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Surface soils in portions of the Sydney (New South Wales, Australia) urban area are contaminated with lead (Pb) primarily from past use of Pb in gasoline, the deterioration of exterior lead-based paints, and industrial activities. Surface soil samples (n=341) were collected from a depth of 0-2.5cm at a density of approximately one sample per square kilometre within the Sydney estuary catchment and analysed for lead. The bioaccessibility of soil Pb was analysed in 18 samples. The blood lead level (BLL) of a hypothetical 24 month old child was predicted at soil sampling sites in residential and open land use using the United States Environmental Protection Agency (US EPA) Integrated Exposure Uptake and Biokinetic (IEUBK) model. Other environmental exposures used the Australian National Environmental Protection Measure (NEPM) default values. The IEUBK model predicted a geometric mean BLL of 2.0±2.1µg/dL using measured soil lead bioavailability measurements (bioavailability =34%) and 2.4±2.8µg/dL using the Australian NEPM default assumption (bioavailability =50%). Assuming children were present and residing at the sampling locations, the IEUBK model incorporating soil Pb bioavailability predicted that 5.6% of the children at the sampling locations could potentially have BLLs exceeding 5µg/dL and 2.1% potentially could have BLLs exceeding 10µg/dL. These estimations are consistent with BLLs previously measured in children in Sydney., (Copyright © 2017 Elsevier Inc. All rights reserved.)

The Imperial Smelting Furnace (ISF) for producing lead and zinc simultaneously has operated on four continents and in eleven countries from the 1950's. One of the process changes that the ISF introduced was the production of a finely granulated slag waste. Although this slag contained significant amounts of residual lead (Pb) and zinc (Zn), because of its glassy nature it was considered environmentally benign. From the Cockle Creek smelter near Boolaroo at the northern end of Lake Macquarie, NSW, Australia, it is estimated that around 2.1 million tonnes of the fine slag was distributed into the community and most remains where it was originally utilised. Residual tonnages of slag of this magnitude are common worldwide wherever the ISF operated. Studies of base metal smelting slags have concluded that mineralogical and morphological characteristics of the slag play a critical role in moderating environmental release of toxic elements. Scanning electron microscopy (SEM) and microanalysis of the ISF slags has shown that the Pb and associated elements are present as discrete nodules (∼6-22 μm) in the slag and that they are not associated with Zn which is contained in the glass slag phase. Using an automated SEM and analysis technique (QEMSCAN(®)) to "map" the mineralogical structure of the particles, it was possible to quantitatively determine the degree of access infiltrating fluids might have to the reaction surface of the Pb phases. The level of access decreases with increasing particle size, but in even the largest sized particles (-3350 + 2000 μm) nearly 80% of the Pb-containing phases were totally or partially accessible. These results provide evidence that the toxic elements in the slags are not contained by the glassy phase and will be vulnerable to leaching over time depending on their individual phase reactivity., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Human teeth and bones incorporate trace amounts of lead (Pb) from the local environment during growth and remodeling. Anthropogenic activities have caused changes in the natural Pb isotopic background since historical times and this is reflected in the Pb isotopes of historical European teeth. Lead mining and use increased exponentially during the last century and the isotopic compositions of modern human teeth reflect the modern anthropogenic Pb. USA teeth show the most radiogenic Pb and Australian teeth show the least radiogenic Pb, a result of different Pb ores used in the two regions. During the last century the Australian Pb was exported to Europe, Asia, South America, and Africa, resulting in swamping of the local environmental Pb signal by the imported Pb. As a result, the modern human teeth in Europe show a significant drop to lower isotopic values compared with historical times. Similarly, modern human teeth in other regions of the world show similar Pb isotopic ratios to modern European teeth reflecting the Pb imports. The specific pattern of human Pb exposure allows us to use the Pb isotopic signal recorded in the skeleton as a geo-referencing tool. As historical European teeth show a distinct Pb signal, we can identify early European skeletal remains in the New World and likely elsewhere. In modern forensic investigations we can discriminate to some extent Eastern Europeans from Western and Northern Europeans. Australians can be identified to some extent in any region in the world, although there is some overlap with Western European individuals. Lead isotopes can be used to easily identify foreigners in the USA, as modern USA teeth are distinct from any other region of the world. By analogy, USA individuals can be identified virtually in any other region of the world., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Leaching of toxic metals from slag waste produced during smelting of Pb-Zn ores is generally considered to be negligible. A 1.4 million tonne stockpile of slag containing up to 2.5% Pb and other contaminants has accumulated on a smelter site at North Lake Macquarie, New South Wales, Australia, and it has also been freely used within the community for landscaping and drainage projects. It had been suggested that Pb in fine particles derived from the slags may be a potential contributor to the blood Pb of some children in this community, although there is conflicting evidence in the literature for such a hypothesis. Bioaccessibility of lead and selected metals derived from nine slag samples collected from areas of public open space was examined using a relatively simple in vitro gastric dissolution technique. Size analyses of the slag samples demonstrate that finely-sized material was present in the slags which could be ingested, especially by children. The finer-sized particles contain high levels of Pb (6,490-41,400 ppm), along with Cd and As. Pb bioaccessibility of the slags was high, averaging 45% for -250 microm material and 75% for particles in the size range -53+32 microm. Increasing bioaccessibility and Pb concentration showed an inverse relationship to particle size. Almost 100% of Pb would be bioaccessible in the smallest slag particles (<20 microm), which also contained very high Pb levels ranging from 50,000 to 80,000 ppm and thus constitute a potential health hazard for children.

Objective: Our objective was to evaluate the association of dietary intakes of selected micronutrients and blood lead (PbB) concentrations in female adults and in children., Design: With longitudinal monitoring, we measured daily intakes of the micronutrients calcium, magnesium, sodium, potassium, barium, strontium, phosphorus, zinc, iron (limited data), and copper from 6-day duplicate diets (2-13 collections per individual) and PbB concentrations. Participants were three groups of females of child-bearing age (one cohort consisting of 21 pregnant subjects and 15 nonpregnant controls, a second cohort of nine pregnant migrants), and one group of 10 children 6-11 years of age., Results: Mean PbB concentrations were <5 microg/dL. A mixed linear model that included only group and time accounted for 5.9% of the variance of the PbB measurements; neither the effect of time nor the effect of group was significant. The model containing all of the micronutrients (except iron, for which there was a great deal of missing data), along with time and group, accounted for approximately 9.2% of the variance of PbB; this increase was not statistically significant. There was, however, a significant association of PbB with phosphorus, magnesium, and copper when all micronutrients were included in the statistical analysis, perhaps reflecting a synergistic effect., Conclusions: In contrast to most previous studies, we found no statistically significant relationships between the PbB concentrations and micronutrient intake. In adults and older children with low PbB concentrations and minimal exposure to Pb, micronutrient supplementation is probably unnecessary.

