Screening for elevated lead levels in childhood and pregnancy: an updated summary of evidence for the US Preventive Services Task Force

Policy Changes and Child Blood Lead Levels by Age 2 Years for Children Born in Illinois, 2001-2014

Objectives. To evaluate how lowering the blood lead level (BLL) intervention threshold affects childhood lead testing policy.Methods. We geocoded 4.19 million Illinois lead testing records (2001-2016) and linked to 2.37 million birth records (2001-2014), data on housing age, industrial emissions, and roads. We used multinomial logistic regression to determine predictors of BLLs of 10 micrograms per deciliter (µg/dL) or greater, 5 to 9 µg/dL, and 4 µg/dL.Results. We found that 2.2% of children had BLLs of 10 µg/dL or greater, 8.9% had BLLs of 5 to 9 µg/dL, and 5.7% had BLLs of 4 µg/dL. Pre-1930 housing was associated with more than 2- to 4-fold increased relative risk of BLLs above all thresholds. Housing built in 1951 to 1978 was associated with increased relative risk of BLLs of 5 to 9 µg/dL (relative risk ratio [RRR] = 1.14; 95% confidence interval [CI] = 1.06, 1.21) but not with increased relative risk of BLLs of 10 µg/dL or greater (RRR = 0.99; 95% CI = 0.84, 1.16). At a given address, previous BLLs of 5 to 9 µg/dL or BLLs of 10 µg/dL or greater were associated with increased risk of BLLs of 5 to 9 µg/dL or BLLs of 10 µg/dL or greater among current occupants by 2.37- (95% CI = 2.20, 2.54) fold and 4.08- (95% CI = 3.69, 4.52) fold, respectively.Conclusions. The relative importance of determinants of above-threshold BLLs changes with decreasing intervention thresholds.Public Health Implications. States may need to update lead screening guidelines when decreasing the intervention threshold.

More Guidelines than states: variations in U.S. lead screening and management guidance and impacts on shareable CDS development

BACKGROUND

Pediatric lead exposure in the United States (U.S.) remains a preventable public health crisis. Shareable electronic clinical decision support (CDS) could improve lead screening and management. However, discrepancies between federal, state and local recommendations could present significant challenges for implementation.

METHODS

We identified publically available guidance on lead screening and management. We extracted definitions for elevated lead and recommendations for screening, follow-up, reporting, and management. We compared thresholds and level of obligation for management actions. Finally, we assessed the feasibility of development of shareable CDS.

RESULTS

We identified 54 guidance sources. States offered different definitions of elevated lead, and recommendations for screening, reporting, follow-up and management. Only 37 of 48 states providing guidance used the Center for Disease Control (CDC) definition for elevated lead. There were 17 distinct management actions. Guidance sources indicated an average of 5.5 management actions, but offered different criteria and levels of obligation for these actions. Despite differences, the recommendations were well-structured, actionable, and encodable, indicating shareable CDS is feasible.

CONCLUSION

Current variability across guidance poses challenges for clinicians. Developing shareable CDS is feasible and could improve pediatric lead screening and management. Shareable CDS would need to account for local variability in guidance.

Is the Concentration of Cadmium, Lead, Mercury, and Selenium Related to Preterm Birth?

Environmental pollution and exposure of people to heavy metals cause many bad obstetric outcomes. Our aim is to demonstrate the role of cadmium (Cd), lead (Pb), mercury (Hg), and selenium (Se) in preterm labor etiology with a case-control study. In this study, between November 2017 and April 2018, preterm delivery mothers and term delivery mothers were compared in Çorum, Turkey. All deliveries were performed with cesarean sections and there were 30 mothers in the control group and 20 in the study group. The maternal blood, maternal urine, umbilical cord blood, and heavy metal levels in the amnion fluid in both groups were studied. Graphite furnace atomic absorption spectrometry was used to determine the blood concentration of Cd, Pb, Hg, and Se. We found lower levels of selenium in blood and urine of preterm delivery mothers and umbilical cord and amnion fluids of preterm infants (p < 0.01). We found a statistically significant positive correlation at selenium levels between mother's blood and umbilical cord blood (r (50) = 0.896, p < 0.001) and between maternal urine and amniotic fluid (r (50) = 0.841, p < 0.001). We have not found a similar correlation between mother and fetus of other metals (p > 0.05). We found that selenium levels were lower in mothers who were preterm birth in the light of the data in our study. We could not determine the positive or negative correlation of Cd, Pb, and Hg levels in blood, urine, and amniotic fluid samples with preterm birth.

Factors Associated With High Blood Lead Levels in a Sample of 100 Children in Tehran

Background:

Lead is considered a neurotoxic agent. We aimed to evaluate the blood lead level (BLL) in young population and determine probable risk factors of lead exposure in Iran.

