Search PubMed⌕ Search

Biomedical subjects

D Bellinger

Publications and source records attributed to D Bellinger.

At least 37 records · Page 2Linked to original sources
PubMed1994

The impact of soil lead abatement on urban children's blood lead levels: phase II results from the Boston Lead-In-Soil Demonstration Project.

The Boston Lead-In-Soil Demonstration Project was a randomized environmental intervention study of the impact of urban soil lead abatement on children's blood lead levels. Lead-contaminated soil abatement was associated with a modest reduction in children's blood lead levels in both phases of the project; however, the reduction in Phase II was somewhat greater than that in Phase I. The combined results from both phases suggest that a soil lead reduction of 2060 ppm is associated with a 2.25 to 2.70 micrograms/dl decline in blood lead levels. Low levels of soil recontamination 1 to 2 years following abatement indicate that the intervention is persistent, at least over the short-term. Furthermore, the intervention appears to benefit most children since no measurable differences in efficacy were observed for starting blood and soil lead level, race, neighborhood, gender, and many other characteristics. However, soil abatement did appear to be more beneficial to children in the higher socioeconomic classes, with low baseline ferritin levels, and who spent time away from home on a regular basis and lived in nonowner occupied housing, and with adults who had lead-related hobbies and almost always washed their hands before meals. Children who lived in apartments with consistently elevated floor dust lead loading levels derived almost no benefit from the soil abatement. It was not possible to separate the effects of the variables that had a beneficial impact on efficacy because they were closely correlated and the number of subjects was small. We recommend that further research be conducted to identify subgroups of children to whom soil lead abatement might be targeted.

Boston↗
PubMed1993

Lead-contaminated soil abatement and urban children's blood lead levels.

OBJECTIVE: To test the hypothesis that a reduction of 1000 ppm or more of lead in soil accessible to children would result in a decrease of at least 0.14 mumol/L (3 micrograms/dL) in blood lead levels. SETTING: Urban neighborhoods with a high incidence of childhood lead poisoning and high soil lead levels. DESIGN: Randomized controlled trial of the effects of lead-contaminated soil abatement on blood lead levels of children followed up for approximately 1 year after the intervention. PATIENTS: A total of 152 children less than 4 years of age with venous blood lead levels of 0.34 to 1.16 mumol/L (7 to 24 micrograms/dL). Children were largely poor and had a mean age at baseline of 32 months, a mean blood lead level of 0.60 mumol/L (12.5 micrograms/dL), and a median surface soil lead level of 2075 ppm. INTERVENTIONS: Children were randomized to one of three groups: the study group, whose homes received soil and interior dust abatement and loose paint removal; comparison group A, whose homes received interior dust abatement and loose paint removal; and comparison group B, whose homes received only interior loose paint removal. MAIN OUTCOME MEASURES: Change in children's blood lead levels from preabatement levels to levels approximately 6 and 11 months after abatement. RESULTS: The mean decline in blood lead level between preabatement and 11 months after abatement was 0.12 mumol/L (2.44 micrograms/dL) in the study group (P = .001), 0.04 mumol/L (0.91 microgram/dL) in group A (P = .04), and 0.02 mumol/L (0.52 microgram/mL) in group B (P = .31). The mean blood lead level of the study group declined 0.07 mumol/L (1.53 micrograms/dL) more than that of group A (95% confidence interval [CI], -0.14 to -0.01 mumol/L [-2.87 to -0.19 micrograms/dL]) and 0.09 mumol/L (1.92 micrograms/dL) more than group B (95% CI, -0.16 to -0.03 mumol/L [-3.28 to -0.56 micrograms/dL]). When adjusted for preabatement lead level, the 11-month mean blood lead level was 0.06 mumol/L (1.28 micrograms/dL) lower in the study group as compared with group A (P = .02) and 0.07 mumol/L (1.49 micrograms/dL) lower than in group B (P = .01). The magnitude of the decline independently associated with soil abatement ranged from 0.04 to 0.08 mumol/L (0.8 to 1.6 micrograms/dL) when the impact of potential confounders, such as water, dust, and paint lead levels, children's mouthing behaviors, and other characteristics, was controlled for. CONCLUSIONS: These results demonstrate that lead-contaminated soil contributes to the lead burden of urban children and that abatement of lead-contaminated soil around homes results in a modest decline in blood lead levels. The magnitude of reduction in blood lead level observed, however, suggests that lead-contaminated soil abatement is not likely to be a useful clinical intervention for the majority of urban children in the United States with low-level lead exposure.

