Hydrocarbons,Pb-Concentrations,and Pb-Isotope Ratios in Contaminated Alluvial Soils (Southern Québec,Canada)

Hydrocarbon-contaminated layers found over 100 kilometers of riverbanks (southern Québec) were investigated. Analytical results for hydrocarbons, trace metals, Pb concentrations, and Pb isotopic signatures (²⁰⁶Pb/²⁰⁷Pb, ²⁰⁸Pb/²⁰⁶Pb, ²⁰⁴Pb/²⁰⁶Pb) of contaminated soil are presented. Soil samples show hydrocarbon concentrations (C₁₀-C₅₀) ranging from <60 to 660 mg kg^?1. Higher concentrations were found in the Richmond site (southern Québec). The values for Pb-concentrations ranged between 7 and 149 mg kg^?1 with median value of 23 mg kg^?1. For the Pb isotope ratios, the values obtained in the hydrocarbon layer range from 1.124 to 1.175 ± 0.011 (²⁰⁶Pb/²⁰⁷Pb), 2.085 to 2.126 ± 0.011 (²⁰⁸Pb/²⁰⁶Pb), and 0.054 to 0.057 ± 0.000 (²⁰⁴Pb/²⁰⁶Pb). The combination of various techniques used allows us to distinguish the various sources of contaminants. The study also reveals that Pb and other trace metal elements continue to be found in the fluvial environment, even after many years, and this soil pollution could affect the quality of streams and living organisms.     

Identification of the origin of infantile saturnism based on lead isotopic and elemental ratios

BackgroundIn France, the prevalence of childhood lead poisoning is becoming rare since the avoidance of lead in paints in 1949 and the gradual replacement of water pipes. Chronic lead toxicity is well known and is well correlated to blood lead concentration.AimHere we report a case of severe lead poisoning occurring in a young female child with a pica behavior.MethodsA blood sample and four environmental samples were analyzed using inductively coupled plasma- mass spectrometry (ICP-MS). Lead concentration, lead isotopes and elemental ratios were compared.ResultsThe determination of ²⁰⁸Pb/²⁰⁶Pb, ²⁰⁶Pb/²⁰⁷Pb and Cd/Pb has allowed us to identify the origin of lead poisoning.Discussion-conclusionThe source of contamination was eliminated and the child benefited from a psychological and medical follow up. Her outcome was positive. This case illustrated the potential interest of the use of elemental and isotopic ratios for clinical practice as the ICP-MS measurement has allowed a quick response and a rapid eviction of the contamination’s source.     

Lead (Pb) Isotope Baselines for Studies of Ancient Human Migration and Trade in the Maya Region

We examined the potential use of lead (Pb) isotopes to source archaeological materials from the Maya region of Mesoamerica. The main objectives were to determine if: 1) geologic terrains throughout the Maya area exhibit distinct lead isotope ratios (²⁰⁶Pb/²⁰⁴Pb, ²⁰⁷Pb/²⁰⁴Pb, and ²⁰⁸Pb/²⁰⁴Pb), and 2) a combination of lead and strontium ratios can enhance sourcing procedures in the Mesoamerica region. We analyzed 60 rock samples for lead isotope ratios and a representative subset of samples for lead, uranium, and thorium concentrations across the Maya region, including the Northern Lowlands of the Mexican Yucatan Peninsula, the Southern Lowlands of Guatemala and Belize, the Volcanic Highlands, the Belizean Maya Mountains, and the Metamorphic Province/Motagua Valley. Although there is some overlap within certain sub-regions, particularly the geologically diverse Metamorphic Province, lead isotopes can be used to distinguish between the Northern Lowlands, the Southern Lowlands, and the Volcanic Highlands. The distinct lead isotope ratios in the sub-regions are related to the geology of the Maya area, exhibiting a general trend in the lowlands of geologically younger rocks in the north to older rocks in the south, and Cenozoic volcanic rocks in the southern highlands. Combined with other sourcing techniques such as strontium (⁸⁷Sr/⁸⁶Sr) and oxygen (δ¹⁸O), a regional baseline for lead isotope ratios can contribute to the development of lead isoscapes in the Maya area, and may help to distinguish among geographic sub-regions at a finer scale than has been previously possible. These isotope baselines will provide archaeologists with an additional tool to track the origin and movement of ancient humans and artifacts across this important region.     

