Community characteristics associated with elevated blood lead levels in children

OBJECTIVES: To identify community characteristics associated with children having elevated blood lead levels (> or = 10 micrograms/dL) and examine whether these characteristics can be used to identify children with elevated blood lead levels. PARTICIPANTS AND SETTING: A total of 20,296 children in Monroe County, New York (< 6 years old) who had blood lead testing in the first 12 months after statewide mandated reporting of blood lead tests began. DESIGN: A logistic regression analysis was conducted to examine the association of children's blood lead levels and community characteristics by using community characteristics of 653 census block groups. RESULTS: The following community level variables were associated with increased risk of elevated blood lead levels in children: residence within the city [odds ratio (OR), 2.0; 95% confidence interval (CI), 1.6, 2.7]; block groups with a higher proportion of individuals of Black race (OR, 1.6; CI, 1.4, 2.0); higher screening rate (OR, 1.9; CI, 1.6, 2.4); lower housing value (OR, 1.6; CI, 1.2, 2.0); housing built before 1950 (OR, 1.5; CI, 1.3, 1.8); higher population density (OR, 1.5; CI, 1.3, 1.8); higher rates of poverty (OR, 1.4; CI, 1.2, 1.8); lower percent of high school graduates (OR, 1.3; CI, 1.1, 1.6), and lower rates of owner-occupied housing (OR, 1.2; CI, 1.0, 1.4). Community characteristics were comparable with clinic-based individual risk assessment to identify children with elevated blood lead levels. CONCLUSIONS: These data demonstrate that community characteristics can be used to develop screening strategies to identify children who have elevated blood lead levels and shift our efforts toward identifying houses containing lead hazards before occupancy and before children are unduly exposed.     

Plasma lead levels in normal and lead-intoxicated children

Lead reaches tissues through the plasma, where the concentration of this ion is characteristically low. Little information exists on the mechanisms which determine the dynamics of lead in plasma. Measurement of plasma lead levels have been determined in normal and lead-intoxicated children, newborn infants, and children with sickle-cell disease. The results in all groups were remarkably similar and constant over a wide range of blood lead concentration and regardless of hematocrit. These results lend further support to the postulate that the red cell represents a repository for lead, maintaining plasma lead concentration within closely defined limits, and that methods other than an isolated measurement of plasma lead will be necessary to uncover a presumably dynamic transport system between red cell and plasma.     

Combined iron deficiency and lead poisoning in children. Effect on FEP levels

Concern for the concomitant occurrence of iron deficiency and elevated blood lead in children is raised by animal studies documenting increased gastrointestinal lead absorption in the presence of iron deficiency. An elevation in free erythrocyte protoporphyrin (FEP) above 35 mg/dl is seen with both iron deficiency and lead toxicity. To determine whether the degree of elevation in FEP is useful in predicting which children with elevated blood lead levels have concomitant iron deficiency, 109 children suspected of having an elevated lead burden were studied. A complete blood count, reticulocyte count, FEP, lead, and ferritin were measured on each child. The effect of the independent variables, lead and iron status, both alone and in combination, on the dependent variable, FEP, was analyzed through a linear regression model. Lead status alone accounted for 42 percent of the explained variance in FEP, and the lead-iron interaction increased the explained variance by only an additional 1 percent. Screening for iron deficiency in children with elevated blood lead should continue to be based on dietary and socioeconomic risk factors and not on degree of elevation in FEP.     

Six children with lead poisoning

Although most commonly seen in children from lower socioeconomic backgrounds, all children are at risk for lead poisoning. Management is a potential problem for all primary care providers. Because few individuals in the primary care practice of pediatrics have many patients with lead poisoning, it may be difficult to understand the nuances of management. We describe six patients, each of whom reflects different aspects of lead poisoning in children, and discuss the lessons we have learned in the course of their treatment. We have found that graphic representation of the blood lead and erythrocyte protoporphyrin values is helpful in the longitudinal follow-up of these youngsters.     

