Pb Paint Research Articles

Lead-based paint detection using perovskite fluorescence and X-ray fluorescence

BackgroundIngestion of flakes of Pb-based paint by infants remains a global health hazard with life-long consequences. Pb-based paint was banned for residential use in the US and Western Europe decades ago but is still sold in many countries. This study evaluates the performance of a new kit for detecting exposed Pb-based paint relying on the formation of Pb-halide perovskite that fluoresces bright green under a UV flashlight after spraying a non-toxic reagent. ResultsTests with the Lumetallix kit were conducted in parallel with X-fluorescence and inductively-coupled plasma atomic emission analysis upon acid digestion using paint currently sold in Côte d'Ivoire and samples of older US paint. Comparison of the three different methods indicates a detection limit for the Lumetallix kit of approximately 500 mg kg−1 (ppm) Pb in paint, with a sensitivity of 95 % and selectivity of 94 % relative to that threshold (n = 76). This detection limit is an order of magnitude below the US definition of Pb-based paint of 0.5 % (5,000 ppm) Pb by weight. SignificanceBecause the kit is easy to use, exposed paint posing a risk could reliably be screened at scale by the general public. Any follow-up for confirmation and mitigation based on XRF measurements will need to consider that Pb-based paint covered with low-Pb paint will not respond to the kit but will be detected by XRF through the overpainted layer.

United States house dust Pb concentrations are influenced by soil, paint, and house age: insights from a national survey

BackgroundLead (Pb) in house dust contributes significantly to blood lead levels (BLLs) in children which may result in dire health consequences. Assessment of house dust Pb in the United States, relationships with Pb in soil and paint, and residential factors influencing Pb concentrations are essential to probing drivers of house dust Pb exposure.ObjectivePb concentrations in vacuum-collected house dust are characterized across 346 homes participating in the American Health Homes Survey II (AHHS II), a US survey (2018–2019) evaluating residential Pb hazards. Connections between house dust Pb and soil Pb, paint Pb, and other residential factors are evaluated, and dust Pb concentration data are compared to paired loading data to understand Pb hazard standard implications.ResultsMean and median vacuum dust Pb concentrations were 124 µg Pb g−1 and 34 µg Pb g−1, respectively. Vacuum-collected dust concentrations and dust wipe Pb loading rates were significantly correlated within homes (α < 0.001; r ≥ 0.4). At least one wipe sample exceeded current house dust Pb loading hazard standards (10 µg ft−2 or 100 µg Pb ft−2 for floors and windowsills, respectively) in 75 of 346 homes (22%). House dust Pb concentrations were correlated with soil Pb (r = 0.64) and Pb paint (r = 0.57). Soil Pb and paint Pb were also correlated (r = 0.6).ImpactThe AHHS II provides a window into the current state of Pb in and around residences. We evaluated the relationship between house dust Pb concentrations and two common residential Pb sources: soil and Pb-based paint. Here, we identify relationships between Pb concentrations from vacuum-collected dust and paired Pb wipe loading data, enabling dust Pb concentrations to be evaluated in the context of hazard standards. This relationship, along with direct ties to Pb in soil and interior/exterior paint, provides a comprehensive assessment of dust Pb for US homes, crucial for formulating effective strategies to mitigate Pb exposure risks in households.

Early childhood lead exposure is not reflected in adult bone lead: Results of a sub-cohort of African American women in the Cincinnati lead study

IntroductionPb in bone may serve as a biomarker for cumulative Pb dose over decades. We hypothesized that adult female bone Pb concentrations (BoPb) would be significantly associated with average childhood blood Pb levels (BlPb) in a birth cohort exposed to relatively high levels of Pb from Pb paint residues. Methods94 African American women with a mean age of 32.7 years were recruited from the Cincinnati Lead Study (CLS) cohort. Subjects were born to women residing where there had been a high incidence of childhood Pb poisoning. Biomarkers of Pb exposure were serial BlPb concentrations spanning the prenatal period to approximately 6.5 years of age. BoPb was assessed in the tibia using the McMaster 109Cd K-XRF fourth generation system. Covariates included nutritional variables related to bone health. ResultsBlPb concentrations began to rise around 6 months of age and declined at later ages. Study participants were obese with a mean Body Mass Index of 34.4 and suboptimal vitamin D status as indicated by a mean 25-OH-D of 18.5 ng/ml. Average tibia Pb was −2.0 ± 8.6 μgPb/g bone mineral. In multiple linear regression, there was no significant association between BoPb at approximately age 30 and childhood cumulative BlPb(CumBlPb). DiscussionCollectively, BoPb of this group of subjects was not detectable. We suggest that the reason these subjects’ BoPb did not reflect their early exposure was that a significantly smaller proportion of Pb body burden resides in bone in young children. As the child grows what Pb there was in bone is diluted and any remaining signal is weak. It has been claimed that BoPb in older children, adolescents, and adults can recapitulate historical exposure to Pb during earlier development; however, in some populations, BoPb at later ages may not be an adequate biomarker to capture childhood exposure to Pb.

