Adverse Effects Of Lead Research Articles

Effect of lead exposure on lymphocyte subsets and activation markers

Lead is a common environmental pollutant which has adverse effects on the immune system. We studied frequency of peripheral blood populations of CD4, CD8, and CD56 expressing cells and presence of activation marker (CD25) and CD45 isoforms by flow cytometry. Among 59 lead-exposed individuals (26 three-wheeler drivers, 33 battery workers) and 21 healthy controls, blood lead levels were 6.7 ± 4.5 μg/dL, 132 ± 103 μg/dL, and 4.5 ± 2.0 μg/dL, respectively. The percentage of CD4+ cells was significantly lower (P < 0.001) and of CD45RA+ cells higher (P < 0.05) in both lead-exposed groups as compared to controls. There was a significant negative correlation between the CD4+ cell percentage and blood lead levels and length of exposure. Our data highlight the adverse effect of lead on immune cells which may have serious consequences for those with chronic exposure to lead.

Lead levels in milk and blood from donors to the Breast Milk Bank in Southern Brazil

Brazilian scientific literature on the adverse effects of lead on the general population is still very limited. Lead, a potentially toxic substance, has become a public health problem due to its effects, mainly those affecting the central nervous system and on the synthesis of heme. The aim of this study is to evaluate the level of lead exposure of donors to the Breast Milk Bank in the city of Londrina, Parana, by estimating the levels of that metal in milk and blood samples. This is a cross-sectional study conducted during the period between January and July 2007. All mothers enrolled as donors in the Breast Milk Bank were included in this study. A total of 92 volunteers presenting the following inclusion criteria were evaluated in the project: volunteers who were healthy, without any chronic disease, full-term pregnancy, breastfeeding between the 15th and 210 th day after giving birth, and living in the city of the study. Lead in milk and blood was quantified using the inductive coupled plasma mass spectroscopy (ICP-MS) technique. All mothers signed a consent form approved by the Research Ethics Committee from Londrina State University. The median lead concentration in milk samples was 3.0 microg/L, varying from 1.0 to 8.0 microg/L. The median of lead in blood was of 2.7 microg/dl, varying from 1.0 to 5.5 microg/dl. In Spearman correlation analysis, significant but modest correlations could be observed between the concentration of lead in blood and in milk (r(s)=0.207, p=0.048), hemoglobin and ALAD activity (r(s)=-0.264, p=0.011), level of lead in blood and mother's age (r(s)=0.227, p=0.029). However, for hematocrit and hemoglobin, the correlation was higher (r(s)=0.837, p<0.001). No statistically significant associations were found between concentrations of lead in milk and blood and demographic variables studied, obtained through interviews and validated questionnaire. The mean of milk/blood lead ratio was equal to 0.11. In general, the values found in the present study are similar to those obtained in populations in other countries, and are within background levels.

Interactive Effects of a DRD4 Polymorphism, Lead, and Sex on Executive Functions in Children

Prior studies have examined independent effects of a dopamine receptor D4 polymorphism (DRD4-7) and lead exposure on executive functions but not their interaction or the role of sex as a modifier of their effects. Multivariable analyses were used to examine effects of DRD4-7 genotype, 60-month blood lead level, and sex on spatial working memory, rule learning and reversal, spatial span, and planning for 174 children. DRD4-7 was associated with poorer spatial working memory, and increasing blood lead levels were associated with impaired rule learning and reversal, spatial span, and planning. Adverse effects of lead on planning and rule learning and reversal were seen primarily for boys. In addition, the effect of lead on rule learning and reversal was evident predominately for those lacking DRD4-7. We observed independent effects of DRD4-7 and lead on various executive functions and modifications of lead effects by DRD4 genotype and sex.

