The association of lead exposure and motor performance mediated by cerebral white matter change

The goals were to determine if lead exposure is associated with cerebral white matter changes (WMC) and if so, does WMC mediate the relation between lead and psychomotor slowing as measured by Grooved Pegboard (GP). In the literature, age is the strongest predictor of WMC and therefore 61 lead smelter workers age 50 and under were included in the study population. Mean (range) age was 40 (23-50) years, years of education was 9 (0-13), duration of employment was 19 (1-26), current blood lead (PbB) was 29 (16-42) microg/dl, working lifetime weighted integrated blood lead (IBL) was 826 (65-1451) microg year/dl, working lifetime weighted average blood lead (TWA) was 42 (17-59) microg/dl, and bone lead (PbBn) was 39 (-12-90) microg Pb/g bone mineral. WMC, recorded as hyperintensities on T2-weighted MRI of the brain were graded. Lead variables were entered in a logistic regression attempting to differentiate normal versus abnormal MRI, after controlling for age and cerebrovascular risk factors. Direct effects of lead on GP and indirect effects of lead on GP through WMC was modeled using multiple linear regression analyses after controlling for the covariates. WMC were present in 23% of MRIs. Logistic regression of WMC on lead exposure metrics demonstrated significantly elevated odds ratios for IBL, TWA, and PbBn after the covariates. Of the lead exposure variables, IBL (beta=0.339, p<0.10) had a larger direct effect on GP after adjusting for the covariates than PbBn (beta=0.265, p<0.10). After adjusting for the lead term and covariates WMC accounted for an additional effect on GP performance after PbBn (beta=0.261, p<0.10) and after IBL (beta=0.278, p<0.05). Path analysis demonstrated that some of the relationship of both PbBn and IBL with GP is mediated by WMC.

Spermatozoa nucleus takes up lead during the epididymal maturation altering chromatin condensation

Lead (Pb) alters sperm chromatin condensation (CC) and the mechanisms are investigated. During spermatogenesis, protamines replace histones and disulfide bonds formation during epididymal maturation condense the chromatin. We evaluated sperm Pb uptake in testis and epididymis and the effects on CC in mice (0.06% Pb(2+)/16 weeks/drinking water). Spermatozoa from caput epididymis (CP) and cauda epididymis-vas deferens (CE-VD) were obtained and CC was measured by SCSA. Lead levels in spermatozoa from CP were lower than those from CE-VD, and correlated with a decreased CC, while Pb in CE-VD spermatozoa correlated with an increased CC. Lead accumulation into the nucleus was observed and Pb binding to nuclear sulfhydryl groups decreased chromatin decondensation in vitro. Our results suggest that spermatozoa take up Pb during testicular development and epididymal transport and alter CC, depending of the timing of Pb incorporation into the sperm nucleus, which finally may interfere with the chromatin decondensation process after fertilization.

Lead content in autopsy liver tissue in samples from Greenlandic Inuit and Danes

OBJECTIVES

To measure the quantity of lead (Pb) in liver tissue samples from Greenlandic Inuit, and compare the results with those obtained in Caucasian Danes.

STUDY DESIGN

Observational, descriptive survey on environmental pathology.

METHODS

The setting was related to forensic medicine and hospitalised care in Nuuk, Ilulissat and Copenhagen. Participants were 50 Greenlandic Inuit (27 men) with a median age of 61 years (range 23-83) and 74 Danes (44 men) with a median age of 60 years (range 15-87). Liver tissue samples (normal by macroscopic and microscopic examination) were obtained at autopsy. Total liver lead content was measured by X-ray fluorescence spectrometry with a detection limit of 0.05 micromol/kg dry weight.