Complexities in attributing lead contamination to specific sources in an industrial area of Philadelphia, PA

Globally, lead (Pb) contamination is one of the top ten chemical exposure issues affecting public health. The identification of specific Pb sources provides valuable information to determine assignment of liability for site cleanup, improve sampling plans and develop remedial strategies. This paper examines Pb concentrations and Pb isotopic data from samples collected at and near the site of a Pb paint production facility with a long operating history. Although high soil Pb concentrations were found at the site, Pb concentrations in surrounding neighborhoods did not simply decline with distance from the site. We evaluated soil concentrations and isotopic mixing lines to explore potential sources of Pb pollution. Three-isotope plots showed overlap of site samples and the surrounding neighborhood, consistent with pollution from the facility affecting offsite soils. A major challenge in separation of potential sources, however, is that the isotopic signatures of other potential Pb sources fall within the range of the soil data. The long operational site history, soil disturbances, the presence of nearby smelters, and other local and remote sources affect identification of lead sources. This analysis demonstrates that source attribution can be confounded by incomplete site and material sourcing information. An integrated approach that includes in-depth site characterization and an evaluation of historical activities (e.g., Pb ores used over time, amounts of Pb emitted by all area smelters, land use changes, and soil disturbances) is important for determining source attribution. This analysis provides insight into future site investigations where soil lead contamination has resulted from a long industrial history in an urban setting.

Predictive modeling of indoor dust lead concentrations: Sources, risks, and benefits of intervention

Lead (Pb) contamination continues to contribute to world-wide morbidity in all countries, particularly low- and middle-income countries. Despite its continued widespread adverse effects on global populations, particularly children, accurate prediction of elevated household dust Pb and the potential implications of simple, low-cost household interventions at national and global scales have been lacking. A global dataset (∼40 countries, n = 1951) of community sourced household dust samples were used to predict whether indoor dust was elevated in Pb, expanding on recent work in the United States (U.S.). Binned housing age category alone was a significant (p < 0.01) predictor of elevated dust Pb, but only generated effective predictive accuracy for England and Australia (sensitivity of ∼80%), similar to previous results in the U.S. This likely reflects comparable Pb pollution legacies between these three countries, particularly with residential Pb paint. The heterogeneity associated with Pb pollution at a global scale complicates the predictive accuracy of our model, which is lower for countries outside England, the U.S., and Australia. This is likely due to differing environmental Pb regulations, sources, and the paucity of dust samples available outside of these three countries. In England, the U.S., and Australia, simple, low-cost household intervention strategies such as vacuuming and wet mopping could conservatively save 70 billion USD within a four-year period based on our model. Globally, up to 1.68 trillion USD could be saved with improved predictive modeling and primary intervention to reduce harmful exposure to Pb dust sources.

Using community science for detailed pollution research: a case-study approach in Indianapolis, IN, USA.

Heavy metal contamination in urban environments, particularly lead (Pb) pollution, is a health hazard both to humans and ecological systems. Despite wide recognition of urban metal pollution in many cities, there is still relatively limited research regarding heavy metal distribution and transport at the household-scale between soils and indoor dusts-the most important scale for actual human interaction and exposure. Thus, using community-scientist-generated samples in Indianapolis, IN (USA), we applied bulk chemistry, Pb isotopes, and scanning electron microscopy (SEM) to illustrate how detailed analytical techniques can aid in interpretation of Pb pollution distribution at the household-scale. Our techniques provide definitive evidence for Pb paint sourcing in some homes, while others may be polluted with Pb from past industrial/vehicular sources. SEM revealed anthropogenic particles suggestive of Pb paint and the widespread occurrence of Fe-rich metal anthropogenic spherules across all homes, indicative of pollutant transport processes. The variability of Pb pollution at the household scale evident in just four homes is a testament to the heterogeneity and complexity of urban pollution. Future urban pollution research efforts would do well to utilize these more detailed analytical methods on community-sourced samples to gain better insight into where the Pb came from and how it currently exists in the environment. However, these methods should be applied after large-scale pollution screening techniques such as portable X-ray fluorescence (XRF), with more detailed analytical techniques focused on areas where bulk chemistry alone cannot pinpoint dominant pollution mechanisms and where community scientists can also give important metadata to support geochemical interpretations.

