Should children with developmental and behavioural problems be routinely screened for lead?

’As safe as houses; the risk of childhood lead exposure from housing in England and implications for public health’

BACKGROUND AND AIM

Exposure to lead can harm a child's health, including damage to the nervous system, delayed growth, hearing loss, and many other adverse health effects, as well as implications for social, economic, educational and social well-being. Lead exposure in children is still a concern and cases require public health management to find the exposure source and interrupt the exposure pathway. Housing characteristics can indicate the presence of lead-contaminated paint and leaded water supply pipes. We aimed to explore the relationship between housing characteristics and elevated blood lead concentration (BLC) in children in England.

METHODS

We used a retrospective cohort design and included all cases of lead exposure in children reported to the UK Health Security Agency between 2014 and 2020 via surveillance. A case was a child aged under 16 years, resident in England, BLC of ≥ 0.48 μmol/L (10 µg/dL) and referred for public health management. We collected case demographic details and housing characteristics (age and type). We explored associations between elevated BLC and risk factors, using generalised linear mixed effects models and compared cases' housing type to that expected nationally.

RESULTS

Two hundred and sixty-six out of 290 cases met the case definition. There was no difference in BLCs between genders, age groups, deprivation, and housing type. After adjusting for reporting source, housing age and type, cases residing in housing built pre-1976 had a BLC of 0.32 (95%CI 0.02, 0.63) µmols/L (6.63 (95%CI 0.42, 13.0) µg/dL) higher than cases living in housing built after this time. Cases were 1.68 times more likely to be living in terraced housing (housing adjoined to one another) than other children and less likely to live in apartments and detached properties.

CONCLUSION

This study suggests an association between housing characteristics and BLC in children. Housing age and type may act as a proxy for lead exposure risk through exposure to leaded paint, lead water pipes, and lead contaminated dust from indoor and outdoor sources. Public health action should consider targeting families more at risk in older housing by raising awareness of the potential presence of lead pipes and paint. Interventions should include working with wider stakeholders including other housing and environmental professionals, the private sector, as well as parents and carers.

Lead, Soils, and Children: An Ecological Analysis of Lead Contamination in Parks and Elevated Blood Lead Levels in Brooklyn, New York

Although the prevalence of elevated childhood blood lead levels (BLLs) has been declining, there are still an estimated 500,000 children (1 to 5 years) with BLLs above the CDC's reference value (≥ 5 μg/dL). The objective of this study was to evaluate the ecological association between soil lead (Pb) concentrations in greenspaces in Brooklyn, NY and elevated BLLs of children aged 1 to 5 years old. Soil samples (n = 1504) were collected from a wide variety of parks within 43 neighborhood tabulation areas (NTAs) located in Brooklyn, NY, analyzed with a portable XRF with a subset (n = 350), and also analyzed by ICP-MS. Lead concentrations were right skewed with a mean of 160.4 ppm and a median of 113.1 ppm. The Pb concentration range spanned three orders of magnitude with most samples (66.7%) ≥ 80 ppm and 6.7% of samples ≥ 400 ppm. Elevated BLL (≥ 5ug/dL) data on children 1 to 5 years were obtained from the New York City Department of Health and Mental Hygiene (2011-2015). Weighted median soil Pb concentrations were calculated for each NTA and stratified into quartiles. The overall median rate of children from 1 to 5 years old with BLLs ≥ 5 µg/dL was 28.6 per 1000; the median rate was highest (p = 0.070) in the fourth quartile (Pb concentrations ≥ 150 ppm) compared to the first quartile (Pb concentrations < 88 ppm), 37.2 vs. 28.3 per 1000, respectively. We then used multivariable linear regression to determine the ecological association between BLL rates and soil Pb concentrations. In the final stepwise multivariable regression model, controlling for known risk factors, there was a significant positive association between soil Pb concentrations and increased childhood BLL rates (beta = 0.0008; p = 0.004). Our findings suggest that there is an ecological association between high soil Pb levels and increased rates of elevated childhood BLLs.

Case epidemiology from the first three years of a pilot laboratory-based surveillance system for elevated blood-lead concentrations among children in England, 2014-17: implications for public health action

BACKGROUND

Children incur lead toxicity even at low blood-lead concentrations (BLCs), and testing in England is opportunistic. We described epidemiology of cases notified to a passive laboratory-based surveillance system (SS), the Lead Poisoning in Children (LPIC) SS to inform opportunities to prevent lead exposure in children in England.

METHODS

Surveillance population: children <16 years of age and resident in England during the reporting period September 2014-17. Case definition: children with BLC ≥0.48 μmol/l (10 μg/dl). We extracted case demographic/location data and linked it with laboratory, area-level population and socio-economic status (SES) data. We described case BLCs and calculated age-, gender- and SES-specific notification rates, and age-sex standardised regional notification rates.

