Evaluación biológica de la exposición laboral al plomo / Biological assessment of the work-related exposure to lead

Introducción: El plomo, por su amplio uso causa una gran contaminación ambiental y problemas de salud en muchas partes del mundo. La Organización Mundial de la Salud incluyó el plomo dentro de una lista de diez productos químicos causantes de graves efectos sobre la salud. Objetivo: Evaluar los niveles de plomo en sangre y de protoporfirina libre eritrocitaria en un grupo de trabajadores expuestos a plomo inorgánico. Métodos: Estudio descriptivo de corte transversal donde se evaluaron 776 casos que acudieron a los laboratorios del Instituto Nacional de Salud de los Trabajadores en el año 2018, provenientes de diferentes sectores industriales. Se les realizó la determinación de plomo en sangre a 288 y la de protoporfirina a 488, según métodos establecidos en el laboratorio. Los datos obtenidos fueron procesados utilizando Microsoft Excel® y el paquete estadístico Statgraphics Centurion XVI.II. Resultados: El 92 por ciento de los pacientes fue del sexo masculino. La concentración de plomo en sangre osciló entre 5 µg/dL y 89 µg/dL para un promedio en hombres de 24 µg/dL ± 21 µg/dL y en las mujeres de 11 µg/dL ± 9 µg/dL. Para la protoporfirina, esta fluctuó entre 21 µg/dL y 274 µg/dL, con un promedio de 47 µg/dL ± 22 µg/dL en hombres y 66 µg/dL ± 32 µg/dL en las mujeres. El 8 por ciento de los casos evaluados tuvo valores de plomo en sangre mayores de 60 µg/dL y para la protoporfirina el 5 por ciento de los casos presentaron valores por encima de 85 μg/dL. Conclusiones: Algunos casos evaluados presentaron niveles elevados de plomo que superan los límites permitidos, lo que pone en evidencia la necesidad de reforzar las medidas de protección aplicadas a los trabajadores y la importancia de detectar precozmente el problema en el ámbito laboral, antes de que aparezcan repercusiones derivadas de una intoxicación por plomo(AU)

Introduction: Lead, due to its large use, causes a major environmental pollution and health problems in many places around the world. The World Health Organization included lead in a list of ten chemical products causing severe effects in health. Objective: To assess lead levels in blood and free-erythtocyte protoporphyrin (FEP) levels in groups of workers exposed to inorganic lead. Methods: Descriptive. cross-sectional study where 776 cases coming from different industrial sectors were assessed in the laboratories of the National Institute of Workers Health in the year 2018. It was conducted to 288 of the cases a test to determine if there was lead in blood and a test for FEP to 488 cases, according to the methods established in the laboratory. The data collected were processed using Microsoft Excel® and the statistical program called Statgraphics Centurion XVI.II. Results: 92 percent of the patients were males. Lead concentration in blood ranged from 5 µg/dL and 89 µg/dL, for an average in men of 24 µg/dL ± 21 µg/dL, and in women of 11 µg/dL ± µg/dL. FEP concentration swung from 21 µg/dL to 274 µg/dL, with an average of 47 µg/dL ± 22 µg/dL in men, and 66 µg/dL ± 32 µg/dL in women. 8 percent of the assessed cases presented values of lead in blood higher than 60 µg/dL and for FEP, 5 percent of the cases presented values higher than 85 µg/dL. Conclusions: Some of the assessed cases presented high levels of lead which exceed the permitted levels; so, this demonstrates the need of reinforzing the protection measures applied to the workers and the importance of early detecting this problem in work-related environments prior to the onset of repercutions derived from lead poisoning(AU)

Laboratory and genetic assessment of iron deficiency in blood donors.

