Whole Blood Lead Concentrations Research Articles

Estrogen-Containing Contraceptive Use and Blood Lead Concentrations in a Cohort of Young Women [ID 2683459

INTRODUCTION: Toxic metal lead is stored in the skeleton and, with increased bone turnover, is mobilized to systemic circulation. Given the bone-conserving properties of estrogens, we hypothesized that current users of estrogen-containing contraception would have lower blood lead concentrations. METHODS: We conducted a cross-sectional analysis using baseline data from the Study of Environment, Lifestyle & Fibroids (SELF). During 2010–2012 (baseline), 1,693 self-identified Black women, ages 23–35, enrolled. Data on contraceptive use were ascertained by interview. We quantified lead concentrations in whole blood using inductively coupled plasma mass spectrometry (ICP-MS). Among 1,555 participants, we estimated the percent difference in blood lead concentrations and 95% CIs between current users and nonusers of estrogen-containing contraception using multivariable linear regression, adjusting for potential confounders. RESULTS: The geometric mean blood lead concentrations for estrogen-containing contraceptive users and nonusers were 0.41 micrograms/dL (95% CI: 0.39, 0.43) and 0.51 micrograms/dL (95% CI: 0.50, 0.52), respectively. After adjustment, current use of estrogen-containing contraception was associated with 10% lower blood lead concentrations (95% CI: −15%, −4%). Considering estrogen-containing contraceptive type, compared to nonusers, combined oral contraceptive users (n=187) had 9% lower blood lead concentrations (95% CI: −15%, −2%) and vaginal ring/transdermal patch users (n=33) had 17% lower blood lead concentrations (95% CI: −29%, −4%). CONCLUSION: As hypothesized, we observed lower blood lead concentrations with current use of estrogen-containing contraception. Further research is warranted to confirm the results and to understand the relationship between lead exposure, hormonal contraception, and bone health to limit systemic lead exposure.

Blood lead concentration and exposure related factors in Korea from the National Environmental Health Survey (KoNEHS) II (2012–2014)

This study evaluated lead concentrations in blood and related factors among the South Korean population based on data from the Korea National Environmental Health Survey (KoNEHS) II (2012–2014) conducted by the National Institute of Environmental Research and the Ministry of Environment. Personal data were obtained from non-institutionalized civilian Korean individuals in an interview with trained community surveyors using a structured questionnaire (n = 6,455, aged 19 or older, mean age 49.7 years). The lead concentrations in whole blood were analyzed by atomic absorption spectrophotometry (AAS) with a Zeeman-effect-based background corrector. The precision and accuracy of the analytical methods were verified by internal and external quality controls (G-EQUAS, Germany). Statistical analysis was performed using weighted KoNEHS II data separated by sex, and the lead concentration was expressed as a geometric mean (GM). Multiple linear regression was performed using the SPSS 23.0 software package (SPSS Inc., Chicago, IL, USA). The total GM of lead concentrations was 19.5 µg/L. Lead concentrations increased with age and were higher in males (22.8 µg/L) than in females (16.6 µg/L). Smokers and drinkers had higher concentrations than non-smokers and non-drinkers of both sexes. People who used herbal medications had higher concentrations than those who did not among females. People of both sexes living in rural areas had higher lead concentrations than those in urban areas. Lead concentrations also varied with educational level, total family income, the type of water regularly consumed, and occupation. The average lead concentration of the general adult population in Korea has rapidly decreased over time from 45.8 µg/L (1999) to 19.45 µg/L (2012–2014); however, it remains higher than that of the United States, Germany, and Canada. The factors significantly related to lead concentration in South Korea were age, sex, smoking and alcohol drinking status, herbal medication usage by females, residential area, drinking water at home, and occupation. These factors could be used to improve occupational and environmental hygiene among the Korean population.

Blood Lead, Cadmium and Zinc Correlations in Elderly Rural Residents.

