Laboratory diagnosis of increased lead absorption

Investigation of the Relationship Between Heavy Metals (Cadmium, Arsenic, and Lead) and Metallothionein in Multiple Sclerosis

BACKGROUND AND AIM

Multiple sclerosis (MS) is one of the most common neurological disorders. Metals are important for the maintenance and preservation of homeostasis and dysregulated metal homeostasis has an impact on neurodegeneration. Environmental factors are considered to contribute to MS risk and progression. Heavy metals such as arsenic (As), cadmium (Cd), and lead (Pb) are widely found in the environment and because of their toxic nature, they pose a great danger to human health. Metallothioneins (MTs) play important roles in metal homeostasis and detoxification of heavy metals.

OBJECTIVE

The aim of this study was to investigate the relationship between levels of heavy metals (As, Cd, and Pb) and MT levels in MS patients and also to assess the oxidative stress status of patients.

METHOD

Fifty subjects (20 healthy subjects and 30 MS patients) were included. Demographic characteristics of the patients, plasma MT levels, blood Cd, As, and Pb levels, as well as iron (Fe), copper (Cu), and zinc (Zn) levels, were determined. Malondialdehyde (MDA) levels were investigated as a marker of oxidative stress.

RESULTS

MT levels were slightly higher in the MS group (p > 0.05). As Cd and Pb levels were significantly higher in the control subjects. MDA levels were significantly higher in MS patients.

CONCLUSION

Our results support the relevance of MT and MDA levels in MS. Further clinical studies with larger cohorts will provide more insights into these factors.

Risk of Environmental Chemicals on Bone Fractures Is Independent of Low Bone Mass in US Adults: Insights from 2017 to 2018 NHANES

(1) Objective: To assess the association of environmental chemical factors with osteopenia and/or bone fractures. (2) Methods: All data were extracted from the National Health and Nutrition Survey (NHANES) 2017–2018 of American adults aged 20–59 years old; invalid data were excluded based on dual-energy X-ray absorptiometry. For the ultimate valid data set, multivariate logistic regression models were applied to evaluate the association of environmental chemical factors with osteopenia and bone fractures. (3) Results: The valid dataset was obtained from 2640 individuals, who completed a questionnaire of demographic characteristics. Urinary manganese and monomethylarsonic acid were positively associated with osteopenia in American adults, but not bone fracture. However, several environmental factors (e.g., arsenous acid, arsenocholine, dimethylarsinic acid, and 2-thioxothiazolidine-4-carboxylic acid) did not affect bone mineral density, but were significantly associated with bone fracture. (4) Conclusions: Multiple environmental chemical factors significantly affect bone mass or fracture risk. However, the risk of environmental chemical factors on fractures is independent of osteopenia in US Adults. The influence of environmental chemical factors on bone quality should be considered and monitored.

Lead, Mercury and Cadmium in Fish and Shellfish from the Indian Ocean and Red Sea (African Countries): Public Health Challenges

The main aim of this review was to assess the incidence of Pb, Hg and Cd in seafood from African countries on the Indian and the Red Sea coasts and the level of their monitoring and control, where the direct consumption of seafood without quality control are frequently due to the poverty in many African countries. Some seafood from African Indian and the Red Sea coasts such as mollusks and fishes have presented Cd, Pb and Hg concentrations higher than permitted limit by FAOUN/EU regulations, indicating a possible threat to public health. Thus, the operationalization of the heavy metals (HM) monitoring and control is strongly recommended since these countries have laboratories with minimal conditions for HM analysis.

Tooth lead levels as an estimate of lead body burden in rats following pre- and neonatal exposure

Accurate assessment of early life lead exposure requires an accessible and reliable biomarker.

Clinical description of toxic neuropathies

Toxic neuropathy, although rare, is an important consideration in the setting of a known or suspected toxic exposure in the workplace or other environment. This chapter discusses the clinical and electrodiagnostic evaluation of peripheral neuropathies, highlighting findings that direct further workup and may point to specific toxins as etiology. The difficulty of establishing causality of a toxin in relation to peripheral neuropathy is discussed; guidelines for establishing causality are presented. Examples of common industrial toxins are listed, including their typical industrial uses and their mechanisms of action in producing neuropathy. Characteristic clinical presentations of specific toxic neuropathies are highlighted with selected case studies.

Occupational lead exposure among automotive garage workers - a case study for Jimma town, Ethiopia

Background

In Ethiopia, although there are numerous small-scale and medium industries which use lead-based raw materials that may pose health risks to workers, there are no workplace regulations for lead exposure. Moreover, there are no studies carried out on the blood lead levels (BLLs) of workers or on the contribution of common workplace practices to lead poisoning.

Method

A cross-sectional study on the BLLs of 45 automotive garage workers and 40 non-garage workers was carried out in the town of Jimma, Ethiopia. In addition to BLL analysis, data on some risk factors such as smoking, and chewing ‘khat’ (the leaves of Catha adulis) were gathered through structured questionnaires and interviews and data analysis was performed using SPSS (version 16). The t-test was used to compare mean BLLs of study groups. The analysis of variance (ANOVA), Kruskal-Wallis, Pearson chi-square and odds ratio tests were used to investigate the associations between specific job type, smoking and/or ‘khat’ chewing, service years and occurrence of non-specific symptoms with BLLs.