206/207PB isotopic ratios applied to particulate transport processes-North eastern Irish Sea

Samples of suspended particulate matter (SPM) were collected from the north eastern Irish Sea, under different tidal conditions. The SPM was extracted with 1M HCl and concentrations of Pb and stable isotopic ratios of Pb (^206/207Pb) determined using atomic absorption spectrometry and ICP-MS. Lead concentrations were found to be in the range 49 to 115 μg g⁻¹ for spring tides and 72 to 148 μg g⁻¹ for neap tides. The^206/207Pb ratios, which were between 1.140 and 1.194, were used to establish possible sources of SPM during the tidal cycle. Samples of surface sediments from along the coastline showed evidence of anthropogenic Pb contamination in the vicinity of Liverpool Bay, with low^206/207Pb ratios of about 1.144, which increased northwards away from the estuary. The results are discussed in terms of the tidally-induced transport of SPM in the coastal boundary zone of the Irish Sea.     

Stable lead isotope ratios from distinct anthropogenic sources in fish otoliths: a potential nursery ground stock marker

Variations measured in the lead (Pb) stable isotope ratios in otoliths of juvenile tropical reef fish Scarus perspiculatus, Abudefduf abdominalis and Dascyllus albisella reflect mixing of anthropogenic lead from the Kaneohe Bay watershed and 'background' lead characteristic of the adjacent ocean. The otoliths and water samples collected in a transect across the bay demonstrated nearly identical Pb isotopic trends. The Pb isotopic composition of the watershed has a low 206Pb/204Pb signature primarily reflecting past combustion of tetra-ethyl Pb additive in fuels. Ocean water not contaminated by this watershed signature has a different, high 206Pb/204Pb isotopic composition, similar to previously measured Asian anthropogenic aerosols and natural eolian dusts, where the anthropogenic signal dominates. Where a history of past anthropogenic Pb contamination exists, it may be possible to use the ratios of Pb stable isotopes in fish otoliths to reconstruct the nursery grounds of fish.     

Lead isotopic evidence for an Australian source of aeolian dust to Antarctica at times over the last 170,000 years

Systematic analysis of Pb, Sr and Nd isotopes of 32 fluvial clay samples (< 2 µm fraction) from many of the major tributaries of the vast (1.10⁶ km²) Murray Darling Basin (MDB), located in semiarid southeastern Australia, displays similar isotopic values between some MDB clays and dust from several ice core samples from the EPICA Dome C in Antarctica. Close scrutiny of several ratios of the four Pb isotopes, and in particular ²⁰⁸Pb/²⁰⁷Pb versus ²⁰⁶Pb/²⁰⁷Pb, shows that several samples from the Darling-sub-basin of the MDB display similar values for the same isotopes for Dome C samples from different ages, and more particularly during wet phases in Australia [Marine Isotopic Stages 5e, 3 and 1]. The combination of Nd and Sr isotopic ratios from the same MDB fluvial clays clearly eliminates the Murray sub-basin, and supports the Darling sub-basin as a potential source of aeolian material to Antarctica. Overall, the Australian dust supply to Antarctica predominantly occurred during interglacial periods.The work presented here shows that aerosols generated in southeastern Australia can travel to parts of West Antarctica and this is supported by atmospheric observations and models. In addition, evidence of Australian dust in Antarctic ice cores further implies dust deposition in the Southern Ocean would have occurred in the past. Current meteorological observations also imply that the western Pacific and Indian Ocean sector of the Southern Ocean would frequently receive aeolian dust components originating from southeastern Australia.     

Biological Fractionation of Lead Isotopes in Sprague-Dawley Rats Lead Poisoned via the Respiratory Tract

Objectives

It was considered that lead isotope ratios did not change during physical, chemical, or biological processes. Thus, lead isotope ratios have been used as fingerprints to identify possible lead sources. However, recent evidence has shown that the lead isotope ratios among different biological samples in human are not always identical from its lead origins in vitro. An animal experiment was conducted to explore the biological fractionation of lead isotopes in biological systems.

Methods

24 male Sprague-Dawley (SD) rats were divided into groups that received acute lead exposure (0, 0.02, 0.2, or 2 mg/kg body weight of lead acetate) via the respiratory route every day for 5 days. Biological samples (i.e., blood, urine, and feces) were collected for comparison with the lead acetate (test substance) and the low-lead animal feed (diet) administered to the rats. The lead isotope ratios were determined by inductively coupled plasma mass spectrometry (ICP-MS).