CaEDTA vs CaEDTA plus BAL to treat children with elevated blood lead levels.

The effectiveness of CaEDTA alone vs CaEDTA plus BAL was compared retrospectively in a group of 72 children with lead levels between 2.41 mumol/L (50 micrograms/dL) and 2.90 mumol/L (60 micrograms/dL). The children who received both drugs had higher median zinc protoporphyrin (ZnP) concentrations at the initiation of therapy than children who received CaEDTA alone (160 micrograms/dL vs 96 micrograms/dL, p less than .01). There was a significantly increased incidence of vomiting and abnormal liver-function test results in the children who received both drugs. The children who received CaEDTA alone had a greater percent mean fall in lead level at one to three weeks postchelation (30.5% vs 18.1%, p less than .05). Children who received both CaEDTA and BAL had a greater percent decrease in ZnP at four to eight months postchelation, but there was no difference in percent decrease in lead levels. Children who received both drugs also had a greater number of repeat courses of chelation by six months. The addition of BAL to CaEDTA for treatment of children with lead levels of 2.41 mumol/L (50 micrograms/dL) to 2.90 mumol/L (60 micrograms/dL) produced greater toxicity and does not seem to prevent repeat chelations within six months.     

Iron deficiency in young Lebanese children: association with elevated blood lead levels

OBJECTIVE: To measure the prevalence of transferrin saturation (TS) <12%, and iron-deficiency anemia (IDA) in Lebanese children, and their association with dietary habits, sociodemographic characteristics, and blood lead levels. PROCEDURE: A cross-sectional study was performed over a period of 2 years. Of 268 children studied, 142 (53%) were boys and 126 (47%) were girls with an age range of 11 to 75 months. Information collected included nutritional status, blood counts, TS, and blood lead levels. RESULTS: The total prevalence of TS<12% and IDA were 33.6% and 20.5%, respectively, and were associated with not having received iron supplements. IDA was more prevalent among males (P=0.04). TS<12% and IDA were significantly associated with elevated blood lead levels in the first age group (11 to 23 mo) (P=0.04, odds ratio=3.19) and (P=0.006, odds ratio=4.59), respectively. CONCLUSIONS: IDA is common in Lebanese children and is associated with increased blood lead levels, lack of iron supplementation, and cultural dietary habits. Remedial measures such as iron fortification of commonly consumed food are needed on the national level. Lead exposure must be controlled and awareness must be raised about the potentially devastating consequences of combined iron deficiency and lead poisoning on young children.     

Effects of elevated blood lead levels in preschool children in urban Vellore

Objectives

To study the burden and associated risk factors for elevated blood lead levels among pre-school children (15–24 months) in urban Vellore, and to study its effects on child cognition and anemia.

Design

An investigative study through Mal-ED cohort.

Setting

Eight adjacent urban slums in Vellore, Tamil Nadu.

Participants

251 babies recruited through Mal-ED Network.

Outcome measures

Blood lead levels using Graphite Furnace Atomic Absorption Spectrophotometry method at 15 and 24 mo; hemoglobin estimation by azidemethemoglobin method; cognitive levels using Bayley Scales of Infant Development III.

Results

Around 45% of children at 15 months and 46.4% at 24 months had elevated blood lead levels (>10 μg/dL). Among children who had elevated blood lead levels at 15 months, 69.2% (45/65) continued to have elevated levels at 24 months. After adjusting for potential confounders, children from houses having a piped drinking water supply and houses with mud or clay floors were at significantly higher risk of having elevated blood lead levels at 15 months. Thirty one percent (21/67) of the children with elevated blood lead levels had poor cognitive scores. Children with elevated blood lead levels at 15 months had higher risk (Adjusted OR 1.80; 95% CI 0.80–3.99) of having poorer cognitive scores at 24 months. More than half of the children (57%) were anemic at 15 months of age, and elevated blood lead levels were not significantly associated with anemia.