Results

The mean BLL of the automotive-garage workers was found to be significantly greater than that of the controls. The BLLs of all the lead-exposed individuals were found to be over 10 μg/dL, and 53% of them had BLLs ranging 12 – 20 μg/dL, with the remaining 47% having over 20 μg/dL. The BLL of the workers increased with the duration of working in an automotive garage.

Individuals involved in manual car painting comprise a larger percentage (58%) of those with the highest BLLs (≥ 20 μg/dL). Lead accumulation in individuals who chew ‘khat’ in the work place was found to be faster than in those who are not used to chewing ‘khat’. ‘Khat’ is an evergreen shrub native to tropical East Africa, with dark green opposite leaves which are chewed when fresh for their stimulating effects.

Conclusion

The findings of the study have clearly demonstrated that the BLLs of automotive-garage workers in Jimma town are considerably high with a range of 11.73 – 36.52 μg/dL and the workers are in danger of impending lead toxicity. The BLLs of the workers are influenced by their occupational practices, chewing Catha adulis leaves at the workplace, and the time spent working in an automotive garage.

Disposition of lead (Pb) in saliva and blood of Sprague-Dawley rats following a single or repeated oral exposure to Pb-acetate

Biological monitoring for lead (Pb) is usually based upon a determination of blood Pb concentration; however, saliva has been suggested as a non-invasive biological matrix for assessing exposure. To further evaluate the potential utility of saliva for biomonitoring, the disposition of Pb was evaluated in whole blood (WB), red blood cells (RBC), plasma, parotid gland, bone, and saliva following either a single oral dose of 100mg Pb-acetate/kg body weight in rats or approximately 1-week after 5 sequential daily oral gavage doses of 1, 10, or 100mg Pb-acetate/kg/day. Saliva volume, pH, total saliva protein, and alpha-amylase activity were also determined. At specified times post-dosing groups of animals were anesthetized and administered pilocarpine to induce salivation. Saliva was collected, the animals were humanely sacrificed, and tissue samples were likewise collected, weighed, and processed for Pb analysis. Following a single dose exposure to Pb-acetate, Pb was detectable in all samples by 30 min post-dosing. For both the single and repeated dose treatments the concentration of Pb was highest in WB and RBC relative to plasma and saliva. However, the Pb rapidly redistributed (within 5-days post-treatment) from the blood into the bone compartment based on the substantial decrease in WB and RBC Pb concentration, and the concurrent increase in bone Pb following repeated exposure at all dose levels. Although there is clear variability in the observed Pb concentrations in plasma and saliva, there was a reasonable correlation (r(2)=0.922) between the average Pb concentrations in these biological matrices, which was consistent with previous observations. The single oral dose of Pb-acetate resulted in a decrease in salivary pH which recovered by 24h post-dosing and a decrease in alpha-amylase enzyme activity which did recover within 5-days of ceasing exposure. It is currently unclear what impact these slight functional changes may or may not have on Pb salivary clearance rates. These results demonstrate a feasibility to rapidly detect Pb in saliva and suggest that saliva may correlate best with plasma Pb concentration.

Elevation of Blood Lead Levels in Emergency Department Patients with Extra-articular Retained Missiles

BACKGROUND

Patients who survive gunshot wounds often have retained missiles. Unlike intra-articular retained missiles, extra-articular retained missiles (EARMs) are not routinely removed. Cases of lead toxicity from EARMs have been described. This study seeks to determine whether blood lead levels are elevated in emergency department patients with EARMs compared with matched controls, whether clinical symptoms of lead toxicity are more prevalent in patients with EARMs than in controls, and whether longer missile retention times or recent hypermetabolic conditions are associated with higher blood lead levels.

METHODS

One hundred twenty adults with EARMs and 120 age- and gender-matched controls with no history of gunshot wound were prospectively enrolled on presentation to a large urban emergency department. Whole blood lead (WBL), zinc protoporphyrin, and hemoglobin levels were obtained. Patients completed a questionnaire regarding time since gunshot injury; symptoms of lead toxicity; and occurrence within 30 days of any surgery, alcohol abuse, illicit drug abuse, diabetic ketoacidosis, hyperthyroidism, infection, fracture, pregnancy, or lactation.

RESULTS

Five EARM patients (4%) and no control patients (0%) had WBL greater than our threshold for medical follow-up (20 microg/dL). Mean WBL was 6.71 microg/dL (95% confidence interval [CI], 5.68-7.74 microg/dL) in EARM patients and 3.16 mug/dL (95% CI, 2.79-3.53 microg/dL) in controls. This difference was statistically significant when analyzed by matched pairs t test (p = 0.0001). There was no difference in the number of symptoms associated with lead toxicity that were noted by EARM patients versus controls (p = 0.377). Longer duration of missile retention was not associated with higher blood lead levels (r = 0.125, p = 0.172). Of the five hypermetabolic conditions analyzed, only fractures were associated with elevated blood lead levels (9.95 microg/dL [95% CI, 5.77-14.13 microg/dL] in EARM patients with fractures vs. 6.23 microg/dL [95% CI, 5.23-7.23 microg/dL] in EARM patients without fractures).

CONCLUSION

Patients with EARMs have significantly elevated blood lead levels compared with matched controls. The occurrence of a bony fracture within the past 30 days is associated with a higher lead level. In 96% of patients with EARMs, elevated lead levels were not clinically significant and did not change patient management.