Using Community Science to Better Understand Lead Exposure Risks.

Lead (Pb) is a neurotoxicant that particularly harms young children. Urban environments are often plagued with elevated Pb in soils and dusts, posing a health exposure risk from inhalation and ingestion of these contaminated media. Thus, a better understanding of where to prioritize risk screening and intervention is paramount from a public health perspective. We have synthesized a large national data set of Pb concentrations in household dusts from across the United States (U.S.), part of a community science initiative called “DustSafe.” Using these results, we have developed a straightforward logistic regression model that correctly predicts whether Pb is elevated (>80 ppm) or low (<80 ppm) in household dusts 75% of the time. Additionally, our model estimated 18% false negatives for elevated Pb, displaying that there was a low probability of elevated Pb in homes being misclassified. Our model uses only variables of approximate housing age and whether there is peeling paint in the interior of the home, illustrating how a simple and successful Pb predictive model can be generated if researchers ask the right screening questions. Scanning electron microscopy supports a common presence of Pb paint in several dust samples with elevated bulk Pb concentrations, which explains the predictive power of housing age and peeling paint in the model. This model was also implemented into an interactive mobile app that aims to increase community‐wide participation with Pb household screening. The app will hopefully provide greater awareness of Pb risks and a highly efficient way to begin mitigation.

Early life lead exposure from private well water increases juvenile delinquency risk among US teens

Early life exposure to environmental lead (Pb) has been linked to decreased IQ, behavior problems, lower lifetime earnings, and increased criminal activity. Beginning in the 1970s, limits on Pb in paint, gasoline, food cans, and regulated water utilities sharply curtailed US environmental Pb exposure. Nonetheless, hundreds of thousands of US children remain at risk. This study reports on how unregulated private well water is an underrecognized Pb exposure source that is associated with an increased risk of teenage juvenile delinquency. We build a longitudinal dataset linking blood Pb measurements for 13,580 children under age 6 to their drinking water source, individual- and neighborhood-level demographics, and reported juvenile delinquency records. We estimate how early life Pb exposure from private well water influences reported delinquency. On average, children in homes with unregulated private wells had 11% higher blood Pb than those with community water service. This higher blood Pb was significantly associated with reported delinquency. Compared to children with community water service, those relying on private wells had a 21% (95% CI: 5 to 40%) higher risk of being reported for any delinquency and a 38% (95% CI: 10 to 73%) increased risk of being reported for serious delinquency after age 14. These results suggest that there could be substantial but as-yet-unrecognized social benefits from intervention programs to prevent children's exposure to Pb from private wells, on which 13% of the US population relies.

Using Public Health Data for Soil Pb Hazard Management in Ohio

To evaluate how frequently elevated soil lead (Pb) hazards (≥400 ppm Pb) were identified in existing blood Pb site investigations in Ohio. This study evaluated 3050 site investigations from the Ohio Department of Health for children with blood Pb levels at or above 10 μg dL that contained bare soil Pb data. Data were collected from existing databases maintained by the Ohio Department of Health. All data were de-identified prior to analysis. The data used included blood Pb level test results for children (18 years or younger) in Ohio, with most data coming from children younger than 6 years. The main outcome measures were blood Pb levels and identified Pb concentrations in environmental media, including soil, paint, and dust. Data were organized and summarized according to county. Summary statistics were generated on the basis of type of environmental media and county. Soil samples were collected in approximately 5% of all blood Pb cases in Ohio between 1999 and 2015. Median bare soil Pb was 1030 mg Pb kg (range, 0-345 021 mg Pb kg soil). Fifty-six of Ohio's 88 counties had at least 1 soil sample above 10 000 ppm (mg Pb kg). Multiple Pb hazards were identified, including bare soil (74% frequency), deteriorated exterior Pb paint (74%), deteriorated interior Pb paint (72%), and settled Pb dust (72%). Bare soil collected from identified dripline areas contained 2638 ppm Pb above soils collected from bare soil play areas (P = .02). Ninety assessments (3%) contained a bare soil hazard, with no other identified hazards. No trend was found comparing county mean or median Pb with county population. Previously identified high-risk counties for elevated blood Pb levels did not have an elevated prevalence of bare soil Pb hazards compared with other counties (P = .64). Site investigators should anticipate finding and managing elevated bare soil Pb in locations throughout Ohio. When communicating with the public about bare soil Pb hazards, practitioners and policy makers should emphasize the importance of addressing all potential Pb exposure sources. Findings demonstrate the importance of the individual home environment for exposure, as previously identified high-risk counties for elevated blood Pb levels were not different from other counties.