Methods:

In a cross-sectional study, a total of 100 children were entered and their BLLs were checked.

Results:

In all, 25 and 8 patients had BLLs above 5 and 10 µg/dL, respectively. There was a significant univariate correlation between BLL and place of living, water pipe type, using dairy products, and stature in both cut-offs of 5 and 10 µg/dL. Binary regression analysis showed that pipe type was associated with high BLLs at cut-offs of 5 and 10 µg/dL, respectively. Also, there was an association between 50th percentile of stature for age and cut-off of 5 µg/dL.

Conclusions:

Higher BLLs may be seen in short stature pediatric population. Polyvinyl chloride (PVC) and polypropylene water pipes may even cause more release of lead and result in higher absorption of this metal in the pediatric population.

Evaluating Evidence on Intermediate Outcomes: Considerations for Groups Making Healthcare Recommendations

INTRODUCTION

Groups making recommendations need evidence about whether preventive services improve health outcomes (HOs). When such evidence is not available, groups may choose to evaluate evidence about effects on intermediate outcomes (IOs) and the link between IOs and HOs. This paper aims to describe considerations for assessing the evidence linking changes in IOs to changes in HOs.

METHODS

Working definitions of IOs, HOs, and other outcomes were developed. All current U.S. Preventive Services Task Force (USPSTF) recommendations through April 2016 were examined to identify how evidence of the IO-HO link was gathered and the criteria that appeared to be used to determine the adequacy of the evidence. Methods of other expert and recommendation-making groups were also examined.

RESULTS

Forty-four USPSTF recommendations involved a relevant IO-HO link. The approaches used most commonly to gather evidence about the link were selected review (19 of 44, 43%) and systematic review (12 of 44, 27%). Some key considerations when assessing the adequacy of evidence about the IO-HO link include adjustment for confounding, proximity of the IO to the HO in the causal pathway, and independence of IO-HO relationship from specific treatments.

CONCLUSIONS

Considerations were identified for recommendation-making groups to use when gathering and assessing the adequacy of evidence about the IO-HO link. Using a standard set of written principles could improve the transparency of assessments of the IO-HO link, especially if used together with judgment in a reasoned conjecture and refutation process. Ideally, the process would result in an estimate of the magnitude of change in HOs that is expected for specified changes in IOs.

Effects of wheat-flour biscuits fortified with iron and EDTA, alone and in combination, on blood lead concentration, iron status, and cognition in children: a double-blind randomized controlled trial

BACKGROUND

Lead is a common neurotoxicant and its absorption may be increased in iron deficiency (ID). Thus, iron fortification to prevent ID in populations is a promising lead mitigation strategy. Two common fortificants are ferrous sulfate (FeSO₄) and ferric sodium EDTA (NaFeEDTA). EDTA can chelate iron and lead.

OBJECTIVES

Our study objective was to determine the effects of iron and EDTA, alone and in combination, on blood lead (BPb) concentration, iron status, and cognition.

DESIGN

In this 2 × 2 factorial, double-blind placebo-controlled trial, 457 lead-exposed Moroccan children were stratified by school and grade and randomly assigned to consume biscuits (6 d/wk at school) containing 1) ∼8 mg Fe as FeSO₄, 2) ∼8 mg Fe as NaFeEDTA that contained ∼41 mg EDTA, 3) ∼41 mg EDTA as sodium EDTA (Na₂EDTA), or 4) placebo for 28 wk. The primary outcome was BPb concentration; secondary outcomes were iron status and cognitive outcomes from subtests of the Kaufman Assessment Battery for Children and the Hopkins Verbal Learning Test. These outcomes were measured at baseline and endpoint. All data were analyzed by intention-to-treat.

RESULTS

The adjusted geometric mean BPb concentration at baseline was 4.3 μg/dL (95% CI: 4.2, 4.3 μg/dL), and at endpoint these values were 3.3 μg/dL (95% CI: 3.1, 3.5 μg/dL) for FeSO₄, 2.9 μg/dL (95% CI: 2.7, 3.0 μg/dL) for NaFeEDTA, 3.3 μg/dL (95% CI: 3.1, 3.5 μg/dL) for EDTA, and 3.7 μg/dL (95% CI: 3.5, 3.9 μg/dL) for placebo. We found an effect of iron (P = 0.009) and EDTA (P = 0.012) for reduced BPb concentrations at endpoint, but no iron × EDTA interaction. Iron fortification improved iron status, but there were no positive effects of iron or EDTA on cognitive test scores.

CONCLUSIONS

Food fortification with iron and EDTA additively reduces BPb concentrations. Our findings suggest that NaFeEDTA should be the iron fortificant of choice in lead-exposed populations. This trial was registered at clinicaltrials.gov as NCT01573013.

Is Prenatal Lead Exposure a Concern in Infancy? What Is the Evidence?

