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PubMed1995

Oral dimercaptosuccinic acid and ongoing exposure to lead: effects on heme synthesis and lead distribution in a rat model.

Lead (Pb) exposure and subsequent toxicity continues to be a significant problem in the United States. Treatment with meso-2,3-dimercaptosuccinic acid (DMSA) has been reported to be effective in reducing the body's Pb burden, with fewer adverse side effects than other chelating agents. The oral availability and relative safety of DMSA presents the controversial option of treating patients with Pb poisoning on an outpatient basis. Despite recommendations that children be removed from the Pb contaminated environment, some children will inevitably be exposed to environmental Pb while receiving oral DMSA therapy. The study hypothesized that oral DMSA chelation therapy is beneficial even when faced with continued dietary Pb. Sprague-Dawley rats were exposed to Pb in water for 35 days and then placed in various treatment groups, including groups administered oral DMSA with and without concurrent Pb exposure. The concentration of Pb in blood and critical organs and Pb diuresis were measured. The effect of Pb on heme synthesis was determined by assaying the urinary delta-aminolevulinic acid (delta-ALA), and blood zinc protoporphyrin (ZPP). DMSA reversed the hematological effects of Pb, decreased the blood, brain, bone, kidney, and liver Pb concentration, and produced a marked Pb diuresis, even when challenged with ongoing Pb exposure. In conclusion, even though DMSA treatment without exposure to Pb is optimal, oral DMSA could be beneficial even when challenged with ongoing Pb exposure.

Administration, Oral↗
PubMed1975

[Lead-content of foodstuffs. 4. Lead-content of infant foods (author's transl)].

The lead contents in more than 120 glass bottles or packages of infant foods were determined. About 75% of the values were below 100 mug Pb/kg of product. The highest value was 238 mug Pb/kg. The weekly intake of a 6 month-old infant (7.2 kg body weight) fed exclusively with commercial baby foods was found to be about 320 mug Pb, or about 45 mug Pb/kg body weight.

Animals↗
PubMed2002

In vitro lead bioaccessibility and phosphate leaching as affected by surface application of phosphoric acid in lead-contaminated soil.

Phosphate treatment of lead-contaminated soil may be a cost-effective remedial alternative for in situ stabilizing soil Pb and reducing Pb toxicology to human. The leaching behaviors of the P added to soil surface and the effect on subsurface Pb bioaccessibility must be addressed for this remedial technology to be acceptable. A smelter-contaminated soil containing an average of 2,670 mg Pb kg(-1), collected from the Jasper County Superfund Site located in Jasper County, Missouri, was surface treated with 10 g P kg(-1) as phosphoric acid (H(3)PO(4)). Following a simulated column leaching and 90-day treatment of field plots, respectively, bioaccessible Pb, P, and pH in soil profile were measured. Surface treatment using H(3)PO(4) effectively stabilized soil Pb and reduced leachable Pb and the bioaccessibility. Phosphate leached into deeper profile significantly lowered bioaccessible Pb in subsurface. Reduction of Pb bioaccessibility increased as a linear function of increasing soil P. Although surface H(3)PO(4) treatment resulted in an enhanced leaching of added P and may increase potential risk of surface and groundwater pollution, the P leaching under field conditions is very limited. Lime addition following the treatment may reduce the leachability of added P and further immobilize soil Pb.

Animals↗
PubMed2006

Biomonitoring of lead, zinc, and cadmium in streams draining lead-mining and non-mining areas, southeast Missouri, USA.