Conclusions

Elevated blood lead levels are common among preschool children living in urban slums of Vellore. Poorer conditions of the living environment are associated with elevated lead levels.     

Need for the lead mobilization test in children with lead poisoning

We evaluated the recommendation of the Centers for Disease Control, that children with moderate lead poisoning undergo the lead mobilization test (LMT) to determine the need for a full course of chelation treatment. Current criteria for selection for this test include a blood Pb concentration (bPb) between 25 and 55 micrograms/dl and an erythrocyte protoporphyrin level greater than 35 micrograms/dl. To determine whether the eligibility criteria could be refined to a smaller group of patients, we compared bPb determinations obtained on the day of the LMT in 198 children with moderate Pb poisoning to the results of the LMT. We found that children with bPb less than 25 micrograms/dl were unlikely to respond to the test dose of calcium disodium ethylenediamine tetraacetate with a Pb diuresis (24/25 patients had low urinary Pb excretion on the LMT). In contrast, 88% of children with bPb greater than or equal to 40 micrograms/dl were likely to excrete sufficient Pb to indicate the need for a full course of chelation. We conclude that the LMT is indicated for children with bPbs between 25 and 40 micrograms/dl. Children with bPb between 40 and 55 micrograms/dl may receive chelation therapy without having an LMT, if the performance of the LMT is not practical. Patients with levels less than 25 micrograms/dl should be followed clinically and removed from further Pb exposure.     

健康教育对轻中度铅中毒儿童干预作用的随机临床对照研究

目的评价健康教育对轻、中度儿童铅中毒的干预效果.方法血铅水平在100 μg/L以上的儿童200名,随机分为2组实验组107名,对照组93名.研究开始阶段,两组均要求儿童父母填写一份KABP问卷和家庭社会环境与健康问卷,随后对实验组采取健康教育进行干预,而对照组不采取任何措施.干预的时间为3个月,随后对2组的全部儿童进行血铅水平复测.结果实验组干预后父母的铅中毒知识均有所提高,前后比较差异均有高度统计学意义;而对照组对儿童铅中毒的概念和预防知识也有部分提高.实验组在健康教育后,儿童及父母多种接触铅高危行为也有显著改善;而对照组只有少数改善.两组儿童血铅水平均有所下降,血铅下降值分别为55 μg/L和33 μg/L,具有统计学意义(t=4.979, 3.398, P<0.01);但实验组比对照组多下降22 μg/L(t=3.531, P<0.01).采用多元逐步回归分析排除可能的混杂因素后,有14个变量最终进入血铅水平变化的逐步回归方程,这些变量有父母预防儿童铅中毒知识的提高、对儿童铅中毒态度的转变及儿童吃零食习惯的改变等.结论对父母进行健康教育可明显提高家长对儿童铅中毒预防知识的了解,有效降低轻中度铅中毒儿童的血铅水平.健康教育可作为轻中度儿童铅中毒临床处理的常规手段之一.     

Hazards of 'deleading' homes of children with lead poisoning

"Deleading" the homes of children with lead poisoning is a necessary step to terminate the child's exposure to lead. Lead poisoning as a result of lead exposure during the process of deleading has occurred in deleading workers but has not been well documented among children whose homes are deleaded. We treated four children with classes I through III lead poisoning (range of blood lead [Pb-B] level, 1.6 to 2.75 mumol/L [33 to 57 micrograms/dL]) who had significant elevation of their Pb-B levels (range, peak 4.34 to 6.27 mumol/L [90 to 130 micrograms/dL]) following deleading of their homes. The methods used for deleading included scraping, sanding, and burning of the paint. Symptoms included irritability (n = 3) and vomiting (n = 1). The elevation of the Pb-B levels was detected early, allowing prompt chelation therapy. Because exacerbation of lead poisoning may occur in children following deleading of their homes, safer approaches of deleading should be determined.