Lead remediation and changes in human lead exposure: some physiological and biokinetic dimensions

This paper presents a qualitative and quantitative analysis of the various aspects of lead remediation effectiveness with particular reference to human health risk assessment. One of the key elements of lead remediation efforts at such sites as those under the Superfund program deals with populations at elevated exposure and toxicity risk in the proximity of, or at, the site of remediation, especially remediation workers, workers at other tasks on sites that were remediated down to some action level of lead concentration in soils, and groups at risk in nearby communities. A second element has to do with how one measures or models lead exposure changes with special reference to baseline and post-remediation conditions. Various biomarkers of lead exposure can be employed, but their use requires detailed knowledge of what results using each means. The most commonly used approach is measurement of blood lead (Pb-B). Recognized limitations in the use of Pb-B has led to the use of predictive Pb exposure models, which are less vulnerable to the many behavioral, physiological, and environmental parameters that can distort isolated or 'single shot' Pb-B testings. A third aspect covered in this paper presents various physiological factors that affect the methods by which one evaluates Pb remediation effectiveness. Finally, this article offers an integrated look at how lead remediation actions directed at one lead source or pathway affect the total lead exposure picture for human populations at elevated lead exposure and toxicity risk.

Elements in environmental and occupational medicine

Occupational and environmental medicine traditionally dealt with elements, particularly with heavy metals. The interest was justified by the wide exposure in the workplace and in the general environment and by the evidence of their specific biological and toxicological effects. During the last 2 decades of 20th century the availability of indicators of exposure or of internal dose has substantially increased thanks to improvement in AAS-ETAAS techniques and to the entrance of ICP-MS into the field of biological monitoring. There are now more and more demands for controlling pre-analytical and analytical factors, for analysing biological matrices in addition to blood and urine and for setting up methods for elements not yet extensively studied in respect to their possible biological or toxicological role. Finally, deeper knowledge has to be reached in order to evaluate the significance of elements and, possibly, of their species in biological fluids at current doses and in order to face their effects, especially those in the first portion of the dose-response curve, which is going to be the main field of interest of occupational and environmental toxicology for the next few years.

Determination of cadmium and lead in urine of some Nigerian subjects

Forty-one urine samples of smokers and non-smokers from Ile-Ife, Nigeria were analyzed for normal cadmium and lead levels after acid digestion. Results of the preliminary study show that concentrations of cadmium obtained were generally low compared with lead. The mean urinary levels from non-smokers ranged from 0.05 - 0.02 to 0.16 - 0.01 wg ml-1 and from 0.02 - 0.03 to 0.88 - 0.04 wg ml-1 for cadmium and lead respectively, whilst, for smokers, urinary levels varied between 0.07 - 0.01 and 0.23 - 0.02 wg ml-1 and between 0.28 - 0.03 and 1.02 - 0.02 wg ml-1 were obtained for cadmium and lead, respectively. Cd levels in urine of smokers and non-smokers are higher than the recommended normal level of 0.0085 wg ml-1, while levels of Pb are above the 0.08-0.15 wg ml-1 exposure range. Results of spiking experiments with urine gave high percentage recoveries for both elements (Cd, 87.9 - 0.40%) and (Pb, 90.40 - 0.12%). Blank determination was done for background correction.

Correlation between concentration in urine and in blood of cadmium and lead among women in Asia

The objectives of the present study are to examine if there exists a quantitative relationship between lead in urine (Pb-U) and that in blood (Pb-B), and also between cadmium in urine (Cd-U) and that in blood (Cd-B) among the general populations who are environmentally (and not occupationally) exposed to these elements at various levels. For this purpose, peripheral blood and morning spot urine samples were collected in 1991-1998 from approximately 50 non-smoking adult women each in four cities in south-east Asia and five cities in mainland China, and two cities each in Japan and Korea. The samples were wet-ashed and then analyzed by inductively-coupled plasma mass spectrometry for Pb-B, Cd-B, Pb-U and Cd-U. Measured values were subjected to analysis to detect possible correlation between the pairs of parameters. A significant correlation between Pb-B and Pb-U was observed when the intensity of Pb exposure (as expressed by Pb-B) was relatively high so that the correlation was significant in all cases studied when Pb-B level was, e.g. 50 microg/l or above. It was also observed that the correlation between Cd-B and Cd-U was significant when Cd-B was, e.g. > 1 microg/l. Thus, it is possible to deduce that, in environmental health, Pb-B and Cd-U levels can be estimated on a group basis from Pb-U and Cd-B, respectively, when Pb and Cd exposure levels are relatively high, e.g. with Pb-B and Cd-B of > 50 microg/l and > 1 microg/l.

Urinary excretion of lead and delta-aminolevulinic acid in workers occupationally exposed to tetraethyl lead

Forty-nine refinery workers and 50 motor mechanics were selected and examined for total lead (PbT), inorganic lead (PbI), and delta-aminolevulinic acid (ALA) in urine. The worker groups were exposed to tetraethyl lead (TEL) mainly by inhalation, but motor mechanics received additional exposure by skin because of hand cleansing with gasoline. The levels of urinary ALA (ALA-U) and urinary PbT (PbT-U) in refinery workers and motor mechanics were found to be significantly higher than the control group (p<0.05). The correlation between the ALA-U and PbT-U was found significant in both worker groups (p<0.001); however, relatively higher positive correlation was found between ALA-U and urinary inorganic lead (PbI-U) in TEL-exposed workers.