Combined exposure to heavy metals could be expected among residents of two villages in Stara Zagora Municipality due to significant pollution sources in the region, confirmed by increased heavy metal concentrations in plant samples identified by previous studies. The risk is increased for retired villagers who consume food produced in their own farms. To determine blood levels of lead, cadmium and zinc and the correlation between them in high-risk elderly rural inhabitants in comparison with a control group. Lead, cadmium and zinc concentrations in whole venous blood were measured by atomic absorption spectrometry in exposed and in control groups adjusted by sex, age, smoking habit, lifestyle and duration of residence in the settlements. Blood values of lead and cadmium in the exposed group were significantly higher than these in the control group (p<0.001). A statistically significant positive correlation between lead and cadmium blood levels was estimated for the exposed group (ρ=0.39, p=0.023). Blood zinc levels correlated negatively with both lead (ρ=-0.41, p=0.015) and cadmium blood levels (ρ=-0.44, p=0.009). No correlations between the studied metals were found in the control group. The observed results could be explained by a long-term combined exposure to lead and cadmium in the studied elderly residents. The negative correlation of zinc blood levels versus lead and cadmium could be result of competition. Complete protein intake and supplementation with zinc, calcium and iron after control measurements are advisable for elderly rural inhabitants to reduce the health risk from heavy metal exposure.

Antioxidant enzymes status and reproductive health of adult male workers exposed to brick kiln pollutants in Pakistan.

The present study was designed to study the effect of brick kilns emissions on the reproductive health and biochemical status of brick kiln workers and people living in the area near brick kilns. Body mass index (BMI) was significantly reduced in brick makers, carriers, and bakers compared to the control. Red blood cells count and hematocrit (%) were significantly high in brick bakers while MCH was significantly reduced in brick makers and brick bakers. Heavy metals (lead, cadmium, and chromium) concentration in whole blood of the brick kiln workers were significantly higher as compared to the control. Antioxidant enzymes (CAT, SOD, POD, GSH, and GR) were significantly reduced in brick kiln workers as compared to the control while TBARS level were significantly high in brick bakers as compared to the control. Plasma leutinizing hormone (LH) was significantly high in brick bakers while testosterone concentrations were significantly reduced in brick makers, carriers, and bakers. The present study shows that brick kiln workers and people living in the brick kiln vicinity are exposed to heavy metals and other pollutants that is a serious threat to their health. Alternate technology is needed to be developed and brick kilns should be replaced.

Lead concentrations in whole blood, serum, saliva and house dust in samples collected at two time points (12 months apart) in Santo Amaro, BA, Brazil

Whole Blood Lead Level (BLL) is the main marker used to verify lead contamination. The present study explores how BLL is associated with lead concentrations in serum, saliva and house dust. Samples were collected twice from Santo Amaro, BA, Brazil, a region that was contaminated by a lead smelter in the past; a time interval of 12 months was allowed between the two collections. It is noteworthy that the following measures have recently been taken to diminish exposure of the population to lead: streets have been paved with asphalt, and educational campaigns have been launched to reduce exposure to contaminated dust.Results: Compared with the first time point, all the samples collected at the second time point contained lower lead concentration (p<0.05), which suggested that the adopted measures effectively reduced exposure of the population to lead present in contaminated soil and dust. Statistically significant correlations only existed between lead in blood collected in the first year and lead in blood collected in the second year (Spearman's r=0.55; p<0.0001; n=62), and lead in house dust collected in the first year and lead in house dust collected in the second year (Spearman's r=0.5; p<0.0001; n=59).Conclusions: Results support the validity of lead determination in blood and in house dust to assess lead exposure over time. However, lead in blood and lead in dust did not correlate with lead in serum or lead in saliva.

The impact of low-level lead toxicity on school performance among children in the Chicago Public Schools: a population-based retrospective cohort study.

BackgroundEnvironmental lead exposure poses a risk to educational performance, especially among poor, urban children. Previous studies found low-level lead exposure was a risk factor for diminished academic abilities, however, this study is distinct because of the very large sample size and because it controlled for very low birth weight and early preterm birth–two factors closely associated with lower academic performance. In this study we examined the association between lead concentration in whole blood (B-Pb) of Chicago Public School (CPS) children and their performance on the 3rd grade Illinois Standard Achievement Tests (ISAT) reading and math scores.MethodsWe examined 58,650 children born in Chicago between 1994 and 1998 who were tested for blood lead concentration between birth and 2006 and enrolled in the 3rd grade at a CPS school between 2003 and 2006. We linked the Chicago birth registry, the Chicago Blood Lead Registry, and 3rd grade ISAT scores to examine associations between B-Pb and school performance.ResultsAfter adjusting for other predictors of school performance including poverty, race/ethnicity, gender, maternal education and very low birth weight or preterm-birth, we found that B-Pbs below 10 μg/dL were inversely associated with reading and math scores in 3rd grade children. For a 5 μg/dL increase in B-Pb, the risk of failing increased by 32% for reading (RR = 1.32, 95%CI = 1.26, 1.39) and math (RR = 1.32, 95%CI = 1.26, 1.39). The effect of lead on reading was non-linear with steeper failure rates at lower B-Pbs. We estimated that 13% of reading failure and 14.8% of math failure can be attributed to exposure to blood lead concentrations of 5 to 9 vs. 0 to 4 μg/dL in Chicago school children.ConclusionsEarly childhood lead exposure is associated with poorer achievement on standardized reading and math tests in the third grade, even at very low B-Pbs. Preventing lead exposure in early childhood is critical to improving school performance.