Child, Preschool↗
PubMed1993

Pre- and postnatal low-level lead exposure and children's dysfunction in school.

The contributions of pre- and postnatal low-level lead exposures to the risk of learning problems were evaluated among 1923 children who were born in one Boston hospital in 1979-1980 and followed to age 8 years. In this relatively privileged group, more than 20% of the children had a mother with some formal postgraduate education. Prenatal lead exposure was estimated with a measurement of umbilical cord blood lead content, and postnatal lead exposure was approximated with measurement of lead in the dentin of an exfoliated deciduous tooth. Information about potential confounders and effect modifiers was obtained from maternal interview shortly after delivery and from a mailed questionnaire completed and returned when the child was approximately 6 years old. An assessment of each child's function in school was provided by the teacher, who completed a questionnaire near the end of the school year in which the child reached the age of 8 years. We considered a learning problem to be related to lead exposure if its adjusted prevalence increased with each loge increase in lead, and if the adjusted prevalence was elevated among children with high levels (i.e., approximating the highest decile) of umbilical cord blood lead (i.e., > or = 10 micrograms/dl) or dentin lead (i.e., > or = 5 micrograms/g). Girls with elevated umbilical cord blood lead levels were more likely than their peers to be dependent and inpersistent and to display an inflexible and inappropriate approach to tasks (defined as the "tasks" cluster). Boys with elevated umbilical cord blood lead levels were more likely than others to have difficulty with both simple directions and sequences of directions. Among girls, elevated deciduous tooth dentin lead content was associated with reading and spelling difficulties, the tasks cluster, and with "not functioning as well as peers." Elevated dentin lead levels were not overrepresented among boys with any of the assessed learning clusters. These findings are consistent with the inference that lead levels still prevalent among children (i.e., blood < 15 micrograms/dl) are associated with some learning problems in girls.

Child↗
PubMed1993

Relationships between serial blood lead levels and exfoliated tooth dentin lead levels: models of tooth lead kinetics.

Because bones and permanent teeth accumulate lead, exfoliated deciduous teeth have been utilized as retrospective markers of cumulative exposure in epidemiological surveys. In this paper we describe four models of lead uptake by the coronal dentin of shed primary teeth, each with different assumptions and ramifications. Each model is characterized by different relationships between blood lead at several ages and tooth lead. Values observed in our cohort of normal Boston children are most compatible with models positing the largest lead contribution coming at older ages (i.e., closer to age at exfoliation). Characteristics of models incompatible with our data include (1) lead deposition only during initial calcification and (2) no loss or resorption of lead.

Dentin↗
PubMed1993

Cell proliferation in breast carcinoma assessed by a PCNA grading system and its relation to other prognostic variables.

This study was undertaken to relate the expression of the proliferating cell nuclear antigen (PCNA), a proliferation marker of putative prognostic significance, to some more established prognostic factors in a series of 60 consecutive breast cancer surgical specimens. PCNA was detected by the PC10 monoclonal antibody (MAb) using an immunohistochemical method and PCNA immunostaining was estimated on a semiquantitative basis, a cut-off value of 50% of positively stained tumour cells discriminating between the high (> 50%) and low (< 50%) PCNA grade. The PCNA grade did not correlate with tumour size and axillary node status. However, a high PCNA grade tended to be associated with a poor histological grade and there was an inverse relationship with oestrogen-receptor status, as determined by means of the immuno-histochemical staining for the oestrogen-induced pS2 protein. These conflicting results suggest that the possible prognostic usefulness of PCNA immunostaining, as a measure of cell proliferation rate, in breast cancer is yet to be demonstrated and can be validated only by direct relation to survival data.

