Blood lead, behaviour and intelligence test performance in preschool children

Harvey, Peter; Hamlin, Mary; Kumar, R.; Delves, H. T.

doi:10.1016/0048-9697(84)90341-3

Cited by 79 publications

(43 citation statements)

References 11 publications

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“…A similar phenomenon has been observed with respect to lead exposure (13)(14)(15). In previous analyses of our cohort, we reported that in the second year of life, children from lower social classes expressed deficit at lower levels of prenatal lead exposure than did children from the highest social class (16).…”

Section: Discussionsupporting

confidence: 50%

“…In our prospective study of lead and cognitive development, children with high umbilical cord blood lead levels (10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25) Ag/dL) achieved significantly lower Mental Development Index scores through 2 years of age than did infants whose cord blood lead levels were low (< 3 ,g/dL) or medium (6-7 jig/dL) (1). In contrast to the results of the infant assessments, cord blood lead level was not significantly related to children's performance on the McCarthy Scales of Children's Abilities at age 57 months (2).…”

Section: Introductionmentioning

confidence: 99%

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Antecedents and Correlates of Improved Cognitive Performance in Children Exposed in Utero to Low Levels of Lead

Bellinger¹,

Leviton²,

Sloman³

1990

Environmental Health Perspectives

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Up to 2 years of age, children with umbilical cord blood lead levels of 10 to 25 4g/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 % standard deviation. Higher prenatal lead exposum 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 sociodemogaphic characteristics.

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Section: Discussionsupporting

confidence: 50%

Section: Introductionmentioning

confidence: 99%

Antecedents and Correlates of Improved Cognitive Performance in Children Exposed in Utero to Low Levels of Lead

Bellinger¹,

Leviton²,

Sloman³

1990

Environmental Health Perspectives

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“…Several early studies reported that a given blood or tooth lead level was associated with neurodevelopmental deficits of greater magnitude or persistence among children from the lower socioeconomic strata (Winneke and Kraemer, 1984;Harvey et al, 1984;Bellinger et al, 1988Bellinger et al, , 1990Tong et al, 2000). For instance, in one prospective study, the dose-effect relationship differed according to SES beginning in the second year of life, when socioeconomic influences on child development are typically first evident.…”

Section: Ses As a Modifier Of The Association Between Lead And Childrmentioning

confidence: 99%

Lead neurotoxicity and socioeconomic status: Conceptual and analytical issues

Bellinger

2008

NeuroToxicology

128

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Socioeconomic status (SES) is usually considered to be a potential confounder of the association between lead exposure and children's neurodevelopment, but experimental and epidemiological data suggest that SES might also modify lead neurotoxicity. The basis of this effect modification is uncertain, but might include differences among SES strata in co-exposures to other neurotoxicants, genetic susceptibilities, environmental enrichment, and stress. The role of SES in the causal nexus is likely to include other dimensions, however. It conveys information about lead exposure opportunities as well as about predictors of child outcome that are correlated with but causally independent of lead. Failure to distinguish these aspects of SES will lead to an underestimate of lead's contribution, and might even result in attributing to SES health effects that should be attributed to lead. Conventional models, which treat SES and SES-related factors solely as potential confounders, do not capture the possibility that a child's early lead exposure alters the behaviors that the child elicits from others. Failure to model lead's contribution to such time-varying covariates will also tend to bias estimates of lead neurotoxicity toward the null. On a transgenerational level, low SES might be a proxy for vulnerability to lead. To estimate the burden of lead-associated neurotoxicity on a population level, we need to apply analytical approaches that model a child's development and its context as a complex system of interdependent relationships that change over time.Socioeconomic status (SES) has played a central role in efforts to characterize the magnitude of the risk that lead poses to children. Because exposure is often greater among children of low SES (Baghurst et al., 1999) and low SES is a powerful predictor of neurodevelopment (Tong et al., 2007), it has long been recognized that due consideration must be given to the possibility that any observed association between lead exposure and neurodevelopment is, in part, an artifact of residual confounding, and thus reflects a Type I error of inference. Indeed, adjusting for SES and related covariates can result in reductions of 50% or more in the magnitude of lead's regression coefficient (e.g., Bellinger et al., 1992). Whether an investigator adequately handled this issue, avoiding a Type I error of inference, became one of the central determinants of whether the inferences drawn from a lead study were viewed as credible.The role of SES in lead studies is likely to be much more complex than that of solely a confounder, however. Two dimensions of this issue are discussed in this paper. The first section summarizes epidemiologic and experimental findings suggesting that SES and SES-related aspects of a child's social environment modify the neurotoxicity of lead such that children of

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“…Los niños que pertenecen a un nivel socioeconómico bajo (los de escuelas pú-blicas) se encuentran en mayor riesgo de tener altas concentraciones de plomo. 19 Autores como Bellinger, 20 Dietrich, 21 Winneke 22 y Schroeder 17 argumentan que, por sí solo, el nivel socioeconómico no explica los niveles de plomo en sangre, sino que influye en la "calidad del cuidado ambiental". Desafortunadamente, los padres de niños de escuelas públicas tienen menos oportunidades para desarrollar habilidades orientadas al cuidado y educación de sus hijos.…”

Section: Discussionunclassified

“…13 Existen estudios donde se indica que los varones pudieran tener mayor sensibilidad a la neurotoxicidad del plomo que las niñas; no obstante, se trata de un resultado que amerita interpretarse con cautela pues no hay evidencias que apoyen esa heterogeneidad biológica. 19 La edad y el grado escolar permiten indagar sobre la "calidad del cuidado ambiental", si bien, tanto los niños de menor y mayor edad se encuentran expuestos a diversas fuentes potenciales de intoxicación por plomo, los niños de los primeros grados están en mayor desventaja que los de grados superiores.…”

Section: Discussionunclassified