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Lead is a naturally-occurring element. It has been known to man for a long time, and it is one of the longest established poisons. The current consensus is that no level of lead exposure should be deemed "safe." New evidence regarding the blood levels at which morbidities occur has prompted the CDC to reduce the screening guideline of 10 $\mu$g/dl to 2 $\mu$g/dl. Measurable cognitive decline (reduced IQ, academic deficits) have been found to occur at levels below 10mg/dl. Knowledge of lead pharmacology allows us to better understand its absorption and metabolization, mechanisms that produce its medical consequences. Based upon an original and very simplified compartmental model of Rabinowitz (1973) with only three major compartments (blood, bone and soft tissue), extensive biophysical models sprouted over the following two decades. However, none of these models have been specifically designed to use new knowledge of lead molecular dynamics to understand its deleterious effects on the brain. We build and analyze a compartmental model of lead pharmacokinetics, focused specifically on addressing neurotoxicity. We use traditional phase space methods, parameter sensitivity analysis and bifurcation theory to study the transitions in the system's behavior in response to various physiological parameters. We conclude that modeling the complex interaction of lead and calcium along their dynamic trajectory may successfully explain counter-intuitive effects on systemic function and neural behavior which could not be addressed by existing linear models. Our results encourage further efforts towards using nonlinear phenomenology in conjunction with empirically driven system parameters, to obtain a biophysical model able to provide clinical assessments and predictions., Comment: 38 pages, 20 color figures, 110 references

Background: Human exposure to lead can occur in a variety of ways, all of which involve exposure to potentially toxic elements as environmental pollutants. Lead enters the body via ingestion and inhalation from sources such as soil, food, lead dust and lead in products of everyday use and in the workplace. The aim of this review is to describe the toxic effects of lead on the human body from conception to adulthood, and to review the situation regarding lead toxicity in Poland. Results: Pb is very dangerous when it is absorbed and accumulates in the main organs of the body, where it can cause a range of symptoms that vary from person to person, the time of exposure and dose. Lead in adults can cause an increase in blood pressure, slow nerve conduction, fatigue, mood swings, drowsiness, impaired concentration, fertility disorders, decreased sex drive, headaches, constipation and, in severe cases, encephalopathy or death. Conclusions: Exposure to lead in Poland remains an important public health problem. This review will cover the range of lead exposures, from mild to heavy. Public health interventions and policies also are needed to reduce occupational and environmental exposure to this element.

Introduction. Lead is a toxic metal which, even at low blood levels, can alter normal neurodevelopment in children, so no blood lead level is acceptable. Lead absorption from diet accounts for the highest contribution to blood lead levels in the population who is not exposed to contaminated environments or because of their occupation. The objective of this study was to determine the contribution of diet to lead exposure among children aged 1 to 7 years who attended Hospital de Niños de La Plata for health check-ups. Population and methods. The study was conducted between June 2015 and May 2016. A questionnaire on the frequency of food intake was administered to 91 children whose average age ± standard deviation was 3.0 ± 1.7 years, and foods included in the analysis were selectedbased on this questionnaire. Selected foods were purchased from different regional stores. Composite samples were made up of different food groups. Lead levels corresponding to each food group were determined and, finally, the daily intake of lead was estimated for the studied population. Results. The daily intake of lead was 138 µg/day. The food groups with the higher intake rates were processed meat products (15.4%), bakery products (14.8%), milk (12.5%), and meat (11.7%). Conclusions. Children aged 1 to 7 years attending a public hospital in La Plata have a lead burden from dietary intake of 138 µg/day., Introducción. El plomo es un metal tóxico, que, aun en bajas concentraciones sanguíneas, es capaz de alterar el normal desarrollo neurológico de los niños, por lo que no existe un nivel aceptable de plombemia. La absorción de plomo de los alimentos es la mayor contribución a los niveles de plombemia de la población no expuesta laboralmente o a ambientes contaminados. El objetivo fue determinar la contribución dietaria a la exposición al plomo en niños de 1 a 7 años de edad que concurrían por controles de salud al Hospital de Niños de La Plata. Población y métodos. El estudio se realizó entre junio de 2015 y mayo de 2016. Se realizó un cuestionario de frecuencia de consumo de alimentos sobre 91 niños cuya edad promedio ± desvío estándar fue de 3,0 ± 1,7 años, sobre la cual se seleccionaron los alimentos por analizar. Se compraron los alimentos seleccionados en diversos comercios de la región. Se armaron muestras compuestas de diversos grupos de alimentos. Se determinó la concentración de plomo en los grupos de alimentos y, finalmente, se estimó la ingesta diaria de plomo de la población estudiada. Resultados. La ingesta diaria de plomo fue de 138 µg/día.Los grupos de alimentos que tuvieron mayor contribución fueron los productos cárnicos procesados (15,4%), los panificados (14,8%), la leche (12,5%) y la carne (11,7%). Conclusiones. Los niños de 1 a 7 años que concurren a un hospital público de La Plata tienen una carga de plomo en la dieta de 138 µg/día., Facultad de Ciencias Exactas, Centro de Investigación y Desarrollo en Ciencias Aplicadas, Centro de Investigaciones del Medioambiente

Lead and zinc are mostly present at the same occupational source and usually found as co-contaminants. Lead is known to associate with detrimental effects to humans. Zinc however is an essential nutrient and its deficiency causes debilitating effects on growth and development. Besides, it acts as core ion of important enzymes and proteins. The purpose of this study was to examine if zinc concentrations are associated with blood lead levels and if zinc may prevent lead-induced DNA damage. Blood samples were collected from 92 workers as participants occupationally exposed to lead or lead and zinc and 38 comparison participants having no history of such exposure. Lead and zinc levels were determined from blood by atomic absorption spectrophotometry and genetic damage was assessed by comet assay. Correlation was calculated by Spearman’s rho. Lead concentrations were observed to increase among workers with increase in years of exposure. There was a significant difference (p

Objectives Lead is one of the major causes of workplace poisoning and lead contamination on skin is a possible route of lead absorption. Using a colourimetric method with sodium sulphide (Na2S), we examined whether the lead on skin represents longer-term lead exposure. Methods This cross-sectional study of 119 lead-handling workers in a battery recycling plant in Japan was conducted in July 2004. The main outcome measure was skin-colour darkening on the workers' hands, visualised by wetting the seemingly clean hands of the workers with 1% Na2S solution (128 mmol/L): the Na2S test. This study then examined the relationships between the Na2S test results and workers' blood lead concentration (BLC) and hygiene activities. Results The Na2S test produced skin-colour darkening of the hands of 92 (77%) of the lead workers, although 88 of them had washed their hands with soap and 50 had bathed before taking the test. In the bivariate analyses, a positive result in the Na2S test was associated with not washing hands (p = 0.009), not bathing (p = 0.061), and a higher BLC (p = 0.008). The association between the results of the Na2S test and BLC was still significant in the multivariate linear regression analysis adjusted for age and hand washing (p Conclusions Lead contamination on workers' hands, otherwise unapparent, was clearly demonstrated by the Na2S test. The result of this test was associated with BLC in addition to the hygiene activities after the last work with lead. As the lead contamination on the hand is persistent, simply encouraging hand washing may not be sufficient to reduce lead intake into body.

