Environmental inequality and disparities in school readiness: The role of neurotoxic lead.

Developmental science has increasingly scrutinized how environmental hazards influence child outcomes, but few studies examine how contaminants affect disparities in early skill formation. Linking research on environmental inequality and early childhood development, this study assessed whether differences in exposure to neurotoxic lead explain sociodemographic gaps in school readiness. Using panel data tracking a representative sample of 1266 Chicago children (50% female, 16% White, 30% Black, 49% Hispanic, µage = 5.2 months at baseline, collected 1994-2002), analyses quantified the contribution of lead contamination to class and racial disparities in vocabulary skills and attention problems at ages 4 and 5. Results suggested that lead contamination explains 15%-25% and 33%-66% of the disparities in each outcome, respectively, although imprecise estimates preclude drawing firm inferences about attention problems.

Concentrated poverty, ambient air pollution, and child cognitive development.

Why does growing up in a poor neighborhood impede cognitive development? Although a large volume of evidence indicates that neighborhood poverty negatively affects child outcomes, little is known about the mechanisms that might explain these effects. In this study, we outline and test a theoretical model of neighborhood effects on cognitive development that highlights the mediating role of early life exposure to neurotoxic air pollution. To evaluate this model, we analyze data from a national sample of American infants matched with information on their exposure to more than 50 different pollutants known or suspected to harm the central nervous system. Integrating methods of causal inference with supervised machine learning, we find that living in a high-poverty neighborhood increases exposure to many different air toxics during infancy, that it reduces cognitive abilities measured later at age 4 by about one-tenth of a standard deviation, and that about one-third of this effect can be attributed to disparities in air quality.

Toxic Neighborhoods: The Effects of Concentrated Poverty and Environmental Lead Contamination on Early Childhood Development.

Although socioeconomic disparities in cognitive ability emerge early in the life course, most research on the consequences of living in a disadvantaged neighborhood has focused on school-age children or adolescents. In this study, we outline and test a theoretical model of neighborhood effects on cognitive development during early childhood that highlights the mediating role of exposure to neurotoxic lead. To evaluate this model, we follow 1,266 children in Chicago from birth through school entry and track both their areal risk of lead exposure and their neighborhoods' socioeconomic composition over time. With these data, we estimate the joint effects of neighborhood poverty and environmental lead contamination on receptive vocabulary ability. We find that sustained exposure to disadvantaged neighborhoods reduces vocabulary skills during early childhood and that this effect operates through a causal mechanism involving lead contamination.

Effect Decomposition in the Presence of Treatment-induced Confounding: A Regression-with-residuals Approach.

Analyses of causal mediation are often complicated by treatment-induced confounders of the mediator-outcome relationship. In the presence of such confounders, the natural direct and indirect effects of treatment on the outcome, into which the total effect can be additively decomposed, are not identified. An alternative but similar set of effects, known as randomized intervention analogues to the natural direct effect (rNDE) and the natural indirect effect (rNIE), can still be identified in this situation, but existing estimators for these effects require a complicated weighting procedure that is difficult to use in practice. We introduce a new method for estimating the rNDE and rNIE that involves only a minor adaptation of the comparatively simple regression methods used to perform effect decomposition in the absence of treatment-induced confounding. It involves fitting (a) a generalized linear model for the conditional mean of the mediator given treatment and a set of baseline confounders and (b) a linear model for the conditional mean of the outcome given the treatment, mediator, baseline confounders, and a set of treatment-induced confounders that have been residualized with respect to the observed past. The rNDE and rNIE are simple functions of the parameters in these models when they are correctly specified and when there are no unobserved variables that confound the treatment-outcome, treatment-mediator, or mediator-outcome relationships. We illustrate the method by decomposing the effect of education on depression at midlife into components operating through income versus alternative factors. R and Stata packages are available for implementing the proposed method.

Neighborhoods, Schools, and Academic Achievement: A Formal Mediation Analysis of Contextual Effects on Reading and Mathematics Abilities.

Although evidence indicates that neighborhoods affect educational outcomes, relatively little research has explored the mechanisms thought to mediate these effects. This study investigates whether school poverty mediates the effect of neighborhood context on academic achievement. Specifically, it uses longitudinal data from the Panel Study of Income Dynamics, counterfactual methods, and a value-added modeling strategy to estimate the total, natural direct, and natural indirect effects of exposure to an advantaged rather than disadvantaged neighborhood on reading and mathematics abilities during childhood and adolescence. Contrary to expectations, results indicate that school poverty is not a significant mediator of neighborhood effects during either developmental period. Although moving from a disadvantaged neighborhood to an advantaged neighborhood is estimated to substantially reduce subsequent exposure to school poverty and improve academic achievement, school poverty does not play an important mediating role because even the large differences in school composition linked to differences in neighborhood context appear to have no appreciable effect on achievement. An extensive battery of sensitivity analyses indicates that these results are highly robust to unobserved confounding, alternative model specifications, alternative measures of school context, and measurement error, which suggests that neighborhood effects on academic achievement are largely due to mediating factors unrelated to school poverty.

Estimating Moderated Causal Effects with Time-varying Treatments and Time-varying Moderators: Structural Nested Mean Models and Regression with Residuals.