RESULTS

Between 2014 and 2017 there were 86 newly notified cases, giving an annual average notification rate of 2.76 per million children aged 0-15 years. Regionally, rates varied from 0.36 to 9.89 per million. Rates were highest in the most deprived quintile (5.38 per million), males (3.75 per million) and children aged 1-4 years (5.89 per million).

CONCLUSIONS

Males, children aged 1-4 years, and children in deprived areas may be at higher risk, and could be targeted for primary prevention. Varied regional notification rates suggest differences in clinician awareness of lead exposure and risk factors; guidelines standardising the indications for BLC-testing may assist secondary prevention.

Lead in New York City's soils: Population growth, land use, and contamination

Soil is an important exposure pathway for lead (Pb) and predictor of blood lead levels (BLL) among children. Over the past two decades, many areas within New York City (NYC) have undergone a transition from industrial and manufacturing land use to residential housing. This can bring new residents to areas which contain the legacy of historic Pb contamination. The objective of this study was to evaluate the difference in soil Pb concentrations between community parks and greenspaces in areas undergoing rapid redevelopment and land use changes and stable areas without redevelopment. Three high- and three low-risk Pb contaminated areas within NYC were identified based on an additive index that included population growth, industrial land use, and new construction. Soil samples (n=358) were collected across 34 parks and analyzed with an XRF with a subset also analyzed by ICP-MS. Areas within NYC, evaluated in this study, with a high-risk index had significantly (p<0.0001) larger mean concentrations of Pb in soil (374 mg/kg vs. 150 mg/kg, respectively) and double the rate of children under the age of six years with BLL > 5ug/dL (37.94 vs. 18.72 per 1000, respectively) compared to low-risk areas. There was a statistically significant (p <0.05) positive correlation between street density, manufacturing/industrial land density and population density change within 0.40 km of a park and soil Pb concentrations. However, we were unable to estimate the source-specific contribution of Pb concentrations in soil, since many of the variables assessed were correlated with one another. Regardless of the source, large population increases are occurring in areas with elevated soil Pb levels. In the three high-risk areas investigated in this study, the population has increased by over 35,000 residents between 2010 to 2017 compared to just 8,500 in the low-risk areas.

Examining the relationship between blood lead level and stunting, wasting and underweight- A cross-sectional study of children under 2 years-of-age in a Bangladeshi slum

Elevated blood lead level (BLL) is known to cause cardiac, immune, and cognitive damage but had not been thoroughly studied in relation to stunting among children under two years of age. We primarily aimed to assess the relationship between elevated BLL, the accumulation of concerned amount of the metal lead in blood and stunting and secondarily-wasting and underweight amongst Bangladeshi children less than two years of age. For this cross-sectional study, BLL measurements, anthropometric data, and socioeconomic indicator information were collected and analyzed for 729 children under two years of age upon enrollment in the MAL-ED study conducted in a Bangladeshi slum area. Univariate, bivariate and multivariate analyses were carried out to observe the proportion and mean and contribution of elevated BLL and other relevant variables in explaining the occurrence of stunting. Of the enrolled subjects, 39.0% were stunted [length-for-age z score (LAZ<-2)], 50.3% were male, and 86.6% had an elevated BLL (≥5μg/dL). Mean BLL of stunted children was 8.47 ± 3·37 μg/dL and 8.10 ± 3·80 μg/dL for non-stunted children. Proportion of children with elevated BLL was not significantly different between the stunted and non-stunted groups (p>0.05). When adjusted for other variables, elevated BLL was found to be a significant predictor of stunting and underweight (p<0.05) but not wasting (p>0.05). Elevated BLL (p<0·01), child's gender and weight (p<0·001), maternal body mass index (BMI) (p<0.05) and severe household food insecurity (p<0·05) were all significantly associated with stunting in the multivariate model. Increased odds of stunting was also observed for increased BLL. The findings suggest that chronic lead poisoning is significantly associated with high level of stunting among child slum dwellers in Bangladesh. These findings strengthen the argument for improved lead reduction efforts in Bangladesh, where lead poisoning and stunting are both highly prevalent.

Blood Lead Level in Children with Neurological Disorders

OBJECTIVE

We aimed to investigate the blood lead level (BLL) in children with neurologic disorders of unknown causes and compare with normal children.