Effect of various concentrations of lead nitrate on the induction of micronuclei in mouse bone marrow

The frequency of micronuclei was evaluated in the bone marrow of mice of either sex administered with 0, 0.625, 1.25, 2.5, 5, 10, 20, 40 and 80 mg/kg b.wt of lead nitrate at 12, 24 and 36 h post-treatment. The frequency of micronucleated polychromatic erythrocytes (MPCE) and micronucleated normochromatic erythrocytes (MNCE) increased significantly at 12, 24 and 36 h after treatment with lead nitrate compared to non-drug treated controls. The frequency of micronuclei did not show a dose related increase and the elevation in the frequency of micronuclei was fluctuating type. One important observation which emerged from this study was that the male mice were more sensitive to the induction of micronuclei compared to female mice. This was evidenced by higher frequencies of MPCE in males than females at all the doses for all the post-treatment time periods. The lead nitrate treatment resulted in a spurt in the erythropoiesis as is evidenced by a significant increase in the ratios of polychromatic to normochromatic erythrocytes (P/N ratio) compared to non-drug treated controls at 12, 24 and 36 h post-treatment. The P/N ratio was significantly higher in females than males at 12 and 24 h post-treatment.

Measurement by ICP-MS of lead in plasma and whole blood of lead workers and controls

OBJECTIVES

To test a simple procedure for preparing samples for measurement of lead in blood plasma (P-Pb) and whole blood (B-Pb) by inductively coupled plasma mass spectrometry (ICP-MS), to measure P-Pb and B-Pb in lead workers and controls, and to evaluate any differences in the relation between B-Pb and P-Pb between people.

METHODS

P-Pb and B-Pb were measured by ICP-MS in 43 male lead smelter workers and seven controls without occupational exposure to lead. For analysis, plasma and whole blood were diluted 1 in 4 and 1 in 9, respectively, with a diluted ammonia solution containing Triton-X 100 and EDTA. The samples were handled under routine laboratory conditions, without clean room facilities.

RESULTS

P-Pb was measured with good precision (CV = 5%) even at concentrations present in the controls. Freeze storage of the samples had no effect on the results. The detection limit was 0.015 microgram/l. The P-Pb was 0.15 (range 0.1-0.3) microgram/l in controls and 1.2 (0.3-3.6) micrograms/l in lead workers, although the corresponding B-Pbs were 40 (24-59) micrograms/l and 281 (60-530) micrograms/l (1 microgram Pb/I = 4.8 nmol/l). B-Pb was closely associated with P-Pb (r = 0.90). The association was evidently non-linear; the ratio B-Pb/P-Pb decreased with increasing P-Pb.

CONCLUSIONS

By means of ICP-MS and a simple dilution procedure, P-Pb may be measured accurately and with good precision down to concentrations present in controls. Contamination of blood at sampling and analysis is no major problem. With increasing P-Pb, the percentage of lead in plasma increases. In studies of lead toxicity, P-Pb should be considered as a complement to current indicators of lead exposure and risk.

Lead: intestinal absorption and bone mobilization during lactation

The aim of this study was to examine lead (Pb) intestinal absorption, its mobilization and redistribution during lactation in rats chronically exposed to lead. Lead and calcium (Ca) concentrations were measured in blood, milk, femurs, liver and kidney samples obtained from pregnant and lactating mother rats which were subjected to different schedules of exposure to Pb: 158 days before and during lactation (group A), 144 days before lactation (group B) and 14 days only during lactation (group C). Results were compared to those of non-pregnant but Pb-exposed matched rats and non-exposed control rats. In groups A and B during lactation, Pb in blood (PbB), liver and kidney increased while Pb in bone decreased. Since there was not an external source of Pb in group B during lactation, the results indicate resorption of Pb in bone as the main source of Pb in the organism. In group A, there was an additional increase of PbB when compared to group B as a result of Pb intestinal absorption. In group C a significant increase in PbB due to intestinal absorption and deposit in bone was found when compared to non-pregnant 144 days old rats, suggesting that the three processes intestinal absorption, bone resorption and bone absorption were taking place. These data indicate that Pb stored in bone as a result of prior maternal exposure, should be considered as a major source of self intoxication and of Pb in milk available to suckling pups.

Lead exposure in the city of Arar, Saudi Arabia

In follow-up to a case of lead encephalopathy, high prevalences of lead exposure (23%) and iron deficiency (60%) were found in children who lived in Arar, Saudi Arabia. Environmental factors had minor effects on the blood lead concentrations of these children. We concluded that traditional cosmetics and remedies were the major sources of lead exposure in this Arar population.

X-ray fluorescence in the assessment of inter-elemental interactions in rat liver following lead treatment

Energy dispersive X-ray fluorescence technique was employed to study the interactions of lead (50 and 100 mg/kg body wt) with K, Fe, Cu, Zn, Br and Rb in rat liver. Lead was administered orally to rats daily for dosage periods of 1 and 4 months (short and long terms). Hepatic Fe levels were found to increase significantly with the supplementation of low and high doses of lead for both the treatment periods, although the increase was more pronounced following long-term treatment. The levels of hepatic K, Cu and Br were seen to decrease significantly over both time intervals. Moreover, hepatic Rb contents were lowered with the short-term supplementation of low doses of lead. In contrast, Rb and Zn levels were increased when lead was administered for the longer period at both dose levels.