RESULTS

In the entire series, Inuit had higher liver lead contents than Danes (p < 0.0001). Inuit men had higher liver lead content than Inuit women (p = 0.02). In Danes, men tended to have higher liver lead contents than women, but the difference was insignificant. The median (5-95 percentile) lead content was 14.96 micromol/kg dry liver (4.83-74.80) in Inuit, and < 0.05 micromol/kg dry liver (< 0.05-29.44) in Danes. All Inuit had liver lead contents above the detection limit, whereas 60 Danes (81%) had liver lead content below the detection limit. There was a positive correlation between liver lead content and age in both Inuit (rs = 0.46, p = 0.002) and Danes (n = 14; rs = 0.71, p = 0.01). Inuit had higher hepatic lead indices (liver lead content divided by age) than Danes (p < 0.0001). In Inuit, median hepatic lead index was 0.258, being higher in men than in women (p = 0.02). In Danes, the median hepatic lead index was 0.001, again higher in men than in women (p = 0.03).

CONCLUSIONS

Our results show a gender-related difference in hepatic lead content, i.e. Inuit men have higher liver lead contents than women. Furthermore, Inuit men and women have higher hepatic lead contents than Danish men and women. In both Inuit and Danes, the liver lead content increases with age. One reason for the high lead levels in Inuit may be ingestion of seabirds contaminated by lead shot.

Lead (Pb) exposure and its effect on APP proteolysis and Aβ aggregation

Alzheimer's disease (AD) is a progressive neurodegenerative disorder with clinical manifestations appearing in old age, however, the initial stages of this disease may begin early in life. AD is characterized by the presence of excessive deposits of aggregated beta-amyloid (Abeta) peptides, which are derived from the beta-amyloid precursor protein (APP) following processing by beta-secretase and gamma-secretase. Recently, we have reported that developmental exposure of rats to Pb resulted in latent elevation of APP mRNA, APP, and Abeta in old age. Here we examined whether latent up-regulation in APP expression and Abeta levels is exacerbated by concurrent disturbances in APP processing or Abeta aggregation. Among the environmental metals tested, only Abeta solutions containing Pb promoted the formation of Abeta aggregates at nanomolar concentrations. The lifetime profiles of alpha-, beta-, and gamma-secretases remained constant in adult and aging animals, and developmental exposure to Pb did not alter them. Furthermore, the addition of various concentrations of Pb (0.1 to 50 microM) to cerebral cortical extracts derived from control animals also did not affect the proteolytic activities of these enzymes. Therefore, we propose that amyloidogenesis is promoted by a latent response to developmental reprogramming of the expression of the APP gene by early exposure to Pb, as well as enhancement of Abeta aggregation in old age. In rodents, these events occur without Pb-induced disturbances to the enzymatic processing of APP. The aforementioned results provide further evidence for the developmental basis of amyloidogenesis and late-life disturbances in AD-associated proteins by environmental agents.

Simultaneous effect of lead and cadmium on granulosa cells: a cellular model for ovarian toxicity

Lead (Pb) and cadmium (Cd) are known reproductive toxicants, which accumulate in granulosa cells of the ovary. Female Charles foster rats were treated with sodium acetate (control), lead acetate and cadmium acetate either alone or in combination at a dose 0.05 mg/kg body weight intra-peritoneally for 15 days daily. Animals were killed at proestrous stage and granulosa cells were isolated from the ovaries. Binding of (125)I-luteinizing hormone ((125)I-LH), (125)I-follicle stimulating hormone ((125)I-FSH) and 17beta-hydroxysteroid dehydrogenase activity were measured. As these receptors are localized on the surface of the cell membrane, we also estimated the membrane parameters of these cells. Our results demonstrated that both lead and cadmium caused a significant reduction in gonadotropin binding, which altered steroidogenic enzyme activity of granulosa cells. These changes exhibited a positive correlation with membrane changes of the granulosa cells.