MATERIALS & METHODS

In this prospective case-control study, 68 patients aged 1 to 18 yr with neurologic disorders of unknown causes, were referred to pediatric neurology clinics and wards, Shiraz, Iran selected during a 12 months period from Sep 2013. They were compared with 1:1 ratio, age, and sex-matched healthy children. BLL was checked from all participants using 3 cc heparinized venous blood sample. Level of ≥5 mcg/dl was considered toxic dose.

RESULTS

Totally, 136 children (68 cases and 68 controls) with mean ages of 5.20±4.12 and 4.18±3.86 yr, respectively, were enrolled. Mean BLL was higher in case group than in controls but the difference was not significant (P=0.84), though they were less than toxic levels in both. In addition, the difference in mean BLLs was not significant in terms of living place, sex, and age. Totally, 17.7% of the study sample had BLL ≥5 mcg/dl. The frequency of BLL ≥5 mcg/dl was significantly higher in case group (P=0.024) with an odds ratio 2.9 times higher (95% CI: 1.066-7.60).

CONCLUSION

Strategies in public health must focus on practicing primary and secondary preventions of lead exposure in children.

A clinical study of the effects of lead poisoning on the intelligence and neurobehavioral abilities of children

Background

Lead is a heavy metal and important environmental toxicant and nerve poison that can destruction many functions of the nervous system. Lead poisoning is a medical condition caused by increased levels of lead in the body. Lead interferes with a variety of body processes and is toxic to many organs and issues, including the central nervous system. It interferes with the development of the nervous system, and is therefore particularly toxic to children, causing potentially permanent neural and cognitive impairments. In this study, we investigated the relationship between lead poisoning and the intellectual and neurobehavioral capabilities of children.

Methods

The background characteristics of the research subjects were collected by questionnaire survey. Blood lead levels were detected by differential potentiometric stripping analysis (DPSA). Intelligence was assessed using the Gesell Developmental Scale. The Achenbach Child Behavior Checklist (CBCL) was used to evaluate each child’s behavior.

Results

Blood lead levels were significantly negatively correlated with the developmental quotients of adaptive behavior, gross motor performance, fine motor performance, language development, and individual social behavior (P < 0.01). Compared with healthy children, more children with lead poisoning had abnormal behaviors, especially social withdrawal, depression, and atypical body movements, aggressions and destruction.

Conclusion

Lead poisoning has adverse effects on the behavior and mental development of 2–4-year-old children, prescribing positive and effective precautionary measures.

The effects of metallothionein 2A polymorphism on lead metabolism: are pregnant women with a heterozygote genotype for metallothionein 2A polymorphism and their newborns at risk of having higher blood lead levels?

OBJECTIVES

Numerous studies indicate that certain genetic polymorphisms modify lead toxicokinetics. Metallothioneins are protective against the toxicity of many metals, including lead. The aim of this study was to determine whether the maternal metallothionein 2A (MT2A) -5 A/G single-nucleotide polymorphism is related to the lead levels in maternal blood, placental tissue and cord blood in 91 pregnant women and their newborns.

METHODS

Venous blood from the mother was collected to investigate lead levels and MT2A polymorphism. Cord blood and placenta were collected for lead levels. Analyses were made using an Atomic Absorption Graphite Furnace Spectrophotometer. Standard PCR-RFLP technique was used to determine MT2A polymorphism.

RESULTS

Blood lead levels of heterozygote genotype (AG) mothers were statistically higher than those of homozygote genotype (AA) (P < 0.05). Maternal lead levels were significantly associated with cord blood lead levels for pregnant women with AA genotype (P < 0.001). This association was not statistically significant for pregnant women with AG. In contrast, the mean value of cord blood lead level for newborns with mothers of AG genotype was slightly higher than others, though the difference was not significant. No significant difference existed in placenta lead levels between the groups.

CONCLUSION

This study suggests that pregnant women with AG genotype for MT2A polymorphism might have high blood lead levels and their newborns may be at risk of low-level cord blood lead variation.

Lead: ongoing public and occupational health issues in vulnerable populations: a case study

BACKGROUND

Lead has been recognized increasingly as a public health risk, although with the introduction of wide-ranging occupational and public health measures, levels of blood lead in the general population of the UK and other developed nations have been in decline in recent years. Nonetheless, cases of lead poisoning still occur.

METHODS

We report on a large cluster of exposed lead workers and their families, including several children. The focus of the occupational and public health investigations was to identify the different groups at risk and the pathways by which potential exposures were taking place.

RESULTS

Lead in the workplace was found to account for the raised blood lead levels amongst the workers with exposure occurring as a result of insufficient demarcation between 'clean' and 'dirty' areas, and from contamination of personal belongings with lead. Furthermore, there was evidence of para-occupational exposure of family members.