We evaluated exposure of aquatic biota to lead (Pb), zinc (Zn), and cadmium (Cd) in streams draining a Pb-mining district in southeast Missouri. Samples of plant biomass (detritus, periphyton, and filamentous algae), invertebrates (snails, crayfish, and riffle benthos), and two taxa of fish were collected from seven sites closest to mining areas (mining sites), four sites further downstream from mining (downstream sites), and eight reference sites in fall 2001. Samples of plant biomass from mining sites had highest metal concentrations, with means 10- to 60-times greater than those for reference sites. Mean metal concentrations in over 90% of samples of plant biomass from mining sites were significantly greater than those from reference sites. Mean concentrations of Pb, Zn, and Cd in most invertebrate samples from mining sites, and mean Pb concentrations in most fish samples from mining sites, were also significantly greater than those from reference sites. Concentrations of all three metals were lower in samples from downstream sites, but several samples of plant biomass from downstream sites had metal concentrations significantly greater than those from reference sites. Analysis of supplemental samples collected in the fall of 2002, a year of above-average stream discharge, had lower Pb concentrations and higher Cd concentrations than samples collected in 2001, near the end of a multi-year drought. Concentrations of Pb measured in fish and invertebrates collected from mining sites during 2001 and 2002 were similar to those measured at nearby sites in the 1970s, during the early years of mining in the Viburnum Trend. Results of this study demonstrate that long-term Pb mining activity in southeast Missouri has resulted in significantly elevated concentrations of Pb, Cd, and Zn in biota of receiving streams, compared to biota of similar streams without direct influence of mining. Our results also demonstrate that metal exposure in the study area differed significantly among sample types, habitats, and years, and that these factors should be carefully considered in the design of biomonitoring studies.

Animals↗
PubMed1989

Influence of 2,3-dimercaptosuccinic acid on gastrointestinal lead absorption and whole-body lead retention.

2,3-Dimercaptosuccinic acid (DMSA) is a new orally active heavy metal chelator for the treatment of childhood Pb intoxication on an outpatient basis. The influence of DMSA, as well as other chelating agents, on gastrointestinal 203Pb absorption and whole-body 203Pb retention was examined. Groups of Sprague-Dawley rats (230-260 g) were gavaged with a solution containing approximately 25 mg/kg Pb [as Pb(NO3)2] plus 15 microCi 203Pb. Some groups were then immediately given 0.11 mmol/kg of either DMSA, CaNa2EDTA, D-penicillamine, or BAL by oral gavage, while other groups received the same drugs by ip injection. Control groups received solutions of the drug vehicles po or ip. Whole-body Pb retention and gastrointestinal Pb absorption (whole body retention + urinary Pb excretion) were significantly decreased in rats that received DMSA po. This finding implies that the use of DMSA to treat childhood lead intoxication on an outpatient basis is not associated with a risk for increased Pb absorption.

Administration, Oral↗
PubMed1991

Natural skeletal levels of lead in Homo sapiens sapiens uncontaminated by technological lead.

Lead, Ba and Ca concentrations were determined in tooth enamel, femur and rib from buried skeletons of PreColumbian Southwest American Indians, 10 subjects who lived 1000 years ago on the Pacific coast at 34 degrees N, and 13 subjects who lived 700 years ago in a desert valley tributary of the Colorado River at 37 degrees N 111 degrees W, both groups living in environments uncontaminated by technological Pb. For the coastal tribe, average Pb/Ca ratios were 1.1 x 10(-7) in enamel, 2.3 x 10(-7) in femur and 4.7 x 10(-7) in rib, while Ba/Ca ratios were 1.2 x 10(-5) in enamel, 32 x 10(-5) in femur and 38 x 10(-5) in rib (wt ratios). For the desert tribe, average Pb/Ca ratios were 4 x 10(-7) in enamel, 11 x 10(-7) in femur and 37 x 10(-7) in rib, while Ba/Ca ratios were 1.1 x 10(-5) in enamel, 7.5 x 10(-5) in femur and 6.2 x 10(-5) in rib. It is shown that biologic levels of Pb and Ba in buried femur and rib at both burial sites and in buried enamel at the Arizona site are obscured by excessive diagenetic additions of Pb and Ba from soil moisture. It is shown that one-third of the Pb in enamel at the Malibu site is biologic, yielding a skeletal Pb/Ca (wt) ratio of 4 x 10(-8). This is equivalent to a mean skeletal concentration of 13 ng Pb g-1 bone ash, and a mean natural body burden of 40 micrograms Pb/70 kg adult Homo sapiens sapiens, uncontaminated by technological Pb. This value is about one-thousandth of the mean body burden of 40 mg industrial Pb/70 kg adult American today, which indicates the probable existence within most Americans of dysfunctions caused by poisoning from chronic, excessive overexposures to industrial Pb.