Lead poisoning in whooper and tundra swans

Six weak whooper swans (Cygnus cygnus) and two weak tundra swans (Cygnus columbianus) were found at Swamp Miyajima (Hokkaido, Japan) in May 1998. Anorexia, depression, green watery feces, pale conjunctiva, and anemia were observed. Radiographs showed from six to 38 suspected lead pellets in the gizzard. Blood lead concentrations were 2.5-6.7 microg/g (mean+/-SD=4.6+/-1.14 microg/g) on day 1. After blood collection, the birds were treated with calcium disodium ethylenediaminetetraacetate (CaEDTA) given intravenously and force fed. Despite treatment, seven birds died the next day. Green, bile-stained livers and pale or green kidneys were observed on necropsy. Microscopically, bile pigment was widespread in the liver and acid-fast intranuclear inclusion bodies were observed in renal tubular epithelium. Lead concentrations in livers and kidneys were 14.0-30.4 microg/g and 30.2-122 microg/g wet weight, respectively. Only one bird survived and this whooper swan continued to be treated with CaEDTA and activated charcoal. No lead shot was observed in the proventriculus and gizzard by radiography on day 64 and the blood lead concentration decreased from 2.9 microg/g to 0.09 microg/g during that same period. After 4 mo of rehabilitation, the whooper swan was returned to the wild. Lead intoxication continues to be a problem at Swamp Miyajima.

Evaluation of increased proportion of cells with unusually high sister chromatid exchange counts as a cytogenetic biomarker for lead exposure

Sister chromatid exchange (SCE) frequency and high-frequency cells (HFCs) were analyzed in 50 storage battery plant workers with mean blood lead level (BLL) of 40.14 +/- 9.99 microg/dL. The mean BLL in the control group (n=30) was 9.77 +/-1.67 microg/dL. This difference in mean BLLs between control and exposed group was statistically significant (p<0.05) and reflects clearly the lead exposure in the workers. Urinary aminolevulinic acid (U-ALA) was also determined in both control (3.37+/- 0.89 mg ALA/g creatinine) and exposed groups (12.39+/- 6.18 mg ALA/g creatinine) and U-ALA excretion was statistically higher (p<0.05) in lead-exposed workers. The relationship between biomarkers of lead exposure/effect and HFC percentage was higher than the relationship between biomarkers of lead exposure/effect and SCE frequency. Accordingly, HFC analysis seemed to be more sensitive than the SCE analysis as a cytogenetic biomarker for lead exposure. Additionally, the statistically significant correlation (r2=0.880, p<0.01) between U-ALA excretion and HFC percentage in lead-exposed workers supported the probability of ALA mediated indirect mechanism for lead genotoxicity.

The Effects of Early Lead Exposure on the Brains of Adult Rhesus Monkeys: A Volumetric MRI Study

Little is known about direct effects of exposure to lead on central nervous system development. We conducted volumetric MRI studies in three groups of 17-year-old rhesus monkeys: (1) a group exposed to lead throughout gestation (n = 3), (2) a group exposed to lead through breast milk from birth to weaning (n = 4), and (3) a group not exposed to lead (n = 8). All fifteen monkeys were treated essentially identically since birth with the exception of lead exposure. The three-dimensional MRI images were segmented on a computer workstation using pre-tested manual and semi-automated algorithms to generate brain volumes for white matter, gray matter, cerebrospinal fluid, and component brain structures. The three groups differed significantly in the adjusted (for total brain size) volumes of the right cerebral white matter and the lateral ventricles. A significant reduction was noted in right cerebral white matter in prenatally exposed monkeys as compared to controls (p = 0.045). A similar reduction was detected in the white matter of the contralateral hemisphere; however, this difference did not achieve statistical significance (p = 0.143). Prenatally exposed monkeys also had larger right (p = 0.027) and left (p = 0.040) lateral ventricles. Depending on the timing of exposure during development, lead may exhibit differential effects with resultant life-long alterations in brain architecture.

