During the past 45 years, exposure to lead has declined dramatically in the United States. This sustained decline is measured by blood and environmental lead levels and achieved through control of ...lead sources, emission reductions, federal regulations, and applied public health efforts.
Explore regulatory factors that contributed to the decrease in exposure to lead among the US population since 1970.
We present historical information about the control of lead sources and the reduction of emissions through regulatory and selected applied public health efforts, which have contributed to decreases in lead exposure in the United States. Sources of lead exposure, exposure pathways, blood lead measurements, and special populations at risk are described.
From 1976-1980 to 2015-2016, the geometric mean blood lead level (BLL) of the US population aged 1 to 74 years dropped from 12.8 to 0.82 μg/dL, a decline of 93.6%. Yet, an estimated 500 000 children aged 1 to 5 years have BLLs at or above the blood lead reference value of 5 μg/dL established by the Centers for Disease Control and Prevention. Low levels of exposure can lead to adverse health effects. There is no safe level of lead exposure, and child BLLs less than 10 μg/dL are known to adversely affect IQ and behavior. When the exposure source is known, approximately 95% of BLLs of 25 μg/dL or higher are work-related among US adults. Despite much progress in reducing exposure to lead in the United States, there are challenges to eliminating exposure.
There are future challenges, particularly from the inequitable distribution of lead hazards among some communities. Maintaining federal, state, and local capacity to identify and respond to populations at high risk can help eliminate lead exposure as a public health problem. The results of this review show that the use of strong evidence-based programs and practices, as well as regulatory authority, can help control or eliminate lead hazards before children and adults are exposed.
The purpose of this article is to consider alternate uses of the blood lead reference value for children. There are two possible approaches. Historically the reference value has been used to guide ...clinical and public interventions for individual children. As the distribution of blood lead levels in the population has been lowered over time, the blood lead level at which interventions are recommended has also been reduced. The use of a reference value of 3.5 μg/dL, based on the 98 percentile of blood lead levels for children in 2011-2014 National Health and Nutrition Examination Survey is under review. For several reasons, adopting the new reference value to guide clinical and public health management puts practitioners in an untenable position. First, the changes in the brain caused by lead are significant and persistent. However, these adverse impacts are subtle and although clearly identified at the population level, not predictive for individual children. In addition, the recommended interventions have not been shown to reduce blood lead levels once they are elevated. Finally, clinical laboratory and office-based blood lead testing devices are not required to quantify blood lead levels < 4 μg/dL and in many cases cannot reliably test for low blood lead levels. Revising the reference value also will undoubtedly result in diversion of resources away from those population-based interventions which have demonstrated success. We argue for second approach, in the management of lead poisoning in the US from one of evaluation and management at the individual level to one of population based primary prevention. This would require a strategy directed at controlling or eliminating lead in children's environment before they are exposed. The reference value, as a benchmark, is essential to ensure that primary prevention efforts are successful.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Centuries of human activities, particularly housing and transportation practices from the late 19th century through the 1980's, dispersed hundreds of millions of tons of lead into our urban areas.
...The urban lead burden is evident among humans, wild and domesticated animals, and plants. Animal lead exposures closely mirror and often exceed the lead exposure patterns of their human partners. Some examples: Pigeons in New York City neighborhoods mimicked the lead exposures of neighborhood children, with more contaminated areas associated with higher exposures in both species. Also, immediately following the lead in drinking water crisis in Flint MI in 2015, blood lead levels in pet dogs in Flint were 4 times higher than in surrounding towns. And combining lead's neurotoxicity with urban stress results in well-characterized aggressive behaviors across multiple species.
Lead pollution is not distributed evenly across urban areas. Although average US pediatric lead exposures have declined by 90% since the 1970s, there remain well defined neighborhoods where children continue to have toxic lead exposures; animals are poisoned there, too. Those neighborhoods tend to have disproportionate commercial and industrial lead activity; a history of dense traffic; older and deteriorating housing; past and operating landfills, dumps and hazardous waste sites; and often lead contaminated drinking water. The population there tends to be low income and minority. Urban wild and domesticated animals bear that same lead burden.
Soil, buildings, dust and even trees constitute huge lead repositories throughout urban areas.
