Exposure to lead and other metals in children from Katowice district, Poland

Sex differences in cadmium and lead concentrations in different biological matrices in athletes. Relationship with iron status

PURPOSE

The present study aimed to analyse sex differences in cadmium and lead concentrations in plasma, urine, platelets and erythrocytes and to relate these concentrations to biomarkers of iron status.

METHODS

A total of 138 soccer players divided according to sex: men (n = 68) and women (n = 70) participated in the present study. All participants resided in the city of Cáceres (Spain). Erythrocyte, haemoglobin, platelet, plateletcrit, ferritin and serum iron values were determined. Cadmium and lead concentrations were quantified by inductively coupled plasma mass spectrometry.

RESULTS

The women had lower haemoglobin, erythrocyte, ferritin and serum iron values (p < 0.01). Regarding cadmium, the women showed higher concentrations in plasma, erythrocytes and platelets (p < 0.05). As for lead, they also showed higher concentrations in plasma, relative values of erythrocytes and relative values of platelets (p < 0.05). Significant correlations were observed between cadmium and lead concentrations with biomarkers of iron status.

CONCLUSIONS

Cadmium and lead concentrations are different between sexes. Biological differences between sexes and iron status could influence cadmium and lead concentrations. Lower serum iron concentrations and markers of Fe status increase Cd and Pb concentrations. Ferritin and serum iron have been directly related to increased Cd and Pb excretion.

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.

The Relation Between Low-Level Lead Exposure and Oxidative Stress: a Review of the Epidemiological Evidence in Children and Non-Occupationally Exposed Adults

Experimental studies in animals and observational studies in occupationally exposed adults indicate that higher lead exposure results in higher biomarkers of oxidative stress. However, this evidence cannot be extended to the general population who typically experience lower levels of lead exposure. This systematic review evaluates the epidemiological evidence on the association between lead and oxidative stress in non-occupationally exposed general population, with a particular focus on the pediatric population. Studies were identified through a systematic search of Medline and Web of Science. Ultimately, evidence from 15 studies conducted in children and 22 studies in adults from the general population was reviewed. Overall, the published findings are inconsistent, and there are very few well-designed studies on the relation between lead exposure and oxidative stress in the general population. The strength of the current evidence is discussed in light of the methodological approaches employed, and recommendations are made for future research directions. These include designing prospective studies with repeat measurements of clinically relevant oxidative stress markers to answer the question of causality and sensitive windows and reanalyzing previously published data, but using multivariable statistical approaches and adjustment for relevant explanatory factors.

Neurotoxicants, Micronutrients, and Social Environments

SUMMARY—Systematic research evaluating the separate and interacting impacts of neurotoxicants, micronutrients, and social environments on children's cognition and behavior has only recently been initiated. Years of extensive human epidemiologic and animal experimental research document the deleterious impact of lead and other metals on the nervous system. However, discrepancies among human studies and between animal and human studies underscore the importance of variations in child nutrition as well as social and behavioral aspects of children's environments that mitigate or exacerbate the effects of neurotoxicants.

In this monograph, we review existing research on the impact of neurotoxic metals, nutrients, and social environments and interactions across the three domains. We examine the literature on lead, mercury, manganese, and cadmium in terms of dispersal, epidemiology, experimental animal studies, effects of social environments, and effects of nutrition.

Research documenting the negative impact of lead on cognition and behavior influenced reductions by the Center for Disease Control in child lead-screening guidelines from 30 micrograms per deciliter (μg/dL) in 1975 to 25 μg/dL in 1985 and to 10 μg/dL in 1991. A further reduction is currently being considered. Experimental animal research documents lead's alteration of glutamate-neurotransmitter (particularly N-methyl-D-aspartate) activity vital to learning and memory. In addition, lead induces changes in cholinergic and dopaminergic activity. Elevated lead concentrations in the blood are more common among children living in poverty and there is some evidence that socioeconomic status influences associations between lead and child outcomes. Micronutrients that influence the effects of lead include iron and zinc.

Research documenting the negative impact of mercury on children (as well as adults) has resulted in a reference dose (RfD) of 0.1 microgram per kilogram of body weight per day (μg/kg/day). In animal studies, mercury interferes with glutamatergic, cholinergic, and dopaminergic activity. Although evidence for interactions of mercury with children's social contexts is minimal, researchers are examining interactions of mercury with several nutrients.

Research on the effects of cadmium and manganese on child cognition and behavior is just beginning. Experimental animal research links cadmium to learning deficits, manganese to behaviors characteristic of Parkinson's disease, and both to altered dopaminergic functioning.

