Neuropsychological effects of lead in children: interactions with social background variables.
ABSTRACT Following a short and selective summary of findings from psychological studies on lead-induced cognitive dysfunction in man, our own studies in lead-exposed children are briefly described in more detail. These studies, run in the cities of Duisburg and Stolberg, were based on tooth lead levels as the principal indicator of long-term cumulative lead exposure. From a comprehensive sample of neuropsychological outcome measures, only few significant findings emerged, namely lead-related deficits of visual-motor integration and of reaction performance, but not of general intelligence. Without exception, the observed lead effects were small compared to those of social background. An interesting interaction was found between lead exposure and social background for visual-motor integration and for reaction performance: for both these measures, but not for intelligence, the degree of association between performance deficit and lead exposure was more pronounced in socially disadvantaged children than in those from a more middle-class background. This finding was tentatively discussed within a transactional model of development. The common practice of simply controlling the effects of confounding social factors by analysis of covariance or related techniques appears doubtful in this context.
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ABSTRACT: In order to establish safe exposure levels to toxic chemicals, risk assessment guidelines have been developed. These guidelines evaluate epidemiologic and animal research data on a particular chemical, as well as dose-response relationships, animal to human extrapolation and assessment of exposure levels of populations. Using the guidelines, risk characterization is established in order to determine a strategy for reducing undesirable risk to human populations. Using both human neonatal lead exposure data and results from rodent and primate studies, this review examines the possibility that behavioral measurements are sufficient to provide adequate risk assessment guidelines for lead intoxication of the developing organism. The overall trend in these data during the past 10 years has been to show that exposures to inorganic lead at levels previously considered safe have long-lasting significant alterations in behavioral measures, suggesting that central nervous system function has been altered irreversibly. The conclusion is drawn that behavioral toxicology can provide sensitive, quantitative and reliable data for risk assessment and that in the future these methodologies could be used to set exposure guidelines for other neurotoxic chemicals.Neurotoxicology and Teratology 09/1990; 12(5):547–551. · 3.22 Impact Factor
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ABSTRACT: BACKGROUND:Airborne polycyclic aromatic hydrocarbons (PAHs) are pollutants generated by combustion of fossil fuel and other organic material. Both prenatal PAH exposure and maternal psychological distress during pregnancy have each been associated with neurodevelopmental problems in children. The goal was to evaluate potential interactions between prenatal exposure to airborne PAHs and maternal psychological distress during pregnancy on subsequent behavioral problems in children.METHODS:In a longitudinal birth cohort study, 248 children of nonsmoking white women in the coal-burning region of Krakow, Poland, were followed from in utero until age 9. Prenatal PAH exposure was measured by personal air monitoring during pregnancy, maternal demoralization during pregnancy by the Psychiatric Epidemiology Research Instrument-Demoralization, and child behavior by the Child Behavior Checklist.RESULTS:Significant interactions between maternal demoralization and PAH exposure (high versus low) were identified for symptoms of anxious/depressed, withdrawn/depressed, social problems, aggressive behavior, internalizing problems, and externalizing problems. The effects of demoralization on syndromes of anxious/depressed, withdrawn/depressed, rule-breaking, aggressive behavior, and the composite internalizing and externalizing scores were seen only in conjunction with high PAH exposure. Fewer significant effects with weaker effect sizes were observed in the low-PAH-exposure group.CONCLUSIONS:Maternal demoralization during pregnancy appears to have a greater effect on child neurobehavioral development among children who experienced high prenatal PAH exposure. The results provide the first evidence of an interaction between prenatal exposure to maternal demoralization and air pollution on child neurobehavioral development, indicating the need for a multifaceted approach to the prevention of developmental problems in children.PEDIATRICS 10/2013; · 5.30 Impact Factor
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ABSTRACT: Controversy over lead's effect on children's cognition rests in part on the assumption that if such an effect exists it can be characterized by a single estimator (e.g., the same rate of decline in IQ with increasing exposure, the same neuropsychological presentation), which will be found by any study that is valid. Accordingly, efforts to resolve inconsistencies in study findings have focused almost exclusively on data analytic issues germane to bias, in particular confounding and its statistical control. Relatively little consideration has been given to the role of effect modification i.e., the impact on effect estimation of differences in the “experimental systems” employed in human epidemiological studies. Lack of consistency in findings could be due to differences among study cohorts in exposure/ toxicokinetic factors (e.g., dose, timing), differences in environmental characteristics (e.g., co-exposures, co-morbidity, developmental supports, assessment setting), or differences in the distribution of genetic characteristics that affect lead metabolism. Recent findings regarding lead's impact on the development of nervous system structure and function are consistent with the hypothesis that contextual factors affect the form in which lead toxicity is expressed and may contribute to the failure to date to identify a lead-associated “behavioral signature.” Characterizing the neuropsychological effects of lead might be facilitated by greater use of a clinical “process” approach to assessment, which would permit the type of fine-grained analyses of lead-associated performance differences often employed in studies of behavioral toxicity in animal models.Neurotoxicology and Teratology 06/1995; 17(3):201–212. · 3.22 Impact Factor