Blood lead levels of children and its trend in China

To evaluate Chinese children's blood lead levels (BLLs) and identify its distribution features, we collected articles on children's BLLs published from Jan, 2004 to Aug, 2007 with sampling time since 2001, by searching Chinese Biomedical Disk (CBMDisk), Chinese Journal Full-test Database (CJFD) and other ways. After a rigorous investigation, 35 articles eligible for inclusion criteria were reviewed. Meanwhile, to reveal the trend of Chinese children's BLLs, the data was compared with the results from our former study carried out in 2004, which reviewed the articles published since 1995 to 2003. The results showed that the mean BLLs of Chinese children from 2001 to 2007 was 80.7 μg/L (45.5-165.3 μg/L), and 23.9% (3.2%-80.7%) of children's BLLs was higher than 100 μg/L. Both BLLs and prevalence of BLLs higher than 100 μg/L were lower than that of 1995 to 2003. Of 24 provinces or cities, only 4 showed higher BLLs and higher prevalence rates of lead poisoning (BLLs ≥ 100 μg/L) than that of 1995 to 2003. The mean BLLs of children living in industrial areas were higher than those in urban and suburban areas, and suburban higher than urban areas. Boys' BLLs were 79.3 μg/L, significantly higher than girls 76.9 μg/L (P < 0.001). The results also showed that children's BLLs increased with their ages, and the decreased BLLs for all age were observed comparing with the results of our former study in 2004. Overall, our study revealed that the BLLs of children in China showed a decreasing trend after gasoline with lead was banned in China in 1st July 2000. Our study also showed that the BLLs of children in China were still higher than that in developed countries, which suggested that children's lead poisoning prevention and controlling would be a long-term mission in China.     

Blood lead levels of Jamaican children island-wide

An island-wide survey of 1081 basic school children, mainly in the age group 2-6 years, is reported. The range of blood lead levels (BLLs) was 1.4 to 202 microg/dL with arithmetic and geometric means of 7.3 microg/dL (standard deviation, 13 microg/dL) and 4.35 microg/dL respectively. Two hundred and thirty children were identified with blood lead levels above 10 microg/dL and among these, 80 were provided with medical attention and of eleven who received chelation, six children were desperately ill from acute lead poisoning necessitating repeated sessions of chelation therapy. The higher blood lead values were found mainly in poor areas of the urban Kingston and St. Andrew Corporate Area, and in St. Catherine where there remain observable though reduced effects from a lead-contaminated area. Environmental interventions, including building an increased national awareness, have also been carried out to reduce the immediate and future dangers of lead poisoning. The most important source of the lead exposure is the recovery of lead from old automobile batteries and even a quite small smelter can contaminate a significant area. Further work is in progress to identify and examine historical and active smelter sites, their possible effects on childhood health, and their remediation.     

Blood lead levels in Finnish preschool children

The blood lead (PbB), hemoglobin and hematocrit were measured in 286 Finnish children living in the three largest cities of Finland (n = 172), in rural areas (n = 54) and in a lead smelter area (n = 60). PbB was determinated using an atomic absorption spectrophotometric micro method. The precision of the method was good, as was the accuracy tested by an international interlaboratory comparison. The mean PbB in urban, rural and lead smelter areas varied between 6.0–6.7 μg/100 ml⁷ (range 3–17 μg/100 ml) and there were no significant differences between the residential areas. The mean values of hemoglobin and hematocrit were in the normal range. The PbB values in Finnish children studied were low compared with many international studies but at a similar level as in some recent Scandinavian studies.     

Blood lead levels in Jamaican school children

Blood lead levels are reported for a total of 421 schoolchildren in 13 schools in rural and urban environments in Jamaica, including one highly contaminated community. In the rural areas blood lead levels ranged from 3 to 28.5 microg dl(-1), with a median of 9.2 microg dl(-1); the range and median in the urban schools were 4-34.7 and 16.6 microg dl(-1), respectively. Forty-two percent of the rural and 71% of the urban blood lead levels exceeded the US Centers for Disease Control and Prevention intervention level of 10 microg dl(-1). Except in the contaminated area, the relationship between soil lead levels, which in Jamaica are in general typical of tropical lateritic soils, and blood lead levels is not clear-cut. Very high blood lead levels of 18 to > 60 microg dl(-1) with a median of 35 microg dl(-1) were observed among children in the contaminated area, the site of a former lead ore processing plant. These high blood lead levels were significantly reduced, by the implementation of relatively simple mitigation strategies which involved isolation of the lead, education, and a food supplementation programme, to levels similar to those observed in the urban schools. These values, however, remain higher than are desirable and unfortunately, all the sources of lead are not yet identified. The recent discontinuation of the use of leaded petrol is expected to result in significant reductions in exposure to lead.     