Results

There are significant differences (p<0.05) in lead isotope ratios between blood, urine, and feces. Moreover, a nonlinear relationship between the blood lead concentration and the blood lead isotope ratios was observed. There is also a threshold effect to the fractionation function. Only the blood isotope ratio of ²⁰⁴Pb/²⁰⁶Pb matches the test substance well. As for feces, when ²⁰⁴Pb/²⁰⁶Pb ratio is considered, there is no significant difference between feces-test substance pairs in medium and high dose group.

Conclusions

The biological fractionation of lead isotopes in SD rats was observed. Moreover, there might be a threshold for the biological fractionation of lead isotopes which is depending on whole blood lead level. It is considered to be more reliable that we compared the isotope ratios of potential lead hazards with both blood and feces lead fingerprints especially for ²⁰⁴Pb/²⁰⁶Pb ratio under high-dose exposure.     

Remediation of Clay Soils Contaminated with Potentially Toxic Elements: The Santo Amaro Lead Smelter,Brazil, Case

The remediation of clayey soil contaminated by potentially toxic elements is a challenging task, especially because of the low permeability and strong affinity of such toxic elements, which prevent the effective use of low-cost in situ remediation methods. The clay soil from the region of the former Santo Amaro primary lead smelter has high concentrations of potentially toxic elements, especially Pb, Cd, Sb, and Zn. This study presents a preliminary evaluation of remediation by soil washing and thermal stabilization, which can support clean-up initiatives for this site. The treatment results indicate that soil washing using EDTA can be an effective method to clean up the soil; however, the solid-liquid separation step by filtration is slow. Soil thermal treatment at temperatures higher than 800°C in an oxidant atmosphere results in the formation of ceramic structure because of the high smectite content, which stabilizes the potentially toxic elements. The estimated cost for remediation by soil excavation, replacement, and stabilization, of the critically contaminated site at the Santo Amaro region is estimated at about 20 to 30 million US$.     

Trace Metal Inventories and Lead Isotopic Composition Chronicle a Forest Fire’s Remobilization of Industrial Contaminants Deposited in the Angeles National Forest

The amounts of labile trace metals: [Co] (3 to 11 µg g⁻¹), [Cu] (15 to 69 µg g⁻¹), [Ni] (6 to 15 µg g⁻¹), [Pb] (7 to 42 µg g⁻¹), and [Zn] (65 to 500 µg g⁻¹) in ash collected from the 2012 Williams Fire in Los Angeles, California attest to the role of fires in remobilizing industrial metals deposited in forests. These remobilized trace metals may be dispersed by winds, increasing human exposures, and they may be deposited in water bodies, increasing exposures in aquatic ecosystems. Correlations between the concentrations of these trace metals, normalized to Fe, in ash from the fire suggest that Co, Cu, and Ni in most of those samples were predominantly from natural sources, whereas Pb and Zn were enriched in some ash samples. The predominantly anthropogenic source of excess Pb in the ash was further demonstrated by its isotopic ratios (²⁰⁸Pb/²⁰⁷Pb: ²⁰⁶Pb/²⁰⁷Pb) that fell between those of natural Pb and leaded gasoline sold in California during the previous century. These analyses substantiate current human and environmental health concerns with the pyrogenic remobilization of toxic metals, which are compounded by projections of increases in the intensity and frequency of wildfires associated with climate change.     

Essential residues for DNA binding activity of ManR fromAnabaena sp. PCC 7120

Cyanobacterial ManR is a member of the OmpR family of response regulator that regulates the expression of themntABC andmntH in response to Mn²⁺ signals. Single-alanine substitutions of I204, L207 and R208 residues of the ManR, which constituted the DNA recognition helix, were obtained by the overlap extension method of PCR. EMSA was used to detect the complexes of the proteins of ManR mutants I204A, L207A, R208A, and the DNA fragment of promoter region of themntH gene fromAnabaena sp. PCC 7120. Results showed the formation of the complexes of the proteins of ManR mutants and DNA could not be detected, indicating that the mutagenesis of the residues I204, L207 and R208 in the ManR HTH domain could lead to the elimination of DNA binding activity of the ManR. Homologous analysis showed that residues I204, L207 and R208 of the ManR are also conservative in the αhelix 3 region of effector domain of other proteins of OmpR/PhoB subfamily, indicating that they are essential residues for DNA binding activity. No significant alteration between wild type and mutant proteins was detected by Far-UV CD spectra at the secondary structure level.     