The aim of this study was to investigate the relationship of blood lead (Pb) levels with copper (Cu), zinc (Zn), calcium (Ca), magnesium (Mg), iron (Fe), and hemoglobin (Hb) in children aged from 0–6 years in Wuhan, China. A total of 1047 children from six communities, which were randomly selected in Wuhan city and three communities, located in the urban area and others in the suburban area, were recruited for this study between November 2012 and July 2013. The levels of elements in the blood were detected using an atomic absorption spectrometer, and Hb level was tested by an automated hematology analyzer. The results showed that the mean blood lead level (BLL) is 33.72 ± 19.03 μg/L. The BLL was significantly higher among boys than girls (P

High blood lead levels (BLLs) can be found in Inuit from Nunavik. At the same time, various nutrients such as calcium could lower lead absorption and toxicity. We examined the effect of dietary calcium intakes on BLLs in 245 preschool Inuit children attending childcare centres in Nunavik. Calcium intake was assessed with one 24-h dietary recall and BLLs were determined by inductively coupled plasma mass spectrometry in whole blood samples. Multiple imputation was performed to deal with missing data. Median blood lead concentration was 0.08 μmol/L. A high proportion of children did not meet the Estimated Average Requirement for vitamin D intake (73 %) and, to a lower extent, for calcium (20 %). Calcium intake was negatively associated with BLLs ( p = 0.0001) while child’s age and energy intake were positively associated with BLLs ( p = 0.015 and p = 0.024, respectively). Consuming traditional foods rich in calcium as well as milk and alternatives may protect against lead exposure.

A cross-sectional study was performed on 275 pupils from the third and fourth grade of three elementary schools (three urban areas with different traffic conditions) in Zagreb. Lead exposure was environmental, mostly through leaded gasoline. The difference in traffic density around the schools was consistent with biological indicators of lead absorption. The aim of the study was to clarify the relationship between characteristic biological indicators of lead absorption including indicators of hematological status with some psychological functions. Lead absorption in pupils was relatively low (mean blood lead: 70.8 ± 17.88 μg/L). Pupils' socio-economic status was evaluated by parents' education. The results obtained indicate that gender and school were associated with both biological and psychological variables. After adjusting for age, parental education, and gender, lead appears to have no association with cognitive or psycho-motor measures. The nonstandardized regression coefficients for blood lead—as a measure of the size of lead effect on VIQ, NIQ, and IQ—were −0.016, −0.031, and −0.025, respectively, all nonsignificant.

Ingestion of elemental lead foreign bodies is felt to have a low risk of clinically significant lead absorption unless gastrointestinal pathology and/or prolonged transit time are present. We present a case of ingestion of a large quantity of small diameter lead shot accompanied by rapid elevation of blood lead levels.A 5 1/2-year-old previously healthy girl was found eating the pellets from an ankle weight. She vomited and complained of abdominal pain. In the emergency department, she had no complaints and normal vital signs. An abdominal X-ray showed thousands of small, round, metallic density objects in the stomach. Her white blood cell count was 14,700/mm3, and the hemoglobin, mean corpuscular volume, free erythrocyte protoporphyrin, zinc protoporphyrin, biochemistry panel 21, and urinalysis were normal. She had no prior lead level for comparison. Whole-bowel irrigation was begun and she passed over 11 stools with pellets as well as other foreign bodies (erasers, bead, etc.) in the first 24 hours. Pellets were still seen on X-ray the following day so she received a high-fiber diet and bisacodyl tablets 10 mg/d. On hospital day 2, her admission blood lead (drawn 13 hours after ingestion) was reported as 57 microg/dL (2.7 microm/L) and chelation was begun with oral 2,3-dimercaptosuccinic acid 10 mg/kg 3x/d for 5 days, then 2x/d for 14 days. Her peak measured lead level was 79 microg/dL approximately 36 hours after ingestion. She excreted 2,273 microg lead in the urine during her first 24 hours of chelation. Her blood lead dropped to 14.3 microg/dL by the end of chelation. She did not develop any apparent signs of lead poisoning.Acute elevations of blood lead concentrations may occur rapidly after ingestion of multiple small elemental lead objects.

Dietary calcium is well known to decrease gastrointestinal lead absorption and thereby reduce the risk for lead poisoning. Because children in economically deprived urban centers are especially likely to have excessive lead exposure, we surveyed dietary calcium intakes of 314 children from the greater Newark, New Jersey, area. The areas of Newark and adjacent communities studied had been previously identified as containing significant sources of environmental lead by geographic information systems technology. An abbreviated National Cancer Institute Health Habits and History Questionnaire, modified to focus on foods high in calcium, was used to determine dietary calcium. Calcium intakes were then compared to the new Dietary Reference Intake (DRI) guidelines. The respondents were primarily the parents of African-American and Hispanic children ranging in age from 1 to 8 years, with a mean age of 3.5 years. The most recent blood lead concentration was 11.4 +/- 0.8 microg/dL (mean +/- standard error), and 48.6% had concentrations at or above the current guideline of 10 microg/dL. Quintiles of calcium intake were: 221 +/- 13; 488 +/- 9; 720 +/- 6; 885 +/- 6; and 1,389 +/- 49 mg/day. Fifty-five of 175 (31.4%) children aged 1-3 years had calcium intakes below the DRI, as did 82 of 139 (59.0%) children aged 4-8 years. The percentage of mothers reporting lactose intolerance in their children was 2.5%. The observation that the children in the highest quintile easily exceeded the DRIs for calcium suggests that urban parents who include dairy foods in their childrens' meals can provide a diet that meets the DRI guidelines. Children in the lowest quintiles are at risk of increased absorption of the environmental lead to which they are inevitably exposed, as well as other problems associated with a low intake of dietary calcium. The data suggest that both lead exposure and low dietary calcium continue to pose significant health risks to urban minority children. Images Figure 1 Figure 2 Figure 3