More than 9 million individuals donate blood annually in the United States. Between 200 and 250 mg of iron is removed with each whole blood donation, reflecting losses from the hemoglobin in red blood cells. Replenishment of iron stores takes many months, leading to a high rate of iron depletion. In an effort to better identify and prevent iron deficiency, blood collection centers are now considering various strategies to manage donor iron loss. This article highlights laboratory and genetic tests to assess the iron status of blood donors and their applicability as screening tests for blood donation.

Toxicity of Pb-contaminated soil to Japanese quail (Coturnix japonica) and the use of the blood-dietary Pb slope in risk assessment.

This study relates tissue concentrations and toxic effects of Pb in Japanese quail (Coturnix japonica) to the dietary exposure of soil-borne Pb associated with mining and smelting. From 0% to 12% contaminated soil, by weight, was added to 5 experimental diets (0.12 to 382 mg Pb/kg, dry wt) and fed to the quail for 6 weeks. Benchmark doses associated with a 50% reduction in delta-aminolevulinic acid dehydratase activity were 0.62 mg Pb/kg in the blood, dry wt, and 27 mg Pb/kg in the diet. Benchmark doses associated with a 20% increase in the concentration of erythrocyte protoporphyrin were 2.7 mg Pb/kg in the blood and 152 mg Pb/kg in the diet. The quail showed no other signs of toxicity (histopathological lesions, alterations in plasma-testosterone concentration, and body and organ weights). The relation of the blood Pb concentration to the soil Pb concentration was linear, with a slope of 0.013 mg Pb/kg of blood (dry wt) divided by mg Pb/kg of diet. We suggest that this slope is potentially useful in ecological risk assessments on birds in the same way that the intake slope factor is an important parameter in risk assessments of children exposed to Pb. The slope may also be used in a tissue-residue approach as an additional line of evidence in ecological risk assessment, supplementary to an estimate of hazard based on dietary toxicity reference values.

Echocardiographic assessment of myocardial function in workers occupationally exposed to lead without clinically evident heart disease.

PURPOSE: The aim of the study was to evaluate echocardiographic changes in workers occupationally exposed to low doses of lead. METHODS: We enrolled 63 men occupationally exposed to lead into the study (group I). Unexposed group consisted of 49 healthy men (group II). Blood lead concentration (Pb-B) and blood zinc protoporphyrin concentration (ZnPP) were determined. Transthoracic echocardiographic examination was performed. RESULTS: In the studied groups, selected on the criterion of occupational exposure to lead, comparative analysis of echocardiographic parameters indicated statistically significant differences. A negative linear correlations between ZnPP and E' was observed in group I. It was proved that a higher concentration of ZnPP is independent risk factor of lowering the E' mean value in group I. CONCLUSIONS: Occupational exposure to low doses of lead is associated with the occurrence of discreet morphological and functional heart changes that in the future may predispose to disclosed pathology of heart.

Zinc protoporphyrin levels have added value in the prediction of low hemoglobin deferral in whole blood donors.

BACKGROUND: Increased zinc protoporphyrin (ZPP) levels can indicate iron deficiency and may be predictive for low hemoglobin (Hb) deferral in blood donors. Prediction models for Hb deferral in whole blood donors have already been developed. In this study, we examined if addition of ZPP to these prediction models improves risk estimation of Hb deferral. STUDY DESIGN AND METHODS: This study included 4598 Dutch whole blood donors. Information on ZPP levels measured at the previous visit was added to the existing prediction models to estimate the risk of Hb deferral. Models were compared using the following measures: concordance (c)-statistic, continuous net reclassification improvement (NRI), and clinical net benefit (NB). RESULTS: Seventy-six male donors (2.9%) and 69 female donors (3.5%) were deferred because of a low Hb level. Previous ZPP level was associated with risk of Hb deferral (odds ratio for interquartile range of previous ZPP level, men 2.0 [95% confidence interval {CI}, 1.7-2.3]; women 2.2 [95% CI, 1.9-2.4]) in a multivariable risk model. Addition of ZPP into the models resulted in an increase of the c-statistic from 0.93 to 0.94 for men and from 0.80 to 0.85 for women. The added value of ZPP was confirmed by measures of clinical usefulness. NRI for men was 0.42, and for women, 0.56. At relevant threshold probabilities between 10 and 15%, NB was higher for models considering ZPP. CONCLUSION: This study shows that ZPP measurements obtained at the previous visit may have added value in the risk prediction of Hb deferral in whole blood donors.