Alteration of coenzyme specificity in halophilic NAD(P) glucose dehydrogenase by site-directed mutagenesis

Structural analysis of glucose dehydrogenase from Haloferax mediterranei revealed that the adenosine 2′-phosphate of NADP⁺ was stabilized by the side chains of Arg207 and Arg208. To investigate the structural determinants for coenzyme specificity, several mutants involving residues Gly206, Arg207 and Arg208 were engineered and kinetically characterized. The single mutants G206D and R207I were less efficient with NADP⁺ than the wild type, and the double and triple mutants G206D/R207I and G206D/R207I/R208N showed no activity with NADP⁺.In the single mutant G206D, the relation k_cat/K_NAD⁺ was 1.6 times higher than in the wild type, resulting in an enzyme that preferred NAD⁺ over NADP⁺. The single mutation was sufficient to modify coenzyme specificity, whereas other dehydrogenases usually required more than one or two mutations to change coenzyme specificity. However, the highest reaction rates were reached with the double mutant G206D/R207I and with coenzyme NAD⁺, where the k_cat was 1.6 times higher than the k_cat of the wild-type enzyme with NADP⁺. However, catalytic efficiency with NAD⁺ was lower, as the K_m value for coenzyme was 77 times higher than the wild type with NADP⁺.     

Estimating the Mean Residence Time of Lead in the Organic Horizon of Boreal Forest Soils using 210-lead, Stable Lead and a Soil Chronosequence

Knowledge about the residence time of lead in the organic horizon (mor layer; O-horizon) overlaying forest mineral soils is important for the prediction of past and future lead levels in the boreal environment. To estimate the mean residence time (MRT) of lead in the mor layer, we use in this study from Northern Sweden three different approaches: (1) lead-210 is applied as a tracer of lead migration; (2) estimations of loss rates of stable lead (concentrations and ²⁰⁶Pb/²⁰⁷Pb ratios) from the mor layer at an undisturbed forest setting, and (3) a study of lead in a soil series with sites of different age (a chronosequence of 20–220 years). In the last two approaches we compared measured inventories in the soil with estimated inventories derived using analyses of lake sediments. The results suggested a MRT of about 250 years in the mor layer in the mature forest and in the older parts of the chronosequence it was at least >170 years. The agreement between the three different approaches gives good credibility to this estimate. It is also supported by a modeling of trends in the ²⁰⁶Pb/²⁰⁷Pb ratio both between single cores and with depth in the mor layer. Our results suggest that it will take centuries for the deeper parts of the mor layer of undisturbed boreal forest soils to fully respond to decreased atmospheric lead pollution. However, data from the chronosequence indicate that the response could be much faster (MRT<50 years) in the mor layer at early stages of forest succession where graminoid and broadleaved litter fall dominates over conifer litter.     

Eutrophication of mountain lakes in Japan due to increasing deposition of anthropogenically produced dust

Atmospheric dust has wide-reaching effects, not only influencing climate conditions, but also ecosystems. The eastern region of the Asian continent is one of the largest emitters of dust in the world, and recent economic growth in the region has been accompanied by an increase in anthropogenic emissions. However, the effects of increased Asian dusts on aquatic ecosystems are not well understood. We examined fossil pigments and zooplankton remains from ²¹⁰Pb-dated sediments taken from high mountain lakes of Hourai-Numa and Hachiman-Numa, located in the Towada-Hachimantai National Park of Japan Islands, to uncover historical changes in the phyto- and zooplankton community over the past 100?years. Simultaneously, we measured the geochemical variables of TOC, TN, TP, ??¹³C, ??¹⁵N, and lead isotopes (²⁰⁷Pb/²⁰⁶Pb, ²⁰⁸Pb/²⁰⁶Pb) in the sediments to identify environmental factors causing such changes. As a result, despite few anthropogenic activities in the watersheds, alpine lakes in Japan had increased algal and herbivore plankton biomasses by 3?C6 fold for recent years depending on the surrounding terrestrial vegetation and landscape conditions. Biological and biogeochemical proxies recorded from the lake sediments showed that this eutrophication occurred after the 1990s when P deposition increased as a result of atmospheric loading of dust transported from the Asian continent. The continued increase of anthropogenically produced dust may therefore impart damaging impacts on mountain ecosystems even if they are protected from direct anthropogenic disturbances.     