BACKGROUND

Exposure to unhealthy and unsafe environments cause 1 in 4 deaths in childhood each year. Early exposure to lead beginning prenatally and continuing throughout childhood is one of the mechanisms associated with unhealthy and unsafe environments, particularly in industrial countries and urban communities. Lead is a known heavy metal that crosses the placenta and blood-brain barrier depositing in fetal tissues.

PURPOSE

The purpose of this integrative review was to determine which maternal-fetal dyads were at high risk for elevated umbilical cord lead (Pb) levels and to examine the consequences associated with elevated umbilical cord Pb levels.

SEARCH STRATEGY

PubMed was searched to obtain English language publications from 2005 to March 2015 for studies examining the effects of prenatal lead exposure on infant outcomes using key terms "lead" combined with "infant." A total of 17 articles were retained for analysis.

FINDINGS

Infants with elevated umbilical cord blood lead levels were associated with maternal demographic factors and country of origin. Maternal-specific exposure to lead products prior to or during pregnancy was associated with elevated umbilical cord blood lead levels. The consequences of prenatal lead exposure to the infant at birth anthropometrically were mixed. The evidence on neurological consequences of prenatal exposure to lead appears to reflect changes in cognitive impairment; however, it needs further study.

IMPLICATIONS FOR PRACTICE

The major recommendation is primary prevention of lead exposure across the life span. Implementation of policies that reduce the availability of leaded products to reduce leaded products, especially ones aimed at children and women of childbearing age.

IMPLICATIONS FOR RESEARCH

Research needs to be focused in 2 directions: (1) prevention of lead exposure during pregnancy and (2) prevention of lead leaching from bones for all women of childbearing age.

Lead in school children from Morelos, Mexico: levels, sources and feasible interventions

Background: Lead is a pervasive pollutant, associated at low levels to many adverse health effects. Objective: To investigate lead levels, exposure pathways and intervention possibilities in school children from Alpuyeca, in Morelos, Mexico. Methods: Blood lead concentrations (BPb) were measured in 226 children in 2011. Exposure pathways were assessed through a questionnaire, lead measurements in different environmental matrices and spatial aggregation analysis of lead concentrations. Results: BPb ranged from 1.5 to 36.5 µg/dL, with a mean (SD) of 7.23 (4.9) µg/dL. Sixty-four and 18% of the children had BPb > 5 µg/dL and > 10 µg/dL, respectively. The use of lead glazed ceramics was reported in almost half of the households; it was the main BPb determinant and it was associated with an increased risk of having BPb > 5 g/dL by 2.7 times (p = 0.001). Environmental samples were within US EPA’s lead recommended limits, and blood lead levels were randomly distributed in the community. Conclusions: Lead remains a public health problem in Alpuyeca, Mexico. Unlike other local pollutants, lead exposure prevention can be achieved inexpensively and in a short term. Interventions should make mothers aware of lead’s health effects and empower them to safeguard their children’s health by avoiding the culturally ingrained use of lead glazed pottery.

The utility and financial implications of obtaining routine lead levels for child psychiatric inpatients

This study attempted to challenge the CDC recommendations regarding routine screening blood lead levels in children. The purpose was to determine the efficacy of obtaining routine lead levels on all patients admitted to a child psychiatric inpatient unit. A retrospective chart review of children admitted to a psychiatric inpatient unit during a 12 month period. The audit determined average lead levels and costs associated with the screening program. 1 of 61 admitted children was found to have an elevated lead level. Number needed to treat was determined to be 98. The cost per case detected was determined to be over $8,600. Routine screening for blood lead levels in all children admitted to a psychiatric inpatient unit does not appear efficacious or cost effective.

Sources of potential lead exposure among pregnant women in New Mexico

The objectives of this study were to ascertain the prevalence and potential sources of lead exposure among pregnant women residing in a socially-disadvantaged immigrant community in Albuquerque, New Mexico. Pregnant women (n = 140) receiving prenatal care through a community clinic participated in a structured interview and screening to measure their blood lead levels (BLLs). Potential sources of lead exposure were ascertained by the CDC and New Mexico Department of Health questionnaires. Self-reported risk factors were examined as predictors of BLLs using multiple linear regression and partial least squares discriminant analysis. Most patients were Spanish-speaking (88.6%), Latina (95%), foreign-born (87.1%), lacked health insurance (86.4%), and had a high school education or lower (84.3%). While risk factors were prevalent in this population, only three women (2.1%) had BLLs ≥3 μg/dL. Results of multivariate analyses demonstrated that pica symptoms in pregnancy, history of elevated BLLs before pregnancy, use of non-commercial pottery, and living in older houses were important predictors of elevated BLLs. Although the prevalence of other risk factors relevant to immigrant communities (i.e., use of traditional/folk remedies and cosmetics, seasonings and food products from Mexico) was high, they were not predictive of elevated BLLs. Clinics providing prenatal care to immigrant Hispanic communities should carefully assess patients' pica symptoms, use of non-commercial pottery, and a history of elevated BLLs. Moreover, additional efforts need to focus on the development of screening questionnaires which better reflect exposures of concern in this population.