We close our review with a discussion of policy implications, and we recommend interdisciplinary research that will enable us to bridge gaps within and across domains.

Direct Quantification of Rare Earth Elements Concentrations in Urine of Workers Manufacturing Cerium, Lanthanum Oxide Ultrafine and Nanoparticles by a Developed and Validated ICP-MS

Rare earth elements (REEs) have undergone a steady spread in several industrial, agriculture and medical applications. With the aim of exploring a sensitive and reliable indicator of estimating exposure level to REEs, a simple, accurate and specific ICP-MS method for simultaneous direct quantification of 15 REEs (⁸⁹Y, ¹³⁹La, ¹⁴⁰Ce, ¹⁴¹Pr, ¹⁴⁶Nd, ¹⁴⁷Sm, ¹⁵³Eu, ¹⁵⁷Gd, ¹⁵⁹Tb, ¹⁶³Dy, ¹⁶⁵Ho, ¹⁶⁶Er, ¹⁶⁹Tm, ¹⁷²Yb and ¹⁷⁵Lu) in human urine has been developed and validated. The method showed good linearity for all REEs in human urine in the concentrations ranging from 0.001–1.000 μg∙L⁻¹ with r² > 0.997. The limits of detection and quantification for this method were in the range of 0.009–0.010 μg∙L⁻¹ and 0.029–0.037 μg∙L⁻¹, the recoveries on spiked samples of the 15 REEs ranged from 93.3% to 103.0% and the relative percentage differences were less than 6.2% in duplicate samples, and the intra- and inter-day variations of the analysis were less than 1.28% and less than 0.85% for all REEs, respectively. The developed method was successfully applied to the determination of 15 REEs in 31 urine samples obtained from the control subjects and the workers engaged in work with manufacturing of ultrafine and nanoparticles containing cerium and lanthanum oxide. The results suggested that only the urinary levels of La (1.234 ± 0.626 μg∙L⁻¹), Ce (1.492 ± 0.995 μg∙L⁻¹), Nd (0.014 ± 0.009 μg∙L⁻¹) and Gd (0.023 ± 0.010 μg∙L⁻¹) among the exposed workers were significantly higher (p < 0.05) than the levels measured in the control subjects. From these, La and Ce were the primary components, and accounted for 88% of the total REEs. Lanthanum comprised 27% of the total REEs while Ce made up the majority of REE content at 61%. The remaining elements only made up 1% each, with the exception of Dy which was not detected. Comparison with the previously published data, the levels of urinary La and Ce in workers and the control subjects show a higher trend than previous reports.

Lead Assessment in Biological Samples of Children with Different Gastrointestinal Disorders

Lead (Pb) levels have been evaluated in the biological samples of children with different gastrointestinal disorders. Blood, scalp hair, and urine samples of children (of age 4-10 years) complaining about different gastrointestinal disorders were analyzed. For comparison, age matched healthy subjects were also included in this study. Biological samples were digested in a microwave oven prior to Pb determination by graphite furnace atomic absorption spectrometry. Significant differences in Pb profile were found between the diseased and referent children. Elevated Pb contents were observed in case of diseased children than WHO permissible limit, while normal results were obtained for healthy referents. The results were compared with those of healthy children having the same age, socioeconomic status, and residential areas.

Metallic Profile of Whole Blood and Plasma in a Series of 99 Healthy Children

In recent years, special emphasis has been put on heavy metals. Children are very sensitive to accumulation of metals. Furthermore, as regards elements, the reference values in children are scarce in the literature as it is difficult to obtain the large quantity of blood necessary to analyze many metals by the conventional atomic absorption spectrometry technique. An inductively coupled plasma mass spectrometry (ICP-MS) procedure that uses a reduced sample of 0.3 mL whole blood or plasma is adapted to multielemental determinations. We applied a previously validated technique for adults that simultaneously quantifies 25 elements by ICP-MS in whole blood and 23 in plasma in a series of 99 healthy children ranging from under 5 years to <18 years, without exposure to metal or drug-containing metals. The aims of the study were to compare metallic concentrations according to the age among children and metallic concentration differences between children and adults. The blood and plasma pediatric metallic profile is a practical useful tool for many purposes in clinical toxicology, forensic toxicology and any cases of metal environmental exposure.