Assessment of cardiovascular risk in workers occupationally exposed to lead without clinical presentation of cardiac involvement.

PURPOSE: The objective of this study was to assess, with aid of SCORE system, of 10-year risk of fatal cardiovascular incidents among workers occupationally exposed to lead, without circulatory system disorders. METHODS: The studies included 83 men (mean age: 55.14±4.62 years): the 1st group consisted of persons occupationally exposed to lead (group I, n=40), and 2nd group - persons not exposed to lead (group II, n=43). 10-Year risk of fatal cardiovascular incidents was assessed with application of SCORE risk chart designed for Polish population. RESULTS: In the first group, mean values of SCORE calculated on the basis of the chart including total cholesterol concentration in serum were significantly higher. Also, there were significantly higher: mean values of SCORE calculated on the basis of the chart including total cholesterol to HDL cholesterol ratio, mean values of relative SCORE, percentage of individuals with risk estimated as increased, percentage of individuals with risk estimated as significantly increased. Simultaneously, the significantly lower percentage of individuals with risk estimated as small or moderate was found in the occupationally exposed subjects. CONCLUSIONS: Persons occupationally exposed to lead compounds are burdened with significantly higher 10-year risk of fatal cardiovascular incident than individuals from the same population not exposed to lead.

Assessment of semen function and lipid peroxidation among lead exposed men.

The study population included healthy, fertile men, employees of Zinc and Lead Metalworks (n=63). Workers exposed to lead were divided into two groups: a group with moderate exposure to lead (ME) - blood lead level (PbB) 25-40 microg/dl and a group with high exposure to lead (HE) PbB=40-81 microg/dl. The control group consisted of office workers with no history of occupational exposure to lead. Evaluation of lead, cadmium and zinc level in blood and seminal plasma, zinc protoporphyrin in blood (ZPP), 5-aminolevulinic acid in urine (ALA), malondialdehyde (MDA) in seminal plasma and sperm analysis were performed. No differences were noted in the concentration of cadmium and zinc in blood and seminal plasma in the study population. Lipid peroxidation in seminal plasma, represented as MDA concentration, significantly increased by about 56% in the HE group and the percentage of motile sperm cells after 1 h decreased by about 34% in comparison to the control group. No statistically significant correlation between other parameters of sperm analysis and lead exposure parameters nor between lead, cadmium and zinc concentration in blood and seminal plasma were found. A positive association between lead intoxication parameters (PbB, ZPP, lead seminal plasma) and MDA concentration in sperm plasma and inverse correlation with sperm cells motility (PbB, ZPP) was found. An increased concentration of MDA was accompanied by a drop in sperm cells motility. In conclusion, we report that high exposure to lead causes a decrease of sperm motility in men most likely as a result of increased lipid peroxidation, especially if the level in the blood surpasses the concentration of 40 microg/dl.

Nutritional assessment of iron status and anemia in children under 5 years old at public daycare centers.