Total metal concentrations and partitioning of Cd, Cr, Cu, Fe, Ni and Zn in sewage sludge

Application of the BCR three-step sequential extraction procedure to sewage sludge samples collected at an urban wastewater treatment plant (Dom ale, Slovenia) is reported. The total concentrations of Cd, Cr, Cu, Fe, Ni and Zn and their concentrations in fractions after extraction were determined by flame or electrothermal atomic absorption spectrometry (FAAS, ETAAS) under optimised measurement conditions. Total acid digestion including hydrofluoric acid (HF) treatment and aqua regia extraction were compared in order to estimate the efficiency of aqua regia extraction for determination of total metal concentrations in sewage sludge. It was found experimentally that aqua regia quantitatively leached these heavy metals from the sewage sludge and could therefore be applied in analysis of total heavy metal concentrations. The total concentrations of 856 mg kg⁻¹ Cr, 621 mg kg⁻¹ Ni and 2032 mg kg⁻¹ Zn were higher than those set by Slovenian legislation for sludge to be used in agriculture. Total concentrations of 2.78 mg kg⁻¹ Cd, 433 mg kg⁻¹ Cu and 126 mg kg⁻¹ Pb were below those permitted in the relevant legislation. CRM 146R reference material was used to follow the quality of the analytical process. The results of the BCR three-step sequential extraction procedure indicate high Ni and Zn mobility in the sludge analysed. The other heavy metals were primarily in sparingly soluble fractions and hence poorly mobile. Due to the high total Ni concentration and its high mobility the investigated sewage sludge could not be used in agriculture.     

Sources of Cd,Cu, Pb and Zn in biowaste

Biowaste, the separately collected organic fraction of municipal solid waste, can be reused for soil conditioning after composting. In this way, environmentally harmful waste management strategies, such as landfilling or incineration, can be reduced. However, frequent application of composts to soil systems may lead to the accumulation of heavy metals in soils, and therefore legal criteria were laid down in a decree to guarantee the safe use of composts. The heavy metal content of biowaste-composts frequently exceeds the legal standards, and thus raises a conflict between two governmental policies: the recycling of solid waste on the one hand, and the protection of natural ecosystems and public health on the other hand. In this study, the heavy metal content (Cd, Cu, Pb and Zn) of biowaste was compared with the natural background content of Cd, Cu, Pb and Zn in the different constituents of biowaste. For this, the physical entities of biowaste were physically fractionated by wet-sieving and subsequent water-elutriation. In this way, organic and inorganic fractions of different particle sizes were obtained and the content of Cd, Cu, Pb and Zn and the organic matter content of the different fractions were determined. On the basis of particle size, density and visual appearance, the particle-size fractions were assigned to various indoor and outdoor origins of the biowaste. It was found that a large amount of biowaste was not organic, but over 50% was made up of soil minerals due to the collection of biowaste constituents from gardens. The heavy metal content of the various fractions in biowaste was compared with the natural background contents of heavy metals in the constituents of biowaste, i.e. food products, plant material, soil organic matter and soil minerals, by collecting literature data. The heavy metal content in the fractionated physical entities of biowaste corresponded with the natural background concentration of its constituents and indicated that biowaste was not contaminated by other sources. However, the natural background content of biowaste constituents will result in heavy metal contents for biowaste-compost that will exceed the legal standards. It is advised that the legal standards for composts should be critically re-examined. The protection of soil systems could be better guaranteed if the input of heavy metals was evaluated for all inputs of fertilisers and soil conditioners, i.e. animal manures, various types of compost and artificial fertilisers.     