Toxic and essential elements in children's blood (<6 years) from Kinshasa, DRC (the Democratic Republic of Congo)

In this study we determined the concentration of 9 trace elements (As, Cd, Cu, Hg, Mn, Mo, Pb, Se and Zn) in whole blood of children (n=100, 64 girls, 36 boys and median age: 36 months) using inductively coupled plasma mass spectrometry (ICP-MS). The proportion of children potentially deficient in essential elements or poisoned by toxic elements was evaluated. The aging effects on the concentration of these elements were also investigated. The median values were 3.17μg/L (As), 0.15μg/L (Cd), 1.1mg/L (Cu), 2.1μg/L (Hg), 10.4μg/L (Mn), 17.7μg/L (Mo), 8.7μg/dL (Pb), 10.7μg/L (Se) and 5.0mg/L (Zn). The concentration of many elements (As, Cd, Hg, Mn, Pb and Zn) showed significant age variations but not sex influence. Regarding levels of the essential elements (Cu, Mn, Mo, Se and Zn), B-Cu, B-Mn, B-Se and B-Zn were in the normal range, whereas exceeded levels were observed for B-Mo. None of these children was deficient in essential elements. Except B-Cd, all toxic elements showed exceeded blood levels. The proportion of children potentially poisoned by toxic elements varies from 10% (n=10) to 95% (n=95) and depends on toxic element: 95% for As, 10% for Hg and 35% for Pb. The main health concerns emerging from this study are the high As, Hg and Pb exposures of the Kinshasan children requiring further documentation, corrective actions and the implementation of appropriate regulations.

Blood selenium concentration in a selected population of children inhabiting industrial regions in Upper Silesia (Poland)

PURPOSE

Present study aimed at determining blood selenium concentration (Se-B) in a selected population of children inhabiting industrial regions.

METHODS

The studies were conducted on a group of 267 children inhabiting industrial regions in Upper Silesia (Poland). Determination of Se-B was performed using hydride generation atomic absorption technique.

RESULTS

In the studied group of children mean Se-B amounted to 76.75±12.52μg/L. Only in 38.20% of studied children the estimated Se-B could be regarded as an optimal. Children with underweight (BMI<15th centile) manifested a significantly lower Se-B than children with BMI within the normal range (BMI 15-85th centile). In the entire study group of children a significant positive linear correlation was disclosed between BMI and Se-B (r=0.16, p<0.05). Regression analysis demonstrated that in the studied subgroup of children (with normal height, body mass and BMI) a higher BMI represented an independent factor of Se-B increase and a more pronounced age an independent factor of Se-B decrease. Moreover, maternal education represented an independent factor of Se-B increase in the studied group of children (with normal height, body mass and BMI).

CONCLUSIONS

Se-B in the studied group children from industrial area in Upper Silesia corresponded with the lower range of blood selenium concentrations noted in recent years in other populations. A negative relationship was documented between age and Se-B and a positive relationship between BMI of a child and maternal education on one hand and Se-B of a child on the other.

Blood lead levels and associated sociodemographic factors among preschool children in the South Eastern region of China

Children are especially vulnerable to lead toxicity, and exposure to lead has been linked to poor school performance and delinquency in children and adolescents. Even low-level lead exposure [blood lead level (BLL) <10 µg/dL] can cause intellectual deficit. In China, BLLs in children decreased slightly after the phasing out of lead in gasoline, but few studies have examined the sociodemographic factors associated with BLL above 10 µg/dL. In this study, we sought to examine the hypothesis that sociodemographic factors predict BLLs. We measured BLLs of 1344 preschool children (3-5 years old) from the China Jintan Child Cohort Study. Children's sociodemographic and health statuses, as well as parental sociodemographic data, were collected using questionnaires. Regression models were used to explore the association between sociodemographic factors and log-transformed BLLs as well as the relationship between sociodemographic factors and the risk of BLL ≥10 µg/dL. We found the median BLL to be 6.2 µg/dL (range: 1.8-32.0 µg/dL); 8% of children had BLLs ≥10 µg/dL. Boys had a higher median BLL (6.4 µg/dL) than girls and were more likely to have BLL ≥10 µg/dL [odds ratio = 1.77, 95% confidence interval 1.14, 2.74]. BLLs increased as children aged, with a median BLL of 6.6 µg/dL among 5-year-old children. Children with siblings had a higher average BLL and greater prevalence of a BLL ≥10 µg/dL than those without siblings. Living in a crowded neighbourhood was also associated with increased BLLs. Mother's lower education, father's occupation (as professional worker) and parental smoking at home were associated with increased BLLs. This study shows that children in this area still have relatively high BLLs even after the phasing out of leaded gasoline. Both children's and parental factors and community condition are associated with increased BLLs. Future efforts are needed to identify other sources of exposure and develop targeted prevention strategies.