Monitoring steel bridge renovation using lead isotopic tracing

Monitoring removal of lead (Pb) paint from steel structures usually involves analysis of environmental samples for total lead and determination of blood Pb levels of employees involved in the Pb paint removal. We used high precision Pb isotopic tracing for a bridge undergoing Pb paint removal to determine if Pb in the environmental and blood samples originated from the bridge paint. The paint system on the bridge consisted of an anti-corrosive red Pb primer top-coated with a Micaceous Iron Oxide (MIO) alkyd. Analysis of the red Pb primer gave uniform isotopic ratios indicative of Pb from the geologically-ancient Broken Hill mines in western New South Wales, Australia. Likewise waste abrasive material, as anticipated, had the same isotopic composition as the paint. The isotopic ratios for other samples lay on 2 separate linear arrays on a207Pb/204Pb versus 206Pb/204Pb diagram, one largely defined by gasoline and the majority of the ambient air data, and the other by data for one sample each of gasoline and ambient air and underwater sediments. Isotopic ratios in background ambient air samples for the project were characteristic of leaded gasoline. Air sampling during paint removal showed a contribution of paint Pb ranging from about 20 to 40%. Isotopic ratios in the blood of 8 employees prior to the commencement of work showed that 6 of these had been previously exposed to the Broken Hill Pb possibly from earlier bridge paint removal projects. One subject appeared to have increased exposure to Pb probably from the paint renovations.

Identification of lead sources in residential environments: Sydney Australia

Interior and exterior dust, soil and paint were analysed at five brick urban Sydney homes over 15 months to evaluate temporal variations and discriminate sources of lead (Pb) exposure. Exterior dust gauge Pb loading rates (μg/m2/28 days), interior vacuum dust Pb concentrations (mg/kg) and interior petri-dish Pb loading rates (μg/m2/28 days), were correlated positively with soil Pb concentrations. Exterior dust gauge Pb loading rates and interior vacuum dust Pb concentrations peaked in the summer. Lead isotope and Pb speciation (XAS) were analysed in soil and vacuum dust samples from three of the five houses that had elevated Pb concentrations. Results show that the source of interior dust lead was primarily from soil in two of the three houses and from soil and Pb paint in the third home. IEUBK child blood Pb modelling predicts that children's blood Pb levels could exceed 5 μg/dL in two of the five houses.

Extent, Characterization, and Sources of Soil Lead Contamination in Small-Urban Residential Neighborhoods

We present high spatial-resolution mapping of soil lead (Pb) concentrations in a small-urban residential setting. X-ray fluorescence was used to measure soil Pb at170 properties in the City Park neighborhood of Appleton, Wisconsin. Greater than two-thirds of soil samples collected from drip lines contained more than 400 μg g of Pb, and one third exceeded 1200 μg g. Soils adjacent to homes built before 1960 contained significantly higher Pb levels than those near younger homes. Three front yard locations (drip line, mid-yard, and terrace) were sampled at 71 properties. A general decline in soil Pb with increasing distance from the house was observed. Detailed sampling of individual homes within a single residential block revealed Pb-contaminated soil radiating outward from homes in all directions, creating a "bulls-eye" pattern. Approximately 40% of yard space exceeded concentrations of 400 μg g. These patterns of contamination are consistent with Pb paint as the main contributor of Pb to soil. This has important implications because spatial distribution of Pb contamination is fundamentally different if paint, rather than automobile exhaust, is the primary source. Selective sequential extraction analyses suggest that roughly half of the soil Pb resides in chemically reactive and bioavailable phases. The extent and persistence of soil Pb, the resurgence of home gardening, and the serious health consequences of Pb ingestion argue for attention to this problem, not just in dense urban centers but also in smaller urban settings across the country.