Adult↗
PubMed1991

Lead exposure from lead crystal.

In a study of the elution of lead (Pb) from crystal decanters and glasses, port containing 89 micrograms Pb/l was placed in decanters and the Pb content of the wine rose steadily to 3518 micrograms/l after 4 months. Wines and spirits stored in crystal decanters for a long time contained Pb at concentrations up to 21,530 micrograms/l. In a short-term experiment white wine eluted small amounts of Pb from crystal glasses within minutes.

Alcoholic Beverages↗
PubMed1981

Effect of lead and zinc administration on liver, kidney and brain levels of copper, lead, manganese and zinc and on erythrocyte ALA-D activity in rats.

Albino male rats were given lead (Pb) and zinc (Zn) orally, singly or in combination, for 14 consecutive days. Liver Pb was increased and liver manganese (Mn) was decreased in animals receiving Pb. The combination of Pb and Zn led to increased Pb and decreased copper (Cu) and Mn. Kidney Zn was increased in rats given Zn or the combination of Pb and Zn. There were no changes in kidney Cu or Mn in any group. Brain Pb levels were significantly increased in animals given Pb and Zn levels in those given Zn. Erythrocytic amino levulinic acid dehydratase (ALA-D) activity was significantly decreased by Pb but not by Pb + Zn.

Animals↗
PubMedDate not supplied

Lead exposure and the cognitive development of urban preschool children: the Cincinnati Lead Study cohort at age 4 years.

The purpose of this analysis was to determine if significant associations could be observed between prenatal/postnatal blood lead (PbB) levels and the cognitive development of 258 urban, inner-city children at 4 years of age. These children have been followed since birth with frequent assessments of general health, PbB, and neuropsychological status. The Kaufman Assessment Battery for Children (K-ABC) was administered at approximately 4 years of age. Higher neonatal PbB levels were associated with poorer performance on all K-ABC subscales. However, this inverse association was limited to children from the poorest families. Maternal PbB levels were unrelated to 4-year cognitive status. Few statistically significant associations between postnatal PbB levels and K-ABC scales could be found. However, the results did suggest a weak inverse relationship between postnatal PbB levels and performance on a K-ABC subscale which assesses visual-spatial and visual-motor integration skills. In these results we note both contradiction and accord with previously published prospective studies.

Child, Preschool↗
PubMedDate not supplied

Lead exposure and the central auditory processing abilities and cognitive development of urban children: the Cincinnati Lead Study cohort at age 5 years.

This analysis examined the relationship between lead exposure as registered in whole blood (PbB) and the central auditory processing abilities and cognitive developmental status of the Cincinnati cohort (N = 259) at age 5 years. Although the effects were small, higher prenatal, neonatal, and postnatal PbB levels were associated with poorer central auditory processing abilities on the Filtered Word Subtest of the SCAN (a screening test for auditory processing disorders). Higher postnatal PbB levels were associated with poorer performance on all cognitive developmental subscales of the Kaufman Assessment Battery for Children (K-ABC). However, following adjustment for measures of the home environment and maternal intelligence, few statistically or near statistically significant associations remained. Our findings are discussed in the context of the related issues of confounding and the detection of weak associations in high risk populations.

Auditory Perceptual Disorders↗
PubMed2004

Effects of soil amendments on lead uptake by two vegetable crops from a lead-contaminated soil from Anhui, China.