Trace element distribution in rat brain following lead and lithium supplementation--a study using an EDXRF spectrometer

Distribution of K, Fe, Cu, Zn, Br and Rb in whole brain samples following combined Pb and Li administration to female Porton rats has been investigated by using the Energy Dispersive x-Ray Fluorescence (EDXRF) technique. Brain K, Cu and Rb levels are diminished, whereas Fe and Br levels are enhanced significantly following short-term (1 month) and long-term (4 months) combined treatment with Li (1.1 g/kg diet) and two doses of Pb (50 and 100 mg/kg body weight). The Zn levels are lowered following combined treatment with Li and both the doses of Pb given for short-term only.

Lead poisoning from retained lead projectiles. A critical review of case reports

Case reports demonstrate that embedded lead projectiles (bullets, pellets) have the potential to cause lead poisoning. They also show that the relationship between blood lead concentration and lead poisoning is the same as in lead poisonings of occupational origin and that latent periods between lodgement and the onset of lead poisoning varies from less than a half year to several decades. Nevertheless neither the quantitative relationships between projectiles and blood concentrations nor the number at risk and the number affected are known. The aim of this review is to show the limitations of case studies through the analysis of negative and positive case reports, diagnostic and monitoring methods, differences between bullets and pellets, and factors affecting the disintegration of projectiles and the distribution of released lead.

Distribution of blood lead levels in 1,047 Saudi Arabian children with respect to province, sex, and age

Relationships between blood lead concentrations in 1,047 children aged 2 mo to 16 y and age, sex, and province (i.e., residence) were examined. The relationships were consistent with other studies, in which mean blood lead concentrations reportedly increased during the first 5 y of life, after which began to decrease, reaching a minimum at approximately 16 y of age. However, boys who were more than 6 y of age had higher blood lead concentrations than similarly aged girls. Blood lead levels of children living in the Eastern Province were higher than levels found in children from other provinces. Most of the children in this study who had elevated blood lead concentrations resided in small towns, e.g., Ehssa, Abqiq, Hofouf, rather than in cities such as Dammam and Dahran. Factors, such as socioeconomic status and cultural habits (e.g., diet, use of traditional remedies and cosmetics), may have contributed to this result.

Combined action of lead and lithium on essential and nonessential elements in rat blood

The effects of lead and lithium ingestion, separately and in combination, on the levels of K, Fe, Cu, Zn, Br, Rb, and As in rat blood were studied by the Energy Dispersive X-ray Fluorescence technique. Two different doses of lead acetate, i.e., 50 and 100 mg/Kg body wt (low and high doses), were administered orally to rats, daily, for 1 and 4 months (short and long terms), whereas lithium in the form of lithium carbonate was given to rats in food (1.1 g/kg diet) for 1 and 4 mo separately, and also to rats receiving lower and higher doses of lead. K levels were found to be depressed significantly with lead treatment, whereas Fe contents were enhanced marginally after 1 mo of treatment when only the higher dose of lead was given. As, Br, and Rb contents were found to be elevated following lead treatment for short and long terms at both the dose levels. However, Cu contents were lowered, whereas Zn contents were raised only after long term treatment with lead. The Fe, Cu, As, and Br contents remained unaltered, whereas K, Rb, and Zn contents were reduced significantly when lithium was administered for short term. Moreover, Cu and Fe levels were also found to be reduced and Br contents were enhanced only after long term treatment. During the combined treatment with lead and lithium for short and long terms, the levels of K, As, and Rb were observed to decrease, whereas Fe contents were enhanced when estimated for both doses of lead. On the contrary, Cu levels were lowered only with the higher dose of lead acetate when given in combination with lithium for 1 and 4 mo. Br contents were only effectively decreased after 4 mo of treatment.

Biokinetics of iodine-131 in rat thyroid following lead and lithium supplementation

The impact of lead as an environmental pollutant on the I-131 uptake and retention in rat thyroid was assayed alone and in combination with lithium treatment. Lead treatment significantly stimulated the 2- and 24-h uptake of I-131 in the thyroid, and the 24-h uptake showed the maximum stimulation after 3 mo of lead treatment. On the contrary, lithium supplementation reduced the uptake significantly and the maximum decrease was noticed after 2 mo of lithium administration. Further, simultaneous lead and lithium treatment resulted in more pronounced increase in the uptake of I-131 by the thyroid, which was maximum after 3 mo of combined treatment. The thyroid biological half-life of I-131 (Tbiol) was found to be increased significantly following lead and lithium treatments when given separately. Interestingly, combined lead and lithium treatment given up to 2 mo further prolonged the Tbiol of I-131, thus reflecting its increased retention.

Blood lead levels among populations differentially exposed to vehicular exhaust in Rohtak, India

In the absence of local industrial sources of lead, leaded gasoline has been suggested as the major source of lead in the urban atmosphere of Rohtak town, situated near Delhi metropolitan city and with a high vehicular density. Blood lead levels were measured in 42 male volunteers from within the Rohtak area with varying degrees of exposure to vehicular exhaust. The occupationally exposed group with a daily exposure of 10-12 h in automobile workshops was found to have the highest levels of blood lead (mean value 21.26 microg dl(-1)) followed by roadside population (mean value 14.91 microg/dl(-1)). This group of people had a daily exposure of 8-10 h in their business establishments, situated at a distance of less than 5 to about 10 ft (< 1.5-c. 3.0 m) from the road with an average traffic density of 8000 vehicles day(-1). Urban residents were found to have higher blood lead levels (mean value 9.85 microg/dl(-1)) than the rural ones (mean value 3.34 microg/dl(-1)). The values were found to increase correspondingly with the increase in age and smoking habits within the particular categories of volunteers. The levels found in the present study are comparable to those reported from other major cities of India, but well within the tolerable limits as recommended by the European Economic Community.