Ceiling or attic dusts provide an indirect measure of air pollution integrated over varying time periods. We undertook an investigation into the particle-size distributions and sources and exposure pathways of metals in ceiling dusts from 38 houses in the city of Sydney, Australia. The houses ranged in age from 4 to 106 years and were grouped into three settings: industrial, semi-industrial, and non-industrial. The main roof types were terracotta tile (n=23), cement tile (n=8), and corrugated iron (n=4), with two slate and one asbestos. Soils and rocks from the Sydney area were also analyzed to provide "background" values and allow the estimation of enrichment factors. The bulk of the dusts contained particles derived from soil of crustal origin and organic plant material, with an anthropogenic component estimated at up to 25%. Particle sizes from selected dust samples showed a bimodal distribution, and the volumes of fine dusts were 50% <63 microm, 30%<38 microm, and 7%<10 microm; the highest metal concentrations were in the finest fractions. The geometric mean concentrations of important anthropogenic-derived metals from the industrial setting were 17294 microg/g Zn, 1660 microg/g Pb, 111 microg/g Cr, 261 microg/g Cu, and 26 microg/g As. The metals Cd, Cu, Pb, Sb, and Zn were consistently higher in the industrial settings than in the other settings. Median regression analyses showed that there were significant differences in the urban setting for the metals Cd, Co, Ni, Pb, and Zn. Enrichment factors for metals in the dust from the industrial site houses compared with background soils and rocks from the Sydney area were As, x 5; Cr, x2; Co, x3; Cu, x 12; Pb, x10; Sb, x 26; and Zn, 596. For the three roof types of terracotta tile, cement, and iron, median regression analyses showed that there were no significant effects with respect to age. Median regression analyses for terracotta tile, cement tile, and corrugated iron roofs showed a "roof" effect for Cu and V. Significant correlations (P0.03) were observed between most of the metals As-Cd-Cu-Pb-Sb-Zn, especially from the industrial settings. Pathways of dust exposure in this study are classified as being passive or active based upon the probable route of dust infiltration. Ceiling dusts pose a probable health hazard if the dust is disturbed and allowed to plume within the living areas of a dwelling, thereby exposing the occupants, especially children, to elevated levels of metals and fine particulates. Modeling shows that exposure to the elevated levels of Pb in dust could give rise to blood lead concentrations exceeding current guidelines for the industrial and semi-industrial areas.

Potential exposure during mining and milling of uranium ore has resulted in the industry being highly regulated. Exposure can arise from inhalation of the daughter product radioactive gas radon (222Rn), inhalation of radioactive dust particles from mining and milling, direct irradiation from outside the body, and ingestion of radionuclides (e.g. uranium or radium) in food or water. Making use of the highly unusual lead isotopic signature for uranium ores (high 206Pb/204Pb from the high uranium content, low 208Pb/204Pb from the low Th/U ratio), we undertook a pilot study of nine male mine employees and three controls from the Ranger uranium mine in the Northern Territory Australia to determine if it was feasible to use lead isotopes in blood to identify exposure to uranium-derived materials. The lead isotopic data for the mine employees and controls plot in two distinct fields which are consistent with predicted isotopic patterns. Assuming retention of 10% of the ingested lead, then the increases seen in 206Pb represent intakes of between 0.9 and 15 mg, integrated over the years of exposure. The small amount of lead does not affect blood lead concentrations, but appears to be sufficient to be detectable with sensitive isotopic methods. Further studies, including those on urine, should be undertaken to confirm the veracity of the lead isotope method in monitoring exposure of uranium industry employees.

Pregnancy and lactation are times of physiologic stress during which bone turnover is accelerated. Previous studies have demonstrated that there is increased mobilization of lead from the maternal skeleton at this time and that calcium supplementation may have a protective effect. Ten immigrants to Australia were provided with either calcium carbonate or a complex calcium supplement (approximately 1 g/day) during pregnancy and for 6 months postpartum. Two immigrant subjects who did not conceive acted as controls. Sampling involved monthly venous blood samples throughout pregnancy and every 2 months postpartum, and quarterly environmental samples and 6-day duplicate diets. The geometric mean blood lead at the time of first sampling was 2.4 microg/dL (range, 1.4-6.5). Increases in blood lead during the third trimester, corrected for hematocrit, compared with the minimum value observed, varied from 10 to 50%, with a geometric mean of 25%. The increases generally occurred at 6-8 months gestation, in contrast with that found for a previous cohort, characterized by very low calcium intakes, where the increases occurred at 3-6 months. Large increases in blood lead concentration were found during the postpartum period compared with those during pregnancy; blood lead concentrations increased by between 30 and 95% (geometric mean 65%; n = 8) from the minimum value observed during late pregnancy. From late pregnancy through postpartum, there were significant increases in the lead isotopic ratios from the minimum value observed during late pregnancy for 3 of 8 subjects (p < 0.01). The observed changes are considered to reflect increases in mobilization of lead from the skeleton despite calcium supplementation. The identical isotopic ratios in maternal and cord blood provide further confirmation of placental transfer of lead. The extra flux released from bone during late pregnancy and postpartum varies from 50 to 380 microg lead (geometric mean, 145 microg lead) compared with 330 microg lead in the previous cohort. For subjects replete in calcium, the delay in increase in blood lead and halving of the extra flux released from bone during late pregnancy and postpartum may provide less lead exposure to the developing fetus and newly born infant. Nevertheless, as shown in several other studies on calcium relationships with bone turnover, calcium supplementation appears to provide limited benefit for lead toxicity during lactation.

Anthropogenic emissions of metals from sources such as smelters are an international problem, but there is limited published information on emissions from Australian smelters. The objective of this study was to investigate the regional distribution of heavy metals in soils in the vicinity of the industrial complex of Port Kembla, NSW, Australia, which comprises a copper smelter, steelworks and associated industries. Soil samples (n=25) were collected at the depths of 0-5 and 5-20 cm, air dried and sieved to <2 mm. Aqua regia extractable amounts of As, Cr, Cu, Pb and Zn were analysed by inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma atomic emission spectrometry (ICP-AES). Outliers were identified from background levels by statistical methods. Mean background levels at a depth of 0-5 cm were estimated at 3.2 mg/kg As, 12 mg/kg Cr, 49 mg/kg Cu, 20 mg/kg Pb and 42 mg/kg Zn. Outliers for elevated As and Cu values were mainly present within 4 km from the Port Kembla industrial complex, but high Pb at two sites and high Zn concentrations were found at six sites up to 23 km from Port Kembla. Chromium concentrations were not anomalous close to the industrial complex. There was no significant difference of metal concentrations at depths of 0-5 and 5-20 cm, except for Pb and Zn. Copper and As concentrations in the soils are probably related to the concentrations in the parent rock. From this investigation, the extent of the contamination emanating from the Port Kembla industrial complex is limited to 1-13 km, but most likely <4 km, depending on the element; the contamination at the greater distance may not originate from the industrial complex., (Copryright 2003 Elsevier B.V.)

We compared high-precision lead isotopic ratios in deciduous teeth and environmental samples to evaluate sources of lead in 10 children from six houses in a primary zinc-lead smelter community at North Lake Macquarie, New South Wales, Australia. Teeth were sectioned to allow identification of lead exposure in utero and in early childhood. Blood lead levels in the children ranged from 10 to 42 micro g/dL and remained elevated for a number of years. For most children, only a small contribution to tooth lead can be attributed to gasoline and paint sources. In one child with a blood lead concentration of 19.7 microg/dL, paint could account for about 45% of lead in her blood. Comparison of isotopic ratios of tooth lead levels with those from vacuum cleaner dust, dust-fall accumulation, surface wipes, ceiling (attic) dust, and an estimation of the smelter emissions indicates that from approximately 55 to 100% of lead could be derived from the smelter. For a blood sample from another child, > 90% of lead could be derived from the smelter. We found varying amounts of in utero-derived lead in the teeth. Despite the contaminated environment and high blood lead concentrations in the children, the levels of lead in the teeth are surprisingly low compared with those measured in children from other lead mining and smelting communities.