LONG-TERM EFFECTS OF LIME, PHOSPHORUS, AND IRON AMENDMENTS ON WATER-EXTRACTABLE ARSENIC, LEAD, AND BIOACCESSIBLE LEAD FROM CONTAMINATED ORCHARD SOILS

Lead arsenate was used on orchard soils as a pesticide from 1900 to 1960. An in vitro method has been used to determine the bioaccessiblity of Pb in soils contaminated by Pb paint, fossil fuel combustion, and metallurgical industries. The Pb fraction that is potentially bioavailable from orchard soi

An Alternative Method for Remediating Lead-Contaminated Soils in Residential Areas: A Decision Case Study

Lead (Pb) is one of the most significant environmental contaminants worldwide and has significant human health effects. Historic use of Pb in paint and gasoline, in particular, have made this contaminant ubiquitous in our environment although widespread use of Pb has declined in the USA. Unfortunately, segments of the population are still receiving unacceptable doses of Pb. In the case reported here, citizens of Joplin, MO, will have input on a critical decision regarding the method by which the USEPA will remediate the Pb-contaminated soil in their community. Soil excavation is currently being used with the possibility of switching to phosphorus (P) amendment. Phosphorus added to the soil reacts with Pb to form an insoluble solid phase that is believed to be less harmful to humans compared with untreated soil. The use of P amendment offers advantages compared with soil excavation but has not been used before in residential areas. This case can be used to introduce students to the concepts of soil remediation, toxicology, and soil chemistry as well as social issues such as the use of tax dollars to support remediation. The learning objectives of this case are to understand the most common remediation strategy for Pb-contaminated soils and an alternative to that strategy, understand the concept of bioavailability and how it relates to the physiological effects of a soil contaminant on an organism, appreciate how soil amendments can change the bioavailability of a soil constituent, and to be able to identify the primary pathways of exposure for a soil contaminant and humans.

In vitro formation of pyromorphite via reaction of Pb sources with soft-drink phosphoric acid

Pyromorphite (Pb 5(PO 4) 3Cl) is a Pb mineral whose rapid kinetic formation and thermodynamic stability (Geochim. Cosmochim. Acta 37 (1973) 367, Geochim. Cosmochim. Acta 38 (1974) 887) has gained much attention in recent years as a mechanism to diminish Pb toxicity. Our research examined the in vitro formation of pyromorphite ( K sp=10 −25) to significantly reduce Pb bioavailability via the reaction of PbCl 2 and Pb paint with cola soft drinks (regular, caffeine-free, and diet) that contain phosphoric acid. X-ray diffraction spectroscopy was employed to identify and quantify the crystal phases. The experiments consisted of a two-phase experimental design to simulate stomach and gastrointestinal (GI) conditions comprised of an initial reaction system (stomach) at pH 2.0 for 1 h at 37 °C and second-phase conditions (GI tract) at pH 7.0 for 5 h at 37 °C. The results showed that available Pb in solution was quickly transformed to pyromorphite by a precipitation mechanism. The PbCl 2 experiments observed over 90% Pb removal from solution within 30 s and nearly all (>93–100%) of the Pb was converted to pyromorphite within 6 h. Similar results were observed in the Pb-paint system in which all of the available Pb initially available in solution was stabilized as pyromorphite within a short reaction period. While approximately 69% of the total Pb in the paint was converted to pyromorphite, there were minimal amounts of Pb in solution. It appeared that the dissolution mechanism allowing Pb in the paint to be released into the cola solution was repressed and was attributed to precipitation of pyromorphite on the surfaces of Pb-paint particles that inhibited further Pb release. The results of this research suggest that the in vivo formation of pyromorphite in children that ingest Pb-contaminated material (soil, dust, paint) with a phosphate source, such as a cola soft drink, may significantly reduce Pb bioavailability and allow passage of the pyromorphite material through the GI tract with minimal Pb absorption into the body.