The effect of lead intoxication on endocrine functions

Studies on the effects of lead on the endocrine system are mainly based on occupationally lead-exposed workers and experimental animal models. Although evidence is conflicting, it has been reported that accumulation of lead affects the majority of the endocrine glands. In particular, it appears to have an effect on the hypothalamic-pituitary axis causing blunted TSH, GH, and FSH/LH responses to TRH, GHRH, and GnRH stimulation, respectively. Suppressed GH release has been reported, probably caused by reduced synthesis of GHRH, inhibition of GHRH release or reduced somatotrope responsiveness. Higher levels of PRL in lead intoxication have been reported. In short-term lead-exposed individuals, high LH and FSH levels are usually associated to normal testosterone concentrations, whereas in long-term exposed individuals' low testosterone levels do not induce high LH and FSH concentrations. These findings suggest that lead initially causes some subclinical testicular damage, followed by hypothalamic or pituitary disturbance when longer periods of exposure take place. Similarly, lead accumulates in granulosa cells of the ovary, causing delays in growth and pubertal development and reduced fertility in females. In the parenchyma of adrenals histological and cytological changes are demonstrated, causing changes in plasma basal and stress-mediated corticosterone concentrations and reduced cytosolic and nuclear glucocorticoid receptor binding. Thyroid hormone kinetics are also affected. Central defect of the thyroid axis or an alteration in T4 metabolism or binding to proteins may be involved in derangements in thyroid hormone action. Lead toxicity involves alterations on calcitropic hormones' homeostasis, which increase the risk of skeletal disorders.

Longitudinal monitoring of selected elements in blood of healthy young children

There are limited data on essential nutrients in the whole blood of young children. As part of a longitudinal study of the impact on young children and the environment from the introduction of an organic Mn compound into unleaded gasoline in Australia, we have measured a suite of elements in whole blood. The children, aged between 6 and 31 months at recruitment, have been monitored at 6-month intervals for up to 5 years. Blood samples were analysed by inductively coupled plasma mass spectrometry for Ca, Mg, Fe, Mn, Cu, Zn and Pb. Mixed model analyses of 665 blood samples using backward elimination showed significant positive relationships between Ca, Mg and Zn and season, variable relationships with time, but no association with gender or traffic exposure. The elements Ca, Mg and Zn showed higher concentrations in summer compared with winter, whereas Fe and Pb showed lower concentrations in summer compared with winter. Concentrations of all elements except Fe showed significant effects over time: Ca, Cu, Mg, Pb and Mn showed decreases over time, whereas Zn showed an increase. The mixed model analyses with the individual elements as the dependent variable showed some interesting relationships and require further follow-up as some of these appear to conflict with pre-existing concepts, although the multi-element data on which these concepts are based are limited. The variance for blood Pb and blood Mn arising from the other elements was small with 0.5% in the case of blood Pb and 3.7% for blood Mn.

Framework for gender differences in human and animal toxicology

Differences in exposure, anatomy, physiology, biochemistry, and behavior between males and females are a dominant theme in biology, transcending the plant and animal kingdoms. Yet differences due to sex and gender have not received adequate attention in human or animal toxicology nor always in epidemiology. Generalizations are often made about species' responses to xenobiotics, without data or consideration of female/male differences. Despite the leading role that pharmacology and drug development play in elucidating toxicokinetics, gender studies are relatively recent. Phenomenologic or clinical observations of sex differences often go unexplored, but pharmaceutical companies recognize the importance of enhanced understanding of toxicokinetics and toxicodynamics and emphasize the value of translational or integrational research--bringing laboratory findings to bedside applications and bedside questions to laboratory study. However, for many years Food and Drug Administration guidelines specifically precluded participation of females in many drug studies. Many occupational epidemiology studies, on which much of our understanding of toxic effects is based, begin by excluding women and minorities. Sex differentiation begins in the embryo under genetic and hormonal control. Changes affecting exposure, susceptibility, risk, and health continue throughout life. This paper provides a framework for analyzing the level(s) at which gender differences arise. The framework addresses exposure, toxicokinetics, toxicodynamics, and modulating influences. Men and women differ in many aspects of vulnerability to xenobiotics and other stressors, beginning with their opportunities for exposure. Toxicokinetic differences mainly involve metabolism, with few differences in absorption yet demonstrated. In addition, lifestyle, psychosocial, and hormonal factors modify the kinetics and responsiveness. Some phenomena fit the Classic Sex Hormone Paradigm in which castration (with and without hormone replacement) and administration of the opposite sex hormone demonstrate the primary regulatory role of sex hormones. Many phenomena, however, differ between males and females without showing a clear-cut relationship with the sex hormones. Since every cell both has a sex chromosome (X or Y) and is exposed to hormones, elegant techniques are just beginning to tease apart genetic from hormonal influences. Wherever possible, studies should use balanced gender and gender x age designs and should analyze data by sex and interactions, rather than simply adjusting for (discarding) gender. Power should be adequate, or lack of power (if inevitable) should be clearly stated.