LONGITUDINAL EFFECT OF BLOOD LEAD ON NEUROBEHAVIORAL DEVELOPMENT IN ENVIRONMENTALLY EXPOSED CHILDREN

ISEE-369 Introduction: A number of prospective studies have suggested that children are more susceptible to the effects of lead exposure than adults. Many of these studies focus on the deleterious effect of lead on neurobehavioral functioning and they mainly concentrate on the consequences of high levels of blood lead. The objective of this study was to evaluate the longitudinal effect of blood lead exposure on neurobehavioral development in children at the ages of 12, 18, 24 and 30 months of age. Methods: We studied 664 mother-child pairs recruited in Mexico City from 1994 to 1999. Infant cord blood samples at delivery and venous blood samples were collected in trace metal-free tubes during subsequent visits. The lead concentration in the samples was analyzed using an atomic absorption spectrometry instrument. At each visit, neurobehavioral child development was assessed using the Bayley Scales of Infant Development-II (Spanish Version). The relationship between neurobehavioral development and concurrent blood lead level was estimated using longitudinal mixed-effects regression models with a random intercept. Logarithmic transformation of blood lead levels was used to account for the non-linearity of the association. Results: We found a highly significant association between the Bayley′s Mental Development Index (MDI) score and children blood lead concentrations (p<0.01); an increase of one logarithmic unit of concurrent blood lead levels is associated with a 1.74 point decrease in MDI scores, after adjusting by sex, age, birth weight and mother's IQ. Bayley′s Psychomotor Development Index (PDI) scores were also associated with blood lead levels after adjusting for the same covariates; an increase of one logarithmic unit of concurrent blood lead levels is associated with a 1.55 decrease in PDI scores (p<0.01). We also modeled the association between MDI and concurrent blood lead (non-transformed) stratifying by range of blood lead concentration. The strength of the estimated association was greater at lower blood lead levels. Regression coefficients were b=-0.23 (p<0.01), b=-0.37 (p=0.01) and b =-0.69 (p=0.09), for all observations, Pb<10 μg/dL and Pb<5 μg/dL, respectively. Discussion: This study provides further evidence that the adverse effects of lead in the neurobehavioral development of children are significant even at blood levels below those generally considered toxic. In fact, the deleterious effect of lead on infant development appears to be greater at lower concentrations of lead.

Relationship Between Oxidative Stress, Pathology, and Behavioral Signs of Lead Poisoning in Mallards

Some of the adverse effects of lead (Pb) may be associated with oxidative damage of lipids, proteins, or DNA. In a previous study a linkage was observed between the susceptibilities of waterfowl species to Pb poisoning with oxidative stress. To investigate this relationship among the individuals of a single species, for 3 wk 4 groups of 12 mallards were fed diets containing high or low levels of vitamin E (20 or 220 UI/kg) and high or low levels of Pb (0 or 2 g/kg). During the first week of Pb exposure, mallards developed hemolytic anemia, and during the second week, signs of neurological impairment. Histological findings in the Pb-exposed mallards were hemosiderosis, demyelinization of sciatic and brachial nerves, and tumefaction of renal tubular epithelium with the presence of intranuclear inclusion bodies. Lipid peroxidation increased with Pb exposure in blood, liver, bile, and brain, but decreased in nerves. Glutathione (GSH) increased with Pb exposure in liver and bile, and its oxidized/reduced ratio only increased in bile. Pb exposure inhibited GSH peroxidase activity (GPX) in plasma, liver, and brain, and decreased protein thiols (PSH) in blood and liver. Vitamin E resulted in significantly lower lipid peroxidation in nerves of control birds relative to unsupplemented controls, but did not alleviate any sign of lead posioning. Pb-induced pathological changes associated with hepatic and nervous functions were significantly correlated with lower GPX activity and PSH concentrations in these tissues rather than lipid peroxidation. Data suggest that inhibition of antioxidant enzymes and interaction with sulfhydryl groups of proteins may play a more important role in Pb poisoning of waterfowl than lipid peroxidation.