OBJECTIVES: To assess nutritional iron status and anemia prevalence in children less than 5 years old at public daycare centers in the city of Recife, PE, Brazil. METHODS: A cross-sectional study, with a systematic random sampling of 162 children aged 6 to 59 months. Nutritional iron status was assessed in terms of body iron reserves (serum ferritin), transferrinemia (serum iron, total iron binding capacity, and transferrin saturation %), erythropoiesis (free erythrocyte protoporphyrin) and hemoglobin production (hemoglobin). RESULTS: The prevalence of anemia (hemoglobin < 11.0 g/dL) was 55.6% (95%CI 47.3-63.5), evidence was found of depleted iron stocks (serum ferritin < 12.0 ng/mL) in 30.8% (95%CI 22.9-39.3), low transferrinemia levels (transferrin saturation % < 16) in 60.1% (95%CI 51.7-68.0) and deficient erythropoiesis (free erythrocyte protoporphyrin > 40 micromol/mol heme) in 69.6% (95%CI 61.0-77.1) of the children. Iron parameters were not correlated with sex (p > 0.05). However, children < 24 months exhibited lower hemoglobin concentrations (p < 0.00) and higher levels of free erythrocyte protoporphyrin (p < 0.000) and total iron binding capacity (p < 0.001) when compared with children > 24 months. The significant correlation observed between reserves, transferrinemia and erythropoiesis is a finding that is compatible with the expected lifecycle of iron in the body. CONCLUSIONS: Iron deficiency and anemia appear to be an important public health problem among children less than 5 years old at public daycare centers in Recife. Therefore, effective actions aimed at the prevention and control of this deficiency are strongly recommended in this ecological context.

Avaliação do estado nutricional de ferro e anemia em crianças menores de 5 anos de creches públicas / Nutritional assessment of iron status and anemia in children under 5 years old at public daycare centers

OBJETIVO: Avaliar o estado nutricional de ferro e a prevalência de anemia em crianças menores de 5 anos de creches públicas da cidade do Recife (PE). MÉTODOS: Estudo transversal, com amostra aleatória sistemática de 162 crianças, de 6 a 59 meses. O estado nutricional de ferro foi avaliado em termos de reservas corporais (ferritina sérica), transferrinemia (ferro sérico, capacidade total de ligação do ferro e por cento de saturação da transferrina), eritropoiese (protoporfirina eritrocitária livre) e hemoglobinogênese (hemoglobina). RESULTADOS: A prevalência de anemia (hemoglobina < 11,0 g/dL) foi de 55,6 por cento (IC95 por cento 47,3-63,5), a redução dos estoques de ferro (ferritina sérica < 12,0 ng/mL) foi evidenciada em 30,8 por cento (IC95 por cento 22,9-39,3), baixa transferrinemia ( por cento de saturação da transferrina < 16) em 60,1 por cento (IC95 por cento 51,7-68,0) e eritropoiese deficiente (protoporfirina eritrocitária livre > 40 æmol/mol heme) em 69,6 por cento (IC95 por cento 61,0-77,1) das crianças. Os parâmetros de ferro não apresentaram correlação com o gênero (p > 0,05). No entanto, crianças < 24 meses apresentaram concentrações mais baixas de hemoglobina (p < 0,00) e níveis mais elevados de protoporfirina eritrocitária livre (p < 0,000) e de capacidade total de ligação do ferro (p < 0,001), quando comparadas às crianças > 24 meses. A significante correlação observada entre reserva, transferrinemia e eritropoiese representa achado compatível com o esperado ciclo de vida do ferro no organismo. CONCLUSÕES: A deficiência de ferro e a anemia parecem ser um importante problema de saúde pública entre as crianças menores de 5 anos de creches públicas do Recife. Logo, ações efetivas direcionadas à prevenção e ao controle dessa deficiência são fortemente recomendadas nesse contexto ecológico.

