 50% of the blood lead absorbed from soils and dusts is through house dust with approximately 30% directly from community-wide soils and 30% from the home yard and immediate neighborhood. Both mean blood lead levels and percent of children to exceed 10 microg/dl have paralleled soil/dust lead intake rates estimated from the pathways model. Application of the IEUBK model for lead indicates that recommended USEPA default parameters overestimate mean blood lead levels, although the magnitude of over-prediction is diminished in recent years. Application of the site-specific model, using the soil and dust partitions suggested in the pathways model and an effective bioavailability of 18%, accurately predicts mean blood lead levels and percent of children to exceed 10 microg/dl throughout the 11-year cleanup period. This reduced response rate application of the IEUBK is consistent with the analysis used to originally develop the cleanup criteria and indicates the blood lead goal will be achieved.     

Acidic deposition and human exposure to toxic metals

Acid precipitation affects the solubility of several metals in aquatic systems and in soil. Cadmium levels in tap water samples from geological areas having low resistance to acidic pollution were significantly higher than those in samples from a neighbouring reference area where there was a different geological structure. The median cadmium levels and pH values were 0.14 microgram l-1 and 5.6 respectively, for the acidic areas compared with 0.07 microgram l-1 and 6.4 respectively for the reference area. Further, there was a significant inverse relationship between both cadmium and lead contents and the pH values of the samples. The mobility of the metals was thus dependent on the acidity. The blood lead levels in 195 subjects from the acidic areas were lower than those in 91 subjects from the reference area (medians 60 vs. 70 micrograms l-1); no significant differences were found in blood cadmium or blood mercury levels. Subjects in the acidic areas had lower plasma selenium levels than those from the reference area (medians 85 vs. 90 micrograms l-1); the difference was mainly attributed to subjects with private wells. The data may indicate a negative effect of the acidic pollution on selenium intake via water and/or foods. There was also a positive relationship between intake of fish on the one hand and blood mercury and plasma selenium on the other, which is in accordance with the role of fish as a source of these metals.     

Blood lead levels of children and its trend in China

To evaluate Chinese children's blood lead levels (BLLs) and identify its distribution features, we collected articles on children's BLLs published from Jan, 2004 to Aug, 2007 with sampling time since 2001, by searching Chinese Biomedical Disk (CBMDisk), Chinese Journal Full-test Database (CJFD) and other ways. After a rigorous investigation, 35 articles eligible for inclusion criteria were reviewed. Meanwhile, to reveal the trend of Chinese children's BLLs, the data was compared with the results from our former study carried out in 2004, which reviewed the articles published since 1995 to 2003. The results showed that the mean BLLs of Chinese children from 2001 to 2007 was 80.7 μg/L (45.5-165.3 μg/L), and 23.9% (3.2%-80.7%) of children's BLLs was higher than 100 μg/L. Both BLLs and prevalence of BLLs higher than 100 μg/L were lower than that of 1995 to 2003. Of 24 provinces or cities, only 4 showed higher BLLs and higher prevalence rates of lead poisoning (BLLs ≥ 100 μg/L) than that of 1995 to 2003. The mean BLLs of children living in industrial areas were higher than those in urban and suburban areas, and suburban higher than urban areas. Boys' BLLs were 79.3 μg/L, significantly higher than girls 76.9 μg/L (P < 0.001). The results also showed that children's BLLs increased with their ages, and the decreased BLLs for all age were observed comparing with the results of our former study in 2004. Overall, our study revealed that the BLLs of children in China showed a decreasing trend after gasoline with lead was banned in China in 1st July 2000. Our study also showed that the BLLs of children in China were still higher than that in developed countries, which suggested that children's lead poisoning prevention and controlling would be a long-term mission in China.     

Methane microprofiles in a sewage biofilm determined with a microscale biosensor

Microprofiles of the methane concentration in a 3.5-mm-thick sewage outlet biofilm were measured at high spatial and temporal resolution using a microscale biosensor for methane. In the freshly collected biofilm, methane was building up to a concentration of 175 mumol l-1 at 3 mm depth with a total methanogenesis of 0.14 mumol m-2 s-1, as compared to an aerobic respiration (including methane oxidation) of 0.80 mumol m-2 s-1. A model biofilm was established by homogenisation of an in situ biofilm and 12 days of incubation with surplus sodium acetate. The homogenised biofilm was able to maintain 50% of the methanogenic activity in the absence of external electron donor. Oxygen had only a minor effect on the methane production, but aerobic respiration consumed a substantial part of the produced methane and was thus an important control on methane export from the biofilm. A concentration of 2 mmol l-1 nitrate was shown to inhibit methanogenesis only in the upper layer of the biofilm, whereas a further addition of 2 mmol l-1 sulphate inhibited methanogenesis in the entire biofilm. The study demonstrated the power of the methane microsensor in the study of microhabitats with concurrent production and consumption of methane.     

Limited seasonality effects on blood lead for a small cohort of female adults and children

Many blood lead surveys, especially during the 1970s and 1980s have shown variations of up to 35% in blood lead concentration, with higher values in summer over winter. We have monitored 13 adult females and seven children for periods from 348 to 1337 days as non-pregnant controls in a longitudinal study of mobilization of lead from the maternal skeletal during pregnancy and lactation. Samples of blood, 6-day duplicate diet and environmental samples were analyzed by high-precision thermal ionization mass spectrometry for lead isotope ratios and lead concentrations. There was no statistically significant difference between seasons for blood lead concentrations and dietary intake although there were small differences in the isotopic composition for blood. One explanation for the lack of a seasonal effect in blood lead of our cohort may be the absence of climatic extremes in Sydney. The minimal effects from seasonality observed in this cohort make this an especially useful cohort within which to study effects that could be obscured by seasonal factors.