Until and unless we begin to address the lead repositories in our cities, the urban lead burden will continue to impose enormous costs distributed disproportionately across the domains of the natural environment. Evidence-based research has shown the efficacy and cost-effectiveness of some US public policies to prevent or reduce these exposures. We end with a series of recommendations to manage lead-safe urban environments.
•High lead burdens in urban areas expose humans, domesticated and wild animals, and plants.•Higher exposures fall differentially on different populations even within urban areas.•Urban lead repositories include soil, buildings, dust and even trees.•Urban stress and lead exposure cause recognizable aggressive behaviors in both humans and animals.•Evidence-based research shows cost-effective policies exist to reduce urban lead burdens.
To evaluate trends in children's blood lead levels and the extent of blood lead testing of children at risk for lead poisoning from national surveys conducted during a 16-year period in the United ...States.
Data for children aged 1 to 5 years from the National Health and Nutrition Examination Survey III Phase I, 1988-1991, and Phase II, 1991-1994 were compared to data from the survey period 1999-2004.
The prevalence of elevated blood lead levels, >/=10 microg/dL, among children decreased from 8.6% in 1988-1991 to 1.4% in 1999-2004, which is an 84% decline. From 1988-1991 and 1999-2004, children's geometric mean blood lead levels declined in non-Hispanic black (5.2-2.8 microg/dL), Mexican American (3.9-1.9 microg/dL), and non-Hispanic white children (3.1 microg/dL to 1.7 microg/dL). However, levels continue to be highest among non-Hispanic black children relative to Mexican American and non-Hispanic white children. Blood lead levels were distributed as follows: 14.0% were <1.0 microg/dL, 55.0% were 1.0 to <2.5 microg/dL, 23.6% were 2.5 to <5 microg/dL, 4.5% were 5 to <7.5 microg/dL, 1.5% were 7.5 to <10 microg/dL, and 1.4% were >/=10 microg/dL. Multivariable analysis indicated that residence in older housing, poverty, age, and being non-Hispanic black are still major risk factors for higher lead levels. Blood lead testing of Medicaid-enrolled children increased to 41.9% from 19.2% in 1988-1991. Only 43.0% of children with elevated blood lead levels had previously been tested.
Children's blood lead levels continue to decline in the United States, even in historically high-risk groups for lead poisoning. To maintain progress made and eliminate remaining disparities, efforts must continue to test children at high risk for lead poisoning, and identify and control sources of lead. Coordinated prevention strategies at national, state, and local levels will help achieve the goal of elimination of elevated blood lead levels.
Background: In May 2010, a team of national and international organizations was assembled to investigate children's deaths due to lead poisoning in villages in northwestern Nigeria. Objectives: Our ...goal was to determine the cause of the childhood lead poisoning outbreak, investigate risk factors for child mortality, and identify children < 5 years of age in need of emergency chelation therapy for lead poisoning. Methods: We administered a cross-sectional, door-to-door questionnaire in two affected villages, collected blood from children 2-59 months of age, and obtained soil samples from family compounds. Descriptive and bivariate analyses were performed with survey, blood lead, and environmental data. Multivariate logistic regression techniques were used to determine risk factors for childhood mortality. Results: We surveyed 119 family compounds. Of 463 children < 5 years of age, 118 (25%) had died in the previous year. We tested 59% (204/345) of children < 5 years of age, and all were lead poisoned (≥ 10 μg/dL); 97% (198/204) of children had blood lead levels (BLLs) ≥ 45 μg/dL, the threshold for initiating chelation therapy. Gold ore was processed inside two-thirds of the family compounds surveyed. In multivariate modeling, significant risk factors for death in the previous year from suspected lead poisoning included the age of the child, the mother's work at ore-processing activities, community well as primary water source, and the soil lead concentration in the compound. Conclusion: The high levels of environmental contamination, percentage of children < 5 years of age with elevated BLLs (97%, > 45 μg/dL), and incidence of convulsions among children before death (82%) suggest that most of the recent childhood deaths in the two surveyed villages were caused by acute lead poisoning from gold ore–processing activities. Control measures included environmental remediation, chelation therapy, public health education, and control of mining activities.