Tobacco Smoke Exposure During Pregnancy Increases Maternal Blood Lead Levels Affecting Neonate Birth Weight

To assess the effect of lead exposure from cigarette smoke on fetal growth, blood lead concentrations were measured using inductively coupled plasma mass spectrometry in 150 healthy pregnant women. Mean lead concentrations in plasma and whole blood were significantly higher in the smoking group compared with the nonsmoking group in each trimester of pregnancy (p < 0.001). Logistic regression analysis showed the highest impact of the number of cigarettes smoked per day for serum lead concentration (β = 0.238; p < 0.05), while in whole blood, it was duration of smoking before conception (β = 0.297; p < 0.001). Birth weight of the smoking mothers' infants was significantly lower (mean ± SEM, 3,192 ± 50.8 and 3,569 ± 49.6 g, respectively; p < 0.001) and negatively correlated with lead levels in plasma (r = −0.38; p < 0.001) and in whole blood (r = −0.27; p < 0.001). Therefore, it is suggested that smoking during pregnancy increases lead concentrations in maternal blood. Fetal exposure to low doses of lead in utero may be a serious risk factor causing lower birth weight.

Blood Lead Concentration Is Not Altered by High‐Dose Vitamin D Supplementation in Children and Young Adults With HIV

Optimal vitamin D status is known to have beneficial health effects and vitamin D supplements are commonly used. It has been suggested that vitamin D supplementation may increase blood lead in children and adults with previous lead exposure. The objective was to determine the safety regarding lead toxicity during 12 weeks of high-dose vitamin D3 supplementation in children and young adults with human immunodeficiency virus (HIV). Subjects with HIV (8-24 years) were randomized to vitamin D3 supplementation of 4000 or 7000 IU/day and followed at 6 and 12 weeks for changes in serum 25-hydroxy vitamin D (25D) and whole-blood lead concentration. This was a secondary analysis of a larger study of vitamin D3 supplementation in children and adolescents with HIV. In 44 subjects (75% African American), the baseline mean ± standard deviation serum 25D was 48.3±18.6 nmol/L. Fifty percent of subjects had baseline serum 25D <50.0 nmol/L. Serum 25D increased significantly with D3 supplementation during the 12 weeks. No subject had a whole-blood lead >5.0 μg/dL at baseline or during subsequent visits. Whole-blood lead and 25D were not correlated at baseline, and were negatively correlated after 12 weeks of supplementation (P=0.014). Whole-blood lead did not differ between those receiving 4000 and 7000 IU of vitamin D3. High-dose vitamin D3 supplementation and the concomitant increased serum 25D did not result in increased whole-blood lead concentration in this sample of children and young adults living in a northeastern urban city.

Investigation of lead concentrations in whole blood, plasma and urine as biomarkers for biological monitoring of lead exposure

Lead in blood is a major concept in biomonitoring of exposure but investigations of its alternatives are scarce. The aim of the study was to describe different lead biomarkers' variances, day-to-day and between individuals, estimating their fraction of the total variance. Repeated sampling of whole blood, plasma and urine were conducted for 48 lead-exposed men and 20 individuals under normal environmental lead exposure, in total 603 measurements. For lead workers, the fraction of the total variance attributed to differences between individuals was 91% for whole-blood lead (geometric mean 227 μg/l; geometric standard deviation (GSD): 1.55 μg/l); plasma 78% (0.57 μg/l; GSD: 1.84 μg/l); density-adjusted urine 82%; and unadjusted urine 75% (23.7 μg/l; GSD: 2.48 μg/l). For the individuals under normal lead exposure, the corresponding fractions were 95% of the total variance for whole blood (20.7 μg/l; GSD: 8.6 μg/l), 15% for plasma (0.09 μg/l; GSD: 0.04 μg/l), 87% for creatinine-adjusted urine and 34% for unadjusted (10.8 μg/l; GSD: 6.7 μg/l). Lead concentration in whole blood is the biomarker with the best ability to discriminate between individuals with different mean concentration. Urinary and plasma lead also performed acceptably in lead workers, but at low exposures plasma lead was too imprecise. Urinary adjustments appear not to increase the between-individual fraction of the total variance among lead workers but among those with normal lead exposure.