Erythrocyte delta-aminolevulinic acid dehydratase in birds. II. The effects of lead exposure in vivo

The effects of in vivo exposure to Pb2+ on avian aminolevulinic acid dehydratase (ALA-d) activity were studied, and the activity ratio (activated/non-activated enzyme activity) was assessed as a potential indicator of Pb exposure in birds. A significant negative correlation was observed between blood-Pb concentration and log ALA-d activity (r = -0.827) in Pb-dosed birds. An even better correlation was obtained when data were expressed as an activity ratio (r = 0.961), demonstrating that sample variability is decreased by expressing the results as an activity ratio rather than as enzyme activity. Red blood cell (RBC) ALA-d activity ratio was a sensitive, dose-responsive measure of Pb exposure regardless of the mode of administration of Pb. Dietary Pb concentrations as low as 5 ppm (dry wt) could be estimated through the use of the activity ratio method, and a highly significant positive correlation was observed between dietary Pb concentration over the 5-100 ppm range and the ALA-d activity ratio (r = 0.87). The RBC-ALA-d activity ratio may thus be a useful method for estimating average dietary concentrations of Pb over an environmentally relevant range in situations where the diet is the major source of exposure to Pb, and where it is also impossible or impractical to accurately measure dietary Pb content directly.

The chronic toxicity of aluminium, cadmium, mercury, and lead in birds: a review

The toxicity of chronic dietary metal exposure in birds is reviewed. It is concluded that significant physiological and biochemical responses to such exposure conditions occur at dietary metal concentrations insufficient to cause signs of overt toxicity. Particularly important are reproductive effects which include decreased egg production, decreased hatchability, and increased hatchling mortality. Young, growing birds are typically more sensitive to the toxic effects of chronic metal exposure than adults, and altricial species are often more sensitive than precocial species. Factors which modify the absorption and toxicity of heavy metals, such as Se for the case of Hg, and Ca for the case of Pb and Cd, are discussed. Monitoring strategies for assessing environmental metal exposure in birds are evaluated.

Effects of exposure to lead among lead-acid battery factory workers in Sudan

Health effects of occupational exposure to lead were investigated among 92 exposed workers in lead-acid battery factory and 40 nonexposed workers serving as a control group from an oil mill in Khartoum North industrial area. The two groups were closely similar in age, stature, body weight, and socioeconomic conditions. A highly significant increase (P less than .01) was recorded in blood lead, urinary coproporphyrin, and basophilic stippled red blood cells of the exposed group in comparison to the control group. Central nervous system symptoms (insomnia, fatigue, weakness, and drowsiness) were reported by 50% and other symptoms such as abdominal colic and constipation were reported by 41% of the exposed group. Blue line on the gum was detected only on 2% of the exposed group. Strong associations between exposure to lead and the prevalence of central nervous system symptoms, abdominal colic, and constipation were recorded. Exposure to exceedingly high levels of lead in the working environment causes adverse health effects.

Environmental lead exposure of an urban Indian population

Environmental lead exposure of the Greater Bombay population has been estimated by measuring lead concentrations in air particulates, water, food and cigarette smoke. Atmospheric lead concentrations in different zones of the city varied between 82 and 605 ng m-3. The dietary intake of lead is estimated to be 245 micrograms day-1 and is calculated from the lead content in different food groups and the amount of that group consumed by an average resident of the city. The uptake by a non-smoker living in the city area is estimated to be 33 micrograms of lead per day, 75% of which comes from food, 15% from air and 10% from water. For a suburban resident 85% of the lead intake comes from food. The blood lead measurements and the contribution of atmospheric lead to the blood lead level are discussed.

The effect of low lead doses in vitro and in vivo on the d-ala-d activity of erythrocytes, bone marrow cells, liver and brain of the mouse

The d-ala-d activity in erythrocytes (RBC), femur bone marrow, liver and brain of mice was determined using a modification of the method of Berlin and Schaller (1974). In vitro incubation of lead acetate (PbAc) with these tissues resulted in a dose-dependent inhibition of the d-ala-d activity. The lead concentration which caused a 50% inhibition of the d-ala-d activity after 10 min incubation [ED-50(10 min)] was 0.78 mg PbAc/femur bone marrow, 3.72 micrograms PbAc/ml RBC, 15.85 micrograms PbAc/g brain and 43.05 micrograms PbAc/g liver. An increase in the incubation time to 60 min reduced these ED-50 values between 44% for the erythrocytic enzyme and 67% for the brain enzyme. In vivo treatment of mice with oral lead administration (absorbed dose range: 1-100 micrograms PbAc/kg b.w.) for 1 or 3 months led to a dose-dependent and organ-specific inhibition of the d-ala-d activity. After 3 months of oral lead supply the maximum enzyme inhibition (54%) was found in the bone marrow. At the same time the lowest enzyme inhibition could be seen in the brain which retained 73% of its activity. The erythrocytic and liver enzyme activity was 71% and 72% resp. of the appropriate control. Within 3 weeks after completing the oral lead administration the brain enzyme activity was completely restored. The erythrocytic and liver enzyme activities were still significantly, but not very markedly inhibited, whereas the bone marrow d-ala-d remained seriously depressed. According to these experiments, the lead dose which causes a long term inhibition of the bone marrow and erythrocytic d-ala-d activities is assumed to range between 50 and 100 micrograms PbAc/kg b.w. and day, as an absorbed dose.

