Changes In Blood Lead Research Articles

Blood lead levels in an endangered vulture decline following changes in hunting activity

Lead ammunition stands out as one of the most pervasive pollutants affecting wildlife. Its impact on bird populations have spurred efforts for the phase-out of leaded gunshot in several countries, although with varying scopes and applications. Ongoing and future policy changes require data to assess the effectiveness of adopted measures, particularly in the current context of biodiversity loss. Here, we assessed the long-term changes in blood lead (Pb) levels of Egyptian vultures from the Canary Islands, Spain, which have been severely affected by Pb poisoning over the past two decades. During this period, the reduction in hunting pressure and changes in legislation regarding firearms usage for small game hunting likely contributed to a decrease in environmental Pb availability. As anticipated, our results show a reduction in Pb levels, especially after the ban on wild rabbit hunting with shotgun since 2010. This effect was stronger in the preadult fraction of the vulture population. However, we still observed elevated blood Pb levels above the background and clinical thresholds in 5.6% and 1.5% of individuals, respectively. Our results highlight the positive impact of reducing the availability of Pb from ammunition sources on individual health. Nonetheless, the continued use of Pb gunshot remains an important source of poisoning, even lethal, mainly affecting adult individuals. This poses a particular concern for long-lived birds, compounding by potential chronic effects associated with Pb bioaccumulation. Our findings align with recent studies indicating insufficient reductions in Pb levels among European birds of prey, attributed to limited policy changes and their uneven implementation. We anticipated further reductions in Pb levels among Egyptian vultures with expanded restrictions on hunting practices, including a blanket ban on Pb shot usage across all small game species.

Lead, cadmium, and mercury blood levels in schoolchildren in southern Sweden: Time trends over the last decades

To prevent diseases arising from exposure to toxic metals, more knowledge about their temporal changes is needed, especially in children, the most vulnerable group.This study follows temporal changes in blood lead (BPb), mercury (BHg) and cadmium (BCd) levels in schoolchildren (8–11 years old) from two cities in southern Sweden. One blood sample per 773 children was used for time trend analyses between 2007 and 2022. One further blood sample re-sampled after 2 years, were used to assess intra-individual time trends of BPb (n = 377), BCd (n = 102) and BHg (n = 53) between 1979 and 2019.Geometric mean (range) of BPb, BCd and BHg concentrations during 2007–2022 was 9.9 (2.3–59), 0.09 (0.03–0.34) and 0.73 (0.02–8.2) μg/L, respectively. Living close to a Pb smelter resulted in higher levels of all three metals compared with living in the city or rural area. Annually, the concentrations clearly decreased for BPb (−4.9%, p < 0.001) and weakly for BCd (−0.6%, p = 0.013), while BHg slightly increased (+1.4%, p = 0.029). When stratified by residential area, the decrease of BCd and increase of BHg were significant only in the urban area (−1.8% and +2.8%, respectively; p < 0.01). The BPb decrease rate was the highest in the urban area followed by the rural and Pb smelter areas (−5.8% > -4.5% > -3.9%; p < 0.001). For children re-analysed during 1979–2019, a significant decrease was observed only for BPb (−6.8%; p < 0.001), with a 2% higher decrease rate in the period before than after the Pb-gasoline ban in 1994.The preventive measures against Pb pollution are reflected in the constant decrease of BPb levels over time. However, the area close to a Pb smelter, as indicated by a slower Pb decrease rate, might need further and stricter preventive measures. Exposure to Hg and Cd was low, however, the slight increase in BHg and only a minor decrease in BCd, indicate the need for continuous biomonitoring of children.