Sperm count and chromatin structure in men exposed to inorganic lead: lowest adverse effect levels

Objectives: To obtain knowledge on male reproductive toxicity of inorganic lead at current European exposure levels and to establish lowest adverse effect levels, if any. Methods: A cross sectional survey...

Lead Exposure in Children Living in a Smelter Community in Region Lagunera, Mexico

Industrial growth has created the potential for environmental problems in Mexico, since attention to environmental controls and urban planning has lagged behind the pace of industrialization. The aim of this cross-sectional study was to assess lead exposure in children aged 6-9 yr attending 3 primary schools and living in the vicinity of the largest smelter complex in Mexico. One of the schools is located 650 m distant from a smelter complex that includes a lead smelter (close school); the second is located 1750 m away from the complex and at the side of a heavy traffic road (intermediate school) in Torreón, Coahuila. The third school is located in Gómez Palacio, Durango, 8100 m away from the smelter complex and distant from heavy vehicular traffic or industrial areas (remote school). Lead was measured in air, soil, dust, and well water. Lead in blood (PbB) was determined in 394 children attending the above mentioned schools. Determinations were performed by atomic absorption spectrometry. Diet, socioeconomic status, hygienic habits, and other variables were assessed by questionnaire. Median (range) PbB values were 7.8 µg/dl (3.54-29.61) in the remote school, 21.8 µg/dl (8.37-52.08) in the intermediate school and 27.6 µg/dl (7.37-58.53) in children attending the close school. The percentage of children with PbB >15 µg/dl was 6.8%, 84.9%, and 92.1% respectively. In this order, the geometric means (range) of Pb concentrations in air were 2.5 µg/m3 (1.1-7.5), 5.8 µg/m3 (4.3-8.5), and 6.1 µg/m3 (1.6-14.9). The Pb concentrations in dust from playgrounds areas in the intermediate and close school settings ranged from 1457 to 4162.5 mg/kg. Pb concentrations in drinking water were less than 5 µg/L. Soil and dust ingestion and inhalation appear to be the main routes of exposure. Our results indicate that environmental contamination has resulted in an increased body burden of Pb, suggesting that children living in the vicinity of the smelter complex are at high risk for adverse effects of lead.

Acumulación de plomo en hueso y sus efectos en la salud

The adverse effects of lead have been known for long since the metal affects practically all organs and systems of the human body. Recently, toxic effects have been reported in the cardiovascular and nervous systems at lead levels previously considered to be secure. The main lead storage site in the body is bone. The toxicologic significance of this fact has been clarified only recently. The present study analyzes the role of lead as an endogenous source of exposure, as a chronic exposure biomarker and as a target organ. Recent advances to measure bone lead through fluorescent X-Rays are discussed. Additionally, the importance of bone lead from a public health perspective in places with a chronic history of exposure such as Mexico City, and in some occupational environments is reviewed with particular attention placed on reproductive age women, who are potential lead sources for the fetus and lactating infant.

Adverse health effects of lead at low exposure levels: trends in the management of childhood lead poisoning

An extensive database has provided a direct link between low-level lead exposure during early development and deficits in neurobehavioral-cognitive performance evident late in childhood through adolescence. These consistent studies have demonstrated the presence of a constellation of neurotoxic and other adverse effects of lead at blood lead (BPb) levels at least as low as 10 μg/dl). Federal agencies and advisory groups have redefined childhood lead poisoning as a BPb level of 10 μg/dl. Before discussing some of these studies in greater detail, the pervasiveness of this entirely preventable disease today in millions of American children must be recognized.

Letters to the Editor

Kawatu et al state that effects of lead on cognitive and neurobehavioral development in children may be seen at the 10 to 15 µg/dL blood lead (BPb) level, and they note that I did not cite many articles supporting a dose-dependent adverse effect of lead. Since I granted in my commentary that there may be an effect at BPb levels even below 10 µg/dL, I felt it unnecessary to cite many articles supporting this premise. The question is, at low BPb levels, are there important consequences for the individual child?