Objective: The aim of this study was to confirm the connection between lead poisoning and the use of traditional Ayurvedic metal mineral tonics. Methods: The study group comprised 29 subjects (26 adults and three children) who had previously taken Ayurvedic metal mineral tonics. All subjects were tested for lead absorption by blood lead, erythrocyte delta-aminolevulinic acid dehydratase activity and erythrocyte protoporphyrin. Results: Eighteen samples of Ayurvedic preparations were obtained from 15 subjects and analyzed for lead content. Five adult subjects with established lead poisoning received chelation therapy. In Ayurvedic preparations a wide range of lead content was found (0.9-72, 990 ug Pb/g ; 0.35-29, 900 ug Pb/capsule or tablet). The blood lead, erythrocyte delta-aminolevulinic acid dehydratase and erythrocyte protoporphyrin of the subjects, grouped according to the remedies used, correlated with the lead content in the preparations (p

Distribution of intake and lead levels in dietary and non-dietary sources and of lead absorption were used in a Monte-Carlo simulation to predict blood lead levels in populations of concern. Blood lead levels were determined with and without particular dietary sources, and added risk was estimated for each source. These calculations permit comparisons of relative risk used to evaluate and limit dietary exposure to lead. Added risk of exposure to lead in wine, calcium supplements and ceramic-ware, and drinking water were calculated for adult men, pregnant women, and children, respectively.

Background Previous studies have shown that fasting increases lead absorption in the gastrointestinal tract of adults. Regular meals/snacks are recommended as a nutritional intervention for lead poisoning in children, but epidemiological evidence of links between fasting and blood lead levels (B-Pb) is rare. The purpose of this study was to examine the association between eating a regular breakfast and B-Pb among children using data from the China Jintan Child Cohort Study. Methods Parents completed a questionnaire regarding children's breakfast-eating habit (regular or not), demographics, and food frequency. Whole blood samples were collected from 1,344 children for the measurements of B-Pb and micronutrients (iron, copper, zinc, calcium, and magnesium). B-Pb and other measures were compared between children with and without regular breakfast. Linear regression modeling was used to evaluate the association between regular breakfast and log-transformed B-Pb. The association between regular breakfast and risk of lead poisoning (B-Pb≥10 μg/dL) was examined using logistic regression modeling. Results Median B-Pb among children who ate breakfast regularly and those who did not eat breakfast regularly were 6.1 μg/dL and 7.2 μg/dL, respectively. Eating breakfast was also associated with greater zinc blood levels. Adjusting for other relevant factors, the linear regression model revealed that eating breakfast regularly was significantly associated with lower B-Pb (beta = -0.10 units of log-transformed B-Pb compared with children who did not eat breakfast regularly, p = 0.02). Conclusion The present study provides some initial human data supporting the notion that eating a regular breakfast might reduce B-Pb in young children. To our knowledge, this is the first human study exploring the association between breakfast frequency and B-Pb in young children.

In this study, four experiments using the tapping test were conducted to evaluate the possible subclinical effects of lead exposure on the neuromuscular systems of lead workers at some transfer printing factories in Japan. Decreases in the tapping ability appeared coincidentally with higher blood lead levels. The recovery of the tapping ability after 30 sec rest in the groups of 30-45 micrograms/dl and above 45 micrograms/dl PbB was worse than that in the group with less than 29 micrograms/dl PbB. The recovery of the decreased tapping ability after 60 sec rest was better even in the group with 30-45 micrograms/dl PbB. The tapping ability for 0-10 sec at the first tapping test was sustained after 30 or 60 sec rest in the group with the PbB below 29 micrograms/dl; however, the tapping ability at the second and third tapping test decreased in the two groups with the PbB level above 30 micrograms/dl. The decreased finger tapping speed may be functional evidence of low-grade motor neuropathy among the workers with higher levels of lead absorption.

The clinical recognition of lead toxicity in children in the United States has changed drastically over the past 50 years. Accordingly, both medical management and public policy in such cases needs to be modernized in keeping with these changes. Fifty years ago lead poisoning in children was often only recognized in the severe acute phase (acute lead encephalopathy). Today this condition is rare, and children are detected in screening programs most often in the asymptomatic phase. The removal of lead additives from gasoline and the removal of lead solder from food and beverage cans has greatly reduced the background level of lead absorption during the past decade.1 The changes in exposure to lead and its clinical presentation mandate that we change the approach to the management of childhood lead toxicity. We must place reduced emphasis on chelation therapy and major emphasis on the environmental history to identify the source(s) of lead in the child's environment and steps to separate the child from these sources. The primary source of lead in childhood lead toxicity 50 years ago was deteriorating lead paint in old housing: it remains the primary source in the United States today. Reduction of exposure is the single most important modality of long-term management, as it has been for >50 years. When chelating agents first appeared—2,3-dimercapto-1-propanol (BAL)2 in 1946 and calcium disodium ethylenediaminetetraacetate (CaNa2EDTA)3 in 1950—childhood lead poisoning was recognized clinically only in the severe acute phase. These agents alone reduced the mortality of severe acute lead encephalopathy from 66% to approximately 25% to 30%.4Subsequently, it was found that these agents given in combination5 reduced mortality to about 1% to 2%. They were not effective in reducing the neurologic sequelae.6Ongoing prospective studies conducted now to at least 10½ years …

Lead exposure is widespread among industrial populations in the United States. X-ray fluorescence (XRF) analysis of the lead content of bone offers a promising approach to acquisition of individualized data on chronic lead absorption in occupationally exposed populations. Dosimetric data obtained by XRF will permit accurate definition of dose-response relationships for such chronic consequences of lead exposure as central and peripheral neurologic impairment, renal disease. hypertension, and possibility reproductive dysfunction. Additionally, data on bone lead content obtained by XRF will permit validation of models describing the body lead burden and will allow direct assessment of the efficacy of therapeutic chelation. XRF data may also permit assessment of the possible role of genetic polymorphism of the enzyme delta-aminolevulinic dehydrase as a determinant of the pharmacokinetics and toxicity of lead. In both cross-sectional and prospective epidemiologic studies of body lead burden in occupationally exposed populations, the K-XRF instrument appears to be the technology of choice.