LEAD TOXICITY: CONSEQUENCES AND INTERVENTIONS IN AN INTENSIVELY MANAGED (GYPS COPROTHERES) VULTURE COLONY

The National Zoological Gardens of South Africa (NZG) is involved in the ex situ conservation of Gyps coprotheres, the Cape Griffon vulture (CGV) and houses 24 birds in a 100-yr-old aviary. Following the death of one vulture with high liver lead concentrations, an investigation was launched to ascertain the source(s) and consequences of lead toxicity in this breeding colony. Whole blood from 24 CGV, paint from the enclosure, water, and soil sampled at various locations within the enclosure were evaluated for their lead concentration, and data were gathered from NZG's medical records. The lead concentration in the paint, water, and enclosure soil was 5,100 microg/g, 0.5 microg/dl, and 72.48 +/- 21.83 microg/g, respectively. The whole-blood lead concentrations were 56.58 +/- 11 microg/dl. The breeding history of six pairs within the contaminated enclosure since 2002 showed 45 eggs laid, of which 44% were infertile and 24% successfully reared. The medical records revealed evidence of osteodystrophy despite adequate nutrition. As intervention measures, six birds were treated with Ca2+EDTA and the topsoil inside the enclosure was replaced. As a result, the lead concentration in the enclosure soil dropped to 14.74 +/- 14.39 microg/g, and the whole-blood lead concentrations declined to 42.75 +/- 11.64 microg/dl. It was concluded that lead concentrations in whole blood in excess of 100 microg/dl leads to clinical signs of lead toxicity in the CGV. Lower levels appear to interfere mainly with reproductive potential.

Blood lead levels of contemporary Japanese children

Lead concentrations in whole blood (BPb) of Japanese children were measured to obtain insight into the sources of variation and to estimate health risk. Blood samples were taken from 352 children (aged 1-14 years) at pediatric clinics/hospitals in 3 regions of Japan (Tokyo, Shizuoka, and Osaka) during 2005-2006 (Shizuoka only) and 2008-2010 (3 regions), and BPb was measured by inductively coupled plasma mass spectrometry after acid digestion. Geometric mean BPb of the 352 children was 1.07 μg/dL, among the lowest in the world. Based on this result, the probability of exceeding BPb 10 μg/dL, the action level proposed by the US Centers for Disease Control and Prevention, in general Japanese children was estimated to be negligible. There was a significant negative correlation between BPb and age, while sex difference was not significant. BPb was significantly lower in subjects in Tokyo than in the other two regions. Age-adjusted mean BPb was significantly higher in children with a family member who smoked in their presence than in those who did not have such a family member, indicating that passive smoking had a significant effect on BPb. Health risk of lead exposure is minimal in Japanese children. To lower the exposure level further, reduction of passive smoking is suggested as one of the effective measures.

Comparison of Blood Lead and Blood and Plasma δ-Aminolevulinic Acid Concentrations as Biomarkers for Lead Poisoning in Cattle

Lead (Pb) concentrations in whole blood and δ-aminolevulinic acid (ALA) concentrations in plasma and whole blood from 37 cattle with suspected Pb exposure were determined in order to investigate the usefulness of ALA as a biological indicator for Pb poisoning in cattle. Cows were divided into 4 groups based on blood Pb, as follows: <30ppb (group 1), 30-100ppb (group 2), 100-300ppb (group 3), and >300ppb (group 4). The derivatization reaction for ALA was improved by a greater than 2-fold measure in whole blood and by a 10-fold measure in plasma by adding 75 and 50µl of 0.1N HCl, respectively. Blood Pb concentrations ranged from <25ppb to 1,006ppb (185.5 ± 254.9ppb), with 17 samples containing >50ppb Pb. Delta-aminolevulinic acid concentrations in whole blood and plasma ranged from <62.7ppb to 96.9ppb (77.4 ± 8.4ppb) and from <5.0ppb to 24.0ppb (4.6 ± 3.8ppb), respectively. Whole blood ALA did not correlate with blood lead concentrations in any group. Increase in plasma ALA concentration was dependent on blood Pb concentration. There was no correlation between blood Pb concentration and plasma ALA concentration in group 2 (n = 4), but correlation coefficients were 0.736 in group 3 and 0.807 in group 4, respectively. The correlation coefficient was increased to 0.851 when groups 3 and 4 were combined. Based on these observations, in cattle, plasma ALA is a more reliable biological biomarker for Pb exposure than is blood ALA.