TWO-YEAR RESPONSES OF HEART RATE AND HEART RATE VARIABILITY TO FIRST OCCUPATIONAL LEAD EXPOSURE

Objective: Because of the falling lead exposure, the literature relating autonomous nervous function to blood lead has limited relevance. Design and method: In the longitudinal Study for Promotion of Health in Recycling Lead (URL: https://www.clinicaltrials.gov; Unique identifier: NCT02243904), we recorded the 2-year responses of heart rate, heart rate variability (Cardiax, International Medical Equipment Developing, Budapest, Hungary), and median nerve conduction velocity (Brevio, NeuMed, West Trenton, NJ), a routine test in occupational medicine, to first lead exposure in 195 newly hired workers (91.3% men; mean age, 27.8 years). High- and low-frequency heart rate variability power and orthostatic heart rate variability responses were derived from 5-minute eletrocardiograms in the supine and standing positions by Fourier transform and autoregression. Blood lead was determined by inductively coupled plasma mass spectrometry. Results: From baseline to follow-up, blood lead increased from 4.22 to 14.1 ug/dL and supine/standing HR from 63.6/75.5 to 67.1/78.8 beats per minute. In analyses stratified by fourths of blood lead changes, trends in heart rate and Fourier/autoregressive heart rate variability did not reveal a dose-response curve (0.074&lt; = P&lt; = 0.98). In multivariable-adjusted mixed models, heart rate, Fourier/autoregressive heart rate variability, and nerve conduction velocity changes were unrelated to blood lead except for a weak inverse association between supine heart rate and blood lead changes (-0.55%; P = 0.029). The expected associations between heart rate variability and heart rate changes were preserved with no differences at baseline/follow-up. Analyses ichotomised by baseline median blood lead or cumulative blood lead index (4.30 ug/dL or 32.1 ug/dL × year) suggested an heart rate variability increase versus decrease in the low versus high baseline exposure group. Conclusions: Thus, a &gt; 3-fold blood lead increment did not affect autonomous neural function as captured by heart rate variability.

Two-year neurocognitive responses to first occupational lead exposure.

Objectives:Lead exposure causes neurocognitive dysfunction in children, but its association with neurocognition in adults at current occupational exposure levels is uncertain mainly due to the lack of longitudinal studies. In the Study for Promotion of Health in Recycling Lead (NCT02243904), we assessed the two-year responses of neurocognitive function among workers without previous known occupational exposure newly hired at lead recycling plants.Methods:Workers completed the digit-symbol test (DST) and Stroop test (ST) at baseline and annual follow-up visits. Blood lead (BL) was measured by inductively coupled plasma mass spectrometry (detection limit 0.5 µg/dL). Statistical methods included multivariable-adjusted mixed models with participants modelled as random effect.Results:DST was administered to 260 participants (11.9% women; 46.9%/45.0% whites/Hispanics; mean age 29.4 years) and ST to 168 participants. Geometric means were 3.97 and 4.13 µg/dL for baseline BL, and 3.30 and 3.44 for the last-follow-up-to-baseline BL ratio in DST and ST cohorts, respectively. In partially adjusted models, a doubling of the BL ratio was associated with a 0.66% [95% confidence interval (CI) 0.03–1.30%; P=0.040] increase in latency time (DST) and a 0.35% (95% CI -1.63–1.63%; P=0.59) decrease in the inference effect (ST). In fully adjusted models, none of the associations of the changes in the DST and ST test results with the blood lead changes reached statistical significance (P≥0.12).Conclusions:An over 3-fold increase in blood lead over two years of occupational exposure was not associated with a relevant decline in cognitive performance.

Longitudinally monitored lifetime changes in blood heavy metal concentrations and their health effects in urban birds

Urban heavy metal pollution can impair the health of humans and other organisms inhabiting cities. While birds are suggested as one of the appropriate bioindicators for essential and non-essential trace element monitoring, the process of particular elements' accumulation in blood and its possible adverse health effects during ageing of individuals remain unexplored. We have investigated lifetime changes in blood lead (Pb), cadmium (Cd), arsenic (As) and zinc (Zn) concentrations and searched for links to health-related traits in sub-urban free-living great tit (Parus major) population monitored over a long period of time. The blood As concentrations were under the limit of detection in most samples. The blood Pb levels showed a non-linear relationship to individuals age, where the highest Pb concentrations were measured in nestlings and in a very small group of highly senescent birds (over 7 years old), while no clear trend was observed for the majority of the adult age stages. No age-related patterns were found for blood Cd or Zn concentrations. The positive relationship between date of capture and blood Cd and Zn levels may reflect seasonal changes in diet composition. We did not reveal any anaemia-like conditions (decreased total erythrocyte count or increased immature erythrocyte count) in relation to blood heavy metal concentrations in the investigated birds. Total leukocyte counts, heterophil/lymphocyte (H/L) ratio and total heterophil and lymphocyte counts increased with increasing Pb, Cd and Zn concentrations in blood. This study demonstrates the suitability of avian blood for actual heavy metal spatial and temporal biomonitoring even in situations when the precise age of the individuals remains unknown.