The literature on lead toxicology has been critically reviewed to provide a safety assessment of lead acetate as a hair colouring. The main objectives were: (i) to determine the additional lead contribution from hair-colouring use to the total daily environmental lead intake; and (ii) to assess the toxicological significance of this additional contribution. The review also focuses attention on newer issues of concern over the effects of environmental lead on human health. Data available in animals and humans (including occupational exposure), mainly on lead acetate and other inorganic lead salts, have been presented and evaluated in respect of the following: absorption, distribution and excretion following ingestion; percutaneous absorption; carcinogenicity; genotoxicity; reproductive toxicity; neurological/behavioural status with particular reference to neuropsychological effects in children; and effects on other systems (e.g. cardiovascular). It is concluded that the absorption of lead from hair-colouring use represents about 0.5% of the lead absorption from the current average daily environmental lead intake. No convincing evidence could be found of any deleterious effect of current environmental lead levels on human health and thus the tiny contribution of lead acetate exposure from hair-colouring use can be regarded unequivocally as being toxicologically insignificant.

An attempt was made to study the usefulness of activated carbon fabric (ACF) mask to prevent lead absorption. Indigenous ACF masks were provided to eight workers involved in the manufacture of batteries. Their blood lead levels were determined before and after using these masks. There was a substantial decrease in blood lead level after using the mask among those who were under treatment for high blood lead levels. Three workers who were not under treatment for lead also showed a decrease in blood lead level, after using this ACF mask, suggesting the usefulness of ACF in preventing further exposure. Such a study has not been reported anywhere in the available literature and similar such studies with more number of masks is necessary to evaluate its effectiveness.

Objectives: A changing character of lead exposure has been observed over many years. However, construction workers involved in the renovation of painted steel structures are still severely exposed to lead and its compounds. In 2004, we observed an outbreak of lead poisoning in high voltage tower conservators working abroad. Materials and Methods: As many as 27 male workers with suspected lead poisoning were hospitalized in the Department of Occupational Disease, Nofer Institute of Occupational Medicine, Łodź, Poland. They were involved in removing an old lead-containing paint from high voltage towers. Results: On admission to the department, 70% of treated workers showed laboratory signs of anemia in their blood count. After treatment the signs persisted in 25% of patients. Also alkaline dotting in erythrocytes was present in 13 subjects. Sub-acute lead poisoning manifested by abdominal cramps with coexisting anemia and increased lead absorption symptoms was most frequently diagnosed. Conclusions: The high lead exposure of the examined high voltage tower cleaners was due to specific working conditions. In such cases overprotection of the environment may lead to severe health effects in humans.

To examine the effects of occupational and environmental neurotoxicants on vestibular, cerebellar and spinocerebellar functions, the following three groups of subjects were examined, using a computerized posturography with sway frequency analysis: (1) 49 male chemical factory workers exposed to lead stearate, aged 27-63 (mean 43) years, with concurrent blood lead concentrations (BPbs) of 11-113 (mean 48) microg/100 g and past mean BPbs of 7-52 (mean 24) microg/100 g; (2) 29 male sandal, shoe and leather factory workers, aged 35-73 (mean 51) years, with urinary 2,5-hexanedione (HD) concentrations of 0.41-3.06 (mean 1.20) mg/g creatinine; and (3) 9 females, aged 19-58 (mean 29) years, who were exposed to sarin accidentally 6-8 months before the study (Tokyo Subway Sarin Poisoning, March 20,1995) and showed plasma cholinesterase (ChE) activities of 13-95 (mean 68) IU/l on the day of poisoning. The pattern of posturographic changes in lead workers suggested that the vestibulocerebellum (lower vermis), anterior cerebellar lobe and spinocerebellar afferent pathway were asymptomatically affected; the vestibulocerebellar change reflected concurrent lead absorption and the anterior cerebellar one reflected past absorption. Similarly, vestibulocerebellar and spinocerebellar functions were affected by n-hexane in solvent workers; the effect on the vestibulocerebellar function was probably inhibited by xylene. Also, the chronic (long-term) effect on the vestibulocerebellar function persisted in acute sarin poisoning. It is thus suggested that the vesitibulocerebellar function is most sensitive to all the three chemicals examined. It appears that the computerized posturography with frequency analysis is a useful technique for assessment of vestibular, cerebellar and spinocerebellar effects in occupational and environmental health.

Worker exposure to airborne lead particles was evaluated for a total of 117 workers in 12 work-places of four different industrial types in Korea. The particle sizes were measured using 8-stage cascade impactors worn by the workers. Mass median aerodynamic diameters (MMAD) were determined by type of industry and percentage of lead particles as a fraction of airborne lead (PbA) concentration was determined by particle size. Blood lead (PbB) levels of workers who matched airborne lead samples were also examined. A Scheffé's pairwise comparison test showed that MMAD and the fractions of each of respirable particles and lead particlesor =1 microm relative to PbA varied greatly by the type of industry. The concentrations of lead particlesor =1 microm, which the Center for Policy Alternatives model assumes is relatively constant at 12.5 microg/m3, increased with increasing PbA concentration. In addition, a better correlation was detected between concentrations of particlesor =1 microm and concentrations of respirable lead particles (r = 0.82) than that between concentrations of small particles and PbA (r = 0.61). A simple linear regression indicated that PbB correlated better with respirable lead concentration (r2 = 0.35, P = 0.0001) than with PbA concentration and had a higher slope coefficient. Controlling for respirable lead concentration reduced the partial correlation coefficient between PbA concentration and PbB level from 0.56 to 0.20 (P = 0.053). The results indicate that the contribution of respirable lead particles to lead absorption would be greater than that of PbA. This study concludes that the measurement of PbA only may not properly reflect a worker's exposure to lead particles with diverse characteristics. For the evaluation of a worker's exposure to various types of lead particles, it is recommended that respirable lead particles as well as PbA be measured.