The skeleton is potential endogenous source of lead during pregnancy and lactation. We have undertaken a longitudinal investigation into the mobilization of lead from the human maternal skeleton to determine whether lead is mobilized from the maternal skeleton during pregnancy and lactation, and if so, when and how much is released. Subjects in the study were migrants to Australia (n=15) whose skeletal lead isotopic composition (endogenous lead) was different to that prevailing in the Australian environment (exogenous lead). This migrant cohort was compared with 6 multi-generational Australian controls. Biological and environmental samples were taken pre-pregnancy where possible, throughout pregnancy and postpartum for at least 6 months. Newly-born infants of the migrant and Australian mothers were monitored for 6 months. Blood lead concentrations for the migrant mothers ranged from 1.5 to 20 microg/dl (geometric mean 2.8) and for Australian mothers ranged from 1.9 to 4.3 microg/dl (geometric mean 2.9). There was minimal change in lead isotopic composition of the Australian pregnant controls although there were increases of approximately 40% in blood lead concentration in 3 of 6 cases during the postpartum period and from 0 to 12% in the other 3. In the migrant pregnant subjects, the geometric mean skeletal lead contribution to blood lead using the isotopic composition was approximately 33% (range 10-88%) for 14 subjects using a revised estimate for exogenous lead. Skeletal contribution to blood lead during the postpartum period was significantly greater than during pregnancy (P<0.001). The skeletal contributions to blood lead are higher and the changes are more consistent in those subjects who conceived within 100 days of arrival in Australia compared with those who conceived longer than 100 days. In the migrant subjects, changes in blood lead concentration during pregnancy and postpartum varied from subject to subject with an overall 20% increase; the increases during the postpartum period were greater than during pregnancy (P<0.001). It was estimated that the amount of maternal skeletal lead mobilized during pregnancy and transferred to the infant via cord blood averaged approximately 79%. The increased skeletal contribution to blood lead is attributed to a low daily calcium intake of approximately 500 mgCa/day, a condition which was present in both migrant and Australian subjects. An ongoing clinical trial is providing a new cohort with calcium supplements. A summary of other aspects of the study is included and covers: additional flux released from the skeleton during pregnancy and postpartum; XRF bone lead results; urinary excretion of lead during pregnancy and postpartum; dietary contribution to blood lead in female adults and children; comparison of rates of exchange of lead in blood of newly-born infants and mothers; relationships of lead in breast milk to lead in blood, urine and diet of the infant and mother; changes in blood lead after cessation of breastfeeding; urinary lead isotopes during pregnancy and postpartum indicate no preferential partitioning of endogenous lead into plasma; a comparison of some aspects of the nonhuman primate and human pregnancy studies.

We have used a combination of lead isotopes and scanning electron microscopy to determine the relationships between different exhibits in a murder case. Samples involved lead projectiles removed from the deceased's head and a pillow, lead-rich scrapings and particles (gunshot residues) from spent cartridges and a silencer, and particles from a pillowcase. The lead projectiles had the same isotopic composition. with the lead being derived from the same dominantly geologically old source(s). The lead smear from the silencer had the same isotopic composition as the projectiles, and the lead was probably from the same source. The particles from the spent cartridges had varying elemental compositions ranging from PbO to PbCuZn +/- Ba with or without Si and are consistent with derivation from the primer. The lead isotopic compositions of the particles from the spent cartridges show some variations, but these are markedly different from those of the projectiles, indicating lead from a mixture of geologically old and geologically young lead. The particles from the pillowcase were extremely small (usually <50 microm size) and showed varying isotopic compositions, some consistent with the gunshot residue from the cartridges. As the exhibits had been handled extensively prior to the present investigation, including some being sent to North America, there is a high likelihood that handling was not done in clean room environments and may have been contaminated. In this instance, as we were concerned about contamination, especially of the pillowcase, we felt contamination negated use of the results for assistance in proving the innocence or guilt of the accused. A combination of high-precision lead isotope measurements with scanning electron microscopy provides a powerful tool for forensic investigations if precautions are taken in handling the exhibits.

Selenium concentrations and its spatial distribution in soils, spermatophytes and bryophytes (mosses) around the Cockle Creek Zn-Pb smelter, New South Wales were studied from May to November 2000. Selenium was determined by ICP-MS on soils digested in nitric and hydrochloric acid (HNO3:HCl = 3:1), and plant samples digested in distilled concentrated nitric acid. At distances greater than 3 km, selenium in soils, spermatophytes and bryophytes converge to uniform values, which are considered to represent the background value. Mean selenium in soils around the smelter is two times higher than the background value. Mean concentration of selenium in plants around the smelter is three times greater than that for background plants. Selenium from 'in site' bryophyte is twice that found in the background bryophyte. The transfer coefficients of selenium between plants and soils are low, especially at a distance less than 1 km from the smelter. However, mosses show the reverse trend. This study indicates that the Zn-Pb smelter is one of the anthropogenic point sources of selenium pollution in the Lake Macquarie district.

We have measured the concentration and isotopic composition of lead in blood over a 15-month period for a subject who undertook recreational shooting in outdoor and indoor firing ranges on an irregular basis. We have also measured the isotopic composition in cast lead, Cu-jacketed and Teflon-coated bullets, propellant and primer from which he assembled the cartridges. Blood lead concentration increased from 3.2 to 6.7 microg/dl with use of dominantly cast lead bullets in the outdoor range. In two intervals when no firing was undertaken for 3-4 months, the blood lead concentrations either decreased towards a baseline value in the case where only Cu-jacketed bullets were fired or remained elevated when dominantly cast lead bullets were fired. The propellants contained <2 ppm Pb and contribute negligibly to blood lead. The isotopic composition of the primer used for all bullets was consistent with a source from the US. The bullets were of different materials and made in Australia and the US, with lead from sources of different geological age and hence different isotopic signatures. Variations in blood lead concentration and isotopic composition appear most strongly influenced by the bullets. Although more expensive, the use of Cu-jacketed bullets, non-lead primers and well-ventilated indoor firing ranges would lessen the health impacts of recreational shooting.

As part of a longitudinal investigation into mobilization of lead from the maternal skeleton during pregnancy and lactation, we have determined the daily intake of selected elements (hereafter called micronutrients) for various subjects and compared these intakes with recommended and/or published intakes, especially those of the United States, through the U.S. National Health and Nutrition Examination Survey (NHANES). We also sought to ascertain whether there was any seasonal effect in the diets. Six-day duplicate diets were collected from 15 pregnant and 16 nonpregnant migrants to Australia, 6 pregnant Australian control subjects, and 8 children of nonpregnant migrants (6 to 11 years). Samples of breast milk and infant formula were also analyzed. Blended samples were analyzed by inductively coupled plasma mass spectrometry for the elements Ca, Cu, Fe, Mg, P, K, Na, Zn, Ba, Sr, and Pb. Daily intakes of micronutrients were only about half of the daily intake estimated for non-Hispanic white females and infants in the U.S. NHANES III. Estimates of daily intakes from breast milk were also considerably lower for the migrant and Australian infants compared with the values extracted from tables of food composition and dietary recall for non-Hispanic white infants in the U.S. NHANES III. For example, Ca was a factor of approximately 3 times lower, Fe approximately 50, and Zn approximately 4. We consider our estimates a reliable indication of the daily intakes for several reasons, including the collection of up to nine quarterly collections of 6-day duplicate diets and retention of subjects in a longitudinal prospective study. The low intakes of the essential elements such as Ca, Fe, and Zn in all these population groups are of potential concern from a public health viewpoint.

As an adjunct to a study of lead mobilization during pregnancy and lactation, we have obtained estimates of the daily lead intake and excretion/intake for 15 newly born infants monitored for at least 6 months postpartum. The longitudinal data presented reflect the far lower levels of environmental contribution to lead in blood in the 1990's than that in the earlier studies from the 1970's and early 1980's, the last period for which such dietary information is available in newly born infants. Infants were breast-fed or formula-fed or both and, in the second quarter, were usually fed solid foods (beikost). Lead concentrations were as follows: lead in breast milk, ranged from 0.09 to 3.1 microg/kg with a geometric mean of 0.55 microg/kg, lead in infant formula ranged from 0.07 to 11.4 microg/kg with a geometric mean of 1.6 microg/kg, and lead in beikost ranged from 1.1 to 27 microg/kg with a geometric mean of 2.9 microg/kg. Daily lead intakes ranged from 0.04 to 0.83 microg/kg body weight/day with a geometric mean of 0.23 microg Pb/kg body weight/day, and excretion/intake ranged from 0.7 to 22 with a geometric mean of 2.6. There was no significant difference at the 5% level in lead concentration in daily intakes and excretion/intake for the first quarter versus the second quarter for this small number of subjects. Assuming that there was no contribution from environmental samples such as house dust and ambient air, the contribution of diet to blood has been estimated from lead isotopic measurements with the following ranges: for breast milk only as the dietary source, 40 to 65%; for breast milk and infant formula as the dietary sources, 15 to 70%; and for infant formula and beikost, 20 to 80%. The geometric mean value of the dietary contribution to blood over the 6-month period of approximately 35% is consistent with earlier estimates of uptake of lead in blood in newly born infants when environmental lead concentrations were much higher. Other sources such as air, soil, and dust are considered to contribute minimally to blood lead in these infants because of the low 206Pb/204Pb ratios in environmental media. Thus, we consider that the increased excretion over intake, along with other evidence, reflects mobilization of infant tissues arising especially from rapid bone turnover at this stage of life; the tissue lead has been identified isotopically in urine.