The Influences of Sociodemographic Characteristics and Changes in Blood Lead on the Concentration-Response Relationship between Blood Lead Level and Children's Intelligence Quotient

Blood lead levels (BLLs) have decreased over the last several decades but lead exposure remains a risk and the relationship between socioeconomic status, lead, and neurodevelopment is not well-unde...

Declining exposures to lead and cadmium contribute to explaining the reduction of cardiovascular mortality in the US population, 1988-2004.

Lead and cadmium exposures have markedly declined in the USA following the implementation of large-scale public health policies and could have contributed to the unexplained decline in cardiovascular mortality in US adults. We evaluated the potential contribution of lead and cadmium exposure reductions to explain decreasing cardiovascular mortality trends occurring in the USA from 1988-94 to 1999-2004. Prospective study in 15 421 adults ≥40 years old who had participated in the National Health and Nutrition Examination Survey 1988-94 or 1999-2004. We estimated the amount of change in cardiovascular mortality over time that can be independently attributed to the intermediate pathway of changes in blood lead and urine cadmium concentrations. There was a 42.0% decrease in blood lead and a 31.0% decrease in urine cadmium concentrations. The cardiovascular mortality rate ratio [95% confidence intervals (CIs)] associated with a doubling of metal levels was 1.19 (1.07, 1.31) for blood lead and 1.20 (1.09, 1.32) for urine cadmium. The absolute reduction in cardiovascular deaths comparing 1999-2004 to 1988-94 was 230.7 deaths/100 000 person-years, in models adjusted for traditional cardiovascular risk factors. Among these avoided deaths, 52.0 (95% CI 8.4, 96.7) and 19.4 (4.3, 36.4) deaths/100 000 person-years were attributable to changes in lead and cadmium, respectively. Environmental declines in lead and cadmium exposures were associated with reductions in cardiovascular mortality in US adults. Given the fact that lead and cadmium remain associated with cardiovascular disease at relatively low levels of exposure, prevention strategies that further minimize exposure to lead and cadmium may be needed.

Declining Exposures to Lead and Cadmium Contribute to Explain the Reduction of Cardiovascular Mortality in the United States Population, 1988-2004

Background. Lead and cadmium exposures have markedly declined in the US following the implementation of large-scale public health policies and could have contributed to the unexplained decline in cardiovascular mortality in US adults. We evaluated if population changes in the distribution of blood lead and urine cadmium levels explain changes in cardiovascular mortality over time in a representative sample of the US general population. Methods. Prospective study in 15,421 adults ≥40 years old who had participated in the National Health and Nutrition Examination Survey 1988-1994 or 1999-2004 and had baseline measures of urine cadmium, blood lead, and cardiovascular risk factors, and mortality follow-up for up to 8 years. We estimated the amount of change in cardiovascular mortality rates comparing 1999-2004 to 1988-1994 that can be independently attributed to changes in blood lead and urine cadmium concentrations. Results. During the study period there was a 43.7% decrease in blood lead and a 23.5% decreas...