Background Both an excess of toxic lead (Pb) and an essential iron disorder have been implicated in many diseases and public health problems. Iron metabolism genes, such as the hemochromatosis (HFE) gene, have been reported to be modifiers for lead absorption and storage. However, the HFE gene studies among the Asian population with occupationally high lead exposure are lacking. Objectives To explore the modifying effects of the HFE genotype (wild-type, H63D variant and C282Y variant) on the Pb load and iron metabolism among Asian Pb-workers with high occupational exposure. Methods Seven hundred and seventy-one employees from a lead smelter manufacturing company were tested to determine their Pb intoxication parameters, iron metabolic indexes and identify the HFE genotype. Descriptive and multivariate analyses were conducted. Results Forty-five H63D variant carriers and no C282Y variant carrier were found among the 771 subjects. Compared with subjects with the wild-type genotype, H63D variant carriers had higher blood lead levels, even after controlling for factors such as age, sex, marriage, education, smoking and lead exposure levels. Multivariate analyses also showed that the H63D genotype modifies the associations between the blood lead levels and the body iron burden/transferrin. Conclusions No C282Y variant was found in this Asian population. The H63D genotype modified the association between the lead and iron metabolism such that increased blood lead is associated with a higher body iron content or a lower transferrin in the H63D variant. It is indicated that H63D variant carriers may be a potentially highly vulnerable sub-population if they are exposed to high lead levels occupationally.

Assertions that adequate or supplemental calcium intake can reduce lead absorption in children are based on liberal extrapolation from animal studies, experiments with human adults, and cross-sectional studies of children that have a variety of methodologic weaknesses. Without stronger supporting evidence, statements that diet can ameliorate the deleterious effects of environmental lead could provide a false sense of efficacy and divert efforts from lead abatement and from behavioral modifications that might have more impact.

Objectives This study was conducted to determine whether children of lead workers are at a higher risk of lead absorption and if so, to identify risk factors for absorption, including lifestyle, household, environmental and parental work practices with lead. Methods This cross-sectional study recruited 17 'lead worker' and 13 comparison 'non-lead worker' households. Companies and eligible employees were contacted using mail-out packs. Children were aged between 12 and 72 months. Data collection involved administration of a questionnaire and collection of dust, soil, water, paintscraping samples, and blood from the children for the determination of lead and ferritin levels. Statistical analysis was performed using SPSS. Results Participants included seven of 29 eligible employees from 14 'scheduled' lead workplaces and 12 of 19 eligible employees from 19 'leadlighter' workplaces identified. The average lead level for workers was 13.9 //g/dl, children of lead workers 6.93 /^g/dl (n=22) and comparison group 3.93 pg/dl (n=16). Water lead levels were all

The authors examined the reversibility of cognitive impairment caused by a mild increase in lead absorption among children. The results of our initial study revealed that air and soil outside a lead-recycling plant in Taiwan were seriously contaminated by lead, which was associated with lowered intelligence quotients of 32 children who attended a nearby kindergarten (i.e., kindergarten A). Thirty-five children-who were comparable with respect to age, sex, birth order, sibling number, and parental education level-from another kindergarten (i.e., kindergarten B) located 5 km from the plant were enrolled as the reference group. Following the initial study, kindergarten A school children moved 2 km from the lead-recycling plant. Twenty-eight children in each group were followed successfully 2.5 y later. Blood lead, intelligence quotient, and intelligence quotient-related factors were reassessed. The results showed that the average blood lead level of the exposed pupils dropped 6.9 microg/dl (standard deviation [SD] = 3.9 microg/dl) (p.001), and the average intelligence quotient increased 11.7 points (SD = 13.2) (p.01), compared with the results of the initial study. The average blood lead level of the reference group decreased by 1.7 microg/dl (SD = .1.3) (p.001), whereas the average intelligence quotient increased by 4.2 points (SD = 13.8) (p = .115). There was a significant difference in intelligence quotients between the two groups during the initial study, but the difference subsequently disappeared during the follow up. The authors concluded that intelligence quotient impairment, caused by a mild subclinical elevation of blood lead (i.e., likely no more than 30 microg/dl) for a period of 1-3 y in 3- to 5-y-olds, is at least partially reversible.

The objective of this study was to determine whether workers at a factory in Taiwan, adjacent to lead recycling plant, were affected by lead contamination. Workers at the lead recycling plant itself were found to suffer from lead poisoning; air and soil outside the plant were heavily contaminated by lead. Forty-one of the 45 workers in a forging factory next to the lead recycling plant were enrolled as the exposed group. A comparison group of 51 workers were selected from another forging factory about 20 km away. Each subject was interviewed about his lifestyle, work history, and residence, and blood was drawn for lead measurement by graphite furnace atomic absorption spectrometry. The results showed that two groups were compatible in age, sex, and smoking patterns. Blood lead of the exposed group was significantly higher than that of the comparison group (mean +/- SD: 20.4 +/- 9.4 micrograms/dl vs. 5.9 +/- 2.9 micrograms/dl). The difference was independent of sex and working zones. Blood lead levels were lower among exposed workers who had been employed less than 2 months compared with those employed longer. There was no difference among exposed workers in different outdoor working zones. Five months after improvement of pollution control and decrease in the production volume of the lead factory, 30 exposed workers were retested for blood lead. The blood lead of outdoor workers had an average decrease of 4.2 micrograms/dl while that of indoor workers showed no significant difference.(ABSTRACT TRUNCATED AT 250 WORDS)

OBJECTIVES. Since 1981, 15 states have established registries for surveillance of adult lead absorption, primarily based on reports of elevated blood lead levels from clinical laboratories. I review the status of the registries and recommend steps for further development. METHODS. Companies reported to the New York registry are compared with those cited by the Occupational Safety and Health Administration (OSHA). I present data on US workers and plants with potential lead exposures and blood tests, as well as review registries' reporting requirements. RESULTS. Registries identify many companies not cited by the Occupational Safety and Health Administration, but underreporting occurs because (1) reporting is usually not required from laboratories outside the state, (2) most registries use a blood lead reporting level of 1.21 mumol/L, which excludes many exposed workers, and (3) many companies with potential exposures do not have routine monitoring programs. CONCLUSIONS. Registries' reporting requirements and procedures should be standardized, including a blood lead reporting level of 0.72 mumol/L. Elevated blood lead levels should be a reportable condition nationwide, and a comprehensive national surveillance system should be established: clinical laboratories should be required to report cases to those states with lead registries or directly to the national adult lead registry.

