Interactions between iron deficiency and lead poisoning: epidemiology and pathogenesis

Iron deficiency and lead poisoning are common among infants and children in many parts of the world, and often these two problems are associated. Both conditions are known to cause anemia and appear to produce a more severe form of anemia when in combination. Although the nature of their relationship is not completely elucidated, characterization of a common iron-lead transporter and epidemiological studies among children strongly suggest that iron deficiency may increase susceptibility to lead poisoning. Recent human studies suggest that high iron intake and sufficient iron stores may reduce the risk of lead poisoning. Future clinical trials are necessary to assess the effect of iron supplementation in the public health prevention of lead poisoning and the kinetics of lead in the body.     

FRPs and FOSs lead to innovation in Canadian civil engineering structures

Modern and innovative technologies, developed as part of ISIS Canada activities, are described; these technologies involve new building materials, comprising polymers and super-strong fibers, and innovative sensors incorporating fiber optics. It is argued that the ISIS technologies will pave the way to innovation as well as for rehabilitating and rejuvenating Canada's aging and fast-crumbling infrastructure in a cost-effective manner. This article chronicles the latest developments of ISIS technologies.     

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.     

Blood lead and associated risk factors in Ontario children

The purpose of this study was to determine blood levels in Ontario children and to identify those risk factors associated with higher blood lead levels. A random sample of 1315 children aged 7 and younger from urban, suburban and rural Ontario was selected. Blood lead concentration was determined in finger prick blood samples by graphite furnace atomic absorption spectrophotometry. Measurements of lead in air, tap water, soil, and gasoline were also established. Traffic pattern were determined in each area. A questionnaire was administered to a random sample of 800 families of the children tested to assess the presence of other risk factors. Urban children had higher geometric mean blood lead levels (12.02, S.D. = 4.4 micrograms/dl) than suburban children (9.95, S.D. = 3.5 micrograms/dl), and they, in turn, had higher blood lead levels than rural children (8.91, S.D. = 3.9 micrograms/dl). Each of these differences is statistically significant (p less than 0.001). Fifty four (4.3%) of all children were at or above the alert level of 20 micrograms/dl. The proportion above the alert level did not differ significantly between urban, suburban and rural children. Blood lead levels were slightly higher for males than females and for pre-schoolers aged 3 and 4, compared to school age children aged 5 and 6. The blood lead levels of these children were significantly lower than that of children surveyed near a point source of industrial emissions. Multivariate statistical modelling resulted in a set of characteristics which best explained the differences in children's blood lead levels.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lead concentrations in human bones from the Canadian population

Stable lead was determined in post-mortem samples of human bones from three Canadian cities. All age groups and both sexes were represented. The cities selected for investigation were Winnipeg, Montreal and Charlottetown. No significant difference was found between the locations, although levels tended to be higher for Montreal. Mean lead concentrations (micrograms Pb/g ash) were 8.98 +/- 1.17, 11.11 +/- 1.74 and 8.47 +/- 1.06 for Winnipeg, Montreal and Charlottetown, respectively. Corresponding geometric means were 6.21, 7.88 and 6.71, respectively. Individual values ranged from 0.45 to 240.07 micrograms Pb/g ash. Concentrations were highest in the greater than 20-year age group, indicating increased body burden with age. An increase in lead concentration was observed for the ages 1-11 years with a decrease for the 12-19-year age group. Differences in concentrations between the sexes were not significant. Higher than average concentrations were observed in samples obtained from Winnipeg for the period 1976-1980, particularly in the 1-4-year age group. A similar pattern was observed in the air lead concentrations, suggesting a possible correlation between the concentrations of lead in the air and in bones at Winnipeg.     

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.     

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 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.     

Relationship between soil lead and airborne lead concentrations at Springfield, Missouri, USA

This study tests whether lead deposited to soil from automobiles during past years in a medium-sized US city (population 150,000) may present a current health risk. It examines the relationship between current soil lead concentrations at nine locations within the city of Springfield, Missouri, and airborne lead levels measured at the same locations during years (1975-1981) when lead emissions from automobiles were much greater than at present. A strong, significant correlation is found between soil and airborne lead levels at eight of the sites (r = 0.91, P < 0.005 for soil lead vs. 1979 airborne lead), in low-traffic areas as well as in areas adjacent to heavy traffic flow. Residual lead concentrations in these soils are relatively low, even for the high-traffic sites, as expected for a medium sized city.     

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.     

Blood lead levels in Taiwanese adults: distribution and influencing factors

Five-thousand nine-hundred thirteen Taiwanese adults were selected by multistage sampling methods to investigate environmental lead exposure in Taiwan. The blood specimens were distributed to six laboratories for blood lead levels (BLL) measurement. The mean BLL of the 5913 Taiwanese adults was 8.28 ± 5.39 μg/dl, with a maximum level of 57.6 μg/dl. The median was 7.0 μg/dl and 90th percentile was 15.0 μg/dl. BLLs were associated with gender, ethnic group, education level, smoking, alcohol consumption, herbal drug consumption, milk consumption, sources of drinking water, level of urbanization, and occupational lead exposure. These results showed that BLLs in Taiwanese adults were stable during the 2-year study. Most of the influencing factors were consistent with other studies, while local risk factors, such as Chinese herbal drug consumption are important ways of preventing the general population from overexposure to lead.     

Blood lead, behaviour and intelligence test performance in preschool children

A variety of measures of behaviour and cognitive performance were taken on a group of preschool children together with a sample of venous blood. The relationship between blood lead and intelligence was small and statistically non-significant after controlling for other factors influencing cognitive performance.     