OBJECTIVE: To assess nutritional iron status and anemia prevalence in children less than 5 years old at public daycare centers in the city of Recife, PE, Brazil. METHODS: A cross-sectional study, with a systematic random sampling of 162 children aged 6 to 59 months. Nutritional iron status was assessed in terms of body iron reserves (serum ferritin), transferrinemia (serum iron, total iron binding capacity, and transferrin saturation percent), erythropoiesis (free erythrocyte protoporphyrin) and hemoglobin production (hemoglobin). RESULTS: The prevalence of anemia (hemoglobin < 11.0 g/dL) was 55.6 percent (95 percentCI 47.3-63.5), evidence was found of depleted iron stocks (serum ferritin < 12.0 ng/mL) in 30.8 percent (95 percentCI 22.9-39.3), low transferrinemia levels (transferrin saturation percent < 16) in 60.1 percent (95 percentCI 51.7-68.0) and deficient erythropoiesis (free erythrocyte protoporphyrin > 40 æmol/mol heme) in 69.6 percent (95 percentCI 61.0-77.1) of the children. Iron parameters were not correlated with sex (p > 0.05). However, children < 24 months exhibited lower hemoglobin concentrations (p < 0.00) and higher levels of free erythrocyte protoporphyrin (p < 0.000) and total iron binding capacity (p < 0.001) when compared with children > 24 months. The significant correlation observed between reserves, transferrinemia and erythropoiesis is a finding that is compatible with the expected lifecycle of iron in the body. CONCLUSIONS: Iron deficiency and anemia appear to be an important public health problem among children less than 5 years old at public daycare centers in Recife. Therefore, effective actions aimed at the prevention and control of this deficiency are strongly recommended in this ecological context.

Iron assessment tests: transferrin receptor vis-à-vis zinc protoporphyrin.

OBJECTIVES: To review and compare the biochemical, analytical, and clinical features of two relatively new tests for assessing iron status and diagnosing iron disorders, namely, the serum transferrin receptor concentration (sTfR) and the erythrocyte zinc protoporphyrin/heme ratio (ZnPP/H). To consider the merits of each test for the diagnosis of iron disorders with emphasis on iron-deficient erythropoiesis, especially in the clinically important preanemia stage of iron depletion. CONCLUSIONS: Although the basic biochemical mechanisms underlying the two tests are very different, both of these tests are noteworthy because they are considered to reflect iron status in the bone marrow. The principal advantage to serum transferrin receptor is the lack of a response to anemia of chronic disease (ACD), which affects other iron status indicators, for example, ferritin and transferrin saturation. The principal advantage to erythrocyte zinc protoporphyrin is low cost, but point-of-care testing and simplicity can also be advantages. Both serum transferrin receptor and erythrocyte zinc protoporphyrin have been demonstrated to be useful in a variety of clinical situations. Serum transferrin receptor can be best used in diagnosing iron disorders, especially for patients with pathologies that may affect iron metabolism. Erythrocyte zinc protoporphyrin can be best used as a primary screening test for assessing iron status, especially in patients likely to have uncomplicated iron deficiency. While these applications are primary, both tests are more broadly useful, for example, in monitoring iron therapy.

[Economic assessment of iron deficiency. Replacement of ferritin and serum iron by other parameters]. / Mise en évidence économique d'une déficience en fer. Relève de la ferritine et du fer sérique par d'autres paramètres.

Economic assessment of iron deficiency. Replacement of serum iron and ferritin by other parameters. Serum iron and ferritin are still widely used parameters for the assessment of iron deficiency, in spite of their poor diagnostic performance. Compared to the combined use of ferritin, zinc protoporphyrin and soluble transferrin receptors an increase of the percentage of hypochromic erythrocytes (PEH) was found to be highly sensitive and specific for iron deficiency. We suggest to use it in a two phase strategy. Normal PEH excludes iron deficiency. Increased PEH may be confirmed by zinc protoporphyrin and/or soluble transferrin receptors.

[Re-assessment of indicators for screening lead poisoning].