We conducted a case-control study to determine the contribution of lead to blood from consumption of calcium supplements approximating the recommended daily intakes over a 6-month period. Subjects were males and females ages 21 to 47 years (geometric mean 32 years) with a geometric mean blood lead concentration of 2.5 microg/dL. They were subdivided into three groups. One treatment group (n = 8) was administered a complex calcium supplement (carbonate/phosphate/citrate) and the other treatment group (n = 7) calcium carbonate. The control group (n = 6) received no supplement. The lead isotopic compositions of the supplements were completely different from those of the blood of the subjects, allowing us easily to estimate contribution from the supplements. The daily lead dose from the supplements at 100% compliance was about 3 microg Pb. Three blood samples were taken at 2-month intervals before treatment to provide background values, and three were taken during treatment. Subjects in the treatment group were thus their own controls. Lead isotopic compositions for the complex supplement showed minimal change during treatment compared with pretreatment. Lead isotopic compositions in blood for the calcium carbonate supplement showed increases of up to 0.5% in the (206)Pb/(204)Pb ratio, and for all isotope ratios there was a statistically significant difference between baseline and treatment (p < 0.005). The change from baseline to treatment for the calcium carbonate supplement differed from that for both the control group and the group administered the complex supplement. Blood lead concentrations, however, showed minimal changes. Variations in blood lead levels over time did not differ significantly between groups. Our results are consistent with earlier investigations using radioactive and stable lead tracers, which showed minimal gastrointestinal absorption of lead in the presence of calcium (+/- phosphorus) in adults. Even though there is no discernible increase in blood lead concentration during treatment, there are significant changes in the isotopic composition of lead in blood arising from the calcium carbonate supplement, indicating a limited input of lead from diet into the blood. Because calcium carbonate is overwhelmingly the most popular calcium supplement, the changes we have observed merit further investigation. In addition, this type of study, combined with a duplicate diet, needs to be repeated for children, whose fractional absorption of lead is considerably higher than that of adults.

We have compared lead isotopic ratios and lead concentrations in 53 spot urine and 59 24-h urine samples from 13 subjects covering the interval from pre-pregnancy through 180 days postpartum to estimate the amount of lead excreted in urine and renal clearance relative to blood. The total amount of lead excreted in 24-h urine samples ranges from 0.8 to 5.9 microg Pb with an arithmetic mean of 2.2+/-1.1 microg (geometric mean 1.90 microg). This compares with amounts of 0.9-10 microg of extra lead per day estimated to be released into blood from the skeleton during pregnancy and postpartum. There were no differences in excretion rates during the trimesters of pregnancy and between pregnancy and postpartum time periods. The renal clearance relative to blood ranged from 0.8 to 10 g/h (arithmetic mean 3.2+/-1.9; geometric mean 2.7). Renal clearance relative to blood was somewhat higher in trimesters 2 and 3 compared with postpartum 150-180 days (P = 0.004, 0.006, respectively). Reassessment of earlier published blood and dietary data for Australian pregnant controls indicates there is no increased gastrointestinal absorption of lead during pregnancy and postpartum. This differs from calcium, which shows increased absorption during late pregnancy. In light of the inconvenience of sampling and potential contamination at the low levels of lead found in most of these subjects, we do not consider the 24 h urines to provide sufficient useful information.

We have compared lead isotopic ratios and lead concentrations in 51 matched blood and spot urine samples from 13 subjects covering the interval from before pregnancy through 180 days postpartum to evaluate whether mobilization of lead from the maternal skeleton is preferentially partitioned into plasma; we have used urine as an isotopic proxy for plasma. There was no statistically significant difference in the lead 206/lead 204 and lead 207/lead 206 ratios over pregnancy. The urine data for the postpartum period are in the opposite relationships to that predicted for a preferential partitioning hypothesis. These data provide no support for the hypothesis that lead released from the skeleton is preferentially partitioned into plasma.

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.

Recent longitudinal studies with human subjects and nonhuman primates using high-precision stable lead isotopes show that lead is mobilized from the maternal skeleton during pregnancy and the postpartum period. We have now calculated the cumulative lead release (lead flux in micrograms) mobilized from the skeleton during these periods by means of analysis of monthly PbB samples from recent immigrants to Australia. Results included a statistically significant inverse relationship (P = .006) between the lead flux and the time of conception after the arrival of the subjects in Australia. By using an area-under-the-curve approach to determine the added lead inputs to blood during pregnancy and nursing versus a baseline value, the net lead release to blood varied from 0.9 to 10.1 microg/d, which is equivalent to 0.3 to 4.03 mg of lead. With group PbB concentrations usually less than 3 microg/dL, the observed releases imply a high skeletal turnover of greater than 10% and possibly greater than 30% in some subjects during pregnancy and the postpartum period. These elevated rates in some subjects may partly arise from low daily calcium intakes, being one half to two thirds of that of recommended daily requirements. The lead flux calculated from a cumulative approach was compared with other approaches: first-order kinetics, bone turnover, bone x-ray fluorescence measurements, and the International Commission for Radiological Protection lead pharmacokinetic model. Calculated lead releases and remaining bone lead concentrations would likely not be detectable by current x-ray fluorescence methods.

Lead concentrations were measured in surface dust, airborne dust, air, and grinding material from five engine reconditioning workshops to evaluate the impact on blood lead concentrations (PbB) of 10 employees. Lead in the environmental samples ranged from trace amounts to extremely high concentrations (4667 mg/m2). The highest concentrations in surface wipes were found in areas where engine deposits are removed from valves and valve seats. The amounts of lead in long term dustfall accumulation and static air filter samples varied with the position in the workshop and the amount of ventilation. In all but one workshop, the air lead concentrations exceeded Australian occupational guidelines of 150 micrograms Pb/m3. PbB ranged from 4.5 to 25.3 micrograms/dl. There was an empirical relation between the cleanliness, work practices, ventilation of the workshops, lead concentrations in environmental samples and PbB. Office employees not directly exposed to the leaded dust had the lowest PbB. Those who smoked had the highest PbB. Several relatively inexpensive recommendations were made to the owners to minimise exposure of the workers and in most cases these have been implemented.

We measured high precision lead isotope ratios and lead concentrations in blood, urine, and environmental samples to assess the significance of diet as a contributing factor to blood and urine lead levels in a cohort of 23 migrant women and 5 Australian-born women. We evaluated possible correlations between levels of dietary lead intake and changes observed in blood and urine lead levels and isotopic composition during pregnancy and postpartum. Mean blood lead concentrations for both groups were approximately 3 microg/dl. The concentration of lead in the diet was 5.8 +/- 3 microg Pb/kg [geometric mean (GM) 5.2] and mean daily dietary intake was 8.5 microg/kg/day (GM 7.4), with a range of 2-39 microg/kg/day. Analysis of 6-day duplicate dietary samples for individual subjects commonly showed major spikes in lead concentration and isotopic composition that were not reflected by associated changes in either blood lead concentration or isotopic composition. Changes in blood lead levels and isotopic composition observed during and after pregnancy could not be solely explained by dietary lead. These data are consistent with earlier conclusions that, in cases where levels of environmental lead exposure and dietary lead intake are low, skeletal contribution is the dominant contributor to blood lead, especially during pregnancy and postpartum.