Childhood Lead Poisoning in 1994

Lead poisoning is one of the worst environmental threats to children in the United States and is also entirely preventable. 1 An increased understanding of the adverse effects of lead poisoning—neurological, endocrinological, hematological, reproductive, and growth—resulted in the Centers for Disease Control and Prevention lowering the acceptable blood lead level three times in the last 20 years. 2 The article by Pirkle et al 3 documents the dramatic decrease in blood lead levels from 0.62 to 0.14 μmol/L (12.8 to 2.8 μg/dL) between 1976 to 1980 and 1988 to 1991. Most significantly, the percentage of US children aged 1 to 5 years with blood lead levels 0.48 μmol/L (10 μg/dL) or greater decreased from 88.2% to 8.9%. Decreases in blood lead levels occurred for all age and income groups. This is surely one of the most remarkable public health achievements of the decade and is undoubtedly the result of government

The Adverse Effects of Lead

This article considers the problem of widespread environmental lead contamination. Aspects of its epidemiology and toxicology are presented, with emphasis on the effects of low-level lead exposure on people planning parenthood, on the fetus and on young children. Methods of screening for subclinical lead poisoning and dietary treatment and prevention are discussed. Remedial measures for containing and curtailing environmental lead pollution are recommended.

Phenotypic Aberrations of CD3 + and CD4 + Cells and Functional Impairments of Lymphocytes at Low-Level Occupational Exposure to Lead

To study the immunological effects of low-level occupational exposure to lead, we have examined the phenotypic parameters and functional integrity of peripheral blood lymphocytes in a group of firearms instructors and compared the data to those obtained from healthy unexposed controls. Our results indicate that, among individuals with mildly elevated blood lead levels (>25 μg/dl), detrimental effects on the host's immune functions occur. Such dysfunctions are multicellular as to mechanism and dose dependent in nature. The absolute percentage and number of CD3 + and CD4 + cells were significantly reduced, while the values for CD8 + cells were unchanged. Functional integrity of T cells as determined by responses to mitogens was impaired while that of T-cell-dependent B-lymphocyte function appeared to be within normal range at all stages of maturation. These data suggest the presence of a defective feedback loop which regulates T-cell-dependent functions and cell-to-cell cooperation. Furthermore, the marked deficiency in MLC responses that was also observed suggests that the adverse effect of lead may be due to its high affinity for the TCR and HLA-DR surface receptors thereby interfering with antigen processing from monocytes to T lymphocytes.

Experimental model of lead nephropathy. I. Continuous high-dose lead administration.

This study followed the progression of lead nephropathy in male Sprague-Dawley rats (E) administered lead acetate (0.5%) continuously in drinking water for periods ranging from 1 to 12 months. Control animals (C) were pair-fed. Observations included renal pathology by light and electron microscopy, wet and dry kidney weights, and glomerular filtration rate (GFR) to assess renal function. Urinary excretion of lead, the enzymes N-acetyl-beta-D-glucosaminidase (NAG) and glutathione-S-transferase (GST), and brush border antigens (BB50, CG9, and HF5) were utilized to explore possible markers of kidney injury. GFR was increased significantly after three months of lead exposure, but was decreased significantly after 12 months. Kidney wet weights were significantly greater in E than C from three months on. Kidney dry weight/wet weight ratio was constant up to three months, but decreased in E at 12 months. Glomerular diameters were normal at all time periods; the nephromegaly was related primarily to hypertrophy of proximal tubules. Lead inclusion bodies were found in nuclei of proximal convoluted tubules and pars recta at all times. Tubular atrophy and interstitial fibrosis first appeared at six months, and increased in severity thereafter. Brush borders of proximal tubules were disrupted at one and three months, but recovered thereafter. Focal and segmental glomerulosclerosis was observed in 2 of 10 rats at 12 months. Arteries and arterioles remained normal at all time periods. Urinary NAG was elevated in E above C after three months of lead exposure. However, urinary NAG in C also increased with age, obscuring changes in the 12 month E rats. GST was elevated after three months of lead administration in E, not without an attendant age-related increase in C rats. In three-month E rats, urinary brush border antigens were increased above C, but were decreased at six and 12 months, correlating with the morphologic changes in brush border. We conclude that a high dose of lead in rats may initially stimulate both renal cortical hypertrophy and an increase in GFR. Later, the adverse effects of lead on the tubulointerstitium predominate, and GFR falls. The urinary marker, NAG, was abnormal in the early stages of the disease, but age-related changes obscured its utility at later stages; urinary GST appeared to be a more consistent marker of injury.