Adenocarcinoma, Mucinous↗
PubMed1993

The Boston Teacher Questionnaire. 3. A reassessment.

The prevalence of different types of dysfunction in school was assessed with the Boston Teacher Questionnaire, completed for 1923 children born 8 years earlier in a university-affiliated maternity hospital. Cluster analyses of 15 items on the questionnaire resulted in six two-item clusters and one three-item cluster that were identical for girls and boys. We identified children as having a syndrome if they possessed all features of the cluster-defined syndrome. The most prevalent syndrome, consisting of both daydreaming and distractibility items, occurred in 18.5% of boys and 11.5% of girls. Boys were also more likely than girls to be identified as having the reading syndrome (11.6% and 7.7%, respectively), the hyperactivity/impulsivity syndrome (6.1% and 1.5%), and the syndrome characterized by frustration intolerance and peer problems (9.5% and 4.0%). The prevalences of the remaining three syndromes were similar in both sexes (arithmetic, 11.3% and 10.3%; difficulty following instructions, 5.1% and 4.7%; and the tasks syndrome [characterized by impersistence/dependence/inflexibility], 5.5% and 5.4%). More than 40% of boys and girls with one syndrome also had another. The lower prevalences in this sample than in an earlier-born sample assessed with the same instrument were confined to boys. Reasons for this temporal decrease in one sex only remain obscure. Girls with the reading syndrome were 10 times more likely, and boys with the reading syndrome were five times more likely, than their peers to receive special services and to have repeated a grade.

Attention Deficit Disorder with Hyperactivity↗
PubMed1992

Pre-natal blood lead levels and learning difficulties in children: an analysis of non-randomly missing categorical data.

This paper presents an analysis of categorical variables subject to non-response. We incorporate the incomplete data into the analysis by modelling the distribution of the variables of interest and the non-response mechanism. We discuss issues of model selection and interpretation and the effect of discarding incomplete observations. In addition, we describe how to perform all of the computations with standard statistical software. We discuss the problem of incomplete categorical data within the context of a study of the effect of lead exposure on learning difficulties in children. In this study, many of the children are not observed on some of the variables of interest. It is particularly important in this study to incorporate the incomplete data, since there is evidence that non-response is related to the variables of interest. We reach different conclusions when we incorporate the incomplete data into the analysis than we reach when we discard the incomplete data. We also examine the sensitivity of our conclusions to the choice of a model for the non-response mechanism.

Algorithms↗
PubMed1991

Lead correction.

Explore the source record for details and available documents.

Environmental Exposure↗
PubMed1991

Weight gain and maturity in fetuses exposed to low levels of lead.

The relationship between prenatal low-level lead exposure and fetal growth was evaluated in a sample of 4354 pregnancies in which the mean umbilical cord blood lead level was 7.0 micrograms/dl (SD = 3.3; 10th percentile, 3.4 micrograms/dl, 90th percentile, 10.9 micrograms/dl). Higher cord blood lead levels were significantly associated with gestations of slightly longer duration. Comparing infants with cord blood lead levels greater than or equal to 15 micrograms/dl to those with levels less than 5 micrograms/dl, adjusted risk ratios of 1.5 to 2.5 were observed for low birth weight (less than 2500 g) and for fetal growth indices that express birth weight as a function of length of gestation (e.g., small-for-gestational age, intrauterine growth retardation). The 95% confidence intervals of these risk ratios included 1, however, precluding rejection of the null hypothesis of no association. We conclude that the risk of adverse fetal growth is not increased at cord blood lead levels less than 15 micrograms/dl but that modest increases in risk may be associated with levels greater than or equal to 15 micrograms/dl.

Body Weight↗
PubMed1991

Low-level lead exposure and children's cognitive function in the preschool years.