Amelioration of lead toxicity on rat liver with Vitamin C and silymarin supplements

The aim of the present study was to investigate the impact of the combined administration of Vitamin C and silymarin on lead toxicity. Male albino rats were subdivided into three groups: the first was a control group, the second received lead acetate in diet as 500 mg/kg diet daily, the third received the same lead acetate dose and supplemented with Vitamin C (1 mg/100g body weight) and silymarin (1 mg/100g body weight) by gastric tube three times per week. Blood samples were taken after 2, 4 and 6 weeks of treatment. Significant lead-induced elevations in serum ALT, AST, GGT and ALP activities were observed after different periods of treatment. However, serum LDLc was decreased. The intensities of RNA and apoptotic fragments of DNA were measured as optical density by Gel-pro program. Lead acetate decreased the intensity of DNA at 6 weeks and induced apoptotic DNA fragments reversibly with time. After 2 weeks of lead administration dilation and congestion of terminal hepatic veins and portal vein branches were observed. Lead also induced hepatocyte proliferation without any localized distribution among zones 1-3. Portal inflammatory infiltrate with disruption of the limiting plates (interface hepatitis), steatosis, apoptosis and mild fibrosis were detected especially by sixth week of lead administration. Combined treatment of lead-exposed animals with Vitamin C and silymarin showed marked improvement of the biochemical, molecular and histopathological findings. These experimental results strongly indicate the protective effect of Vitamin C and silymarin against toxic effects of lead on liver tissue.

Inhibition of progenitor cell proliferation in the dentate gyrus of rats following post-weaning lead exposure

Although lead is a potent developmental neurotoxin, the effects of postnatal lead exposure on progenitor cell proliferation in the hippocampus has not been examined. Postnatal day 25 rats were fed a lead containing diet (1500 ppm lead acetate) for 30-35 days and administered bromodeoxyuridine (BrdU, 50 mg/kg, i.p.) during the last 5 days of lead exposure. Animals were killed 24 h after the last BrdU injection. Proliferation of new cells in the subgranular zone and dentate gyrus was significantly decreased in lead-exposed rats compared to control animals that ate a similar diet devoid of lead. These results suggest that postnatal lead exposure can have significant deleterious effects on progenitor cell proliferation and thus the structure and function of the hippocampus.

[Gout nephropathy--ghost or reality?]

Until the past decades, end stage renal disease was considered a major cause of death among patients with gout. Modern long-term follow up studies of renal function however have indicated that hyperuricemia and gout rarely result in kidney damage unless other renal diseases supervene. Subsequently, the use of the EDTA lead mobilization test confirmed that gout in the presence of chronic renal failure is a useful marker of chronic lead intoxication. Chelation treatment with EDTA can slow the progression of renal insufficiency, without apparent damage associated with the use of the chelating agent. Since chronic lead intoxication may remain clinically concealed for years, a high index of suspicion is warranted. Occult lead intoxication should be sought actively in gouty patients with chronic renal insufficiency of unknown etiology.

The effects of meso-2,3-dimercaptosuccinic acid and oligomeric procyanidins on acute lead neurotoxicity in rat hippocampus

Oxidative stress is considered to be a mechanism involved in lead neurotoxicity. Apoptosis is also thought to relate to lead neurotoxicity. The present study, focused on the hippocampus, was designed to investigate the two possible mechanisms involved in lead neurotoxicity and the potential protective effects of 2,3-dimercaptosuccinic acid (DMSA) and oligomeric procyanidins (OPC). It was proved that reactive oxygen species and oxidative damage were implicated in the induction of apoptosis induced by lead in the hippocampus. Administration of DMSA attenuated the oxidative stress and apoptosis in addition to having strong chelating and lead-removing capacity. OPC alone had antioxidant protective effects in the hippocampus but no removing capacity for lead in vivo despite showing higher affinity and stronger chelating ability for Pb(2+) than DMSA in vitro. It is suggested that OPC chelates Pb(2+) but does not discharge it from the body and even accumulates Pb(2+) in some organs. At the same time, a reasonable deduction can also be made that the complex of OPC-Pb(2+) prevents or at least weakens the neurotoxicity of Pb(2+). Whether this complex displays toxicity over a long time span should be studied further.