Blood lead levels and risk factors for lead poisoning among children in Jakarta,Indonesia

The phase-out of leaded gasoline began in Jakarta, Indonesia on July 1, 2001. We evaluated mean blood lead levels (BLLs) and the prevalence of elevated BLLs of Jakarta school children and assessed risk factors for lead exposure in these children before the beginning of the phase-out activities. The study involved a population-based, cross-sectional blood lead survey that included capillary blood lead sampling and a brief questionnaire on risk factors for lead poisoning. A cluster survey design was used. Forty clusters, defined as primary schools in Jakarta, and 15 2nd- and 3rd-grade children in each cluster were randomly selected for participation in the study. The average age of children in this study was 8.6 years (range 6-12) and the geometric mean BLL of the children was 8.6 microg/dl (median: 8.6 microg/dl; range: 2.6-24.1 microg/dl) (n=397). Thirty-five percent of children had BLLs > or =10 microg/dl and 2.4% had BLLs > or =20 microg/dl. Approximately one-fourth of children had BLLs 10-14.9 microg/dl. In multivariate models, level of education of the child's primary caregiver, water collection method, home varnishing and occupational recycling of metals, other than lead, by a family member were predictors of log BLLs after adjustment for age and sex. BLLs of children who lived near a highway or major intersection were significantly higher than those of children who lived near a street with little or no traffic when level of education was not included in the model. Water collection method was a significant predictor of BLLs > or =10 microg/dl after adjustment for age and sex. BLLs in children in this study were moderately high and consistent with BLLs of children in other countries where leaded gasoline is used. With the phase-out of leaded gasoline, BLLs of children in Jakarta are expected to rapidly decline as they have in other countries that have phased lead out of gasoline.     

Blood lead screening in Ontario children: blood lead and free erythrocyte protoporphyrin levels

A blood lead survey was conducted on samples from 2459 children aged 3-6 years to determine the prevalence of lead poisoning in children of this age in the Province of Ontario. Lead poisoning, defined as a blood lead concentration greater than or equal to 1.21 mumol 1-1 (25 micrograms dl-1), was found in 26 subjects (1.1% of the samples). The mean blood lead concentration for children from southern Ontario was 0.50 mumol l-1, and for those from northern Ontario it was 0.37 mumol l-1. Stringent quality controls and independent cross-checks of finger-prick capillary blood sampling were employed in the study. The free erythrocyte protoporphyrin levels were also monitored to detect the presence of iron deficiency in the children.     

Behavior of Mn, Fe, Cu, Zn, Cd and Pb discharged from a wastewater treatment plant into an estuarine environment

To obtain information on the fate of trace metals discharged to an estuarine environment, analyses have been made on water and sediment samples from Back River, MD., and on effluent from the large wastewater treatment plant that discharges there. Within 2–3 km of the outfall, the concentration (in μg 1⁻¹) of all metals decreases as follows: Mn, > 120-90; Fe, > 570-300; Cu, 53-7; Zn, 280-9; Cd, 3.5-0.5 and Pb, 31-<4. Except possibly for Mn and Fe, these decreases are much greater than can be ascribed to simple dilution, so physical, chemical or biological processes must be removing metals to the sediments. Correspondingly, sediment concentrations of Cu, Zn, Cd and Pb are approximately one order of magnitude higher than normally found in uncontaminated areas. After the initial decrease, concentrations of Mn and Cd in the water begin to rise again, suggesting remobilization from the sediments. Comparison of the estimated annual discharge of 8 trace metals to the Chesapeake Bay from wastewater treatment plants and from rivers suggests that the wastewater input may be within one order of magnitude of the fluvial input for Cr, Cu, Zn, Cd and Pb. Of the metals studied, Cd presents the greatest potential for serious pollution because its input from wastewater probably exceeds fluvial input, it appears to be readily remobilized from sediments, and it is known to be toxic to many organisms.     

Blood lead levels in primary school children in Trinidad and Tobago

This study is the first national baseline survey of blood lead levels (BLLs) conducted on primary school children (ages 5-7 years) in Trinidad and Tobago. A total of 1,761 students from 61 schools participated in the study over a 3-month period. Measurements of capillary BLLs were assessed as well as responses to a risk assessment questionnaire. BLLs ranged from <1 microg/dL to 28.6 microg/dL with a geometric mean of 2.8 microg/dL, which compared favourably with results from the U.S. 1991-94 National Health and Nutrition Examination Survey. Fifteen (0.9%) children had a BLL>or=10 microg/dL (10.8-28.6 microg/dL) of which three (0.2%) met the U.S. criteria for lead poisoning (BLL>or=20 microg/dL). Further environmental investigations are required to identify source(s) of lead exposure in cases with high BLL.     