OBJECTIVE: To determine the accuracy of the indicators for detecting lead poisoning. METHODS: Blood and urine specimens in 157 workers exposed to lead were collected. Their blood levels of lead, free erythrocyte protoporphyrin (FEP), zinc protoporphyrin (ZPP), urine delta-aminolevulinic acid and activity of red cell pyrimidine 5'-nucleotidase were determined, with gold standards of blood lead levels of >or= 1.93 micromol/L and >or= 2.90 micromol/L. Accuracy assessment of the indicators mentioned above for detecting lead poisoning was based on the area under the receiver operative characteristic (AUC(ROC)) curve with a software specially for ROC curve analysis and software of Epi-Info, after determining the optimal cut-off points for the above mentioned indicators in detecting those with blood lead >or= 1.93 micromol/L and >or= 2.90 micromol/L. The sensitivity of screening in parallel for detecting those with blood lead >or= 1.93 micromol/L and >or= 2.90 micromol/L was calculated and compared. RESULTS: For detecting those with blood lead level >or= 1.93 micromol/L, the area under ROC curve (AUC(ROC)) of above indicators was 0.978 for ZPP, 0.973 for red cell P5'N, 0.937 for FEP, 0.890 for urine delta-ALA (significantly different from that for ZPP with P < 0.05), and 0.845 for urine lead level (significantly different from that for ZPP with P < 0.05), respectively. For detecting those with blood lead level >or= 2.90 micromol/L, the area under ROC curve (AUC(ROC)) of above indicators was 0.975 for red cell P5'N, 0.954 for ZPP, 0.906 for FEP (significantly different from that for red cell P5'N with P < 0.05), 0.900 for urine delta-ALA (significantly different from that for red cell P5'N with P < 0.05), and 0.750 for urine lead level (significantly different from that for red cell P5'N with P < 0.05). Sensitivity of screening in parallel with ZPP and P5'N was significantly higher than that with urine levels of lead and delta-ALA. CONCLUSION: Determinations of red cell P5'N and ZPP for detecting those with blood lead >or= 1.93 micromol/L and >or= 2.90 micromol/L are more accurate.

Red blood cell zinc protoporphyrin measurement for assessment of peripartum iron deficiency.

OBJECTIVE: To study the effectiveness of the rapid red blood cell zinc protorphyrin (RBC-ZPP) test for the detection of women with iron-deficiency anemia in the peripartum period. DESIGN: Blood was drawn prospectively from 150 healthy parturient women upon admission to the labor and delivery room and 72 hours after delivery. Concentration of RBC-ZPP was measured and correlated with hemoglobin level (p = 0.001), mean corpuscular volume (p = 0.002), hematocrit (p = 0.0001), platelet count (p = 0.002), and serum iron (p = 0.0001), serum ferritin (p = 0.0001) and serum transferrin (p = 0.0001) concentrations. RESULTS: RBC-ZPP concentration showed a significant increase from pre-delivery to 72 hours post-delivery. This change correlated significantly with the changes in all the other parameters studied. CONCLUSION: The RBC-ZPP test is a reliable, rapid, easy-to-perform, and inexpensive method of screening low-risk women, after uneventful vaginal delivery, for iron deficiency.

Weekly iron supplementation is as effective as 5 day per week iron supplementation in Bolivian school children living at high altitude.

OBJECTIVE: To compare the efficacy of a daily and a weekly iron supplementation on the hematological status of anemic children living at high altitude. DESIGN: Double blind iron supplementation trial including a placebo control group. SETTING: A socioeconomically disadvantaged district of La Paz, Bolivia (altitude of 4000 m). SUBJECTS: Anemic (hemoglobin concentration < or = 144 g/L), 3.3-8.3 y old children of both sexes. INTERVENTION: Children received a placebo (n = 57) or a dose of 3-4 mg of elemental iron per kg body weight (FeSO4 tablets) 1 d per week (n = 58) or 5 d per week (n = 58) for 16 weeks. RESULTS: Hemoglobin and zinc erythrocyte protoporphyrin concentrations improved significantly in supplemented groups but not in the placebo group. Changes in hemoglobin during the study were not significantly different between supplemented groups (weekly group: 15.2 +/- 6.9 g/L and daily group: 18.6 +/- 11.1 g/L) but were different from the placebo group (0.5 +/- 7.1 g/L, P < 0.001). At the end of the supplementation period, the hemoglobin distribution was Gaussian, and similar in both supplemented groups. Adjusting for the initial hemoglobin concentration, final hemoglobin and its changes were similar in both supplemented groups. CONCLUSION: Weekly iron supplementation is as efficacious as daily iron supplementation in improving iron status and correcting moderate iron deficiency anemia in Bolivian school children living at high altitude. SPONSORSHIP: Program supported in part by ORSTROM, the French Ministry of Foreign Affairs and the National Secretary's Office of Health, Bolivia.