Lead exposure in female workers who are pregnant or of childbearing age

In adults, high-level lead exposure often occurs in the lead-related industries. Acute lead poisoning has become rare, but chronic exposure to low-level lead remains a public health issue. With recent advances in our understanding of lead toxicity at low-levels, researchers have shifted their focus to studying lead at concentrations below those currently recommended as 'acceptable' in worker protection. As gender plays an important role in the storage, biokinetics, and toxicity of lead, it seems inappropriate to extrapolate findings of lead exposure in men to women. Women's bones release lead more slowly to the bloodstream, so blood levels remain increased for a long time after cessation of high exposure, reflecting the endogenous source of the lead. Particularly in pregnant women, bone lead release could influence health in pregnancy and be extremely harmful to the rapidly growing and developing fetus. Accordingly, female workers of childbearing age should avoid excessive lead exposure. However, because studies of pregnant workers encounter many difficulties and inconveniences, sufficient research has not been conducted in this area. As an alternative, a group of non-occupationally exposed women, matched as well as possible for anthropometric and reproductive variables and with almost the same levels of blood lead, could be recruited for survey.

Barriers to pediatric lead screening: implications from a web-based survey of Vermont pediatricians

The pernicious effects of lead on child health are well documented. The Vermont Department of Health (VDH) recommends screening all 12- and 24-month-old children for elevated blood lead levels (BLL). In 2006, only 41.4% of 24-month-old Vermont children were screened. To identify barriers preventing pediatricians from performing blood lead screening, a survey was distributed to Vermont primary care pediatricians-divided in higher and lower screening groups. Vermont pediatricians were more likely to be lower screeners if they reported negative health outcomes began at BLL >" xbd="641" xhg="618" ybd="1456" yhg="1421"/> 10 microg/dL (odds ratio [OR] = 3.64, 95% confidence interval [CI] = 1.12-11.99), practiced in Chittenden County (OR = 3.34, 95% CI = 1.14-9.78), or disagreed with the VDH's recommendation (OR = 4.90, 95% CI = 1.66-15.50). Adjusted analysis indicated the most significant determinants of lower screening rates were male gender, a perceived dangerous BLL as >10 microg/dL and low self-reported Medicaid population. The VDH may have an opportunity to increase BLL screening emphasizing the significant health risks associated with BLL < or = 10 microg/dL.

Atypical sources of childhood lead poisoning in the United States: a systematic review from 1966-2006

BACKGROUND

Lead poisoning from atypical sources, which excludes the well-established lead-based paint ingestions and exposure in occupational settings, are increasingly reported in medical literature. Our objective is to increase awareness on atypical sources of lead exposure and to formulate recommendations for their detection based on actual reported cases.

METHODS

We systematically retrieved and reviewed reports on pediatric lead poisoning in the U.S. from atypical sources by searching Medline, Embase, CINAHL, Academic Search Premier, AltHealth, websites of state lead poisoning prevention programs, and the U.S. Consumer Product Safety Commission database for reports published from January 1966 to December 2006.

RESULTS

We retrieved 28 published reports that met our inclusion criteria. Of these reports, 20 are case reports and 8 case series, documenting a total of 82 incidents of lead poisoning in children from atypical sources.

CONCLUSION

There are varied sources of atypical lead exposure among U.S. children. The sources were grouped in the following categories based on their utility: fashion accessories, folk remedies, imported condiments & candies, pellets & bullets, and lastly, recreational & domestic items. Based on these findings, we have formulated a questionnaire that may assist in the identification of atypical lead sources in the home.

Molecular mechanisms triggered by mercury

Mercury is an ubiquitous environmental toxin that causes a wide range of adverse health effects in humans. Three forms of mercury exist: elemental, inorganic and organic. Each of them has its own profile of toxicity. Exposure to mercury typically occurs by inhalation or ingestion. Mercury can be an indoor air pollutant, however industry emission remains the most important source of inhaled mercury. Furthermore, fresh water and ocean fish may contain large amounts of mercury and dental amalgam can be another important source of inorganic and mercury vapor. The present review discusses the current information on mercury toxicity and the distinct toxicologic profile of the three forms of mercury. The existing therapeutics, new therapeutics development or agents for treating mercury poisoning will also discussed. Since in general low levels of mercurial are tolerable, herein, we also discuss the defensive mechanisms developed by the cell to protect itself against mercury injury. This aspect may be useful to provide a biological protection against toxic effects exerted by mercury or by specific forms of mercury in view of a medicinal purposes.