CONCLUSIONS

The successful control of lead in this case required multidisciplinary working. Efforts included extensive workplace controls, along with the education and care of workers and their families, though complicated by lack of familiarity with the UK health service amongst the affected groups, language barriers, underlying low levels of literacy and high mobility.

Environmental lead toxicity and nutritional factors

Environmental lead toxicity is an old but persistent public health problem throughout the world and children are more susceptible to lead than adults because of their hand to mouth activity, increased respiratory rates and higher gastrointestinal absorption per unit body weight. In the last decade children's blood lead levels have fallen significantly in a number of countries. Despite this reduction, childhood lead toxicity continues to be a major public health problem for certain at-risk groups of children, and concern remains over the effects of lead on intellectual development. The currently approved clinical intervention method is to give chelating agents, which bind and removed lead from lead burdened tissues. Studies indicate, however, that there is a lack of safety and efficacy when conventional chelating agents are used. Several studies are underway to determine the beneficial effect of nutrients supplementation following exposure to lead. Data suggest that nutrients may play an important role in abating some toxic effects of lead. To explain the importance of using exogenous nutrients in treating environmental lead toxicity the following topics are addressed: (i) different sources of lead exposure/current blood lead levels and (ii) protective effects of nutrients supplementation (some essential elements and vitamins) in lead toxicity.

Investigation of global developmental delay

The investigation of global developmental delay in preschool children varies between centres and between paediatricians. Following a literature search and review of the evidence base, guidelines were developed to assist in the assessment and management of such children presenting to secondary level services. Evidence supporting the use of genetic and biochemical investigations on a screening basis was found, but there was no evidence to support the use of metabolic investigations or neuroimaging in the absence of other positive findings on history or examination. Detailed history and examination are paramount in the assessment of children with global developmental delay. Investigations can be a useful adjunct in determining aetiology. Evidence based guidelines have been developed to assist doctors in the selection of appropriate investigations for this group of children.

Effect of lead exposure on dopaminergic transmission in the rat brain

Lead is a neurotoxicant with known behavioral and neurochemical effects. In this study we attempted to relate the behavioral effects of lead to neurotransmission. Oral administration of 1000 ppm of lead acetate to young rats for 30 days caused a reduction in locomotor activity and stereotypic exploratory behavior during a 20 min testing period. This locomotor hypoactivity induced by lead was accompanied by a reduction in stereotypic behavior (sniffing, lickings, biting and grooming). These outcomes suggested that lead might interfere with catecholaminergic and particularly dopaminergic neurotransmission. Therefore, we examined the effect of the lead acetate on the uptake of dopamine in striatal synaptosomal preparations. The collected data showed a clear inhibition of the uptake of 3H-DA with an IC50 of 3.5 x 10(-5)M. This inhibition of the uptake of dopamine suggests that the behavioral effects of lead may be involved in dopaminergic neurotransmission.

Recent developments in low-level lead exposure and intellectual impairment in children

In the last decade children's blood lead levels have fallen significantly in a number of countries, and current mean levels in developed countries are in the region of 3 Mu g/dL. Despite this reduction, childhood lead poisoning continues to be a major public health problem for certain at-risk groups of children, and concerns remain over the effects of lead on intellectual development in infants and children. The evidence for lowered cognitive ability in children exposed to lead has come largely from prospective epidemiologic studies. The current World Health Organization/Centers for Disease Control and Prevention blood level of concern reflects this and stands at 10 Mu g/dL. However, a recent study on a cohort of children whose lifetime peak blood levels were consistently less than 10 Mu g/dL has extended the association of blood lead and intellectual impairment to lower levels of lead exposure and suggests there is no safety margin at existing exposures. Because of the importance of this finding, we reviewed this study in detail along with other recent developments in the field of low-level lead exposure and children's cognitive development. We conclude that these findings are important scientifically, and efforts should continue to reduce childhood exposure. However, from a public health perspective, exposure to lead should be seen within the many other risk factors impacting on normal childhood development, in particular the influence of the learning environment itself. Current lead exposure accounts for a very small amount of variance in cognitive ability (1-4%), whereas social and parenting factors account for 40% or more.

Maternal blood lead effects on infant intelligence at age 7 months

A sample of 7-month-old African-American infants, exposed to maternal blood lead levels less than 5 microg/dL, were assessed with the Fagan test of Infant Intelligence. The results indicate significant effects on memory and cognitive functioning. Specifically, infants who scored in the upper 5th to 15th percentile of novelty preference scores had lower lead values than those scoring in the lower 5th or 15th percentile. Of note, is the finding that no infant who scored in the upper percentile range was ever classified as having high maternal blood lead levels. These results are in accord with previous studies that report relationships between low-level lead exposure and nonoptimal infant development.