Previous studies have documented that phosphate compounds of lead (Pb) [e.g., pyromorphite Pb5(PO4)3-(X), where X=OH, F or Cl] are comparatively insoluble, and their formation in Pb-contaminated soil may be a means of reducing the bioavailability and chemical lability of Pb in soil. In this study, the effect of phosphate compound amendments on the bioavailability of Pb in a polluted alkaline soil was examined. A Pb-contaminated soil was treated with hydroxyapatite (HA), phosphate rock (PR), water-soluble P fertilizer (single superphosphate, SSP) and the combination of HA with SSP. The bioavailability of Pb was determined in plant uptake studies with vegetables (Brassica campetris L. var. communis, BC) and Brassica oleracea L. var. acephala, BO) and sequential extraction. The results indicated that the Pb concentrations in both shoots and roots of two vegetable plants decreased with increasing quantities of added P compound, and the HA treatment had the best effect at the level of 5000 mg of P kg(-1)as compared with other treatments in which the Pb concentrations in shoots of BO and BC decreased 51.9% and 65.5%, respectively, and the Pb concentrations in roots of BO and BC decreased 67.3% and 57.2%, respectively, as compared with the control treatment. The SSP treatment had little effect on the Pb concentrations in plant tissues. Sequential extraction results indicated that the addition of soil amendments transform soil Pb from nonresidual fractions to residual fraction substantially. The effect of treatments followed this order at the equivalent P addition: HA>PR>HA+SSP>SSP. The results suggested that HA amendments can lower the bioavailability and increase the geochemical stability of soil Pb, so it has the potential for in situ remediation in Pb-contaminated soils.

Biological Availability↗
PubMed2006

Lead fluxes, isotopic and concentration profiles in a peat deposit near a lead smelter (Príbram, Czech Republic).

The content and the isotopic composition of lead (Pb) were studied in a peat deposit on the ridge of the Brdy Hills, in the vicinity of the Príbram metallurgical works, in the Czech Republic. Quadrupole ICP MS was employed to determine the elemental composition and (206)Pb/(207)Pb and (208)Pb/(206)Pb isotope ratios. The individual layers were dated using alpha spectrometric measurement of the (210)Pb activity. The historical time period covered by the studied cores reached back to the 18th century. The Pb concentration in the studied profiles varied from 10 to 550 mg kg(-1). The (206)Pb/(207)Pb ratio varied in the range from 1.154 to 1.194 in the individual parts of the profile. The metallurgy of the Pb ores ((206)Pb/(207)Pb approximately 1.16), lithogenic Pb ((206)Pb/(207)Pb approximately 1.2), metallurgical processing of automobile batteries ((206)Pb/(207)Pb approximately 1.17) and the combustion of coal ((206)Pb/(207)Pb approximately 1.17-1.19) yield isotopic signatures that determine the isotope compositions of the individual profiles. Deposition rates between 15 mg m(-2) year(-1) at the beginning of the 19th century and 320 mg m(-2) year(-1) in the 1980s were determined in the dated profiles. The increased deposition rates determined on the dated profiles correspond to the increasing production of Pb ores in the Príbram mining area at the turn of the 19th and 20th centuries. The maximum for metallurgical production corresponds to the highest deposition rates recorded in 1960s and 1970s. The current deposition rate of 5-89 mg m(-2) year(-1) Pb is related to erosion of contaminated soils and waste dumps.

Czech Republic↗
PubMed1991

Intestinal calcium and lead absorption: effects of dietary lead and calcium.

The combined effects of dietary calcium (Ca) and lead (Pb) status on intestinal Ca and Pb absorption and related parameters were investigated in young growing chicks. Dietary Pb intake resulted in two remarkable, apparently independent and essentially opposite effects on intestinal Ca and Pb absorption, depending on dietary Ca and Pb levels and duration of treatment. The initial response (1 week) to Ca deficiency was stimulated Ca absorption and calbindin-D level, regardless of dietary Pb intake. The later response (2 weeks) was a reversal, by Pb, of the early phase stimulation. Intestinal Pb absorption was similarly enhanced by Ca deficiency initially, and this response was also inhibited by prolonged dietary Pb intake. Ingestion of Pb by chicks fed adequate Ca resulted in generally elevated intestinal Ca absorption and calbindin-D levels after both 1 and 2 weeks. Intestinal Pb absorption was also increased in the adequate Ca situation, but only after 2 weeks at the lower levels of dietary Pb. The results underscore the complicated nature of Pb-Ca interactions and demonstrate the importance of thorough characterization of the animal model system.