Newly born infants (n = 15) were monitored for 6 months after birth or for longer periods to evaluate the changes in isotopic composition and lead concentration in infants as compared with that in women from the same population groups and to determine the clearance rates of lead from blood in the infants. These data represent the first published results for serial blood sampling in a relatively large cohort of newly born infants. Blood lead concentrations decrease from the cord to samples taken at 60 to 90 days and then increase by amounts varying from negligible to 166%. In spite of concern about individual susceptibility to lead pharmacokinetics, changes in isotopic ratio followed a smooth decrease over time for 9 of the 11 infants born to migrant parents, and the patterns of variation were quite reproducible. Data for 2 of 4 infants born to multigenerational Australian parents exhibited little change in isotopic ratio over time, and in the other two cases, the changes were attributed to diet. The rate of exchange (t1/2) for the migrant infants of lead in blood derived from the mother during pregnancy and the lead from the current environment was calculated by using a linear function and ranged from 65 to 131 (91+/-19, mean+/-SD) days. The half-lives for the exchange of skeletal and environmental lead for 7 of the 8 women before significant mobilization of lead from the maternal skeleton ranged from 50 to 66 (59+/-6) days. One explanation for the longer half-lives for infants as compared with the mothers may be the proportionally higher contribution of current environmental (Australian) lead in the infants at parturition. Exchanges of lead in infants are more complex than for the adults, reflecting inputs from sources such as maternal skeletal lead during breast feeding.

Three children were born in the Broken Hill Australia lead mining community with delayed visual maturation of the optic nerve (blindness) within a period of 19 months. Because of the association with the lead pollution, the delayed visual maturation was attributed to lead exposure of the fetus during pregnancy. Lead isotopic analyses of the shed deciduous teeth from the three children demonstrate that they were not exposed to increased levels of lead from a mining or any other source during pregnancy and the etiology of the delayed visual maturation must be sought elsewhere.

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

To determine the potential for using instead of blood as an indicator of lead exposure, especially in infants, lead concentrations and high-precision lead isotopic measurements have been compared in venous blood and "spot" urine (n > 260 from 182 different subjects) collected within the same 24-h period. Physiological conditions for the children and most of the adults were considered to be in a steady-state between body stores and lead in the environment. In the case of some adults, conditions were initially not steady-state because exposure conditions changed (for example, subjects moved to a country with lead of different isotopic composition.) There was a high correlation (r2 = ) between the blood and urine measurements of the isotope ratios but about 10% of measurements were outliers--the blood and urine measurements were further apart than was consistent with the measurement error that was generally obtained. The discrepancy was usually found to be associated with the urine measurement and was attributed to contamination during sampling. Weekly urine and monthly blood monitoring of an adult male over a 24-month period showed and excellent correlations, although the standard deviations were about an order of magnitude higher than the precision measured for replicate analyses of a single blood or urine sample. "Spot" urine analyses for two male subjects gave excellent agreement with 24-h urine samples. Standard deviations of the spot analyses were of similar order to those in the 24-month monitored subject. In cases where female adults from Eastern Europe migrated to Australia, there was generally a more rapid exchange of skeletal lead with Australian environmental lead in urine compared with blood. These data do not support a differential partitioning of endogenous lead into the plasma. At this stage, isotopic measurements of urine can be used as a proxy for isotopic measurements in blood. However, lead concentrations in blood and in urine are only weakly related. Concentrations of lead in urine cannot serve to predict concentrations of lead in blood, particularly at the lower range of exposures, for example, at blood concentrations less than 10 microgram/d1.

A cohort of 15 immigrant females to Australia and 7 native Australian controls were monitored on a monthly basis with high-precision lead isotopic methods during gestation and for 6 months after pregnancy to determine the extent of lead mobilization from the maternal skeleton. Quarterly environmental samples of house dust, drinking water, urban air, gasoline, and a 6-day duplicate diet were also measured. The geometric mean blood lead concentration for the immigrant females on arrival in Australia was 3.0 microg/dl (range: 1.9 to 20 microg/dl), and for the Australian controls was 3.1 gm/dl (range: 1.9 to 4.3 microg/dl). During gestation and after pregnancy, blood lead concentrations varied, with mean individual changes of -14% to 83%. For the immigrant subjects, the percentage change in blood lead concentration was significantly greater during the postpregnancy period than during the 2nd and 3rd trimesters (p < 0.001). Skeletal contribution to blood lead, based on the isotopic composition for the immigrant subjects, increased in an approximately linear manner during pregnancy. The mean increases for each individual during pregnancy varied from 26% to 99%. Skeletal lead contribution to blood lead was significantly greater (p < 0.001) during the postpregnancy period than during the 2nd and 3rd trimesters. The contribution of skeletal lead to blood lead during the postpregnancy period remained essentially constant at the increased level of lead mobilization, although the duration of breastfeeding varied from 1 week to more than 6 months. The increased contribution of skeletal lead to blood lead during the postpregnancy period is attributed to increased mobilization of lead from maternal skeletal stores during lactation. The increased contribution of skeletal lead both during pregnancy and in the postpregnancy period is consistent with increased bone resorption, and may be associated with an inadequate calcium intake observed in quarterly 6-day duplicate diets. Mobilization of skeletal lead stores represents a potentially important source of perinatal lead intake and accumulation in the developing fetus. Only two subjects consumed dietary supplements for calcium, and their mobilization of lead from the skeleton to the blood was the lowest of all the subjects. These two subjects' use of calcium supplements may have reduced mobilization of skeletal mineral stores to supply the calcium needs of pregnancy and lactation. Calcium supplementation may be an important means of limiting fetal exposure to lead.

Blood and environmental samples, including a quarterly 6-day duplicate diet, for nine mother/child pairs from Eastern Europe have been monitored for 12 to >24 months with high precision stable lead isotope analysis to evaluate the changes that occur when the subjects moved from one environment (Eastern Europe) to another with different stable lead isotopes (Australia). The children were between 6 and 11 years of age and the mothers were between 29 and 37 years of age. These data were compared with an Australian control mother/child pair, aged 31 and 6 years, respectively. A rationale for undertaking this study of mother/child pairs was to evaluate if there were differences in the patterns and clearance rates of lead from blood in children compared with their mothers. Blood lead concentrations ranged from 2.1 to 3.9 microg/dl in the children and between 1.8 and 4.5 microg/dl in the mothers, but the mean of differences between each mother and her child did not differ significantly from zero. Duplicate diets contained from 2.4 to 31.8 microg Pb/kg diet; the mean+/- standard deviation was 5.5 +/- 2.1 microg Pb/kg and total daily dietary intakes ranged from 1.6 to 21.3 microg/day. Mean daily dietary intakes relative to body weight showed that the intake for children was approximately double that for the mothers (0.218 vs. 0. 113 microg Pb/kg body weight/day). The correlations between blood lead concentration and mean daily dietary intake either relative to body weight or total dietary intake did not reach statistical significance (p>0.05). Estimation of the lead coming from skeletal (endogenous) sources relative to the contribution from environmental (exogenous) sources ranges from 8 to 70% for the mothers and 12 to 66% for the children. The difference between mothers and children is not statistically significant (p = 0.28). The children do not appear to achieve the Australian lead isotopic profile at a faster rate than their mothers. These data provide evidence that the absorption or uptake of lead from dietary sources is similar in adult females and children of the age in this study. In spite of lower bone lead and faster bone remodeling and recycling in children compared with adult females, we see no differences between the mothers and their children in overall contribution of tissue lead to blood lead. Results from this study suggest that fractional absorption of ingested lead by children 6-11 years of age is comparable with absorption patterns observed among adult females in the 29-37-year-old age range. Because pharmacokinetic models apply a 40-50% absorption even for 7-year-old children, further investigations on fractional absorption of ingested lead by young children are warranted. Further investigations are especially needed in younger children than those who were subjects in the current study, particularly children in the 1-3-year-old age range. In addition, the effect of nutritional status and patterns of food intake on children's lead absorption require investigation, particularly given the increased prevalence of marginal nutritional status among low-income populations that are at increased risk of elevated blood lead levels.