The laboratory assessment of iron status--an update.

The description by Ramsay in 1957 of a practical way of determining the total iron binding capacity of serum (a measure of transferrin concentration) provided a diagnostic test for both iron deficiency and iron overload. Since 1957 the introduction of the assay for serum ferritin (in 1972) has made it possible to assess the levels of storage iron in normal subjects and assays for free erythrocyte protoporphyrin and the circulating transferrin receptor methods to evaluate iron supply for erythropoiesis. In 1957 iron metabolism in man was already well understood but its evaluation relied on measurement of tissue iron concentrations and the use of radioisotopes of iron to measure rates of erythropoiesis. The evaluation can now be carried out using the various blood assays along with the measurement of haemoglobin concentration but interpretation of the measurements in disease still requires an understanding of the way in which these measures are influenced by pathological processes.

Erythropoietin and iron.

Careful evaluation of iron status is of pivotal importance in end-stage renal disease patients before and during r-HuEPO therapy. Absolute (ferritin < 100 micrograms/l) and functional (ferritin normal or supranormal, transferrin saturation < 20%, hypochromic red blood cell [RBC] > 5%) iron deficiency are the main reasons for r-HuEPO hyporesponsiveness. Adequate iron supplementation allows significant reduction of r-HuEPO dosage and costs. Oral iron supplementation is recommended for predialysis and peritoneal dialysis patients with serum ferritin > 100 micrograms/l, whereas i.v. iron supplementation is the therapy of choice in hemodialysis patients. However, neutrophil impairment and other possible side-effects (e.g. cardiovascular complications, malignancy) as a result of i.v. iron therapy suggest that overtreatment with i.v. iron should be avoided.

Screening children exposed to lead: an assessment of the capillary blood lead fingerstick test.

We describe results of a 3-year study in which 499 paired venous and capillary blood specimens, collected by fingerstick on the same day, were analyzed for lead (BPb) and erythrocyte protoporphyrin (EP). False-positive rates (FPRs) and the proportion of false positives were calculated at four BPb thresholds. At the 100 microg/L threshold, the FPR for all data was 13%, but the proportion of false positives was only 5%. The log ratios of capillary-to-venous BPb data indicate that, with the exception of eight outliers, two subpopulations exist that follow a log-normal distribution. These two subpopulations, the "core" (n = 303) and "shifted" (n = 188) groups, on average generated a positive bias at 100 microg/L BPb of 8.6% and 30.3%, respectively. The log ratios of capillary-to-venous EP data followed a normal distribution, indicating that capillary EP is not statistically different from venous EP.

In vivo monitoring of bone-Pb and retrospective exposure: an assessment in occupationally exposed subjects.

In this work we present the preliminary results of an investigation in to the bone burden of lead in occupationally exposed subjects. The assessment of bone lead levels normalised to the mineral content (mg/kg bone mineral) were carried out by means of an in vivo X ray fluorescence techniques (Pb-XRF). The measurements were performed on the second phalanx of the right index finger and the minimum detectable limits of the XRF techniques was estimated around 25-30 mg/kg. Although the blood lead level monitoring over long time seems to indicate working activities in environments with low sources of lead contamination, high Pb-XRF levels, and not well correlated with the exposure time, were found. These anomalous values could be explained in term of the dependence of zinc protoporphyrin assessment against the measurement time.