Administration, Oral↗
PubMed2002

Stable lead isotopic characterisation of the historical record of environmental lead contamination in dated freshwater lake sediment cores from northern and central Scotland.

Sediment cores from three Scottish freshwater lakes, Loch Ness in the remote north and Loch Lomond and the Lake of Menteith, much closer to the heavily populated and industrialised central belt were analysed for 210Pb, 137Cs, Pb and stable Pb isotopic composition (206Pb/207Pb). The radionuclide data were used to establish chronologies for the Loch Ness and Loch Lomond cores, but a chronology could not be developed for the Lake of Menteith core, in which the surface sediment had been subject to intense mixing. Although Pb concentrations generally started increasing during the mid-17th Century, a small peak occurred for Loch Ness in the early 16th Century, perhaps attributable to the influence of medieval mining and smelting in mainland Europe. Temporal trends in the pattern of Pb accumulation were similar for Loch Ness and both sites in Loch Lomond, with 40-50% of the anthropogenic Pb deposited prior to the 20th Century. Fluxes of anthropogenic Pb to the lake sediments peaked during the 1950s at all locations where chronologies could be established. The 5-fold increase in anthropogenic Pb inventory for the southern basin of Loch Lomond relative to Loch Ness reflected geographical proximity to the main polluting sources. The 206Pb/207Pb data for anthropogenic Pb in the sediments from Loch Ness and Loch Lomond exhibited largely similar trends related to five different time periods. Pre-1820, the 206Pb/207Pb ratio was close to that for coal (1.181). From 1820 to 1900, a fairly constant 206Pb/207Pb ratio of approximately 1.17 probably resulted from a combination of emissions from the smelting of indigenous Pb ore (1.170) and coal burning (1.181) in Scotland, and industrial activity to the south in England, where Australian Pb of characteristically low 206Pb/207Pb ratio (1.04) was already in use. From 1901 to 1930, the 206Pb/207Pb ratio declined by <0.01, due to the increasing influence of Australian Pb. From 1931 to 1975/1985, the 206Pb/207Pb ratio of anthropogenic Pb declined by a further 0.03 to 0.04, to minimum values from approximately 1975 to 1985, primarily a consequence of car-exhaust emissions of Pb arising from the introduction of alkyl Pb petrol additives (206Pb/207Pb approximately 1.06-1.09). From 1975/1985 to the mid-1990s, the 206Pb/207Pb ratio of anthropogenic Pb increased by up to 0.015, a consequence of a reduction in car-exhaust emissions of Pb, resulting from reductions in the maximum permitted concentration of Pb in petrol, and the introduction and increasing uptake of unleaded petrol. Source apportionment calculations, on the basis of 206Pb/207Pb values in surface sediment, suggested that the contribution of Pb emissions from the use of leaded petrol was 27-40% of the atmospheric burden by the mid-1990s, in line with estimates from rainwater 206Pb/207Pb data.

Air Pollutants↗
PubMed2001

How to calculate lead concentration and concentration uncertainty in XRF in vivo bone lead analysis.

The authors provide a substantial correction for calculating estimates of lead concentration and uncertainty for in vivo X-ray fluorescent bone analysis with Cd-109 source. Based on general principles, they provide mathematical techniques for propagation of uncertainties in XRF analysis. They give additional considerations for lowering the detection limit and improving spectral data quality.

Biometry↗
PubMed2003

Corrections to "How to calculate lead concentration and concentration uncertainty in XRF in vivo bone lead analysis" by Kondrashov and Rothenberg.

Kondrashov and Rothenberg (Appl. Radiat. Isot. 55 (2001) 799) have published "a substantial correction for calculating estimates of lead concentration and uncertainty for in vivo X-ray fluorescent bone analysis with Cd-109 source" (sic). Our paper shows that their correction fails to consider two important points that render it (i) a correction to a superseded method and (ii) of limited effect. Also, their approach to a "crude" estimate produces measurement uncertainties that are implausibly small. In order that they not be propagated in the literature, our paper also corrects several misstatements and errors in Kondrashov and Rothenberg.