Fluoride increases lead concentrations in whole blood and in calcified tissues from lead-exposed rats

Higher blood lead (BPb) levels have been reported in children living in communities that receive fluoride-treated water. Here, we examined whether fluoride co-administered with lead increases BPb and lead concentrations in calcified tissues in Wistar rats exposed to this metal from the beginning of gestation. We exposed female rats and their offspring to control water (Control Group), 100 mg/L of fluoride (F Group), 30 mg/L of lead (Pb Group), or 100 mg/L of fluoride and 30 mg/L of lead (F + Pb Group) from 1 week prior to mating until offspring was 81 days old. Blood and calcified tissues (enamel, dentine, and bone) were harvested at day 81 for lead and fluoride analyses. Higher BPb concentrations were found in the F + Pb Group compared with the Pb Group (76.7 ± 11.0 μg/dL vs. 22.6 ± 8.5 μg/dL, respectively; p < 0.001). Two- to threefold higher lead concentrations were found in the calcified tissues in the F + Pb Group compared with the Pb Group (all p < 0.001). Fluoride concentrations were similar in the F and in the F + Pb Groups. These findings show that fluoride consistently increases BPb and calcified tissues Pb concentrations in animals exposed to low levels of lead and suggest that a biological effect not yet recognized may underlie the epidemiological association between increased BPb lead levels in children living in water-fluoridated communities.

Disturbances of energetic metabolism in rat epididymal epithelial cells as a consequence of chronic lead intoxication

Adult male Wistar rats were intoxicated with 1% lead acetate (PbAc) administered in drinking water for nine months, which amounts to a period five times longer than the duration of one spermatogenesis. There were mitochondrial ultrastructure disorders of epididymal epithelial cells observed in PbAc-treated rats; also a significant lead-induced decrease in ATP concentration in epididymal epithelial cells (by 32%, P < 0.05), Adenylate Energy Charge value (AEC) (by 8%, P < 0.05) and an increase in ADP (28.5%, P < 0.05), AMP (27%, P < 0.05) and adenosine (by 56%, P < 0.05). The results were measured using high performance liquid chromatography (HPLC) and detected even at low lead concentrations in whole blood (M:7.03 μg/dL; Q1-Q3: 2.99-7.65). The function of mitochondria in cultured epididymal epithelial cells of control and PbAc-treated animals were evaluated using fluorophores: Mitotracker Green FM and JC-1. After incubation with Mitotracker Green FM, we observed active mitochondria producing bright green fluorescence in the cytoplasm of cultured epididymal epithelial cells, both in the control group and the Pb-treated animals. Incubation of cultured epididymal epithelial cells of animals from both groups produced red-orange fluorescence with the mitochondrial JC-1 probe indicating mitochondria with high membrane potential (ΔΨm > 80-100 mV) and green fluorescence in the mitochondria with low membrane potential (ΔΨm < 80 mV). The results showed that a chronic low-level exposure to lead, even without severe clinical symptoms of contamination, disrupted the ultrastructure and energy metabolism of mitochondria in epididymal epithelial cells.

Cadmium, Lead, and Selenium in Cord Blood and Thyroid Hormone Status of Newborns

Cadmium (Cd), lead (Pb), and selenium (Se) concentrations in cord whole blood, sampled from 24 women at the time of delivery in a hospital in Tokyo in 2005, were determined by inductively coupled plasma mass spectrometry with a reaction cell. Signal enhancement caused by nonspectroscopic interference for Se was evident and the standard addition technique was essential for correcting the interference. Median concentration in cord bloods was 0.20 ng/g, 6.7 ng/g (0.67 microg/dL), and 191 ng/g for Cd, Pb and Se, respectively. Lead concentration was lower, whereas Se concentration was higher, than those reported in other countries. The trace element concentration was related to the levels of thyroid stimulating hormone (TSH) and free thyroxin (fT4) in the neonatal blood sampled at 4-6 days postpartum. A significantly negative correlation was observed between Cd concentrations in cord blood and TSH concentration in neonatal blood. The result indicated the possible effect of in utero Cd exposure on thyroid hormone status of newborns and that Cd exposure level should be assessed as a covariate in the survey on the relationship between in utero chemicals (e.g., PCBs) exposure and thyroid hormone status.