Lead poisoning has been noticed for more than a thousand years. Increased lead absorption and/or impaired neurobehavioral function among children who lived nearby lead smelters were reported in many different countries. In November of 1987, a worker from a lead battery recycling smelter suffered from anemia and bilateral weakness of his extremities. He was diagnosed as lead poisoning at the National Taiwan University Hospital (NTUH). A subsequent epidemiological survey of the workers from this recycling smelter showed that 31 out of 64 who came for a medical examination suffered from lead poisoning. Since there was a kindergarten next to the factory, we performed this study to determine whether there was an increased lead absorption among children of the exposed kindergarten and its association with the extent of air and soil pollution in the surrounding area. 12 refs., 1 fig., 4 tabs.

One-hundred and five impacted and erupted sound teeth were analysed for lead content by graphite furnace atomic absorption spectrophotometry. The results showed that lead accumulated before eruption, presumably soon after the onset of dentine formation. The accumulation in dentine was systemic, without any contribution from the oral environment. The amount of lead in dentine may denote the amount of absorption into the body and serve as a precise index to body burden as no absorption from the mouth can take place. In adults, impacted and erupted teeth can be used together in any research and the donor's age can be considered as the period of lead accumulation.

Nutritional factors are known to influence metabolism and toxicity of several metals in animal experiments, but relevant human data are scarce and inconclusive. In this work, we tested the hypothesis that dietary calcium influences lead metabolism in humans. Blood lead concentrations were used as indicators of lead exposure and metabolism. Two groups of peasant women living in similar conditions in two different regions in Yugoslavia (100 in each) were chosen as subjects for this purpose. In region A, the dietary calcium intake was about 940 mg, and in region B about two times lower, i.e., 450 mg/day. The average blood lead concentration was significantly lower in women from region A (69 micrograms/L) than from region B (83 micrograms/L). Our results support the assumption that adequate calcium intake might be one of the preventive measures for decreasing lead absorption. This new evidence, sought for some time by nutritionists and toxicologists, needs further international confirmation.

Excessive lead exposure in shooting instructors at indoor firing ranges and covered outdoor firing ranges has been documented. The City of Los Angeles assessed exposure of its full-time shooting instructors at uncovered outdoor ranges via air monitoring and blood lead-level measurements. Results of these tests revealed that significant lead exposure and absorption can occur at outdoor firing ranges. The use of copper-jacketed ammunition may decrease air lead levels and decrease lead absorption by range instructors.

A group of 184 preschool-aged children with pretreatment blood lead concentrations (PbB) greater than or equal to 50 micrograms/dl, who received inpatient chelation therapy, were followed prospectively as outpatients for 12 months after discharge. Of these, 160 were followed for 24-30 months. Serial PbB data were analyzed according to the type of housing to which each child was discharged. Following therapy, PbB stabilized by 3 months. Thereafter, highly significant differences (P less than 0.001) existed between those living in or visiting old houses in which lead-in-paint hazards had been abated according to local ordinances (m PbB = 38.5 micrograms/dl) and those discharged to "lead-free" public housing (m PbB = 28.8 micrograms/dl) or to recently, totally gutted and renovated old housing (m PbB = 28.7 micrograms/dl). During the period of study (1978-1982), no downward trend in PbB within housing groups was found during the first 12 months of follow-up. Of the 152 children discharged to old housing, 75 had 127 recurrences of PbB greater than or equal to 50 micrograms/dl. This emphasizes the need for close and prolonged follow-up in all cases. These data indicate that substantially improved methods of detection, classification, and abatement of lead hazards must replace traditional methods if lead exposure for young children in old housing is to be reduced to an acceptable level.

Sixty-six workers engaged in lead-glazing pottery with a presumed moderate exposure to lead were studied. The group comprised 20 men with long-term exposure to lead and positive laboratory signs of increased lead absorption (Group A); 22 with long-term exposure and negative laboratory signs (Group B); 11 with short-term exposure and positive laboratory signs (Group C); and 13 with short-term exposure and negative laboratory signs (Group D). In addition, 14 workers employed in casting the kelmet alloys with presumed heavy exposure to lead (Group E) and seven healthy individuals (Group F) were included. Urine samples from all the subjects were analysed to determine, first, the total lead using the ashing technique, and then the precipitable lead using the coprecipitation technique of Cholak, Hubbard, and Burkey (1948), but modified slightly by us. Thus, the non-precipitable lead fraction in urine was the difference between the two measurements and this was also expressed as a percentage of the total lead. The mean total lead and the mean proportion of non-precipitable lead were 0.62 mumol/l and 48.7%, 0.35 mumol/l and 44.9%, 0.40 mumol/l and 48.9%, 0.17 mumol/l and 24.6%, 1.43 mumol/l and 44.3%, 0.14 mumol/l and 18.8% for Groups A, B, C, D, E, and F respectively, showing that a large part of urinary lead was eliminated as precipitable lead in Groups D and F who had normal lead excretion, while about half was eliminated as non-precipitable lead in the other four groups who had excessive lead excretion. No essential difference in the proportion of non-precipitable lead among Groups A, B and C excluded the possibility that the proportion might be directly related to the period of exposure to lead and to the laboratory findings of excessive lead absorption. The mean proportion of non-precipitable lead for the physiological (up to 0.240 mumol/l), intermediate (0.241 to 0.721 mumol/l), and excessive (above 0.722 mumol/l) total lead levels was 26.7, 41.3, and 52.3% respectively, in the lead workers comprising Groups A, B, C, and E each showing increased lead excretion when grouped together. these data suggested that, when urinary lead is within the normal range, it is excreted largely as precipitable lead even in individuals exposed to lead, and that the principal conditions determining the excretion of non-precipitable lead would be the current or recent degree of lead absorption. The excretory mechanisms and the biological significance of the non-precipitable lead are also discussed.

In a community of potters in Barbados where lead glazes traditionally have been used, a survey of 12 potters, 19 of their family members, and 24 controls revealed elevated blood lead levels in the potters, their family members, and the neighbours who used pottery for culinary purposes. Dust from the potters' homes and work areas contained lead in concentrations up to 320,000 ppm. Pottery was found to have lead release levels up to 3,125 microgram/ml. Six people had upper extremity tremor associated with elevated blood lead levels. This survey demonstrates the risk of using lead glazes in pottery production to family members of potters as well as the potters themselves and emphasizes the need for surveillance of occupational hazards in developing countries.