Evaluate the effect of changes in the water disinfection process, and presence of lead service lines (LSLs), on children’s blood lead levels (BLLs) in Washington, DC.
Three cross-sectional analyses ...examined the relationship of LSL and changes in water disinfectant with BLLs in children <6 years of age. The study population was derived from the DC Childhood Lead Poisoning Prevention Program blood lead surveillance system of children who were tested and whose blood lead test results were reported to the DC Health Department. The Washington, DC Water and Sewer Authority (WASA) provided information on LSLs. The final study population consisted of 63,854 children with validated addresses.
Controlling for age of housing, LSL was an independent risk factor for BLLs ≥10
μg/dL, and ≥5
μg/dL even during time periods when water levels met the US Environmental Protection Agency (EPA) action level of 15 parts per billion (ppb). When chloramine alone was used to disinfect water, the risk for BLL in the highest quartile among children in homes with LSL was greater than when either chlorine or chloramine with orthophosphate was used. For children tested after LSLs in their houses were replaced, those with partially replaced LSL were >3 times as likely to have BLLs ≥10
μg/dL versus children who never had LSLs.
LSLs were a risk factor for elevated BLLs even when WASA met the EPA water action level. Changes in water disinfection can enhance the effect of LSLs and increase lead exposure. Partially replacing LSLs may not decrease the risk of elevated BLLs associated with LSL exposure.
► In Washington, DC, between November 2000 and December 2006, children living in homes with an LSL were at increased risk of having higher BLLs than children living in homes without an LSL. ► This association was strongest during 2003 when chloramine alone was used for water disinfection. ► The association persisted after controlling for the age of housing. ► Partial replacement of LSLs did not result in a decrease in the association between LSL and elevated BLL.
In 2010, Médecins Sans Frontières (MSF) discovered extensive lead poisoning impacting several thousand children in rural northern Nigeria. An estimated 400 fatalities had occurred over 3 mo. The US ...Centers for Disease Control and Prevention (CDC) confirmed widespread contamination from lead-rich ore being processed for gold, and environmental management was begun. MSF commenced a medical management programme that included treatment with the oral chelating agent 2,3-dimercaptosuccinic acid (DMSA, succimer). Here we describe and evaluate the changes in venous blood lead level (VBLL) associated with DMSA treatment in the largest cohort of children ≤ 5 y of age with severe paediatric lead intoxication reported to date to our knowledge.
In a retrospective analysis of programme data, we describe change in VBLL after DMSA treatment courses in a cohort of 1,156 children ≤ 5 y of age who underwent between one and 15 courses of chelation treatment. Courses of DMSA of 19 or 28 d duration administered to children with VBLL ≥ 45 µg/dl were included. Impact of DMSA was calculated as end-course VBLL as a percentage of pre-course VBLL (ECP). Mixed model regression with nested random effects was used to evaluate the relative associations of covariates with ECP. Of 3,180 treatment courses administered, 36% and 6% of courses commenced with VBLL ≥ 80 µg/dl and ≥ 120 µg/dl, respectively. Overall mean ECP was 74.5% (95% CI 69.7%-79.7%); among 159 inpatient courses, ECP was 47.7% (95% CI 39.7%-57.3%). ECP after 19-d courses (n = 2,262) was lower in older children, first-ever courses, courses with a longer interval since a previous course, courses with more directly observed doses, and courses with higher pre-course VBLLs. Low haemoglobin was associated with higher ECP. Twenty children aged ≤ 5 y who commenced chelation died during the period studied, with lead poisoning a primary factor in six deaths. Monitoring of alanine transaminase (ALT), creatinine, and full blood count revealed moderate ALT elevation in <2.5% of courses. No clinically severe adverse drug effects were observed, and no laboratory findings required discontinuation of treatment. Limitations include that this was a retrospective analysis of clinical data, and unmeasured variables related to environmental exposures could not be accounted for.
Oral DMSA was a pharmacodynamically effective chelating agent for the treatment of severe childhood lead poisoning in a resource-limited setting. Re-exposure to lead, despite efforts to remediate the environment, and non-adherence may have influenced the impact of outpatient treatment. Please see later in the article for the Editors' Summary.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In 2010, Médecins Sans Frontières discovered a lead poisoning outbreak linked to artisanal gold processing in northwestern Nigeria. The outbreak has killed approximately 400 young children and ...affected thousands more.