Recommendations for medical management of adult lead exposure.

Research conducted in recent years has increased public health concern about the toxicity of lead at low dose and has supported a reappraisal of the levels of lead exposure that may be safely tolerated in the workplace. In this article, which appears as part of a mini-monograph on adult lead exposure, we summarize a body of published literature that establishes the potential for hypertension, effects on renal function, cognitive dysfunction, and adverse female reproductive outcome in adults with whole-blood lead concentrations < 40 μg/dL. Based on this literature, and our collective experience in evaluating lead-exposed adults, we recommend that individuals be removed from occupational lead exposure if a single blood lead concentration exceeds 30 μg/dL or if two successive blood lead concentrations measured over a 4-week interval are ≥ 20 μg/dL. Removal of individuals from lead exposure should be considered to avoid long-term risk to health if exposure control measures over an extended period do not decrease blood lead concentrations to < 10 μg/dL or if selected medical conditions exist that would increase the risk of continued exposure. Recommended medical surveillance for all lead-exposed workers should include quarterly blood lead measurements for individuals with blood lead concentrations between 10 and 19 μg/dL, and semiannual blood lead measurements when sustained blood lead concentrations are < 10 μg/dL. It is advisable for pregnant women to avoid occupational or avocational lead exposure that would result in blood lead concentrations > 5 μg/dL. Chelation may have an adjunctive role in the medical management of highly exposed adults with symptomatic lead intoxication but is not recommended for asymptomatic individuals with low blood lead concentrations.

A critical review of biomarkers used for monitoring human exposure to lead: advantages, limitations and future needs

Lead concentration in whole blood (Blood-Pb) is the primary biomarker used to monitor exposure to this metallic element. However, the difficulty in assessing the exact nature of Pb exposure is dependent not so much on problems with current analytical methodologies, but rather on the complex toxicokinetics of Pb within various body compartments. If we are to differentiate more effectively between Pb that is stored in the body for years and Pb from recent exposure, information on other biomarkers of exposure may be needed. None of the current biomarkers of internal Pb dose has yet been accepted by the scientific community as a reliable substitute for a Blood-Pb measurement. This review focuses on the limitations of biomarkers of Pb exposure, and the need to improve the accuracy of their measurement. We present here only the traditional analytical protocols in current use and we attempt to assess the influence of confounding variables on Blood-Pb levels. Finally, we discuss the interpretation of Blood-Pb data with respect to both external and endogenous Pb exposure, past or recent exposure, as well as the significance of lead determinations in human specimens including hair, nails, saliva, bone, blood, urine, feces, and exfoliated teeth.

A Critical Review of Biomarkers Used for Monitoring Human Exposure to Lead: Advantages, Limitations, and Future Needs

Lead concentration in whole blood (BPb) is the primary biomarker used to monitor exposure to this metallic element. The U.S. Centers for Disease Control and Prevention and the World Health Organization define a BPb of 10 μg/dL (0.48 μmol/L) as the threshold of concern in young children. However, recent studies have reported the possibility of adverse health effects, including intellectual impairment in young children, at BPb levels < 10 μg/dL, suggesting that there is no safe level of exposure. It appears impossible to differentiate between low-level chronic Pb exposure and a high-level short Pb exposure based on a single BPb measurement; therefore, serial BPb measurements offer a better estimation of possible health outcomes. The difficulty in assessing the exact nature of Pb exposure is dependent not so much on problems with current analytical methodologies, but rather on the complex toxicokinetics of Pb within various body compartments (i.e., cycling of Pb between bone, blood, and soft tissues). If we are to differentiate more effectively between Pb stored in the body for years and Pb from recent exposure, information on other biomarkers of exposure may be needed. None of the current biomarkers of internal Pb dose have yet been accepted by the scientific community as a reliable substitute for a BPb measurement. This review focuses on the limitations of biomarkers of Pb exposure and the need to improve the accuracy of their measurement. We present here only the traditional analytical protocols in current use, and we attempt to assess the influence of confounding variables on BPb levels. Finally, we discuss the interpretation of BPb data with respect to both external and endogenous Pb exposure, past or recent exposure, as well as the significance of Pb determinations in human specimens including hair, nails, saliva, bone, blood (plasma, whole blood), urine, feces, and exfoliated teeth.