X-ray fluorescence and stable lead (Pb) isotopic analyses have been undertaken on dusts, known from microscopic investigation to contain significant quantities of industrially- and urban-derived particulate matter, present in the roof cavities of houses in the Illawarra region (N.S.W., Australia), with the objective of examining the historic record of Pb pollution. All investigated houses contained in excess of 250 micrograms g-1 Pb, with dwellings close to a copper smelter, in a large industrial complex including a major steelworks, containing higher (> 2500 micrograms g-1) Pb concentrations. The isotopic composition in the dusts, expressed here as 206Pb/204Pb, is relatively constant at 17.0, irrespective of dwelling age or distance from the industrial complex. Contamination of the dusts by Pb sourced from paint cannot explain the isotopic uniformity of the dust samples. Isotopic modelling indicates that the dusts contain Pb derived from the copper smelter, gasoline-air Pb and a minor contribution from coal-utilising sources. Lead loading was also investigated in the adjacent lagoon, which acts as a natural sink for particulate matter in the Illawarra region. Isotopic data and modelling indicate that one natural and four anthropogenic sources contribute to the Pb burden of this lagoon. The natural source consists of Permian rocks cropping out in the catchment area which have a 206Pb/204Pb of approximately 18.7. The suggested anthropogenic sources are an old disbanded base-metal (Pb) smelter (206Pb/204Pb approximately 16.2-16.3), the copper smelter (206Pb/204Pb approximately 17.9), gasoline-air derived Pb (206Pb/204Pb approximately 16.4-16.5) and industries utilising coal, for example the recently closed thermal coal-fired power station (206Pb/204Pb approximately 18.9). The relative contributions of the base-metal (mainly lead) smelter and gasoline-air Pb in the sediment can only be partly assessed due to the isotopic similarity of these sources. Likewise the natural background and coal source (e.g. power station) contributions can only be estimated from historical data. Age estimations for sediment cores, using 137Cs, provide some control on these assessments. Near surface sediments in the lagoon have a relatively constant 206Pb/204Pb of 17.6-17.7, irrespective of sample location. Isotopic calculations, together with records of particulate matter pollution emissions, indicate a link between the Pb in roof dusts (206Pb/204Pb approximately 17.0) and Pb contamination of the near surface (upper 20 cm) lagoonal sediments via a homogeneous, non-unique source of lead whose isotopic composition closely matches that of the dusts. Over the last 5 decades, atmospheric fallout of Pb-bearing particulate matter appears to have been the dominant pathway for addition of Pb to the lagoon and dwellings in the Illawarra region.

The variation in lead concentration was measured by thermal ionisation mass spectrometry isotope dilution in household tap water throughout the day when the plumbing system was not fully flushed. After collection of an initial 125-ml water sample containing 119 micrograms/l and a 2-l sample, 125-ml samples were collected at hourly intervals for 8 h. The concentrations in the hourly samples remained in the range 35-52 micrograms/l compared with 1.7 micrograms/l for fully flushed water. High precision lead isotopic measurements showed that approximately 50% of the lead in these water samples derives from the tap 'housing' compared with the overall household system. A health risk assessment was performed employing the US Environmental Protection Agency Integrated Exposure Uptake Biokinetic Model. Predicted blood lead levels in infants only exceeded the 'levels of concern' of 10 micrograms/dl when 100% of the water consumed contained 100 micrograms Pb/1. It would appear that unless the infant consumed 100% of first flush water at lead concentrations of approximately 100 micrograms/l, the blood lead would not exceed the recommended 'level of concern'. However, if more than 0.51 was consumed in drinks and formulae using first flush water, then the blood lead could easily exceed the recommended level. Likewise, a pregnant mother could be at risk of consuming considerably more than the 0.51/day first flush water of the concentrations measured, or throughout the day, if the system were not fully flushed.

Stable lead isotopes and lead concentrations were measured in the enamel and dentine of permanent (n = 37) and deciduous teeth (n = 14) from 47 European immigrants to Australia to determine whether lead exchange occurs in teeth and how it relates to lead exchange in bone. Enamel exhibits no exchange of its European-origin lead with lead from the Australian environment. In contrast, dentine lead exchanges with Australian lead to the extent of approximately 1% per year. In one subject, trabecular bone from the tooth socket exchanged almost all its European lead with Australian lead over a a 15-year period (turnover of approximately 6% per year), similar to the approximately 8% per year proposed for lead turnover in trabecular bone. The repository characteristics of intact circumpulpal dentine were investigated by analyses of four sets of contiguous slices from six teeth: 1) a set consisting of slices with intact circumpulpal dentine and cementum; 2) a set in which these areas were removed; 3) another set consisting of slices with intact circumpulpal dentine and cementum; and 4) a set without cementum. These analyses show relatively small differences in isotopic composition between contiguous slices except that circumpulpal dentine appears to be the dominant control on lead concentration. There is a significant correlation (R2 = 0.19, p = 0.01, n = 34) of dentine lead concentration and rate of exchange with residence time from the country of origin and Australian lead, but there is no such correlation with enamel lead concentration. Analyses of permanent and deciduous teeth of subjects from other countries who have resided in Australia for varying lengths of time should resolve some of the questions arising from this pilot study.

The question of the extent of lead mobilization from the maternal skeleton during pregnancy and lactation is one of the most outstanding problems of lead toxicity. We have undertaken a longitudinal cohort study in an urban environment of European female immigrants of child-bearing age (18 to 35 years) to Australia whose skeletal lead isotopic composition has been determined to be different from that in their current environment. The cohort was to consist of 100 immigrants anticipated to provide 20 pregnant subjects who would be compared with two groups of control subjects: a matched immigrant nonpregnant control group and second-generation Australian pregnant control subjects. Pregnant subjects also serve as their own controls for a comparison of changes during gestation with those before conception. High-precision lead isotopic compositions and lead concentrations are measured in maternal blood and urine prenatally, monthly during gestation, and postnatally for 6 months; they are also measured in infant blood and urine for 6 months; environmental measures are sampled quarterly for 6-day duplicate diet, house dust and water, and urban air and gasoline. Because of continuing public health concerns about lead exposure, interim findings from this cohort are being reported. To date there have been 13 conceptions in immigrant subjects, with 7 births, in addition to 3 conceptions in the Australian control group, with 2 births. PbBs have been generally low, with a geometric mean of 3.0 microg/dl, and have ranged from 1.9 to 20 microg/dl. Increases in PbB of approximately 20% during pregnancy have been detectable even in subjects with low blood lead levels. The skeletal contribution to blood lead level, based on isotopic measurements, has exhibited a mean increase (and standard deviation) of 31% +/- 19% with a range from 9% to 65%. Earlier studies that used lead concentrations only have suggested that blood lead levels increased only during the second half of pregnancy. This increase in blood lead levels has also been observed in the present study. However, in two subjects the increases in total blood lead were also detected in the first 2 months of pregnancy. Changes in isotopic composition and blood lead during gestation for Australian pregnant controls were negligible. The ratio of cord/maternal blood lead levels varied from 0.54 to 1.05, and the ratio for the isotopic composition was 0.993 to 1.002. Results of this study confirm that lead is mobilized from skeletal stores at an accelerated rate during pregnancy and is transferred to the fetus. These results also show that mobilization from long-term stores (i.e., bone) contributes significantly to blood lead levels during pregnancy. Furthermore, exposure of the fetus to lead during pregnancy has implications for interpretations of neurobehavioral disorders attributed to only postnatal exposure. Even after 800 days of residence in Australia, the contribution of European skeletal lead to blood lead in nonpregnant subjects can be on the order of 50%, but the current PbB may give no indication of the former high skeletal lead burden.