[Determination of lead in human hair using flame atomic absorption spectrometry and nebulization assisted with hydride generation]

Lead in human hair was determined using flame atomic absorption spectrometry and nebulization assisted with hydride generation and K3Fe(CN)6-HCl system. The method is simple and rapid for operation. The performance of the method was compared with conventional flame atomic absorption spectrometry for direct determination of lead. An improved sensitivity by 13.4 fold was obtained compared to the conventional FAAS for direct determination of lead. The effects of several experimental parameters on the lead determination were optimized, and the influences of interference ions on the determination were investigated. The limit of detection (3sigma) of the proposed method was 2.8 microg x L(-1). The method has been applied to the determination of human hair sample satisfactorily with a recovery of 96%-99%.

Therapeutic efficacy of lipoic acid in combination with dimercaptosuccinic acid against lead-induced renal tubular defects and on isolated brush-border enzyme activities

The combined therapeutic potentials of lipoic acid and dimercaptosuccinic acid were compared against their sole administrations in restoring the altered lead sensitive indices in urine and isolated renal brush-border preparations. Toxicity was induced in male albino rats (Wistar strain) by administering lead acetate (0.2%) in drinking water for 5 weeks, followed by therapy comprising lipoic acid (25 mg/kg body weight) and dimercaptosuccinic acid (20 mg/kg body weight) solely as well as combined during the 6th week. Changes in kidney weights encountered upon lead administration improved after therapy with lipoic acid and dimercaptosuccinic acid. Renal integrity was assessed by measuring the activities of alkaline phosphatase, acid phosphatase, lactate dehydrogenase, leucine aminopeptidase, N-acetyl-beta-D-glucosaminidase, gamma-glutamyl transferase and beta-glucuronidase in urine along with some urinary constituents (urea, uric acid, creatinine, protein and phosphorous). The effects of lead were also studied on isolated brush-border enzymes (alkaline phosphatase, acid phosphatase, gamma-glutamyl transferase and beta-glucuronidase) that showed a decline upon its administration. Increased activities of urinary enzymes were accompanied by increase in the urinary constituents. Increase in renal lead content was paralleled by a drastic fall in the renal delta-aminolevulinic acid dehydratase and a rise in urinary lead levels. Relative to the administration of lead, the combined therapy showed betterment on the renal integrity with respect to the functional parameters assessed, thereby indicating its efficacy over the monotherapies.

Saccade dysfunction associated with chronic petrol sniffing and lead encephalopathy

BACKGROUND

In chronic petrol sniffers, recent exposure to high levels of leaded petrol may give rise to a lead encephalopathy characterised by tremor, chorea, ataxia, hyperreflexia, convulsive seizures, and death. Neurological abnormalities associated with lead encephalopathy involve the cortex, basal ganglia, cerebellum, and brain stem.

OBJECTIVE

To use saccadic eye movement tasks as an experimental tool to determine which CNS changes are associated with chronic petrol sniffing and which with a history of lead encephalopathy, and to what extent these changes are reversible.

METHODS

Saccade function was assessed in chronic petrol sniffers with a history of lead encephalopathy (encephalopathic sniffers), chronic petrol sniffers who had never suffered lead encephalopathy (chronic sniffers), individuals who had sniffed petrol in the past but had not done so for more than six months (ex-sniffers), and individuals who had never sniffed petrol (non-sniffers).

RESULTS

Chronic sniffers showed increased latency of visually guided saccades and antisaccades and increased antisaccade errors which suggested cortical and basal ganglia dysfunction. These abnormalities returned to normal in ex-sniffers. Encephalopathic sniffers showed the same abnormalities as chronic sniffers but with greater severity and additional saccadic signs including dysmetria, gaze evoked nystagmus, and saccade slowing which usually indicate cerebellar and brain stem dysfunction.

CONCLUSIONS

Chronic petrol abuse is associated with cortical and basal ganglia abnormalities that are at least partially recoverable with abstinence. Additional long term cerebellar and brain stem abnormalities are associated with lead encephalopathy.