Battery powered laser-induced plasma spectrometer for elemental determinations

A battery powered, portable laser-induced breakdown spectrometry instrument with a low pulse energy laser and a low resolution, non-gated spectrometer is evaluated. Improvements in the instrument probe design were accomplished through studies of the plasma spatial development, lens-to-sample distance effects and spatial filtering. The prototype was evaluated on paint, steel, ores, and organic samples. Limits of detection ranged from 0.016% for Mn in NIST SRM steel to 0.13% for Ca in NIST SRM organic samples. Acceptable precision (0.4–4.9%) was obtained for steel, ore and organic SRM samples. The poorer precision (4.0–44.1%) obtained for the detection of Pb in paint can be attributed to the heterogeneity of the samples.

Detection of Metals in the Environment Using a Portable Laser-Induced Breakdown Spectroscopy Instrument

A portable instrument, based on laser-induced breakdown spectroscopy (LIBS), has been developed for the detection of metal contaminants on surfaces. The instrument has a weight of 14.6 kg, fits completely into a small suitcase (46 × 33 × 24 cm), and operates from 115 V ac. The instrument consists of a sampling probe connected to the main analysis unit by electrical and optical cabling. The hand-held probe contains a small laser to generate laser sparks on a surface and a fiber-optic cable to collect the spark light. The collected light is spectrally resolved and detected with the use of a compact spectrograph/CCD detector system. The instrument has been evaluated for the analysis of metals in the environment: Ba, Be, Pb, and Sr in soils; Pb in paint; and Be and Pb particles collected on filters. Detection limits in ppm for metals in soils were 265 (Ba), 9.3 (Be), 298 (Pb), and 42 (Sr). The detection limit for Pb in paint was 0.8% (8000 ppm), corresponding to 0.052 mg/cm2. The higher limit obtained for Pb in paint is attributed to the use of the 220.35-nm Pb(II) line instead of the stronger 405.78-nm Pb(I) line used for soils. Spectral interferences prevented use of the 405.78-nm line to determine Pb in paint. The surface detection limit for Be particles on filters was dependent on particle size and ranged from 21 to 63 ng/cm2. The detection limit for Pb particles on filters was 5.6 μg/cm2.

Environmental lead: need for reference materials

The status of the availability and appropriateness of standard reference materials (RMs) currently available for Pb in paint, dust, soil and drinking water is reviewed. The need for RMs which will be most appropriate for environmental Pb analysis in the context of the analytical techniques used, government regulations and health effects, is assessed. Also, the importance of factors such as bioavailability, sample size, homogeneity and composition that should be considered in developing appropriate RMs certified for Pb in paint, dust, soil and drinking water is stressed.

Lead Exposure in a Petroleum Refinery During Maintenance and Repair Activities

Abstract Exposure to inorganic lead (Pb) may result in a petroleum refinery when paints that contain Pb are disturbed. Frequently performed activities that disturb paint include welding, burning, cutting, abrasive blasting, sanding, grinding, and needle gun chipping. The purpose of the study reported in this article was: to determine the Pb content of paint on metal surfaces in a petroleum refinery; to measure air Pb concentrations during abrasive blasting, torch cutting and burning, and power disk sanding/grinding on surfaces coated with Pb paint; and to evaluate the effectiveness of worker exposure controls by monitoring worker blood Pb (PbB) levels. Pb levels on representative metal surfaces were measured, and most painted surfaces were found to contain significant amounts of Pb. Personal air samples collected indicated that abrasive blasting and torch burning/cutting resulted in elevated air Pb levels, while short duration power disk sanding (less than 30 minutes duration) did not result in elevated a...

A study of soil contamination and plant lead uptake in Boston urban gardens

Abstract This study has demonstrated a serious problem of Pb contamination in the normal environment of many urban residents. Many soil samples have been analyzed by X‐ray fluorescence spectroscopy from backyard and play areas as well as from large community gardens and playgrounds. An average Pb level of 800 ppm was found in about 900 soil samples. The elevated Pb levels are definitely traceable to widespread use of Pb paint in the past. Tissues of selected plant species grown in garden soils containing Pb levels ranging from 100–2000 ppm showed differing affinities for Pb uptake. The amount of Pb found in tissues was generally related to the soil Pb concentration but was also organ or tissue related; fruits taking up less than roots and roots less than tops. Experimental design insured that the soil was probably the sole source of Pb in this study. This points to positive translocation of Pb from soil into plant tissue.