Metal speciation and pH effect on Pb,Cu, Zn and Cd biosorption onto Sphaerotilus natans: Langmuir-type empirical model

Biosorption data of lead, copper, zinc and cadmium onto Sphaerotilus natans at different equilibrium pH (3-5 units) were here reported and analysed. Experimental results outlined the positive effect of pH increase on pollutant uptake and also the biomass affinity series (Pb > Cu > Zn > Cd) reflecting the hydrolytic properties of metals. An original empirical model was proposed to represent the effect of pH on heavy metal biosorption inserting q(max) vs. pH empirical functions into the classical Langmuir isotherm.     

Blood lead levels in children after phase-out of leaded gasoline in Bombay, India

The objective of this study was to test for reduction in pediatric blood lead levels (BLLs) in Bombay, India, by comparing BLLs collected in 2002 (after use of leaded gasoline was phased out in Bombay) to those collected in a study conducted by the George Foundation in 1997 (when leaded gasoline was still used in Bombay). We analyzed BLL in a total of 754 children under 12 years of age in two separate sampling campaigns (276 from December 2002 to January 2003 [non-monsoon season]; 478 in June to August 2003 [monsoon season]). BLL was measured using an ESA Lead Care Portable Analyzer. We also measured lead in PM10 samples collected in the study region. These data were compared with a study done by the George Foundation in 1997 before the phase out of leaded gasoline. The George Foundation study reported that 61.8% of the 291 children tested in Bombay had elevated blood lead levels (BLL>or=10 microg/dL). In the present study, 33.2% of the 754 tested children had elevated blood lead levels. The average BLL for the current study population (Geometric Mean=8.36 microg/dL, SD=5.23 microg/dL) was lower than the CDC level of concern (10 microg/dL), with one child diagnosed with lead poisoning (BLL>65 microg/dL). A seasonal trend of BLLs was suggested, with BLL in monsoon season (Geometric Mean=9.1 microg/dL, SD=5.7 microg/dL) higher than that in the non-monsoon season (Geometric Mean=7.3 microg/dL, SD=4.0 microg/dL). A seasonal periodicity of lead in PM10 was found, with lead in monsoon season (Geometric Mean=0.04 microg/m3, SEM=0.000667 microg/m3) lower than that in the non-monsoon season (Geometric Mean=0.38 microg/m3, SEM=0.10 microg/m3). The overall level of airborne dust (PM10) in monsoon season (56.2 microg/m3) was lower than in the non-monsoon season (273.0 microg/m3), presumably due to precipitation. The comparatively higher BLLs in the monsoon season, in the presence of lower air lead levels, suggest ingestion of water or food, with greater lead contamination in the monsoon season, as a possible pathway contributing to elevated BLLs in these children in the monsoon season. These results demonstrate a significant success of the public health system in Bombay, India-achieved by the removal of lead from gasoline. The emphasis should shift in the study region towards sources of lead exposure other than leaded gasoline (lead in paints, lead in Herbal medicines and lead in Kohl).     

Influence of pH and TOC concentration on Cu,Zn, Cd,and Al speciation in rivers

Dissolved ( < approximately 4 nm, dialysis in situ), colloidal ( < 0.45 microm filtered, minus dissolved) and particulate (total, minus < 0.45 microm filtered) concentrations of Cu, Zn, Cd, (Al) in eight (three) mining polluted rivers were determined by atomic absorption spectrometry (flame and graphite furnace). The metal size distribution in the rivers was compared to pH, Ca concentration, alkalinity, conductivity, and total organic carbon (TOC). Data plots based on the present and other studies also yielded information about the interrelations between TOC, pH and metal adsorption in rivers and lakes. Less than 10% of Cu, Zn, and Cd were sorbed on particles or colloids in two rivers with average pH at 3.1 and 5.1, whereas 46%, 21%, and 21% of Cu, Zn, and Cd, respectively, occurred in sorbed form in six pH neutral rivers. In three pH neutral rivers, on average 55% of Al was in colloidal form, whereas the dissolved and particulate fractions were 21% and 23%, respectively. Our data combined with data from similar studies support conclusions from other research suggesting that the percent fraction of metals adsorbed on particles rises steeply from almost zero to nearly 100% within a narrow and element specific pH range. Changes in TOC concentration seem capable of shifting the pH to % metal absorption curves in the order of one pH unit.     