Changes in Systolic Blood Pressure Associated With Lead in Blood and Bone

Several studies have examined longitudinal associations of blood pressure change or hypertension incidence with lead concentration in blood or bone. It is not clear whether the observed associations reflect an immediate response to lead as a consequence of recent dose or rather are a persistent effect of cumulative dose over a lifetime. We followed 575 subjects in a lead-exposed occupational cohort in South Korea between October 1997 and June 2001. We used generalized estimating equation models to evaluate blood pressure change between study visits in relation to tibia lead concentrations at each prior visit and concurrent changes in blood lead. The modeling strategy summarized the longitudinal association of blood pressure with cumulative lead dose or changes in recent lead dose. On average, participants were 41 years old at baseline and had worked 8.5 years in lead-exposed jobs. At baseline, the average +/- standard deviation for blood lead was 31.4 +/- 14.2 microg/dL, and for tibia lead, it was 38.4 +/- 42.9 microg/g bone mineral. Change in systolic blood pressure during the study was associated with concurrent blood lead change, with an average annual increase of 0.9 (95% confidence interval = 0.1 to 1.6) mm Hg for every 10-microg/dL increase in blood lead per year. The findings in this relatively young population of current and former lead workers suggest that systolic blood pressure responds to lead dose through acute pathways in addition to the effects of cumulative injury.

Analysis of kuali and associated blood-lead changes in users

Analysis of kuali and associated blood-lead changes in users

Changes in the lead isotopic composition of blood, diet and air in Australia over a decade: Globalization and implications for future isotopic studies

Source apportionment in biological or environmental samples using the lead isotope method, where there are diverse sources of lead, relies on a significant difference between the isotopic composition in the target media and the sources. Because of the unique isotopic composition of Australian lead, source apportionment has been relatively successful in the past. Over the period of a decade, the 206Pb/ 204Pb ratio for Australian (mainly female) adults has shown an increase from a geometric mean of 16.8–17.3. Associated with this increase, there has been a decrease in mean blood lead concentration from 4.7 to 2.3 μg/dL, or about 5% per year, similar to that observed in other countries. Lead in air, which up until 2000 was derived largely from the continued use of leaded gasoline, showed an overall increase in the 206Pb/ 204Pb ratio during 1993–2000 from 16.5 to 17.2. Since 1998 the levels of lead in air were less than 0.2 μg/m 3 and would contribute negligibly to blood lead. Over the 10-year period, the 206Pb/ 204Pb ratio in diet, based mainly on quarterly 6-day duplicate diets, increased from 16.9 to 18.3. The lead concentration in diet showed a small decrease from 8.7 to 6.4 μg Pb/kg although the daily intake increased markedly from 7.4 to 13.9 μg Pb/day during the latter part of the decade probably reflecting differences in demographics. The changes in blood lead from sources such as lead in bone or soil or dust is not dominant because of the low 206Pb/ 204Pb ratios in these media. Unless there are other sources not identified and analysed for these adults, it would appear that in spite of our earlier conclusions to the contrary, diet does make an overall contribution to blood lead, and this is certainly the case for specific individuals. Certain population groups from south Asia, south-east Asia, the Middle East and Europe (e.g. UK) are unsuitable for some studies as their isotopic ratios in blood are converging towards the increasing Australian values. The increases in blood 206Pb/ 204Pb ratio combined with globalization, which has resulted in the increases in 206Pb/ 204Pb ratio for diet, means that isotopic studies undertaken with a high degree of certainty of outcomes over a decade ago, are now considerably more difficult, not only in Australia but also in other countries where the isotopic differences are even less than in Australia.

Release of lead from bone in pregnancy and lactation

Concentrations and isotope ratios of lead in blood, urine, 24-h duplicate diets, and hand wipes were measured for 12 women from the second trimester of pregnancy until at least 8 months after delivery. Six bottle fed and six breast fed their infants. One bottle feeder fell pregnant for a second time, as did a breast feeder, and each was followed semicontinuously for totals of 44 and 54 months, respectively. Bone resorption rather than dietary absorption controls changes in blood lead, but in pregnancy the resorption of trabecular and cortical bone are decoupled. In early pregnancy, only trabecular bone (presumably of low lead content) is resorbed, causing blood leads to fall more than expected from hemodilution alone. In late pregnancy, the sites of resorption move to cortical bone of higher lead content and blood leads rise. In bottle feeders, the cortical bone contribution ceases immediately after delivery, but any tendency for blood leads to fall may be compensated by the effect of hemoconcentration produced by the postpartum loss of plasma volume. In lactation, the whole skeleton undergoes resorption and the blood leads of nursing mothers continue to rise, reaching a maximum 6–8 months after delivery. Blood leads fall from pregnancy to pregnancy, implying that the greatest risk of lead toxicity lies with first pregnancies.