Vascular endothelial growth factor mediates vasogenic edema in acute lead encephalopathy

Brain injury from inorganic Pb(2+) is considered the most important environmental childhood health hazard worldwide. The microvasculature of the developing brain is uniquely susceptible to high level Pb(2+) toxicity (ie, Pb(2+) encephalopathy) characterized by cerebellar hemorrhage, increased blood-brain barrier permeability, and vasogenic edema. However, the specific molecular mediators of Pb(2+) encephalopathy have been elusive. We found that Pb(2+) induces vascular endothelial growth factor/vascular permeability factor (VEGF) in cultured astrocytes (J Biol Chem, 2000;275:27874-27882). The study presented here asks if VEGF dysregulation contributes mechanistically to Pb(2+) encephalopathy. Neonatal rats exposed to 4% Pb-carbonate develop the histopathological features of Pb(2+) encephalopathy seen in children. Cerebellar VEGF expression increased approximately twofold (p < 0.01) concurrent with the development of cerebellar microvascular hemorrhage, enhanced vascular permeability to serum albumin, and vasogenic cerebellar edema (p < 0.01). No change in VEGF expression occurred in cerebral cortex that does not develop these histopathological complications of acute Pb(2+) intoxication. Pb(2+) exposure increased phosphorylation of cerebellar Flk-1 VEGF receptors and the Flk-1 inhibitor CEP-3967 completely blocked cerebellar edema formation without affecting microhemorrhage formation or blood-brain barrier permeability. This establishes that Pb(2+)-induced vasogenic edema formation develops via a Flk-1-dependent mechanism and suggests that the vascular permeability caused by Pb(2+) is Flk-1 independent.

Bioflavonoids and glutamine in diet and the Mg, Ca, Cu, Zn concentrations in heavy metals intoxicated rats' skins

The effect of bioflavonoids on the Mg, Ca, Cu and Zn concentration in rats' skin intoxicated with heavy metals Pb or Cd. The animals were divided at random into nine groups, each of 6 rats. Group I obtained in drinking water the solution of plumbum nitrate, Pb(NO3)2 in concentration of 500 mg Pb/dm3, group II solution of lead ions--500 mg Pb/dm3 and quercetin--200 mg/dm3 and glutamine 4 g/dm3, group III--lead ions solution (500 mg Pb/dm3), catechin--200 mg/dm3 and glutamine 4 g/dm3, group IV received water solution of Pb(NO3)2--500mg Pb/dm3, naringenin--200 mg/dm3 and glutamine 4 g/dm3, V-VII groups obtained the same that groups I-IV, but instead of lead cadmium chloride (CdCl2) in the amount of 500 mg Cd/dm3 was used. Group IX was a control group, and these animals received redistilled water to drink. All the groups of rats were on a normal diet (LSM dry food) and they got solutions and food ad libitum. After the experiment, the animals were sacrificed under ketamine narcosis and while collecting tissues, the skins (together with furs) used for further studies were also obtained. Heavy metals intoxication caused a significant decrease of magnesium and calcium concentrations in the examined rats' skins, and bioflavonoids with glutamine dietary addition did not improve or improve to a small degree the levels of those elements. Lead, in opposition to cadmium, decreased zinc and copper levels in skins, and bioflavonoids with glutamine caused the return of those elements' concentrations to the values of control group.

Biochemical and ultrastructural evidences for toxicity of lead through free radicals in rat brain

Studies suggest that some lead-induced toxic effects may occur through free radical production and oxidative stress. This study examined the relationship between brain histopathological alterations and oxidative stress in subchronic lead exposure. Male Albino rats received lead acetate at 0.01%, 0.05% and 0.1% w/v in their drinking water for 30 days. Animals given sodium acetate (0.1% w/v) served as control in the same period. At the end of exposure, blood-lead levels, blood catalase (CAT) and superoxide dismutase (SOD) activities and malondialdehyde (MDA) content (in blood and brain) were measured. The brain tissue samples were prepared and analysed by light and scanning electron microscopy. The results show that, the blood-lead levels in treated animals were higher in comparison with control. CAT and SOD activities in animals treated with 0.01% and 0.05% w/v did not increase in comparison with control (P > 0.05) but these values were higher in animals treated with 0.1% w/v lead acetate (P < 0.01). MDA content in blood and brain of animals treated with lead acetate 0.1% w/v, increased significantly (P <0.01), but these values were not significantly increased in other treated animals. No major histopathological alterations were detected in the brains of animals treated with lead acetate at 0.01% and 0.05% w/v. In animals treated with lead acetate 0.1% w/v, demyelinization and collagenous scar formation with neuronal atrophy in hippocampus region was observed. It is concluded that lead acetate induce oxidative stress which has an important role in brain damage in rats.