Our aim was to undertake an interdisciplinary geological- and health-science assessment to clarify lead sources and exposure pathways, identify additional toxicants of concern and populations at risk, and examine potential for similar lead poisoning globally.
We applied diverse analytical methods to ore samples, soil and sweep samples from villages and family compounds, and plant foodstuff samples.
Natural weathering of lead-rich gold ores before mining formed abundant, highly gastric-bioaccessible lead carbonates. The same fingerprint of lead minerals found in all sample types confirms that ore processing caused extreme contamination, with up to 185,000 ppm lead in soils/sweep samples and up to 145 ppm lead in plant foodstuffs. Incidental ingestion of soils via hand-to-mouth transmission and of dusts cleared from the respiratory tract is the dominant exposure pathway. Consumption of water and foodstuffs contaminated by the processing is likely lesser, but these are still significant exposure pathways. Although young children suffered the most immediate and severe consequences, results indicate that older children, adult workers, pregnant women, and breastfed infants are also at risk for lead poisoning. Mercury, arsenic, manganese, antimony, and crystalline silica exposures pose additional health threats.
Results inform ongoing efforts in Nigeria to assess lead contamination and poisoning, treat victims, mitigate exposures, and remediate contamination. Ore deposit geology, pre-mining weathering, and burgeoning artisanal mining may combine to cause similar lead poisoning disasters elsewhere globally.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, OILJ, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK, VSZLJ
Elevated blood lead levels lead to permanent neurocognitive sequelae in children. Resettled refugee children in the United States are considered at high risk for elevated blood lead levels, but the ...prevalence of and risk factors for elevated blood lead levels before resettlement have not been described.
Blood samples from children aged 6 months to 14 years from refugee camps in Thailand were tested for lead and hemoglobin. Sixty-seven children with elevated blood lead levels (venous ≥10 µg/dL) or undetectable (capillary <3.3 µg/dL) blood lead levels participated in a case-control study.
Of 642 children, 33 (5.1%) had elevated blood lead levels. Children aged <2 years had the highest prevalence (14.5%). Among children aged <2 years included in a case-control study, elevated blood lead levels risk factors included hemoglobin <10 g/dL, exposure to car batteries, and taking traditional medicines.
The prevalence of elevated blood lead levels among tested US-bound Burmese refugee children was higher than the current US prevalence, and was especially high among children <2 years old. Refugee children may arrive in the United States with elevated blood lead levels. A population-specific understanding of preexisting lead exposures can enhance postarrival lead-poisoning prevention efforts, based on Centers for Disease Control and Prevention recommendations for resettled refugee children, and can lead to remediation efforts overseas.
Despite significant progress made in recent decades in preventing childhood lead poisoning in the United States through the control or elimination of lead sources in the environment, it continues to ...be an issue in many communities, primarily in low-income communities with a large percentage of deteriorating housing built before the elimination of lead in residential paint. The purpose of this study is to determine whether state laws aimed at preventing childhood lead poisoning are also effective in preventing recurring lead poisoning among children previously poisoned.
An evaluation was conducted to determine whether laws in two representative states, Massachusetts and Ohio, have been effective in preventing recurrent lead poisoning among children less than 72 months of age previously poisoned, compared to a representative state (Mississippi) which at the time of the study had yet to develop legislation to prevent childhood lead poisoning.
Compared to no legislation, unadjusted estimates showed children less than 72 months old, living in Massachusetts, previously identified as being lead poisoned, were 73% less likely to develop recurrent lead poisoning. However, this statistically significant association did not remain after controlling for other confounding variables. We did not find such a significant association when analyzing data from Ohio.
While findings from unadjusted estimates indicated that state lead laws such as those in Massachusetts may be effective at preventing recurrent lead poisoning among young children, small numbers may have attenuated the power to obtain statistical significance during multivariate analysis. Our findings did not provide evidence that state lead laws, such as those in Ohio, were effective in preventing recurrent lead poisoning among young children. Further studies may be needed to confirm these findings.
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