Lead Exposure and Growth in the Early Preschool Child: A Follow-up Report from the Cincinnati Lead Study

This report is a follow-up of an earlier study of the effects of low to moderate prenatal and postnatal lead exposure on children's growth in stature. Two hundred thirty-five subjects were assessed every 3 months for lead exposure (blood lead level) and stature (recumbent length) up to 33 months of age. Fetal lead exposure was indexed by maternal blood lead level during pregnancy. The adverse effects of lead on growth during the first year of life were reported previously. This analysis covers essentially the second and third years of life. The results indicate that mean blood lead level during this period was negatively associated with attained height at 33 months of age (P = .002). This association was, however, evidenced only among those children who had mean blood lead levels greater than the cohort median (greater than or equal to 10.77 micrograms/dL) during the 3- to 15-month interval. The results also suggest that the effect of lead exposure (both in utero as well as during the first year of life) are transient provided that subsequent exposure to lead is not excessive. It appears that maintaining an average blood lead level of 25 micrograms/dL or more during the second and third year of life was detrimental to the child's attained stature at 33 months of age. Approximately 15% of this cohort experienced these levels of lead exposure. Continued follow-up of this cohort will reveal whether these lead-related deficits persist and whether they continue to be dependent on the level of exposure in an earlier period.

No adverse effects of lead on renal function in lead-exposed workers.

A cross-sectional study was performed on 165 male lead-exposed workers to clarify the quantitative relationships between less severe exposure to lead and its effects on renal function in 1985. Mean and range of blood lead concentration (Pb-B) were 36.5 micrograms/dl and 6-73 micrograms/dl, respectively. Duration of lead exposure was 0.1 to 26.3 years. No lead-related changes were detected in serum creatinine concentration, beta-2 microglobulin in urine, creatinine clearance, beta-2 microglobulin clearance, and uric acid clearance. Twenty of the 165 workers had been exposed to lead for more than 10 years with mean duration of 21.0 years. Average concentrations of Pb-B in each individual during 1972 to 1984 were 26.1-66.6 micrograms/dl. Renal function indices of these 20 workers were not different from those of remaining lead-exposed workers whose lead exposure duration were 10 years or less. These results suggest that long-term less severe exposure to lead up to 70 micrograms/dl of Pb-B may not cause adverse effects on renal glomerular function and proximal tubular function.

Effect of lead on postnatal development of the bank vole (Clethrionomys glareolus).

Female bank voles (Clethnonomys glareolus Schreber, 1780) were given lead-contaminated food (2.5, 60, 380, and 730 Μg g−1 of lead) after giving birth to litters. The concentrations of lead in bodies of young voles were determined after 5th, 10th, 15th, and 20th days of life. The concentrations of lead in the offspring increased with elevation of lead level in the diet of mothers. Lead accumulation became remarkable after 15th day, particularly in the bodies of the young born to mothers given 380 and 730 Μg g−1 of dietary lead. The adverse effect of lead on the growth of young voles (declining weight increments) was observed in groups receiving highly contaminated food. The mortality among the young was also monitored. It occurred in whole litters as well as individuals and attained the highest values in groups given 730 Μg g−1 of dietary lead.