Arthroscopic treatment of gunshot wounds to the shoulder

Two cases are presented that demonstrate the utility of arthroscopic intervention for the management of gunshot wounds to the shoulder. The first report involves a 24-year-old man with a retained bullet in his glenohumeral joint after a drive-by shooting The intra-articular bullet was retrieved arthroscopically avoiding chondral injury from the mechanical effects of a loose body as well as the potential local and systemic effects of lead toxicity. Irrigation and debridement was performed to evacuate joint debris, which could have served as a nidus for infection or inflammation. The other case describes a 19-year-old man who sustained a gunshot wound to the lateral portion of his upper arm resulting in a proximal humerus fracture along with a retained bullet in his subacromial space. The bullet was successfully removed arthroscopically avoiding a traditional exposure, which would have complicated his fracture care.

[Experimental and clinical study to remove lead and to prevent lead damage of kidney with salt of high dose KI]

OBJECTIVE

To study and make a salt prevent lead poisoning.

METHODS

SD rats were given 0.25% lead acetate by food intake and were given 10 mg.kg-1.d-1, 20 mg.kg-1.d-1 and 30 mg.kg-1.d-1 potassium iodide from drinking water in respective groups, in order to look for the dose of KI which prevents lead poisoning. The salt to prevent lead poisoning was made, 50 workers were given the salt as to flavouring of daily food intake. PbB, Pbu, ZPP, delta-ALA, NAG(N-acetyl-beta-D-glucosaminidase), RP(Retinol protein) were observed.

RESULTS

The dose of KI to prevent experimental lead poisoning of SD rats was 10 mg.kg-1.d-1 by oral intake. People who contacted lead had an increase of urine lead in the third day, and had most urine lead on ninth day after taking the salt with KI. Normal urine lead on the fourth week. Pre- and post-oral intake of the salt with high dose KI, Hb, ZPP, delta-ALA, PbB, NAG and Rp the people mentioned above had the following indexes, (101.2 and 128) g.L-1 (P = 0.05), (33.5 and 7.7) micrograms.g-1 Hb(P < 0.01), (123.12 and 65.35) mumol.L-1 (P < 0.05), (2.123 and 0.85) mumol.L-1 (P < 0.01), (20.9 and 6.7) U.L-1 (P < 0.01), (1.5 and 0.34) mg.L-1 (P < 0.05) respectively.

CONCLUSION

The salt with 1% KI may remove lead and prevent lead damage of the kidney.

Effect of maternal bone lead on length and head circumference of newborns and 1-month-old infants

The authors evaluated the effects that maternal bone lead stores have in anthropometry at birth in 223 mother-infant pairs. The participants were recruited between April and November 1994. Anthropometric data were collected within the first 12 hr following delivery. Maternal information was obtained 1 mo after delivery occurred. Bone lead burden was determined with in-vivo K-x-ray fluorescence of the tibia (cortical bone) and the patella (trabecular bone). The authors transformed anthropometric measurements to an ordinal 5-category scale, and the association of measurements with other factors was evaluated with ordinal logistic-regression models. Mean bone lead levels were 9.8 microgram/gm bone mineral and 14.4 microgram/gm bone mineral for the tibia and patella, respectively. Birth length of newborns decreased as tibia lead levels increased. Compared with women in the lower quintiles of the distribution of tibia lead, those in the upper quintile had a 79% increase in risk of having a lower birth length newborn (odds ratio = 1.79; 95% confidence interval = 1.10, 3.22). The authors adjusted by birth weight, and the effect was attenuated--but nonetheless significant. Patella lead was positively and significantly related to the risk of a low head circumference score; this score remained unaffected by inclusion of birth weight. The authors estimated the increased risk to be 1.02 per microgram lead/gm bone mineral (95% confidence interval = 1.01, 1.04 per microgram lead/gm bone mineral). Odds ratios did not vary substantially after the authors adjusted for birth weight and other important determinants of head circumference.