Environmental change and the chemical record in Loch Lomond sediments

The chemical record in Loch Lomond sediments deposited since the end of the last Ice Age provides evidence of the Flandrian marine transgression some 5500–7000 ¹⁴C years B.P., sedimentation rates and the influence of man's local activities, environmental pollution and its sources since the onset of the Industrial Revolution, and of elemental mobility linked with the reduction-diffusion-oxidation cycle of early sedimentary diagenesis. Information derived from vertical profiles of halogen elements bromine and iodine, radionuclides ¹⁴C and ²¹⁰Pb, heavy metals lead, zinc, and cadmium, stable lead isotopes ²⁰⁶Pb and ²⁰⁷Pb, and redox-sensitive elements manganese, iron and arsenic is reviewed and assessed.     

Spare interactions of highly potent [Arg14,Lys15]nociceptin for cooperative induction of ORL1 receptor activation

[Arg¹⁴,Lys¹⁵]Nociceptin is a very potent for ORL1 receptor, showing a few times stronger binding activity and much more enhanced biological activity than endogenous nociceptin. This synergistic outcome has been suggested to be due to the interaction with the receptor aromatic and/or acidic amino acid residues crucial to receptor activation. In order to identify such receptor residues in the second ORL1 extracellular loop, we prepared a series of recombinant mutant receptors. The mutant receptor Gln205Ala was found to be as active as wild-type ORL1 for both nociceptin and [Arg¹⁴,Lys¹⁵]nociceptin. In contrast, Asp206Ala and Tyr207Ala exhibited considerably reduced activity for [Arg¹⁴,Lys¹⁵]nociceptin, exhibiting no synergistic activity enhancement. These results suggest that Asp206 and Tyr207 are directly involved in the interaction with nociceptin-[Arg¹⁴,Lys¹⁵]. Trp208Ala was found to bind strongly both nociceptin and [Arg¹⁴,Lys¹⁵]nociceptin, although it elicited no biological activity. All these results indicate that the consecutive amino acid residues Asp206, Tyr207, and Trp208 are critical to the activation of the ORL1 receptor, but not to nociceptin-binding.     

Lichen biomonitoring near Karabash smelter town, ural mountains, Russia, one of the most polluted areas in the world

Biogeochemical signatures were investigated in transplanted and native lichens near a major pollution source using sensitive multi-element chemical analysis. Transplants were established across a 60 km transect centred on the smelter town of Karabash, Ural Mountains, Russia. Statistically significant trends in element concentrations were recorded, some below one part per million. Fine metal particles are accumulated from pollution aerosols. Prolonged exposure may lead to cellular damage and enhanced accumulation or element loss. 206Pb: 207Pb isotope ratios are similar to those associated with airborne particles in Europe and Russia; an outlier near Kyshtym with a lower ratio indicates a source with a higher 235U : 238U ratio. The method is discrete, sensitive, able to detect short-term pollution episodes and useful for understanding element cycling, which is of critical importance for human and environmental health.     

Lead biogeochemistry in a central Ontario Forested watershed

To determine the sources and sinks of atmospherically deposited Pb at a forested watershed (Plastic Lake) in central Ontario, Canada, Pb pools and fluxes through upland, wetland and lake compartments were measured during 2002/2003 and compared with previous measurements taken between 1989 and 1991. In 2002/2003, annual bulk deposition of Pb was 0.49 mg m⁻² compared with 1.90–1.30 mg m⁻² in 1989–1991. Annual Pb concentrations in stream water draining the upland part of the catchment were very low (0.04 μg l⁻¹) and were approximately half those measured in 1989–1991 (0.11–0.08 μg l⁻¹). Leaching losses in stream water were small and mass balance estimates indicate almost complete retention (>95%) of atmospherically deposited Pb in upland soils. In contrast, annual Pb concentrations in stream water draining a wetland were between 0.38 and 0.77 μg l⁻¹, with the highest concentration occurring in 2002/2003 and mass balance calculations indicate that the wetland is a net source of Pb in all measured years. Lead concentrations in the lake outflow were low and the average Pb concentration measured in 2002/2003 (0.09 μg l⁻¹) was approximately half the value recorded in 1989–1991 (0.19 μg l⁻¹ both years). Annual mass balance estimates indicate that the lake retained between 2.47 mg m⁻² (1989/1990) and 1.42 mg m⁻² (2002/2003) and that in 2002/2003 68% of the Pb input to the lake is derived from the terrestrial catchment. These estimates are higher than sediment core records, which indicate around 18 mg m⁻² Pb was retained in sediment during the 1990s. Nevertheless, Pb concentrations decrease with sediment depth and ²⁰⁶Pb/²⁰⁷Pb concentrations increase with depth, a pattern also observed in mineral soils that reflects the substantial contribution of anthropogenic Pb to the watershed. Lead isotope data from soil and sediment indicate a recent anthropogenic Pb signal (²⁰⁶Pb/²⁰⁷Pb ∼ 1.185) in upper soils and sediments and an older anthropogenic signal (²⁰⁶Pb/²⁰⁷Pb ∼ 1.20) in deeper soil and sediment. Lead isotope data in sediment and vegetation indicate that practically all the Pb cycled in the forest at Plastic Lake is anthropogenic in origin.     