IRON STORAGE DISEASE IN CAPTIVE EGYPTIAN FRUIT BATS (ROUSETTUS AEGYPTIACUS): RELATIONSHIP OF BLOOD IRON PARAMETERS TO HEPATIC IRON CONCENTRATIONS AND HEPATIC HISTOPATHOLOGY

This study evaluated the relationship between blood iron parameters and hepatic iron concentrations, and correlation of histologic findings with hepatic iron concentrations in a captive population of Egyptian fruit bats (Rousettus aegyptiacus) and island flying foxes (Pteropus hypomelanus). Blood samples were collected for complete blood counts, plasma biochemical profiles, serum iron concentrations, total iron-binding capacity, whole-blood lead concentrations, and plasma ferritin assays. Liver samples obtained by laparotomy were divided, with one half processed for histologic examination and the other half frozen and submitted for tissue mineral analysis. The histologic sections were scored by two blinded observers for iron deposition, necrosis, and fibrosis. The Egyptian fruit bats had significantly higher liver iron (mean = 3,669 +/- 1,823 ppm) and lead (mean = 8.9 +/- 5.8 ppm) concentrations than the island flying foxes (mean [Fe] = 174 +/- 173 ppm, mean [Pb] = 1.9 +/- 0.5 ppm). Hepatic iron concentrations significantly correlated with tissue lead concentrations, histologic grading for iron and necrosis, serum iron, transferrin saturation, and plasma ferritin (P < 0.001). Blood lead concentrations negatively correlated with tissue lead concentrations (P < 0.001). When the product of transferrin saturation and serum iron was greater than 51, an individual animal had a high probability of having iron overload. When the product of these two variables was greater than 90, there was a high probability that the animal had hemochromatosis. On the basis of this study, it appears that evaluation of serum iron, transferrin saturation, and plasma ferritin are useful and noninvasive methods for diagnosis of hemochromatosis in Egyptian fruit bats.

Lead in finger bone, whole blood, plasma and urine in lead-smelter workers: extended exposure range

To assess the historical exposure and to study the relationships between lead concentrations in whole blood (B-Pb), plasma (P-Pb), urine (U-Pb), finger bone (Bone-Pb) and duration of employment in workers at a secondary lead smelter and to compare the relationships between B-Pb and P-Pb with results from previous studies of populations with a wide range of lead exposure. In 39 lead workers (29 active, ten retired), recruited from those with the highest exposure at a German secondary lead smelter, levels of B-Pb, P-Pb and U-Pb were determined by inductively coupled plasma mass spectrometry (ICP-MS). Bone-Pb was determined by in vivo X-ray fluorescence (XRF). Results were compared with data from a previous study on 90 workers (71 active, 19 retired) with lower exposure, from a Swedish secondary lead smelter, as well as with previously collected data from 42 active Russian lead workers and 34 Ecuadorian lead-exposed subjects. The median values in the active/retired German lead workers were: age 44/59 years, duration of employment 20/38 years, Bone-Pb 71/150 microg/g, B-Pb 500/330 microg/l, P-Pb 2.7/1.1 microg/l, and U-Pb 25/13 micromol/mol creatinine. Bone-Pb increased with duration of employment by 4.2 microg/g per year and 1.6 microg/g per year in German and Swedish workers, respectively. The median Bone-Pb was three times higher in both active and retired German workers than in Swedish smelter workers with essentially the same age distribution and duration of employment. The linear regression equation between B-Pb and log P-Pb in the combined group of Ecuadorian, German, Russian and Swedish lead-exposed subjects (n=176) was B-Pb=545 x log[P-Pb] + 258 (r(s)=0.94; P<0.001). The high Bone-Pb values recorded for the German smelters implied a historical lead exposure of considerable magnitude. The long-term high lead exposure also showed up in the B-Pb levels for both active and retired workers, leading to the implementation of necessary industrial safety measures in order to respond to biological threshold limits. The suggested equation describing the relationship between B-Pb and P-Pb in the combined group of subjects with a wide range of lead exposure can be useful in future cross-sectional and longitudinal studies of lead-exposed populations, relating, e.g., lead exposure to adverse health outcomes.