In a cohort of 170 middle and upper-middle class children participating in a prospective study of child development and low-level lead exposure, higher blood lead levels at age 24 months were associated with lower scores at age 57 months on the McCarthy Scales of Children's Abilities. The mean blood lead level at age 24 months was 6.8 micrograms/dL (SD = 6.3; 75th, 90th, and 99th percentiles: 8.8, 13.7, 23.6, respectively) and for all but 1 child was less than 25 micrograms/dL, the current definition of an "elevated" level. After adjustment for confounding, scores on the General Cognitive Index decreased approximately 3 points (SE = 1.4) for each natural log unit increase in 24-month blood lead level. The inverse association between lead level and performance was especially prominent for visual-spatial and visual-motor integration skills. Higher prenatal exposures were not associated with lower scores at 57 months except in the subgroup of children with "high" concurrent blood lead levels (ie, greater than or equal to 10 micrograms/dL). The concentration of lead in the dentine of shed deciduous teeth was not significantly associated with children's performance after adjustment for confounding.

Age Factors↗
PubMed1990

The long-term effects of exposure to low doses of lead in childhood. An 11-year follow-up report.

To determine whether the effects of low-level lead exposure persist, we reexamined 132 of 270 young adults who had initially been studied as primary school-children in 1975 through 1978. In the earlier study, neurobehavioral functioning was found to be inversely related to dentin lead levels. As compared with those we restudied, the other 138 subjects had had somewhat higher lead levels on earlier analysis, as well as significantly lower IQ scores and poorer teachers' ratings of classroom behavior. When the 132 subjects were reexamined in 1988, impairment in neurobehavioral function was still found to be related to the lead content of teeth shed at the ages of six and seven. The young people with dentin lead levels greater than 20 ppm had a markedly higher risk of dropping out of high school (adjusted odds ratio, 7.4; 95 percent confidence interval, 1.4 to 40.7) and of having a reading disability (odds ratio, 5.8; 95 percent confidence interval, 1.7 to 19.7) as compared with those with dentin lead levels less than 10 ppm. Higher lead levels in childhood were also significantly associated with lower class standing in high school, increased absenteeism, lower vocabulary and grammatical-reasoning scores, poorer hand-eye coordination, longer reaction times, and slower finger tapping. No significant associations were found with the results of 10 other tests of neurobehavioral functioning. Lead levels were inversely related to self-reports of minor delinquent activity. We conclude that exposure to lead in childhood is associated with deficits in central nervous system functioning that persist into young adulthood.

Adolescent↗
PubMed1990

Antecedents and correlates of improved cognitive performance in children exposed in utero to low levels of lead.

Up to 2 years of age, children with umbilical cord blood lead levels of 10 to 25 micrograms/dL achieve significantly lower scores on tests of cognitive development than do children with lower prenatal exposures. By age 5 years, however, they appear to have recovered from, or at least compensated for, this early insult. Change in performance between 24 and 57 months of age was examined in relation to level of postnatal lead exposure and various sociodemographic factors. Among children with high prenatal lead exposure, greater recovery of function was associated with lower blood level at 57 months, higher socioeconomic status, higher Home Observation for Measurement of the Environment scores, higher maternal IQ, and female gender. The difference between the scores at 57 months of children with optimal and less optimal values on these variables generally exceed 1/2 standard deviation. Higher prenatal lead exposure is associated with an increased risk of early cognitive deficit. Furthermore, the risk that a deficit will persist through the preschool years is increased among children with high prenatal exposure and either high postnatal exposure or less optimal sociodemographic characteristics.

Age Factors↗
PubMed1989

Lead, IQ and social class.

Social class (SC) conveys information about a child's potential lead exposure (PB) as well as other, independent determinants of cognition (IQ). Thus, depending on the way in which SC is handled in statistical analyses, the PB-IQ association may be either 'overadjusted' or 'underadjusted' for SC. Two assumptions that underlie the inclusion of SC in correlation/regression analyses of the PB-IQ relationship are: 1) SC is an interval scale and 2) the PB-IQ relationship is homogeneous in all social strata. Simulation analyses are presented to illustrate the impact that different values of the bivariate correlations PB-SC, IQ-SC, and PB-IQ have on the estimate of the PB-IQ adjusted for SC. Alternative approaches to addressing these issues are discussed.

Child↗