Ingestion of lead from ammunition and lead concentrations in white-tailed sea eagles (Haliaeetus albicilla) in Sweden

In this study we show for the first time that lead poisoning from ammunition is a significant mortality factor for white-tailed sea eagle (WSE) (Haliaeetus albicilla) in Sweden. We analyzed 118 WSEs collected between 1981 and 2004 from which both liver and kidney samples could be taken. A total of 22% of all eagles examined had elevated (> 6 µg/g d.w.) lead concentrations, indicating exposure to leaded ammunition, and 14% of the individuals had either liver or kidney lead concentrations diagnostic of lethal lead poisoning (> 20 µg/g d.w.). Lead concentrations in liver and kidney were significantly correlated. In individuals with lead levels < 6 µg/g, concentrations were significantly higher in kidney than in liver; in individuals with lead levels > 20 µg/g, concentrations were significantly higher in liver. The lead isotope ratios indicate that the source of lead in individuals with lethal concentrations is different from that of individuals exhibiting background concentrations of lead (< 6 µg/g d.w.) There were no significant sex or age differences in lead concentrations. A study from the Baltic reported in principle no biomagnification of lead, but background lead concentrations in WSE liver in this study were still four to > 10 times higher than concentrations reported for Baltic fish from the same time period. In contrast to other biota there was no decrease in lead concentrations in WSE over the study period. The proportion of lead poisoned WSE remained unchanged over the study period, including two years after a partial ban of lead shot was enforced in 2002 for shallow wetlands. The use of lead in ammunition poses a threat to all raptors potentially feeding on shot game or offal. The removal of offal from shot game and alternatives to leaded ammunition needs to be implemented in order to prevent mortality from lead in raptors and scavengers.     

Blood lead levels in lactating cows reared around polluted localities; transfer of lead into milk

Lead is pervasive environmental pollutant with potential public health hazard as a contaminant of food from animal origin. The present study examines the blood and milk lead level in animals reared in areas around different industrial activities and to find out correlation between blood and milk lead levels in lactating cows. Blood and milk samples (n = 149) were collected from animals reared around steel processing unit (n = 22), lead-zinc smelter (n = 21), aluminum processing plant (n = 25), rock phosphate mining area cum phosphate fertilizer plant (n = 21), coal mining areas (n = 46) and closed lead but functional zinc smelter (n = 14). Samples were also collected from randomly chosen 52 lactating cows reared in non-polluted areas to serve as controls. Significantly (P < 0.05) higher blood lead level was recorded in animals reared around lead-zinc smelting factories followed by closed lead but functional zinc smelter, aluminum processing unit and steel manufacturing plant, as compared to values recorded for control animals. The highest milk lead level (0.84 +/- 0.11 microg/ ml) was detected in animals reared in the vicinity of lead-zinc smelting unit followed by aluminum processing plant and steel processing unit. Analysis of correlation between blood lead levels and lead excretion in milk through sorting the blood lead values into 9 different ranges irrespective of site of collection of samples (n = 201) revealed significant correlation (r = 0.469 at P < 0.01) between blood and milk lead concentrations. The lactating cows with blood lead levels above 0.20 microg/ml (groups 5-9) had significantly (P < 0.05) higher milk lead excretion than those with blood lead levels from non detectable to 0.20 microg/ml (groups 1-4). Pearson correlation analysis between blood and milk lead concentrations in 122 animals with blood lead <0.20 microg/ml showed non-significant correlation (r = 0.030 at P < 0.05) but a significant correlation was observed between these two parameters with blood lead level above >0.02 microg/ml indicating that the excretion of lead through milk increases with the increased in blood lead level above 0.20 microg/ml.     

Threshold concentrations of biomass and iron for pressure drop increase in spiral-wound membrane elements

In a model feed channel for spiral-wound membranes the quantitative relationship of biomass and iron accumulation with pressure drop development was assessed. Biofouling was stimulated by the use of tap water enriched with acetate at a range of concentrations (1-1000 μg C l⁻¹). Autopsies were performed to quantify biomass concentrations in the fouled feed channel at a range of Normalized Pressure Drop increase values (NPD_i). Active biomass was determined with adenosinetriphosphate (ATP) and the concentration of bacterial cells with Total Direct Cell count (TDC). Carbohydrates (CH) were measured to include accumulated extracellular polymeric substances (EPS). The paired ATP and CH concentrations in the biofilm samples were significantly (p < 0.001; R² = 0.62) correlated and both parameters were also significantly correlated with NPD_i (p < 0.001). TDC was not correlated with the pressure drop in this study. The threshold concentration for an NPD_i of 100% was 3.7 ng ATP cm⁻² and for CH 8.1 μg CH cm⁻². Both parameters are recommended for diagnostic membrane autopsy studies. Iron concentrations of 100-400 mg m⁻² accumulated in the biofilm by adsorption were not correlated with the observed NPD_i, thus indicating a minor role of Fe particulates at these concentrations in fouling of spiral-wound membrane.     

Blood lead levels in Papua New Guinea children living in a remote area

Improved contamination-free micro blood sampling and chemical analysis techniques were used to study the lead in blood (PbB) levels in 100 Papua New Guinea children living in a remote area. Six soil samples from different locations in the area were also chemically analysed as a check on environmental conditions. The mean value for PbB was 5.2 μg/100 ml with a range of 1.0–13.0 μg/100 ml. The standard deviation was 2.5 μg/100 ml. The results indicate much lower PbB levels for children living in a remote area than the earlier commonly reported levels for similar areas. These results indicate a need to reappraise the comparisons often made with PbB levels for urban children.