GSTM1 and TNF-alpha gene polymorphisms and relations between blood lead and inflammatory markers in a non-occupational population

Inflammation is known to be an important underlying condition in the development of a variety of diseases. To investigate whether blood lead induces inflammatory reactions in non-occupationally exposed adults and the effects of genetic susceptibility associated with GSTM1 and TNF-alpha gene polymorphisms on this inflammatory response, we measured blood lead levels in 300 healthy university students. Total serum TNF-alpha and IL-6 levels and WBC counts were determined to evaluate the inflammatory response. Allelic loss of GSTM1 and the TNF-alpha-308 G>A polymorphism were determined by PCR and RFLP. Positive relations between blood lead and three inflammation biomarkers were shown in male subjects with blood lead > or =2.51microg/dl (median value) (TNF-alpha, p=0.015; IL-6, p=0.082; and WBC, p=0.044). However, subgroup analysis by genotype showed an effect of blood lead on the three biomarkers only in individuals with the GSTM1 null (TNF-alpha, p=0.020; IL-6, p=0.096; and WBC, p=0.017) or TNF-alpha GG (TNF-alpha, p=0.017; IL-6, p=0.088; and WBC, p=0.095) genotype, and not in individuals with GSTM1 present (all three inflammatory biomarkers, p>0.1) or the TNF-alpha GA or AA (all three biomarkers, p>0.1) genotype. These results suggest that blood lead affects the inflammatory response and that GSTM1 and TNF-alpha gene polymorphisms are genetic factors associated with lead-induced inflammatory response.

Anthropometric, environmental, and dietary predictors of elevated blood cadmium levels in Ukrainian children: Ukraine ELSPAC group

No comprehensive data on sources or risk factors of cadmium exposure in Ukrainian children are available. In this we measured the blood levels of cadmium among 80 Ukrainian children and evaluated sources of exposure. A nested case-control study from a prospective cohort of Ukrainian 3-year-old children was conducted. We evaluated predictors of elevated blood cadmium using a multivariable logistic regression model. The model included socioeconomic data, parent occupation, environmental tobacco smoke, hygiene, body-mass index, and diet. Dietary habits were evaluated using the 1992 Block-NCI-HHHQ Dietary Food Frequency survey. Elevated cadmium was defined as blood levels in the upper quartile (0.25 microg/L). The mean age for all 80 children was 36.6 months. Geometric mean cadmium level was 0.21 microg/L (range = 0.11-0.42 microg/L; SD = 0.05). Blood cadmium levels were higher among children taking zinc supplements (0.25 vs 0.21 microg/L; P = 0.032), children who ate sausage more than once per week (0.23 vs 0.20; P = 0.007) and children whose fathers worked in a by-product coking industry (0.25 vs 0.21; P = 0.056). In the multivariable model, predictors of elevated blood cadmium levels included zinc supplementation (adjusted OR = 14.16; P < 0.01), father working in a by-product coking industry (adjusted OR = 8.50; P = 0.03), and low body mass index (<14.5; adjusted OR = 5.67; P = 0.03). This is the first study to indicate a strong association between elevated blood cadmium levels and zinc supplementation in young children. Whole-blood cadmium levels observed in this group of Ukrainian children appear to be similar to those reported in other Eastern European countries.

Low blood lead levels do not appear to be further reduced by dietary supplements

OBJECTIVE

Our objective was to evaluate the association of dietary intakes of selected micronutrients and blood lead (PbB) concentrations in female adults and in children.

DESIGN

With longitudinal monitoring, we measured daily intakes of the micronutrients calcium, magnesium, sodium, potassium, barium, strontium, phosphorus, zinc, iron (limited data), and copper from 6-day duplicate diets (2-13 collections per individual) and PbB concentrations. Participants were three groups of females of child-bearing age (one cohort consisting of 21 pregnant subjects and 15 nonpregnant controls, a second cohort of nine pregnant migrants), and one group of 10 children 6-11 years of age.