Blood levels of cadmium,copper, lead and zinc in children in a British Columbia community

The levels of Cd, Cu, Pb and Zn were measured in duplicate whole blood samples of 946 apparently normal children ranging in age from 2 years to 12 years and living in Kamloops, British Columbia, Canada. The metals were determined using atomic absorption spectrometry: graphite furnace AAS for Cd and Pb, and flame AAS for Cu and Zn. The median and extreme values expressed as milligram of metal per litre of whole blood for the total population were: Cd ? 0.0005, Cu 1.11 (0.69–1.78), Pb 0.112 (0.020–0.400), and Zn 4.30 (2.10–6.53). No significant variations were noted in the median metal values either with age or with sex. The median Cu, Pb and Zn values were within the normal range.     

Daily intake of TBT, Cu, Zn, Cd and As for fishermen in Taiwan

The consumption of contaminated seafood has been reported as an important route of human exposure to metals in Taiwan. We consider the concentrations of TBT, Cu, Zn, Cd, As, and the consumption of oysters of Taiwanese to be the important information related to public health in Taiwan. Therefore, the aim of this study was to evaluate the public health risks associated with TBT, Cu, Zn, Cd and As from shellfish for the general population and fishermen of Taiwan. In general, TBT concentrations in various oysters ranging from 0.32 to 1.51 microg/g dry wt. varied with sampling locations. The highest TBT, Cu, and Zn geometric mean (GM) concentrations in oysters of 1.51, 1180 and 1567 microg/g dry wt. were obtained from the Hsiangshan coastal area. The values of oyster consumption for fishermen were 94.1 and 250 g/day for typically and maximally exposed individuals, respectively. In particular, the highest intake (250 g/day) from fishermen was almost two times greater than that of the general population (139 g/day). The THQ (target hazard quotient) values of Hsiangshan's fishermen are 3.87 and 20.50 for TBT and Cu for maximally exposed individuals are higher than other oyster culture areas. It is interesting that those consuming oysters from Hsiangshan, Lukang, Taishi caused abnormally high THQs of TBT and other metals (100% over 1.0), and TBT was attributed to only 3-21% of the total THQs in different fishermen of Taiwan. Our results suggest that current environmental levels of TBT and other metals are associated with a significant potential threat to human health for fishermen resident in coastal areas of Taiwan.     

Blood lead levels in children aged 5-9 years living in Cartagena, Colombia

During June-August 2004, blood lead (BPb) levels and various hematological parameters were evaluated in children aged 5-9 years old at ten primary schools located in eight neighborhoods in Cartagena, Colombia. The schools selected for this study are attended mainly by children from families of low income. A total of 189 subjects participated in the survey. The arithmetic mean+/-standard error BPb level was 5.49+/-0.23 microg/dL (range<1.0-21.0 microg/dL). The geometric mean was 4.74 microg/dL (95% CI: 4.29-5.18). A proportion of the children (7.4%) had BPb levels above the US Centers for Disease Control and Prevention's threshold of concern (10 microg Pb/dL). BPb levels were correlated weakly, but significantly and positively, with red blood cell count (RBC), and negatively with child body size, age, mean corpuscular volume (MCV), and mean corpuscular hemoglobin (MCH). BPb levels did not differ significantly between boys and girls but significant differences were observed between neighborhoods (P<0.001). Activities such as metal melting-related processes and fishing net sinker production are the main sources of Pb exposure in Cartagena.     