Mobilization of lead from human bone tissue during pregnancy and lactation—a summary of long-term research

The skeleton is potential endogenous source of lead during pregnancy and lactation. We have undertaken a longitudinal investigation into the mobilization of lead from the human maternal skeleton to determine whether lead is mobilized from the maternal skeleton during pregnancy and lactation, and if so, when and how much is released. Subjects in the study were migrants to Australia ( n=15) whose skeletal lead isotopic composition (endogenous lead) was different to that prevailing in the Australian environment (exogenous lead). This migrant cohort was compared with 6 multi-generational Australian controls. Biological and environmental samples were taken pre-pregnancy where possible, throughout pregnancy and postpartum for at least 6 months. Newly-born infants of the migrant and Australian mothers were monitored for 6 months. Blood lead concentrations for the migrant mothers ranged from 1.5 to 20 μg/dl (geometric mean 2.8) and for Australian mothers ranged from 1.9 to 4.3 μg/dl (geometric mean 2.9). There was minimal change in lead isotopic composition of the Australian pregnant controls although there were increases of approximately 40% in blood lead concentration in 3 of 6 cases during the postpartum period and from 0 to 12% in the other 3. In the migrant pregnant subjects, the geometric mean skeletal lead contribution to blood lead using the isotopic composition was approximately 33% (range 10–88%) for 14 subjects using a revised estimate for exogenous lead. Skeletal contribution to blood lead during the postpartum period was significantly greater than during pregnancy ( P<0.001). The skeletal contributions to blood lead are higher and the changes are more consistent in those subjects who conceived within 100 days of arrival in Australia compared with those who conceived longer than 100 days. In the migrant subjects, changes in blood lead concentration during pregnancy and postpartum varied from subject to subject with an overall 20% increase; the increases during the postpartum period were greater than during pregnancy ( P<0.001). It was estimated that the amount of maternal skeletal lead mobilized during pregnancy and transferred to the infant via cord blood averaged approximately 79%. The increased skeletal contribution to blood lead is attributed to a low daily calcium intake of approximately 500 mgCa/day, a condition which was present in both migrant and Australian subjects. An ongoing clinical trial is providing a new cohort with calcium supplements. A summary of other aspects of the study is included and covers: additional flux released from the skeleton during pregnancy and postpartum; XRF bone lead results; urinary excretion of lead during pregnancy and postpartum; dietary contribution to blood lead in female adults and children; comparison of rates of exchange of lead in blood of newly-born infants and mothers; relationships of lead in breast milk to lead in blood, urine and diet of the infant and mother; changes in blood lead after cessation of breastfeeding; urinary lead isotopes during pregnancy and postpartum indicate no preferential partitioning of endogenous lead into plasma; a comparison of some aspects of the nonhuman primate and human pregnancy studies.

Changes in blood lead of a recreational shooter

We have measured the concentration and isotopic composition of lead in blood over a 15-month period for a subject who undertook recreational shooting in outdoor and indoor firing ranges on an irregular basis. We have also measured the isotopic composition in cast lead, Cu-jacketed and Teflon-coated bullets, propellant and primer from which he assembled the cartridges. Blood lead concentration increased from 3.2 to 6.7 μg/dl with use of dominantly cast lead bullets in the outdoor range. In two intervals when no firing was undertaken for 3–4 months, the blood lead concentrations either decreased towards a baseline value in the case where only Cu-jacketed bullets were fired or remained elevated when dominantly cast lead bullets were fired. The propellants contained <2 ppm Pb and contribute negligibly to blood lead. The isotopic composition of the primer used for all bullets was consistent with a source from the US. The bullets were of different materials and made in Australia and the US, with lead from sources of different geological age and hence different isotopic signatures. Variations in blood lead concentration and isotopic composition appear most strongly influenced by the bullets. Although more expensive, the use of Cu-jacketed bullets, non-lead primers and well-ventilated indoor firing ranges would lessen the health impacts of recreational shooting.