Season modifies the relationship between bone and blood lead levels: the Normative Aging Study

Bone serves as a repository for 75% and 90-95% of lead in children and adults, respectively. Bone lead mobilization heightens during times of increased bone turnover, such as pregnancy, lactation, hyperthyroidism, and the rapid growth of childhood. Blood lead levels show seasonal periodicity. Children demonstrate peak blood lead levels in mid-summer and a secondary peak in late winter. Pregnant women demonstrate the highest mean blood lead levels in winter (January-March) and the lowest in summer (July-September). This fluctuation in blood lead levels may be related to seasonal patterns of environmental exposures, but it may also be partially related to the increased mobilization of bone lead stores during the winter months. We performed bone lead measurements using a K-x-ray fluorescent instrument to determine micrograms of lead per gram of bone mineral (parts per million) in middle-aged and elderly men who participated in the Normative Aging Study. We obtained measurements of blood and bone lead during the high sun exposure months of May-August (summer; n = 290); the intermediate sun exposure months of March, April, September, and October (spring/fall; n = 283); and the low sun exposure months of November-February (winter; n = 191). Mean blood lead concentrations were 5.8 microg/dl, 6.1 microg/dl, and 6.6 microg/dl for the summer, spring/fall, and winter, respectively. Mean patella (trabecular bone) lead concentrations were 34.3 microg/gm, 29.7 microg/gm, and 29.0 microg/gm for the summer, spring/fall, and winter time periods, respectively. In multivariate regression models, adjusted for age, smoking, alcohol ingestion, and dietary intake of iron and vitamin C, the authors found a strong interaction between season and bone lead level--with bone lead levels exerting an almost 2-fold greater influence on blood levels during the winter months than the summer months. The authors concluded that elevated blood lead levels in winter may be related to increased mobilization of endogenous bone lead stores, potentially from decreased exposure to sunlight, lower levels of activated vitamin D, and enhanced bone resorption.

Lead sources, behaviors, and socioeconomic factors in relation to blood lead of native american and white children: a community-based assessment of a former mining area

Lead poisoning prevention requires knowledge of lead sources and of appropriate residential lead standards. Data are severely lacking on lead sources for Native American children, many of whom live in rural areas. Further, the relation of mining waste to blood lead concentrations (BPbs) of rural children is controversial. In collaboration with the eight tribes of northeastern Oklahoma, we assessed lead sources and their effects on BPbs for rural Native American and White children living in a former mining region. Venous blood lead, residential environmental (soil, dust, paint, water), and caregiver interview (e.g., hand-to-mouth behaviors, socioeconomic conditions) data were obtained from a representative sample of 245 children 1-6 years of age. BPbs ranged from 1 to 24 microg/dL. There were no ethnic differences in BPbs (p= 0.48) nor any patterns of excess lead sources for Native American or White children. Multiple linear regression analyses indicated that mean soil lead, mean floor lead loading, mouthing behaviors, caregivers' education, and residence in former mining towns were all strongly associated with BPbs. Logistic regression results showed mean floor dust lead loading greater than or equal to 10.1 microg/ft(2) (odds ratio [OR], 11.4; 95% confidence interval [CI], 3.5-37.3), and yard soil lead >165.3 mg/kg (OR, 4.1; CI, 1.3-12.4) were independently associated with BPbs greater than or equal to 10 microg/dL. We also found strong interactions between soil lead and poverty (p= 0.005), and dust and soil sources (p= 0.02). Our findings indicate that soil and dust lead derived largely from mining waste pose a health hazard to Native American and White children, and that current residential dust lead standards are insufficient to adequately protect children. Moreover, our finding that poor children are especially vulnerable to lead exposures suggests that residential standards should consider interactions among socioeconomic conditions and lead sources if environmental justice is to be achieved.