Analysis of Variance↗
PubMed2005

Lead isotopic composition of fly ash and flue gas residues from municipal solid waste combustors in France: implications for atmospheric lead source tracing.

Fly ash and flue gas residues from eight municipal solid waste combustors (MSWC) in France (1992--93 and 1998/ 2002) were analyzed for their Pb isotopic composition. Fly ashes are more representative of solid residual particles, whereas flue gas residues reflect mostly the composition of gas phases. Both sample types contain hundreds to thousands of micrograms of metals per gram. Leaching experiments showed that metals are present in condensed phases, probably as sulfates and chlorides, and suggest that Cd, Pb, and Zn are highly fractionated from one another during volatilization/condensation processes occurring during combustion. Although all the samples analyzed define a fairly restricted range in Pb isotopic compositions (206Pb/207Pb = 1.148-1.158 and 208Pb/206Pb = 2.101-2.114) compared to other environmental samples, some MSWC produce materials having distinct isotopic compositions, whereas others display very similar ones. Isotopic heterogeneity is also measured between samples from a single MSWC. This is interpreted as resulting from the heterogeneity of the waste source materials. The range of Pb isotopic composition of incinerator materials form a well-defined linear array in the 208Pb/206Pb versus 206Pb/207Pb diagram. This array is compatible with the previously reported European standard pollution (ESP) line and most probably represent the average lead isotopic composition of industrial atmospheric emissions in France, with the following ratios: 206Pb/207Pb = 1.154+/-0.003 and 208Pb/206Pb = 2.107+/-0.003 (1sigma).

Air Pollutants↗
PubMed2000

Lead(II)-binding properties of the 5'-monophosphates of adenosine (AMP2-), inosine (IMP2-), and guanosine (GMP2-) in aqueous solution. Evidence for nucleobase-lead(II) interactions.

The stability constants of the 1:1 complexes formed between Pb2+ and the nucleosides (Ns), adenosine and guanosine, as well as between the nucleotides (NMP2-), AMP2-, IMP2-, and GMP2-, were determined by potentiometric pH titrations in aqueous solution (25 degrees C; I = 0.1 M, NaNO3). Based on previously established log KPb(R-PO3)Pb versus pKH(R-PO3)H straight-line plots (R-PO3(2-) = simple phosphate monoester or phosphonate ligands where R is a noninteracting site), it is shown that the Pb(IMP) and Pb(GMP) complexes are more stable than is expected on the basis of the basicity of the phosphate group of IMP2- and GMP2-. This means that macrochelates are formed, where the phosphate-coordinated Pb2+ also interacts with N7 of the nucleobase residue. In contrast, the stability of the Pb(AMP) complex is governed by the basicity of the AMP2- phosphate group. These results agree with the observations made for the Pb(Ns)2+ complexes: Pb(adenosine)2+ is very unstable in contrast to Pb(guanosine)2+, the stability of which is very similar to the one of Pb(cytidine)2+ studied previously. The stability constants of the Pb(Ns)2+ complexes also allowed an evaluation of the structure in solution of the monoprotonated Pb(H;NMP)+ complexes, the stabilities of which were also determined. We were able to show that the proton is located at the phosphate group and Pb2+ at the N7/(C6)O site of H(GMP)-; in the case of H(AMP)- Pb2+ is probably about equally distributed between the adenine residue and the monoprotonated phosphate group. On the basis of the stability constants of these complexes and their structures in solution, it is possible to provide a series which reflects the decreasing affinity for Pb2+ of nucleobase residues in single-stranded nucleic acids: guanine approximately equal to cytosine > (hypoxanthine) > adenine > uracil approximately equal to thymine. The Pb2+ affinity of the phosphodiester linkage, -PO3(-)-, is similar to the one of the adenine residue, but is expected to be more significant due to its larger abundance. The relevance of these results for lead-activated ribozymes is briefly discussed.

Adenosine Monophosphate↗