Studies to evaluate the prevalence, sources, and health consequences of lead absorption were conducted among children living near a primary lead smelter. Lead levels in air, soil, and dust were highest at the smelter and decreased with distance. Ninety-nine percent of one- to nine-year-old children living within 1.6 kilometers had blood lead levels greater than or equal 40 mug/dl, indicating increased absorption, and 22% had levels greater than or equal 80 mug/dl. The prevalence of lead levels greater than or equal 40 mug/dl decreased with distance; at 72 kilometers from the smelter it was 1%. Erythrocyte protoporphyrin levels increased with blood lead levels: 17% of children with lead levels of greater than or equal 80 mug/dl were anemic. There was no overt neurologic toxicity. Significant negative correlation was found in 202 five- to nine-year-old children between blood lead levels and motor nerve conduction velocity (r = 0.38, p less than 0.02).

Zinc protoporphyrin (ZnP) has been identified by several investigators as the predominant fluorescent porphyrin accumulating in erythrocytes as a result of chronic lead absorption or iron deficiency anemia. This report describes an evaluation of a new portable hematofluorometer for the determination of ZnP in finer puncture or venous blood samples. Samples were obtained from a number of employees in various job categories at steel operations throughout the United States to study the utility of ZnP as a biologic monitoring method in the occupational environment. Urinary lead, urinary aminolevulinic acid and blood lead were also determined on the same employees to examine any relationships among these measurers and to estimate a biologic threshold limit value for ZnP. The results of this investigation show that there is little elevation of the ZnP level with increasing blood level until the blood lead concentration reaches the area of 50--60 micrograms/dl. A biologic threshold level of 300 micrograms/dL, which correlates with a blood level of 60 micrograms/dL, is suggested as a guideline value for identifying workers requiring further investigation.

In order to examine the prevalence of iron deficiency and environmental lead absorption in children, erythrocyte protoporphyrin (EP) and blood lead (B-Pb) levels were measured in a group of 112 children from Jammu and Srinagar. The mean EP levels were 50 and 59 μg/dl and mean B-Pb were 15 and 8 μg/dl respectively. Similarly, the mean B-Pb and EP levels of papier mache trainees/workers were 23/25 and 96/98 μg/dl respectively. These results suggest higher incidence of iron deficiency in Srinagar children compared with those in Jammu. However, the mean B-Pb level of Jammu children was twice those in Srinagar. While this follow-up study on papier mache trainees/workers shows significant improvement in B-Pb since 1981, these levels are close to the currently recognized cut-off levels for children. Moreover, the continued underlying iron deficiency predisposes these young female trainees/workers to enhanced lead absorption, thus regular monitoring of both EP and B-Pb is recommended.

The physical characteristics and simple lung ventilatory indices (FVC, FEV 1, FEV 1/FVC) of 404 commercial divers employed by companies operating in the North Sea were analysed. These findings were correlated with the diving experience and maximum operating depth of each diver. All the divers were men of average height 176-9 cm, and weight 77-1 kg which is greater than average for active Western males, but only 6% were more than 120% of their predicted weight. The average duration of commercial diving was 7-1 years, 11% of divers having less than one year's experience. Sixty-seven per cent had worked at a maximum depth of 200 ft (61 m) and only 6% had worked deeper than 500 ft (153 m). The mean forced vital capacity (FVC) was 120-4% of the predicted value which indicated that they could voluntarily move large amounts of gas in and out of their lungs. This was greatest in the divers who when deepest. The mean forced expired volume in one second (FEV 1) was 117% of the predicted value showing that expiratory airflow capacity was also increased, but to a lesser extent than the FVC. Thper and activated by zinc. Plasma protein protected the enzyme from both inhibition and activation. ALAD activity was found to be an indicator of the total metal ion concentration in the blood and was therfore considered to be of doubtful value in screening large population for increased lead absorption.

11. of porphyrins in biological material, Methods Biochem Anal 8:211, 1960. Dallman PR, and Siimes MA: Percentile curves for hemoglobin and red cell volume in infancy and childhood, J PEDIATR 94:26, 1979: United States Public Health Service Statement: Preventing lead poisoning in young children, Center for Disease Control, Atlanta, 1978. 12. Cohen GJ, and Ahrens WE: Chronic lead poisoning, J PEDIATR 54:271, 1959. 13. Betts PR, Astley R, and Raine DN: Lead intoxication in children in Birmingham, Br Med J 1:402, 1973. 14. Flanagan PR, Hamilton DL, and Valberg LS: Interrelationships between iron and lead absorption in iron deficiency mice, Gastroenterology 77:1074, 1979.

Among 40 Manchester taxi drivers the mean blood lead was 1.10 mumol/1 (22.8 mug per 100 ml). The mean erythrocyte delta-aminolevulinic acid dehydratase (ALAD) activity among 34 of them was 30.1 units. No significant association was found between the blood lead levels and erythrocyte ALAD activity in these 34 men. No significant association was found between either blood lead elvels or erythrocyte ALAD activity and duration of service or weekly mileage as a taxi driver or with drinking or smoking habits, or age. The mean blood lead of those with homes in the north east quadrant of the city was higher than of those living elsewhere but the difference was not statistically significant. Although there was no correlation between blood lead levels and the source of domestic water, the mean blood lead of those with lead domestic plumbing was appreciably higher than the level of those with copper plumbing. There was no indication that, by virtue of their occupation, the taxi drivers were liable to greater lead absorption than their fellow-citizens.

Among the laboratory tests available for the follow-up of lead-exposed workers, the EDTA mobilization test is presently underestimated in the diagnosis of lead intoxication. The authors present the results of regression comparison between the urinary lead excretion 3 h (PbU 3) or 6 h (PbU 6) after EDTA injection and blood lead (PbB), urinary aminolaevulinic acid (ALAU) and urinary lead (PbU). The results were collected from 133 medical examinations of workers exposed to lead, who put in a claim for compensation to the 'Fund of Occupational Diseases' in Belgium. On the basis of the regression curves, PbU 3 and PbU 6 limit values are calculated for different cut-off values of PbB in excessive lead absorption and lead intoxication. For each of these values the 'sensitivity', 'specificity' and 'validity' are calculated. As a result the authors still consider the EDTA mobilization test as a valuable parameter in the diagnosis of lead absorption.