RESULTS

Mean PbB concentrations were <5 microg/dL. A mixed linear model that included only group and time accounted for 5.9% of the variance of the PbB measurements; neither the effect of time nor the effect of group was significant. The model containing all of the micronutrients (except iron, for which there was a great deal of missing data), along with time and group, accounted for approximately 9.2% of the variance of PbB; this increase was not statistically significant. There was, however, a significant association of PbB with phosphorus, magnesium, and copper when all micronutrients were included in the statistical analysis, perhaps reflecting a synergistic effect.

CONCLUSIONS

In contrast to most previous studies, we found no statistically significant relationships between the PbB concentrations and micronutrient intake. In adults and older children with low PbB concentrations and minimal exposure to Pb, micronutrient supplementation is probably unnecessary.

Elevated blood selenium levels in the Brazilian Amazon

Contaminated fish poses a difficult challenge throughout the world, on the one hand, fish is a very nutritious food source, while on the other hand it accumulates many toxic substances, including mercury (Hg). As part of our efforts in the Brazilian Amazon to maximize nutritional input from fish consumption, a dietary mainstay, and minimize toxic risk, we have been studying the role of selenium (Se), an essential element, that may influence the distribution of Hg in the body and influence Hg neurotoxicity. Se, which is naturally present in the soil, is ingested through consumption of various foods, notably fish, mammals and certain plants. The objectives of the present study were: (i) evaluate whole blood Se (B-Se) and Hg (B-Hg); (ii) characterize B-Se variations with respect to socio-demographic and dietary variables; and (iii) examine the relation between B-Se and B-Hg. A total of 236 persons from six riparian communities of the Tapajós River Basin, a tributary of the Amazon, participated in this study. Whole blood Se and Hg were measured and interview administered questionnaires were used to obtain data on socio-demographic variable, smoking and drinking habits, and fish and fruit consumption. The results show that B-Se are in the upper normal range (median=284.3 microg/L, range=142.1-2029.3 microg/L). No individuals presented B-Se deficiency, but 9 participants from the same extended family had relatively high B-Se levels, potentially a threat to their health. B-Se varied between communities, was significantly higher among alcohol drinkers and farmers, but not associated with age, sex or tobacco consumption. A significant positive relation between B-Se and B-Hg was noted, independently of the overall fish consumption. B-Se increased with consumption of Peacock bass (Cichla sp.), a piscivorous fish species, and coconut pulp (Cocos nucifera L.). The B-Se intercommunity variations may reflect geographic differences in local soil Se levels as well as traditional land use practices in the different ecosystems of the Tapajós River Basin. In this population with relatively high exposure to Hg, Se may play an important role. Further studies should examine, in this region, the sources of Se, its transmission through the terrestrial and aquatic ecosystem and its role with respect to human health.

Predictors of elevated blood lead levels among 3-year-old Ukrainian children: a nested case-control study

OBJECTIVES

Lead is common in the general population. However, data are lacking for the Ukraine and many other countries from the former Soviet Union (FSU). In this study we evaluate the level of blood lead among 212 Ukrainian children and determine predictors of elevated lead levels. We also describe the health effects associated with elevated blood lead.

METHODS

A nested case-control study from a prospective cohort of Ukrainian 3-year-old children was conducted in March 1998. Blood assays were analyzed for lead by labs at the Centers for Disease Control and using portable examination kits. We evaluated predictors of elevated blood lead (blood levels in the upper quartile >4.65 microg/dL) using a multivariable logistic regression model. The model included socioeconomic status, parent occupation, environmental tobacco smoke, hygiene, diet, and health status.

RESULTS

The geometric mean lead level was 3.15 microg/dL (range, 0.7--22.7). In our adjusted model, we observed a strong association between lead levels in the upper quartile and children whose fathers worked manual labor jobs in industries associated with lead exposures [adjusted odds ratio (OR)=2.25; P=0.025] and mothers who smoke indoors (adjusted OR=2.87; P=0.047). Daily hygiene and dietary habits were not associated with elevated lead levels. No increased risks of overall morbidity or lead-associated illness were observed (anemia, dental caries, renal disease, cardiovascular diseases, and musculoskeletal complaints).

CONCLUSION

This is the first study to describe lead levels and associated variables among Ukrainian children in the peer-reviewed literature. Elevated lead levels in these children were associated with paternal occupation and mothers smoking indoors. At age 3 no adverse health effects were observed. More data are needed to determine the level of heavy metal contamination in children from the Ukraine and many other former Soviet nation-states.