Relationships between distribution of lead in erythrocytes in vivo and in vitro and inhibition of ALA-D

Proteins in the ALA-D (delta-aminolaevulinic acid dehydratase) fraction from gel filtration of erythrocyte supernatant (ES) have the highest affinity for lead among erythrocyte constituents in vivo and in vitro. It takes 20-40 hours for erythrocyte components to be equilibrated with lead added in vitro. AT low lead concentrations, under 60 micrograms/100 ml ES, the extent of decrease in ALA-D activity indicates the extent of lead saturation of ALA-D fraction proteins. The saturation is attained at 80-110 micrograms/100 ml ES. Although an appreciable amount of lead is also found in the haemoglobin fraction that contains certain factors concerned in ALA-D inhibition, lead responsible for inducing the inhibition is not bound to haemoglobin fraction proteins but to ALA-D fraction proteins. Of three treatments or agents recovering the enzyme from lead effects, zinc is the only one that can fully restore the inhibition.

Relationships between three indicators of lead exposure in workers: blood lead, delta-aminolevulinic acid and free erythrocyte protoporphyrin

Whole blood lead (Pb-B), urinary delta-aminolevulinic acid (ALA-U) and free erythrocyte protoporphyrin (FEP) were measured in three groups of workers (n = 196) with different degrees of exposure to lead, and one group of men with no previous exposure to the metal (n = 48). Inter-group comparison showed a correlation of r = 0.73 between Pb-B and log of ALA-U, and r = 0.91 between Pb-B and log of FEP. ALA-U and FEP values rose sharply after Pb-B values reached 450-500 micrograms/l.

The laboratory evaluation of microcytic red blood cells

Microcytic red blood cell states are common clinical problems in both adult and pediatric age groups. The recent widespread availability of electronic blood cell counters for performing routine blood counts has increased the detection of microcytic red blood cells. Physicians must workup both symptomatic and asymptomatic patients with microcytic red blood cells before they can initiate proper therapy and/or counseling. The purpose of this review is threefold: (1) to discuss the causes of microcytic red blood cells in terms of disorders of decreased heme production vs. disorders of decreased globin production, (2) to review the clinical laboratory tests useful in differentiating microcytic red blood cell states, and (3) to present a practical approach for the laboratory workup of microcytic red blood cells.

Blood pressure and creatinine clearance in lead-exposed children: the effect of treatment

The authors speculated that normal growth might cause the release of stored lead in children, providing an endogenous source of exposure for years after the acute toxic episode had resolved. The purpose of this study was to answer the following two questions (1) Is a chelation-responsive lead burden present 2 to 5 yr after therapy for acute poisoning? and (2) Does blood pressure or creatinine clearance correlate with body lead burden, as demonstrated by chelation? Thirty-eight children who had undergone ethylene diamine tetraacetic acid mobilization testing at least one time during the course of treatment in a lead clinic returned for follow-up care within 2-5 yr. all were asymptomatic. To determine the current level of body lead burden, a single-dose oral chelation with penicillamine was performed. Blood pressure and creatinine clearances were measured. From the data obtained for each child, we generated a geometric "area" representing the magnitude of lead burden integrated over the length of carriage of this burden. Multiple regression analysis indicated that after adjustment for the background variables of age, sex, height, and weight, none of the three parameters--mobilization ratio "area," blood lead level, or FEP level--was a significant contributor to the variation observed in the blood pressures or creatinine clearances of the 38 lead-exposed children (P greater than .05).

Lead levels in saliva and in blood

The relation between salivary and whole-blood Pb levels was examined in 266 male adults, 196 of whom were Pb-exposed workers. The coefficient of correlation r between salivary and blood Pb levels was .72 (p less than 0.01); the correlation was improved when salivary Pb concentrations were plotted on a logarithmic scale. The results show that the salivary Pb concentration increased very rapidly, in a more or less exponential fashion, after blood Pb levels exceeded 500 micrograms/l. Techniques of saliva collection and Pb determination by flameless atomic absorption spectrophotometry are described. The validity of using salivary Pb as a screening test is evaluated.

Erythrocyte protoporphyrin IX as a diagnostic and therapy evaluating tool in lead poisoning

After lead poisoning was confirmed in nine adult males industrially exposed to lead dusts, therapy was instituted with oral penicillamine. Several laboratory examinations confirmed diagnosis, and also monitored the efficiency of penicillamine therapy. This study sought to investigate the usefulness of protoporphyrin determination in erythrocytes as a tool in diagnostic and therapy-evaluating studies. This determination seems to be a good clinical aid in diagnosis, but is a poor monitor to project eventual recovery of lead-poisoned patients in short-term studies.