In the study of human populations, much emphasis is placed on the concentration of lead in whole peripheral blood. There is a considerable body of evidence which indicates that this measurement reflects recent and current assimilation of lead. While broad ranges in blood lead concentration have been associated with differing risks of toxicity for groups, it is not a precise index of adverse effect per se, even at elevated levels. Within the red blood cell itself there is not a close association between the concentration of lead and such adverse metabolic effects as the increased loss of potassium caused by lead. Above the apparent “threshold zone” of approximately 30–50 μg Pb/100 ml whole blood, equivalent metabolic effects on heme synthesis may be seen over an interval of at least 20 μg Pb/100 ml whole blood. This variation will be examined with particular reference to the interrelationship between the concentrations of lead and protoporphyrin in peripheral blood. The data indicate that limitations in both precision and accuracy of measurement account for a relatively small fraction of the observed variations. Together with other experimental and clinical information, they suggest that concurrent dietary deficiency of iron may be one of the important modifying factors in the responses of subjects with increased lead absorption. It is suggested that suspected adverse effects upon the various organ systems associated with increased lead absorption be measured directly and that the CaEDTA mobilization test for lead should be more fully explored as a measure of the “metabolically active” fraction of the total body lead burden.

This survey in Cockle Creek did not indicate any excessive absorption of lead among the children examined, despite their proximity to a lead smelting complex.

A review of the Lead Industries Association (LIA) position paper which represents LIA's recommended occupational health practices for industries producing or using lead and its inorganic compounds is presented. The LIA strongly recommends the use of a biological standard (particularly a blood lead standard) for protecting the workers and determining compliance with the provisions of the Occupational Safety and Health Act. The position paper states that the best means of controlling and reducing exposure is by engineering controls and work practices; the best means of determining whether these controls and work practices are adequately protecting the worker is by assessing lead absorption through measurement of the blood lead. Attention is drawn to the inadequacies inherent in evaluating exposure by air sampling. (CIS Abstracts Vol 2)

Health examinations for lead poisoning were made on 62 family members from 15 families of homes carrying on lead work, such as quench-hardening in a molten lead bath and type-printing, as work at home. The most interesting findings concern the occurrence of cases with an unduly high lead absorption among children, but not among adult family members other than home lead-workers. The home environments of the children with an unduly high lead absorption represented contamination with housedust high in lead contents. The ingestion of the contaminated housedust by hand-to-mouth is probably responsible for the excessive lead exposure of the affected children. The results of the present study suggest that contamination of housedust with lead due to home lead-work constitutes a possible hazardous source of lead exposure for children.

van Peteghem, Th., and de Vos, H. (1974). British Journal of Industrial Medicine, 31, 233-238. Toxicity study of lead naphthenate. Lead naphthenate is added to oils and greases in order to increase their resistance to high pressures. Experiments on animals and humans showed the possibility of a small amount of percutaneous absorption. An investigation was performed on technicians regularly dealing with these lubricants in order to explore to what extent they had absorbed the lead naphthenate. The degree of absorption was evaluated by measuring the lead content of the blood and the δ-aminolevulinic acid concentration in the urine. Individual results did not permit clearcut conclusions whether an increase in lead absorption had occured or not. Therefore the group of technicians was compared with a group without any occupational contact with lead-containing lubricants but otherwise comparable in occupational and general exposure to lead. To test the significance of the difference between the means of the samples a one-sided t test not assuming equal standard deviations for both populations was used. For any of two compared populations the t test was repeated after rejection of the larger values which were 2·5 standard deviations from the mean value in the exposed population. It appeared that the lead concentration in the blood and the δ-aminolevulinic acid concentration in the urine of people exposed to lead naphthenate-containing lubricants were significantly higher than those concentrations observed in non-exposed persons.

ABSTRACT Eighty-one percent of all hourly paid men who had been employed for more than six months in a factory making lead acid batteries and plastics completed a modified Cornell medical index health questionnaire. Blood lead and erythrocyte protoporphyrin (EPP) were also measured. The questions were grouped into symptom categories as follows: all physical, all psychological, “potentially lead induced,” pulmonary, cardiovascular, gastrointestinal, skin, nervous system, genitourinary, and fatigue. For each symptom category the pooled percentages of men whose symptom scores were above the common median of the three blood lead groups 10-, 40-, and 60 and over μg/100 ml (0·48-, 1·93-, and 2·90 and over μmol/l) within age/smoking subgroups were calculated. In every symptom category the percentages in the two lower blood lead groups differed little, but the percentages were consistently higher in men with blood concentration of 60 μg/100 ml (2·90 μmol/l) and over. Differences between a combined 10-59 μg/100 ml (0·48-2·85 μmol/l) blood lead group and the 60 and over μg/100 ml (≥2·90 μmol/l) group were statistically significant at the 0·01 level for “potentially lead induced” symptoms and at the 0·05 level for skin and psychological symptoms. Broadly similar results were obtained with four log10 EPP groups 0·6-, 1·5-, 1·7-, and ≥2·0, but differences did not reach statistical significance. There was no obvious explanation as to why symptoms that are not found in classic lead poisoning should be increased almost as much as those that are. It was thought that these results could be biased due to the men's knowledge of the symptoms associated with lead exposure, but the possibility that they may be partly due to lead absorption cannot be excluded.

Calcium and phosphorus were mainly responsible for reducing the gastrointestinal absorption of lead in human subjects. The effect of calcium was greater than phosphorus, and their combined effect was more than additive. Increasing weights of calcium and phosphorus progressively reduced lead absorption. The relationship between absorption and increasing weights could be described by two negative exponentials. These effects could be explained if lead competed with calcium and phosphorus for common transport mechanisms in the gut. Milk was also found to reduce lead absorption. Adding milk to the diet of people with low dietary calcium intake could reduce the possibility of increased absorption of ingested lead.

In the past, lead poisoning was recognized when classical symptoms of acute intoxication were present and the blood lead was elevated. The (ethylenediamine tetracetatic acid (EDTA) test is presently the most reliable method for detecting excessive lead stores. We used the EDTA lead mobilization test to demonstrate excessive past lead absorption as a cause of renal disease in lead workers and in both gouty and hypertensive patients with renal failure. These studies show that lead nephropathy occurs in the absence of acute intoxication and that occult poisoning often goes unrecognized because of inappropriate diagnostic criteria.