Relationship between increased blood lead and pregnancy hypertension in women without occupational lead exposure in Tehran, Iran

This study was conducted to assess the relationship between blood lead levels and pregnancy-induced hypertension. Participants were 110 pregnant women, of whom 55 were hypertensive, 27 +/- 5.6 yr of age (mean +/- standard deviation) (range = 17-40 yr); the other 55 women were age- and gravidity-matched normotensive controls. Participants were selected on the basis of their medical history and the results of a questionnaire-based interview. Subjects were at gestational ages 37 +/- 2.5 wk (range = 30-41 wk) and were not occupationally exposed to lead. Blood samples were collected within 24 hr after delivery, and blood lead levels were measured. For the hypertensive cases, blood lead levels were 5.7 +/- 2 microg/dl (range = 2.2-12.6 microg/dl [0.27 +/- 0.10 micromol/l; range = 0.11-0.60 micromol/l]), which were significantly higher than those of the control group (i.e., 4.8 +/- 1.9 microg/dl; range = 1.9-10.6 microg/dl [0.23 +/- 0.09 micromol/l; range = 0.09-0.51 micromol/l]). There were no significant differences in blood lead concentrations among hypertensive subjects with proteinuria (n = 30) and those without proteinuria (n = 25). Results of this study indicated that low-level lead exposure may be a risk factor for pregnancy hypertension.

Assessment of lead exposure and associated risk factors in urban children in Silesia, Poland

A program of childhood lead poisoning prevention was conducted in six cities of Silesia, the most industrialized region of Poland. We analyzed records of 11,877 children aged 24-84 months, tested between 1993 and 1998, to assess children's exposure to lead and associations of blood lead levels (BLL) with season of sampling, questionnaire data, and environmental levels of lead. Air lead concentrations and lead fallout, as measured in the ambient air monitoring system, were below current Polish air quality standards and gradually decreased. The geometric mean (GM) BLL was 6.3 microg/dL (range from 0.6 to 48 microg/dL), and >13% of children had BLL > or =10 microg/dL. Mean BLL declined from 6.8 microg/dL in 1993-1994 to almost 5.5 microg/dL in 1998. GM BLL in spring and summer ('nonheating' season) months were 10% higher than BLL in children tested in fall and winter ('heating' season), although air lead concentrations were lower in nonheating and higher in the heating season. For both the heating and nonheating seasons, there was a significant increase in the mean BLL with increasing air lead concentrations. Poor housing (odds ratio (OR): 1.82; 95% CI: 1.4, 2.3), two or more siblings in the family (OR: 3.12; 95% CI: 2.6, 3.7), lack of recreational trips outside the region (OR: 1.66; 95% CI: 1.47, 1.89), and the time child spent outdoors were associated with elevated BLL. Variables found to affect BLL in the Silesian children should be used to propose criteria to improve identification of children at risk and to focus prevention activities more effectively.

Chromosomal aberrations in peripheral lymphocytes of children as biomarkers of environmental exposure and life style

The original purpose of our study was to determine if the detection of chromosomal aberrations in peripheral lymphocytes of children might be used as a biomarker of environmental pollution and life style. We compared the results of cytogenetic analyses performed in children and adolescents in the periods 1984-1993 and 1994-1999, in a total of 3402 subjects. The frequency of aberrant cells (AB.C.) markedly decreased in the period 1994-1999 compared with the period 1984-1993. The decreases in AB.C. were significant in the age groups 7-15 and 16-19 years: 1.63% AB.C. versus 1.14% AB.C. and 2.02% AB.C. versus 1.08% AB.C., respectively (P<0.01). No difference in the frequency of AB.C. was observed in newborns. Based on our experience, we believe that monitoring the spontaneous level of chromosomal aberrations in children over 5 year periods may be used to examine the general changes in environmental pollution in larger geographic areas.

Trace elements in blood and serum of Swedish adolescents: relation to gender, age, residential area, and socioeconomic status

The influence of gender, age, residential area, and socioeconomic status on the blood and serum levels of 13 trace elements was studied in boys and girls living in two Swedish cities with different socioeconomic and environmental characters. The same groups of adolescents were sampled twice, at ages 15 (n=372) and 17 (n=294) years. All the investigated factors were shown to be of importance. Age was important for most elements; e.g., copper levels in both blood and serum increased in girls, and selenium increased in serum from both genders. Lead decreased approximately 10% in blood from the first to the second sampling, and cadmium increased in blood, however not in nonsmokers. The age factor may also reflect temporal changes in environmental exposure, especially for nonessential elements. Girls had higher levels of cobalt and copper, while lead in blood was higher in boys. Smoking girls had higher copper levels than nonsmoking girls. Residential area influenced all elements. The teenagers with university-educated mothers had higher levels of cadmium in blood than those with only primary school-educated mothers.