Intra- and inter-annual variation of Cd, Zn, Mn and Cu in foliage of poplars on contaminated soil

The uptake of trace metals in the leaves of fast-growing woody species is a crucial factor in ecological risk assessment and in the evaluation of phytoextraction potentials. In this study, we present a long-term data series of foliar Cd, Zn, Mn and Cu concentrations in poplar (Populus trichocarpa x P. deltoides). Leaves were collected every three weeks from 2001 until 2007 on three sites, (i) a new plantation on an alluvial soil polluted by river sediments, (ii) a new plantation on an unpolluted soil and (iii) a 10-year old plantation on a polluted dredged sediment soil. In addition, tree rings were measured on the alluvial soil in order to better assess growth over the past seven years. Foliar concentrations of Cd, Zn and Mn decreased considerably with time in the new plantation on polluted soil. Concentrations of Zn and Mn decreased in the new plantation on unpolluted soil as well. The older plantation on polluted soil did not show changes in foliar concentrations for Cd, Zn or Mn. Foliar Cu concentrations slightly increased for all sites. Within one growing season, foliar concentrations of Cd, Zn, Cu and Mn increased towards the end of the season. The tree ring data of the poplars on the alluvial soil indicated a strong decrease in growth due to declining tree condition from 2005 onwards, the same year that foliar Cd and Zn concentrations markedly decreased. Lower transpiration rates probably induced a lower uptake of dissolved trace metals. It is concluded that stand health and growth rate have a strong impact on the variation of foliar trace metal concentrations over time.     

Distribution of Cd, Zn, Cu and Fe among selected tissues of the earthworm (Allolobophora caliginosa) and Eurasian woodcock (Scolopax rusticola)

We have measured the concentrations of heavy metals in soils, earthworms and tissues of woodcocks in Quaderna Valley, northern Italy. The soil concentration of metals analysed in this research is consistent with data reported by other authors for uncontaminated or slightly contaminated soils. In earthworms, metals were mostly accumulated in the encapsulating chloragogenous tissue; the positive correlation between Cu concentration in the soil and in earthworms is noteworthy. Heavy metal distribution in the tissues of woodcock showed that Cd accumulation in the kidney was linked to the diet. Cu and Fe were preferentially concentrated in the liver and Zn in the testis. Kidney Cd and Zn concentrations were higher in adults than in juveniles. In addition, a main kidney metallothionein isoform, containing Cd and Zn, was isolated. In the kidney, Cd levels were linearly correlated with the concentration of metallothionein. Of the investigated metals, Cd raises the greatest concern, due to the increasing soil contamination by human activities.     

蛋氨酸螯合锌、铁、硒、铜在猪营养中的应用研究进展

微量元素氨基酸螯合物被称作第三代新型微量元素添加剂,其中蛋氨酸螯合物是优良的补充微量元素添加剂。既能补充饲粮中蛋氨酸的不足,又能提高饲料中微量元素的利用率。具有效果好、生物效价高、营养作用显著等优点。文章就蛋氨酸螯合微量元素的种类、研究现状及其在猪生产中的应用作以综述。     

Nutritional status and the serum levels of Mg, Ca, Zn and Cu

Serum Mg, Ca, Zn and Cu levels of 65 Indian children aged 5 months to 3 y 7 months, living in Bombay city, were estimated by atomic absorption spectrometry. Twenty-five well nourished controls exhibited the following serum levels: Mg 2.5 +/- 0.3 mg%, Ca 9.7 +/- 0.6 mg%, Zn 103.2 +/- 9.7 micrograms % and Cu 148.7 +/- 26 micrograms %. The remaining 40 patients were divided into four categories depending on the status of their nutrition; Group I was minimally undernourished, whereas Group IV was the worst effected. Group I (n = 6) had serum values of 2.5 +/- 0.2 mg% Mg, 8.9 +/- 0.6 mg% Ca, 85 +/- 18 micrograms % Zn and 108 +/- 25.8 micrograms % Cu. Group II (n = 20) levels were 2.2 +/- 0.3 mg% Mg, 8.3 +/- 0.9 mg% Ca, 82.6 +/- 16.5 micrograms %, Zn and 89.2 +/- 27.6 micrograms % Cu. Group III (n = 9) were 2.1 +/- 0.3 mg% Mg, 8.3 +/- 0.8 mg% Ca, 88.3 +/- 22.6 micrograms % Zn and 93 +/- 26.9 micrograms % Cu, whereas the most severely undernourished (Group IV) children had serum levels of 2.2 +/- 0.4 mg% Mg, 7.6 +/- 0.8 mg% Ca, 78.4 +/- 15.7 micrograms % Zn and 62.8 +/- 17.5 micrograms % Cu.