The Impact of Low Technology Lead Hazard Reduction Activities among Children with Mildly Elevated Blood Lead Levels

This prospective environmental intervention study was conducted to determine the impact of low-technology lead hazard reduction activities among children with mildly elevated blood lead levels. Children whose homes had severe lead hazards were automatically assigned to the intervention group. Children whose homes had lesser hazards were randomly assigned to the intervention group or comparison group. The one-time intervention focused mainly on cleaning and repainting window areas and educating caregivers to maintain effective housekeeping techniques. Changes in blood lead and dust lead loading levels were observed following the interventions. Analysis of covariance was used to adjust comparisons of postintervention levels for preintervention levels and other variables. The lead hazard reduction activities were associated with a modest decline in blood lead levels among children with severe hazards. The magnitude of the decline depended on the confounder that was controlled; the majority ranged from −1.1 to −1.6 μg/dL. A moderate reduction in window well dust lead loading levels was also observed. While low-technology lead hazard reduction measures appeared to be an effective secondary prevention strategy among children with severe household lead hazards, larger studies are needed to confirm these results.

Effect of Interventions on Children's Blood Lead Levels

Trail, Canada, has been the site of an active lead/zinc smelter for nearly a century. Since 1991, the Trail Community Lead Task Force has carried out blood lead screening, case management, education programs targeted at early childhood groups and the general community, community dust abatement, exposure pathways studies, and remedial trials. From 1989 through 1996, average blood lead levels of children tested for the first time declined at an average rate of 0.6 microg/dl/year, while blood lead levels in Canadian children not living near point sources appeared to be leveling off following the phase-out of leaded gasoline. Since there was no concurrent improvement in local environmental conditions during this time, it is possible that the continuing decline in Trail blood lead levels has been at least partly due to community-wide intervention programs. One year follow-up of children whose families received in-home educational visits, as well as assistance with home-based dust control measures, found that these specific interventions produced average blood lead changes of +0.5- -4.0 microg/dl, with statistically significant declines in 3 years out of 5. Education and dust control, particularly actions targeted toward higher risk children, appear to have served as effective and appropriate interim remedial measures while major source control measures have been implemented at the smelter site.

Changes in blood lead and water lead in Edinburgh. An eight year follow-up to the Edinburgh lead study

This study aimed to measure changes in household water lead and blood lead in young people living in Edinburgh over a period of 8 years. Two hundred and twenty-three families were eligible and 207 (93%) agreed to participate. A half-hour stagnation sample of kitchen cold water was taken from each household, and 171 young people (aged 14–17 years) provided a blood sample for lead analysis. Information on plumbing changes, exposure to other sources of lead and factors which might influence blood lead was collected by questionnaire. Edinburgh is supplied with water treated in one of two treatment plants. There was a different programme of water treatment in each plant. In one (A) lime and orthophosphate was introduced in the interval between the original and follow-up studies. In the other (F) lime treatment began before the original study and orthophosphate was introduced subsequently. In water from treatment plant A, mean water lead levels fell from 34 to 4.3 μ gL⊃-1 (87%). In water supplied from treatment plant F the corresponding values were 9.3 to 3.6 μ gL⊃-1 (61%). These reductions were due to both water treatment and removal of lead plumbing. Houses with no lead plumbing have water lead levels 89% lower than houses with lead tanks, and 47% lower than houses with lead pipes. About one-third of households with lead tanks are predicted to have water lead levels above the current EC limit of 50 μ gL⊃- 1, though only 3% or less of the remaining households would exceed this limit. If the proposed 10 μ gL⊃-1 limit were introduced, 34% of households supplied from plant A and 25% from plant F would breach the limit. Blood lead levels fell from an average of 11.0 μ gdL⊃-1 to 4.0 μ gdL⊃-1. Males had higher values than females and the main factors influencing levels were water lead and age of house. Our results show substantial reductions in household water lead and blood lead in our sample over a period of 8 years and represent an important achievement in public health. However, more progress will be required if the proposed new limit of 10 μ gL⊃-1 for water lead is to be met. There is a need for the continuing surveillance of household water lead and blood lead levels in representative samples of the population.