The efficiency of removal of lead (Pb) and other elements from natural drinking waters using a bench-top water filter system was evaluated in three recently-built houses in Sydney, Australia, and two from rural centres. In addition, one filter system was tested for copper (Cu), Pb and cadmium (Cd) under rigorously-controlled laboratory conditions using Sydney water. For two Sydney houses, the efficiency was evaluated using special filter cartridges concomitant with the ordinary filters. Waters after passing through the filter, was sampled when the filter had been exposed to '0', 50, 100, 150, 200, and 250 l respectively and were analysed for lead isotopes and lead concentrations by high precision isotope dilution mass spectrometry. Samples that passed through the filter after '0', 50, 150 and 250 l collections were analysed for four anions and 39 cations by various methods. Sydney water was fairly uniform in its anion and cation composition, whereas water from the two rural areas contained higher concentrations of Ca, Mg and HCO3. Effects of the filter on the water compositions can be summarised into three groups: (1) elements removed during filtration--Ca, Mg, Sr, Ba, Cu, Pb, Zn and Ni. With 'age' of the filter, the efficiency of removal for Pb was maintained in the two houses with Pb concentrations greater than 10 micrograms/l in the first flush water and was maintained for Cu through all concentrations. Ca, Mg, Sr and Ba were largely removed in the first 50 1 of usage. (2) Elements added during filtration--K, Rb, Ag and P. Except for Ag, which was present throughout the testing period, these elements were added only in the first filtration. (3) Elements unaffected by filtration--Al, Si, Na, Fe, Cl and F. Efficiency of Pb removal from tap water by this system depends generally on the initial Pb content in the water. However, it also seems to depend, to some extent, on Pb speciation and water composition, as found in earlier studies of natural waters. The control in filtering efficiency as a function of Pb speciation and chemical composition becomes more important at low initial Pb concentrations in the water. However, the Pb concentrations at which speciation and water composition appear to play a role in filter efficiency are so low that these factors, though scientifically interesting, have no relevance from a practical point of view, especially the impact on human health. Acidification of six sets of duplicate water samples, one sample immediately after collection and the other acidified after more than 2 weeks, showed negligible changes in Pb or Cu concentrations between duplicates.

Objective: To evaluate the pathway of leaded dust from a lead-zinc-copper mine to houses of employees, and the impact on blood lead concentrations (PbB) of children., Methods: High precision lead isotope and lead concentration data were obtained on venous blood and environmental samples (vacuum cleaner dust, interior dustfall accumulation, water, paint) for eight children of six employees (and the employees) from a lead-zinc-copper mine. These data were compared with results for 11 children from occupationally unexposed control families living in the same city., Results: The median (range) concentrations of lead in vacuum cleaner dust was 470 (21-1300) ppm. In the houses of the mine employees, vacuum cleaner dust contained varying higher proportions of mine lead than did airborne particulate matter measured as dustfall accumulated over a three month period. The median (range) concentrations of lead in soil were 30 (5-407) ppm and these showed no evidence of any mine lead. Lead in blood of the mine employees varied from 7 to 25 micrograms/dl and was generally dominated by mine lead (> 60%). The mean (SD) PbB in the children of the mine employees was 5.7 (1.7) micrograms/dl compared with 4.1 (1.4) micrograms/dl for the control children (P = 0.02). The PbB of all children was always < 10 micrograms/dl, the Australian National Health and Medical Research Council goal for all Australians. Some of the control children had higher PbB than the children of mine employees, probably from exposure to leaded paint as six of the eight houses of the control children were > 50 years old. In five of the eight children of mine employees > 20% of PbB was from the lead mine. However, in the other three cases of children of mine employees, their PbB was from sources other than mine lead (paint, petrol, background sources)., Conclusions: Houses of employees from a lead mine can be contaminated by mine lead even if they are not situated in the same place as the mine. Delineation of the mine to house pathway indicates that lead is probably transported into the houses on the clothes, shoes, hair, skin, and in some cases, motor vehicles of the workers. In one case, dust shaken from clothes of a mine employee contained 3000 ppm lead which was 100% mine lead. The variable contamination of the houses was not expected given the precautions taken by mine employees to minimise transportation of lead into their houses. Although five out of the eight children of mine employees had > 20% mine lead in their blood, in no case did the PbB of a child exceed the Australian National Health and Medical Research Council goal of 10 micrograms/dl. In fact, some children in the control families had higher PbB than children of mine employees. In two cases, this was attributed to a pica habit for paint. The PbB in the children of mine employees and controls was independent of the source of lead. The low PbB in the children of mine employees may reflect the relatively low solubility (bioavailability) of the mine dust in 0.1 M hydrochloric acid (< 40 %), behaviour--for example, limited mouthing activity--or diet.

High-precision lead isotope ratios and lead concentrations have been compared statistically and graphically in women of child-bearing age (n = 77) from two smelter communities and one general urban community to evaluate the relative contributions to blood lead of tissue lead stores and lead from the contemporaneous environment (soil, floor dust, indoor airborne dust, water, food). Blood lead (PbB) contents were generally low (e.g. <10 μg dL(-1)). Statistically significant isotopic differences in blood and environmental samples were observed between the three cities although isotopic differences in blood for individual subjects living in close proximity (∼200 m radius) was as large as the differences within a city. No single environmental measure dominated the biological isotope profile and in many cases the low levels of blood lead meant that their isotopic profiles could be easily perturbed by relatively small changes of environmental exposure. Apportioning of sources using lead isotopes is possibly not feasible, nor cost effective, when blood lead levels are <5 μg dL(-1). Interpretations based on statistical analyses of city-wide data do not give the same conclusions as when the houses are considered individually. Aggregating data from multiple subjects in a study such as this obscures potentially useful information. Most of the measures employed in this study, and many other similar studies, are markers of only short-to-medium integration of lead exposure. Serial sampling of blood and longer sampling times, especially for household variables, should provide more meaningful information.

High precision lead isotope measurements were undertaken to establish the sources and pathways in blood and environmental samples of five families from the Broken Hill lead mining community, New South Wales, Australia. The five families were selected from 27 families investigated to illustrate the different sources and pathways of lead into blood and the importance of monitoring the whole family. The results illustrate that although the major source of lead is from the orebody, paint and petrol can be significant contributors to both house dust and blood leads. The results also show that the sources and pathways can be from the father's occupation and hence monitoring of families is important, especially in high risk locations. In two cases, the elevated blood leads in the children did not derive from their current residence but from other residences in the community.

High precision lead isotope ratios in blood from 58 children aged 1-11 years from the Broken Hill lead mining community have been measured to determine the source and pathways of lead in their blood. Sources of lead are from the Pb-Zn-Ag orebody (lead), from paint and from petrol. Thirty-five of the 58 children (60%) had blood leads (PbB) > or = 0.72 micromol/l (15 microg/dl), the current level of 'personal exposure and source remediation/abatement' compared with a 'background' level of approximately 0.29 micromol/l (6 microg/dl), estimated from adult females who were generally mothers of the children. Six of 17 children aged 7 years or older, had PbBs > or = 0.72 micromol/l (15 microg/dl). Even though the orebody lead is the major contributor to PbB in Broken Hill children, of the 35 children whose PbB is > or = 0.72 microm/l (15 microg/dl), 12 (34%) have approximately 50% or more of their PbB derived from sources such as paint and petrol or both by isotopic identification. The identification of elevated PbB in older children is a concern, especially for females, as there is potential for release of endogenous lead during pregnancy and lactation.