Distribution of lead-203 in human peripheral blood in vitro

In-vitro experiments using 203Pb were performed to identify the lead binding components in human peripheral blood. The distribution of lead in plasma, in the red cell membrane, and within the red cell was also investigated. Studies of the distribution of 203Pb in whole blood showed that at a lead concentration of 2.45 mumol/l (50 micrograms/100 ml) about 94% of lead had been incorporated by the erythrocytes and 6% remained in the plasma. After extraction of lipid by a methanol/chloroform mixture, about 75% of the lead was found to be associated with the protein fraction. The lipid contained about 21% of the 203Pb, the remainder being in the aqueous plasma. SDS polyacrylamide gel electrophoresis of blood plasma showed that almost 90% of the 203Pb was present in the albumin fraction; the remainder was likely to be associated with high molecular weight globulins. Several binding sites were identified on the erythrocyte membrane. The high molecular weight component, about 130 000-230 000, was the most important 203Pb binding site. Chemical modification of membrane proteins suggested that the carboxyl groups are the major ligand responsible for most of the lead binding. SH groups of the membrane may have a minor role, but amino groups did not appear to affect the lead binding. The binding of lead to erythrocytes was not confined to membranes, over 80% of lead in blood penetrates into erythrocytes and binds to intracellular components. Gel chromatography of the haemolysate showed that over 90% of the 203Pb was attached to the haemoglobin molecule.

The action of small doses of lead on erythrocyte D-aminolevulinic acid dehydratase in the mouse

After a single intraperitoneal administration of lead in very small doses [1--100 micrograms Pbac/kg body weight (bw)], there was a dose-dependent, highly significant inhibition of erythrocyte D-aminolevulinic acid dehydratase (D-ALA-D) activity in mice. The maximal inhibition occurred between 3 and 24 h post injection (p.i.). After that, a rapid recovery of the D-ALA-D activity took place so that four days after lead administration, enzyme activity exceeded even the normal value. Only after eight days p.i. did the D-ALA-D value return to the initial level after a biphasic course. After 10 i.p. injections of 0.1 to 10 micrograms Pbac/kg bw, there was again a dose-dependent, highly significant inhibition of the erythrocyte D-ALA-D activity in mice. The maximal inhibition was shown to be 24 h after the last lead injection. In contrast to the single i.p. administration, however, we found a monophasic course for the return of D-ALA-D activity. The D-ALA-D values did not exceed the normal range at any time after 10 i.p. lead injections. Ten and 30 days oral administration of lead corresponding to i.p. doses exhibited similar results in D-ALA-D inhibition.

Lead poisoning. A comprehensive review and report of a case

Lead, a ubiquitous heavy metal which has realized increased use, can cause poisoning by environmental contamination in either its organic or its inorganic form. Lead poisoning can be either acute or chronic, with the latter being the more common. The clinical signs and symptoms of lead poisoning are nonspecific, resulting in a difficult diagnostic problem, especially when it is not industrially related. On occasions, the dentist or oral surgeon may be the first to see an afflicted patient because of oral manifestations.

Occupational lead exposure in Denmark: screening with the haematofluorometer

The zinc protoporphyrin/haemoglobin (ZPP/Hb) ratio was measured in the field with a haematofluorometer. A significant increase in ZPP/Hb ratio with advancing age was found in 1295 men who denied any excess exposure to lead. Ninety-seven per cent of the results were below 110 mumol ZPP/mol Hb(Fe) (4.4 microgram ZPP/g Hb). The ZPP/Hb ratio was determined in a lead-exposed population of 2275 men, and in 305 a blood lead analysis was also performed. A blood lead limit of 2.9 mumol/l (60 microgram/100 ml) corresponds to about 500 mumol ZPP/mol Hb(Fe) (20 microgram/g). This limit was exceeded in workers engaged in secondary lead smelting, storage battery manufacture, car radiator repair, crystal glass manufacture, storage battery repair, ship breaking, metal foundries, the ceramic industry, scrap metal handling, and PVC plastic manufacture. Other occupations caused lower lead exposures with ZPP/Hb ratios between 110 and 500 mumol ZPP/mol Hb(Fe): such ratios were found in men from shooting ranges, in leaded pane manufacturers, gunsmiths, car paint sprayers, type setters, steel rolling mill workers, shipbuilders and welders, car mechanics, lead pigment handlers, and solderers. Increased ZPP/Hb ratios and blood lead levels in 210 workers were associated with a decrease in haemoglobin concentration in the blood. Thus, the haematofluorometer has proved to be very useful for screening purposes. A blood lead determination should be performed if the ZPP/Hb ratio exceeds 300 microgram ZPP/mol Hb(Fe) (12 microgram/g).

Increased blood lead levels in mentally retarded children in Greece

In 60 children with mental retardation of unknown etiology, the whole blood lead, as well as the activity of the red cell delta-aminolevulinic acid dehydratase (delta-ALAD), was measured. Thirty normal children and 30 with mental retardation of known etiology were used as controls. The lead values were found significantly higher in the study patients compared with both control groups (P less than 0.001). The delta-ALAD activity in the 14 patients with blood lead levels greater than or equal to 40 microgram/dl, was significantly reduced compared with the normal controls (P less than 0.001) and the mentally retarded controls (P less than 0.01). In more than 20% of the patients with mental retardation of unknown etiology, indications of significant exposure to lead were found. There was no difference in blood lead values between children from cities and those from rural areas. The possible role of lead in the etiology of mental retardation is discussed.

Lead and hyperactivity: lead levels among hyperactive children

Previous work has demonstrated an association between hyperactivity and increased body lead burdens in school-age children. In the present study it is shown that within a group of hyperactive children those for whom an organic etiology is present have lead burdens lower than in those for whom no apparent cause could be found. These data lead us to reject the notion that hyperactivity per se is responsible for the acquisition of elevated lead levels, and further strengthen the suspicion that for some children lower lead level absorption may be implicated in the development of the hyperkinetic disorder.