Use of Sequentially Administered Stable Lead Isotopes to Investigate Changes in Blood Lead during Pregnancy in a Nonhuman Primate (Macaca fascicularis)

The effects of pregnancy on the flux of lead from maternal bone were investigated in five females from a unique colony of cynomolgus monkeys (Macaca fascicularis) which had been dosed orally with lead (approximately 1100–1300 μg Pb/kg body wt) throughout their lives (about 14 years). Through the use of stable lead isotopes 204Pb, 206Pb, and 207Pb, it was possible to differentiate between the lead contributed to blood lead from the skeleton and the lead contributed from the current oral dose. Blood samples and bone biopsy samples taken before, during, and after pregnancy were analyzed for lead (total and stable isotope ratios) by thermal ionization mass spectrometry. Through the use of end-member unmixing equations, the contribution to blood of lead from maternal bone during pregnancy was estimated and compared to the contribution of lead from maternal bone before pregnancy. A 29 to 56% decrease in bone lead mobilization in the first trimester was followed by an increase in the second and third trimesters, up to 44% over baseline levels. In one monkey, the third-trimester increase did not reach baseline levels. In a single low-lead monkey, a similar decrease in the first trimester was followed by a 60% increase in the third trimester, indicating that a similar pattern of flux is seen over a wide range of lead concentrations. Analysis of maternal bone and fetal bone, brain, liver, and kidneys confirmed a substantial transplacental transfer of endogenous lead. Lead concentrations in fetal bone often exceeded maternal bone lead concentrations. From 7 to 39% of the lead in the fetal skeleton originated from the maternal skeleton.

Relationships among blood lead levels, iron deficiency, and cognitive development in two-year-old children.

The goals of this study were to explore the relationship of declining blood lead levels and cognitive development in 42 moderately lead poisoned children around 2 years of age and to investigate the potential interaction between iron and lead levels in the course of development. The cognitive functioning of children was assessed upon enrollment into a comprehensive intervention and 6 months later. The intervention consisted of chelation treatment, if appropriate, iron supplementation, if needed, and steps to eliminate the source of lead in the home environment. The children were referred because of blood lead levels between 25 and 55 mu g/dl; they were also selected on the basis of age between 18 and 30 months. The outcome measures were the global score on a standardized test of cognitive development and subscale scores for perceptual-motor and language functioning. Cognitive change over 6 months was related to an interaction between change in blood lead and initial iron status. Specifically, the change in standardized score (particularly change in perceptual-motor performance) was strongly related to change in blood lead in children who were iron sufficient at the outset: there was an increase of 1.2 points for every 1 mu g/dl decrease in blood lead. There was no such relationship in iron-deficient children. Secondary analyses suggested that 1) the change in cognitive functioning of iron-deficient children was related to change in hemoglobin, and 2) the decline in blood lead was less in iron-deficient than in iron-sufficient children. Thus, when iron is sufficient, changes in blood lead and changes in cognition are inversely related. When iron is deficient, other processes affect the outcome.

Home abatement and blood lead changes in children with class III lead poisoning.

We studied the effect of home abatement on blood lead (PbB) levels in children from central Massachusetts who had not undergone chelation therapy and whose homes were abated between 1987 and 1990, when stricter abatement guidelines were enacted. One hundred and thirty-two children with a mean preabatement PbB of 25.9 micrograms/dL (1.25 mumol/L) were studied: their mean postabatement PbB (up to 1 year later) was 21.1 micrograms/dL (1.02 mumol/L) (P < .001). This reduction correlated with preabatement PbB; 32 of 33 (97%) with preabatement PbB > or = 30 micrograms/dL (> or = 1.45 mumol/L) were lower postabatement, and 64 of 79 (81%) with PbB 20 to 29 micrograms/dL (0.97-1.40 mumol/L) were lower. However, in children with preabatement PbB < 20 micrograms/dL (< 0.97 mumol/L), only seven of 20 (35%) were lower postabatement and, in fact, there was a significant rise in PbB from 16.8 to 19.3 micrograms/dL (0.81 to 0.93 mumol/L) (P = 0.05). Continued improvement in home abatement technology is needed if that strategy is to be effective in achieving the lower PbB levels now mandated in the 1991 Centers for Disease Control guidelines. Primary prevention of the initial blood lead level elevation remains the most desirable strategy.