The sources and intensity of lead exposure in utero and in early childhood were determined using stable lead isotopic ratios and lead concentrations of incisal and cervical sections of deciduous teeth from 30 exposed and nonexposed children from the Broken Hill lead mining community in Australia. Incisal sections, consisting mostly of enamel, generally have low amounts of lead and isotopic compositions consistent with those expected in the mother during pregnancy. Cervical sections, consisting mostly of dentine with secondary dentine removed by resorption and reaming, generally have higher amounts of lead than the enamel and isotopic compositions consistent with the source of postnatal exposure. There are statistically significant differences in lead concentrations between incisal and cervical sections, representing within-tooth variation, for children with low and high lead exposure (p = 0.0007, 2 x 10(-6), respectively) and for those who have ingested leaded paint (p = 0.009). Statistically significant differences between incisal and cervical sections in these three exposure groups are also exhibited by the three sets of lead isotope ratios (e.g., p = 0.001 for 206Pb/204Pb ratio in the low exposure group). There are statistically significant differences between the low and high lead exposure groups for lead concentrations and isotopic ratios in incisal (p = 0.005 for lead concentration and 6 x 10(-6) for 206Pb/204Pb ratio) and cervical sections (p = 5 x 10(-5) for lead concentration and 6 x 10(-6) for 206Pb/204Pb ratio). The dentine results reflect an increased exposure to lead from the lead-zinc-silver mineral deposit (orebody lead) during early childhood, probably associated with hand-to-mouth activity. Leaded paint was identified as the source of elevated tooth lead in at least two cases. Increased exposure to lead from orebody and paint sources in utero was implicated in two cases, but there was no indication of previous exposure from the mothers' current blood leads, suggesting an acute rather than a chronic exposure for the mothers. Permanent teeth from one subject had lower amounts of lead in the roots compared with the crowns, and the isotopic composition of the crowns were consistent with the data for the deciduous teeth from the same subject. Based on changes in the isotopic composition of enamel and dentine, it is provisionally estimated that lead is added to dentine at a rate of approximately 2-3% per year.

Public health and medical recommendations on prevention of lead toxicity rely on use of blood lead concentrations to assess lead exposure and predict onset of adverse health effects. Blood lead levels have generally been thought to reflect recent environmental lead exposures. However, tissue lead stores are accumulated over a long time period (i.e., years). These tissue stores, primarily from bone, can be remobilized as part of both normal physiologic and pathologic processes. Although chemical analyses do not differentiate lead isotopes, mass spectrometric determinations can differentiate the quantities of stable lead isotopes present in particular samples (e.g., lead 207, lead 206, lead 204, and lead 208). Selected geographic locations may have distinct isotopic profiles. For example, on mainland Australia the 206Pb/204Pb ratios reported in both environmental lead sources and blood samples are typically less than 17.0. By contrast, stable lead isotope profiles in blood samples of adult women immigrating from Eastern Europe and the former Soviet Union usually have 206Pb/204Pb ratios greater than 17.5 and as high as 18.5 on entry into Australia. Longitudinal monitoring of blood samples to determine stable lead isotope profiles by mass spectrometry and chemical analyses of blood samples for total lead content were conducted over a 300-day period. These data show that between 45% and 70% of lead in blood comes from long-term tissue lead stores. Recognition that the predominant source of lead in blood was tissue stores rather than the contemporaneous environment should greatly modify recommendations on use of blood lead to monitor occupational or environmental interventions. In addition, internal biokinetics of lead, documented through presence of tissue lead in blood, underlie the long-term health risks of lead exposure. Transfer of lead to the fetus from maternal tissue stores represents a special area of concern.

A detailed lead isotopic and scanning electron microscope investigation of particulates from three houses in urban Sydney, previously decontaminated by their owners, has shown that they have been recontaminated over varying periods, as short as 6 months. The source of recontamination is lead paint from adjoining dwellings whose paint is thoroughly deteriorated, as well as from unknown sources. In one house, the external to internal lead loading was > 10:1. The pathway for the lead paint contaminants is both airborne and mechanical transport into the houses. Recontamination of houses provides an explanation for the maintenance of elevated blood lead levels in the children residing in these houses. Recontamination can be a major urban problem applicable in any community which used leaded paints on dwellings in the past. It is a matter of concern for families with young children and couples, especially women who are, or intend to become, pregnant.

Lower blood lead averages in mining communities, compared with other child exposure settings, e.g., innercity areas of the United States and smelter communities, have been attributed to lower bioavailability of lead to children in the mining areas. Direct supporting evidence of the lower bioavailability has, however, generally been lacking. Elevated blood lead levels for approximately 85% of children with > 10 micrograms/dl have been reported from the Broken Hill mining community in Australia. Lead isotope, optical, and scanning electron microscope analyses on the lead species from soils and dusts show them to be derived mainly from weathered ore body material. Solubility tests using 0.1M HCl on the -53 + 38 microns fraction of soil and dust show the lead species to have a high degree of bioavailability. Ingestion of soil and dust, either directly or via mouthing activity, is the main source and pathway for elevated blood lead in children from this community.

In vivo experiments with the stable lead isotope, 204Pb, have confirmed that inorganic lead compounds can be absorbed through the skin. Three different analytical techniques--thermal ionization mass spectrometry, inductively coupled plasma mass spectrometry and anodic stripping voltammetry--showed that lead, as lead nitrate or lead acetate, was rapidly absorbed through the skin and detectable in sweat, blood and urine within 6 h of skin application. Of the 4.4 mg of lead applied to the skin in one experiment, 1.3 mg was absorbed within 24 h. Initial rapid uptake was probably via sweat glands and hair follicles, followed by slower absorption via the transepidermal route. While increases in 204Pb concentration and abundance were observed, no increase in total lead in blood or urine was found. It is possible that the physicochemical form of skin-absorbed lead partitions strongly into extracellular fluid, but has a low affinity for erythrocytes. There was no significant difference in uptake of lead into erythrocytes (in vitro) from normal saline, synthetic sweat or sauna sweat. Ultrafiltration of sweat showed that up to 70% of lead in sweat was associated with > 30,000 MW particles. It is possible that percutaneous absorption of lead could contribute significantly to lead body burden, particularly from occupational exposure to lead in dust. Moreover, because lead absorbed through the skin was only just detectable in blood, and blood lead is the main criterion by which industry determines exposure, skin-absorbed lead may remain undetected.

Stable lead isotopes and lead contents in drinking water from a number of Australian cities have been measured to determine the contribution of drinking water to body burden. Lead contents are generally < 2 micrograms/l and thus contribute an insignificant amount to the lead budget in humans in Australia. First-flush and running water samples taken at intervals of up to 10 min show that equilibrium is reached within 1 min or approximately 10 l by volume. There is, however, large variability in both lead content and isotopic composition within the first minute which brings into question the reliability of the recommended sampling time of 30 s. Extremely large isotopic differences between individual dwellings within the one city and between dwellings and the storage tanks for the water supply are attributed to differences in lead residing in the plumbing within the dwellings, usually from lead solder in brass fittings. Isotopic analysis of solder and water from two dwellings confirm this relationship.

This paper documents the first precise lead isotope measurements for men, women and children from the same family in an attempt to determine the source of lead in their blood. The subjects reside in one of the world's largest lead mining cities, Broken Hill, NSW, Australia. Biological and environmental samples have been compared using isotopic compositions and lead contents. Adult males have isotopic profiles (or compositions) which appear to be related to their occupations. Adult females have low blood leads (<10 μg dL(-1)) and their main source of lead is not from the mine dumps around which the city is built but probably from a mixture of petrol, food and perhaps water. The blood lead contents in children from 1 to 14 years old vary and are partly dependent on age. There is a moderate correlation of blood lead and isotopic compositions (r = 0.73) indicating that a significant component of blood lead derives from the mine dumps in children with elevated blood leads. Some children with blood leads <20 μg dL(-1), however, also have a dominant component of mine lead in their blood.