Pathological findings in Crassostrea rhizophorae from Todos os Santos Bay,Bahia, Brazil

Types and frequencies of pathologies were investigated in Crassostrea rhizophorae before and following heavy oyster mortality in Todos os Santos Bay, Bahia, Brazil. The sporozoan Nematopsis sp. was the only parasite present in sufficient numbers to be an important mortality factor, but the intensity of Nematopsis infections remained low until after the major die-off. Pathologies such as ceroidosis, reduction or loss of stored glycogen, decreased gametogenesis, edema, and metaplasia of the digestive diverticula were consistent with the hypothesis of an external environmental stress factor that may have caused feeding to cease, the resultant weakness contributing to high mortalities.     

Latitudinal variations of the yield and quality of agar from <Emphasis Type="Italic">Gelidium robustum</Emphasis> (Gelidiales,Rhodophyta) from the main commercial harvest beds along the western coast of the Baja California Peninsula,Mexico

The yield and quality of agar from Gelidium robustum from the main commercial harvest beds along the western coast of the Baja California Peninsula (Mexico) were evaluated within a latitudinal range of about 800 km (31°47′N to 27°05′N). Samples from six locations, Bahía Todos Santos, El Rosario, Isla de Cedros, Islas San Benito, Punta Eugenia, and Bahía Asunción, were analyzed. Bryozoan, protein, and agar content in the seaweed were estimated. The agar quality was determined by the content of 3,6-anhydrogalactose, sulfate, gel strength, and gelling and melting temperature. All the values of these variables were correlated and then with the satellite-derived data of the sea surface temperature (SST), net primary production (NPP), and photosynthetic active radiation (PAR) measured at each harvest bed during the summer months (June, July, and August) of 2000. In the northern and central region, the agar yield was 35% to 37% (Bahía Todos Santos, El Rosario, Isla de Cedros, and Islas San Benito), whereas lower yields were obtained from the southern beds (Punta Eugenia and Bahía Asunción). In contrast, the agar quality increased from the northern to the southern beds. A lower gel strength was obtained from Bahía Todos Santos and El Rosario (268 ± 16 and 205 ± 5 gcm⁻²) with a higher gel strength obtained from Isla de Cedros, Islas San Benito, and Bahía Asunción (384 to 444 ± 25 gcm⁻²). Yield was not correlated with the bryozoan content but was inversely correlated with the protein content in the seaweed. The sulfate content in the agar was inversely correlated with the gel strength and with the melting temperature. The 3,6-anhydrogalactose content showed slight variations among harvested beds. Analysis of satellite-derived data showed an equatorward increase of the SST, NPP, and PAR. The agar content correlated inversely with the equatorward increase of the NPP, whereas agar quality, i.e., gel strength, correlated positively with the NPP and PAR. No significant effects were observed on the yield and quality of agar with the latitudinal change of the SST.     

Midvale Community Lead Study

Abstract

The primary objective of this study was to ascertain whether children living in close proximity to mill tailings and a former lead smelter site were currently exhibiting elevated blood lead (PbB) concentrations. To address this issue, the mean PbB for community children and the relationship between PbB and the proximity of the child's residence to the site was estimated. A secondary objective was to identify and quantify accessible lead (Pb) and arsenic (As) in the environment (e.g. Pb in soil, dust, paint and water or As in soil and dust). A third objective was to test for association between specific sources of environmental Pb and PbB and to estimate the relative contribution of these proximate sources of lead to the children's PbB. The data analytic methods allowed estimation of both direct and indirect impact of environmentally accessible Pb. The average PbB level of all children screened in Midvale was 5.2 μg dL^?1. Three percent exceeded 15 μg dL^?1; 12.7% exceeded 10 μg dL^?1. Pb-based house paint and Pb contaminated soil were identified as principal contributors to PbB. PbB was found to increase 1.25 μg dL^?1 per 1,000 ppm increase in lead in soil. Proximity of residence to the mill and smelter site was found to be a strong predictor of Pb in soil, and therefore indirectly related to increases in PbB.