Alimentary lead intake of adults in Thuringia/Germany determined with the duplicate portion technique

The daily lead intake in Germany in 1996 was studied using the duplicate portion technique. The study was carried out in four towns in Thuringia (Jena, Ronneburg, Rositz, Steudnitz), in which volunteers collected all foods and beverages over 7 consecutive days. The mean lead content of consumed food and beverages was 66 and 55 microg/kg dry matter for women and men, respectively; the average lead intake was 19 microg/day for both, women and men. In relation to body weight (b.w.) the intake for women was 283 ng/kg and for men 242 ng/kg b.w. These values are well below the WHO limit. An oral lead exposure of the adult population of Thuringia/Germany can be excluded.

Metal-bone interactions

Recent studies indicate that lead and cadmium may exert both direct and indirect actions on bone turnover, indirectly via kidney dysfunction, and directly on osteoblast and osteoclast function. Increased blood lead concentrations, most likely as a result of an increased bone turnover, have been detected in pregnant, lactating, and menopausal women. Lead exposure has also been negatively associated with children's growth in stature. Both lead and cadmium are nephrotoxic and can disturb vitamin D metabolism. Cadmium has been shown to induce kidney damage and osteoporosis/osteomalacia at long-term high-level exposure. A negative association between cadmium dose and bone mass has recently been detected in both occupationally and environmentally exposed people at relatively low cadmium exposure.

Lead exposure and hearing effects in children in Katowice, Poland

The objective of the study was to investigate the relationship between lead exposure and hearing in children in the Katowice region, an industrial area in Poland. Blood lead was determined using inductively coupled plasma mass spectrometry, with appropriate quality control. The concentrations of lead in blood (B-Pb) in 155 children, aged 4-14, ranged from 19 to 281 microg/L (0.09 to 1.4 micromol/L), with a median of 72 microg/L (0.34 micromol/L). The hearing thresholds increased significantly with increasing blood lead levels at all investigated frequencies (0.5, 1, 2, 4, 6, and 8 kHz). The relationship also remained significant for B-Pb below 100 microg/L (0.48 micomol/L; n=107). The brainstem auditory evoked potential latency of wave I was significantly increased (also after adjustment for age) in the group of children with the highest blood lead levels (B-Pb above 100 microg/L, 0.48 micromol/L; n=51), compared to the group with the lowest ones (B-Pb below 46 microg/L, 0.22 micromol/L; n=51). The audiometric results clearly indicate that auditory function in children is impaired at a blood lead concentration even below 100 microg/L (0.5 micromol/L).

Interactions between essential and toxic elements in lead exposed children in Katowice, Poland

OBJECTIVES

To determine the influence of the essential element status on blood concentrations of lead and other toxic metals.

DESIGN AND METHODS

A group of 157 children from Katowice, an industrial area in Poland, was investigated for concentrations of lead and cadmium in whole blood, and mercury, selenium, zinc, copper, and magnesium in whole blood and serum. Relations between these elements, serum ferritin, hematological parameters, as well as serum selenoprotein P and glutathione peroxidase (GSH-px) were examined. Conversion factors for element concentrations (mumol to microgram): lead 207.19, cadmium 112.41, mercury 200.59, selenium 78.96, magnesium 24.31, copper 63.55, and zinc 65.

RESULTS

Blood lead was negatively associated with concentrations of selenium in whole blood and serum as well as selenoprotein P and glutathione peroxidase in serum. The association was mainly apparent at low blood lead concentrations, which may indicate an influence of selenium on the kinetics of lead, rather than an effect of lead on the selenium status. Children with low serum ferritin levels had statistically higher blood cadmium levels and a tendency for higher blood lead levels, indicating increased gastrointestinal absorption of these metals at reduced iron stores. Blood lead was negatively correlated with mean corpuscular hemoglobin concentration, which may reflect the effect of lead on hemoglobin synthesis. There was an association between blood mercury and selenium, indicating a common source of intake through fish consumption.

CONCLUSIONS

The results indicate that selenium and iron status may influence the kinetics of lead.