Individuals differ in how they respond to a particular treatment or exposure, and social scientists are often interested in understanding how treatment effects are moderated by observed characteristics of individuals. Effect moderation occurs when individual covariates dampen or amplify the effect of some exposure. This article focuses on estimating moderated causal effects in longitudinal settings where both the treatment and effect moderator vary over time. Effect moderation is typically examined using covariate by treatment interactions in regression analyses, but in the longitudinal setting, this approach may be problematic because time-varying moderators of future treatment may be affected by prior treatment-for example, moderators may also be mediators-and naively conditioning on an outcome of treatment in a conventional regression model can lead to bias. This article introduces to sociology moderated intermediate causal effects and the structural nested mean model for analyzing effect moderation in the longitudinal setting. It discusses problems with conventional regression and presents a new approach to estimation that avoids these problems (regression-with-residuals). The method is illustrated using longitudinal data from the PSID to examine whether the effects of time-varying exposures to poor neighborhoods on the risk of adolescent childbearing are moderated by time-varying family income.

Are Smart People Less Racist? Verbal Ability, Anti-Black Prejudice, and the Principle-Policy Paradox.

It is commonly hypothesized that higher cognitive abilities promote racial tolerance and a greater commitment to racial equality, but an alternative theoretical framework contends that higher cognitive abilities merely enable members of a dominant racial group to articulate a more refined legitimizing ideology for racial inequality. According to this perspective, ideological refinement occurs in response to shifting patterns of racial conflict and is characterized by rejection of overt prejudice, superficial support for racial equality in principle, and opposition to policies that challenge the dominant group's status. This study estimates the impact of verbal ability on a comprehensive set of racial attitudes, including anti-black prejudice, views about black-white equality in principle, and racial policy support. It also investigates cohort differences in the effects of verbal ability on these attitudes. Results suggest that high-ability whites are less likely than low-ability whites to report prejudicial attitudes and more likely to support racial equality in principle. Despite these liberalizing effects, high-ability whites are no more likely to support a variety of remedial policies for racial inequality. Results also suggest that the ostensibly liberalizing effects of verbal ability on anti-black prejudice and views about racial equality in principle emerged slowly over time, consistent with ideological refinement theory.

Social Class and Income Inequality in the United States: Ownership, Authority, and Personal Income Distribution from 1980 to 2010.

This study outlines a theory of social class based on workplace ownership and authority relations, and it investigates the link between social class and growth in personal income inequality since the 1980s. Inequality trends are governed by changes in between-class income differences, changes in the relative size of different classes, and changes in within-class income dispersion. Data from the General Social Survey are used to investigate each of these changes in turn and to evaluate their impact on growth in inequality at the population level. Results indicate that between-class income differences grew by about 60% since the 1980s and that the relative size of different classes remained fairly stable. A formal decomposition analysis indicates that changes in the relative size of different social classes had a small dampening effect and that growth in between-class income differences had a large inflationary effect on trends in personal income inequality.

Neighborhood Effect Heterogeneity by Family Income and Developmental Period.

Effects of disadvantaged neighborhoods on child educational outcomes likely depend on a family's economic resources and the timing of neighborhood exposures during the course of child development. This study investigates how timing of exposure to disadvantaged neighborhoods during childhood versus adolescence affects high school graduation and whether these effects vary across families with different income levels. It follows 6,137 children in the PSID from childhood through adolescence and overcomes methodological problems associated with the joint endogeneity of neighborhood context and family income by adapting novel counterfactual methods--a structural nested mean model estimated via two-stage regression with residuals--for time-varying treatments and time-varying effect moderators. Results indicate that exposure to disadvantaged neighborhoods, particularly during adolescence, has a strong negative effect on high school graduation and that this negative effect is more severe for children from poor families.

CONTINUITY AND CHANGE IN THE AMERICAN CLASS STRUCTURE: WORKPLACE OWNERSHIP AND AUTHORITY RELATIONS FROM 1972 TO 2010.

This study investigates changes in the American class structure-defined in terms of workplace ownership and authority relations-and trends in status group disparities in class attainment from 1972 to 2010. Although theory and prior research suggest a variety of appreciable changes in class structure and class attainment, data from the General Social Survey indicate that the sizes of different classes remained fairly stable during this time period and that status group disparities in access to ownership and authority persisted largely intact. The 1970s witnessed a decline in the proportion of workers and growth in the proportion of managers and proprietors, but these trends reversed in the 1980s. As a result, by the late 2000s, the ownership and authority structure of the U.S. economy closely resembled that of the early 1970s. Racial and gender disparities in class attainment also did not change significantly over time: blacks and women remained underrepresented (relative to whites and men) in positions of ownership and authority throughout this period. Even after controlling for an extensive set of human capital characteristics, family constraints, and structural economic factors, there is little evidence of status group integration across these key dimensions of economic power.

Duration and timing of exposure to neighborhood poverty and the risk of adolescent parenthood.

Theory suggests that the impact of neighborhood poverty depends on both the duration and timing of exposure. Previous research, however, has not properly analyzed the sequence of neighborhoods to which children are exposed throughout the early life course. This study investigates the effects of different longitudinal patterns of exposure to disadvantaged neighborhoods on the risk of adolescent parenthood. It follows a cohort of children in the PSID from age 4 to 19 and uses novel methods for time-varying exposures that overcome critical limitations of conventional regression when selection processes are dynamic. Results indicate that sustained exposure to poor neighborhoods substantially increases the risk of becoming a teen parent and that exposure to neighborhood poverty during adolescence may be more consequential than exposure earlier during childhood.

The Impact of Education on Inter-Group Attitudes: A Multiracial Analysis.

How does education affect racial attitudes? Past studies focus almost exclusively on Whites' attitudes toward Blacks, neglecting important minority populations. This study extends previous research by analyzing the effects of education on beliefs about racial stereotypes, discrimination, and affirmative action policies among Whites, Asians, Hispanics, and Blacks. Results indicate that Whites, Hispanics, and Blacks with higher levels of education are more likely to reject negative stereotypes, but these effects are less consistent among Asians. And, although education has consistent positive effects on awareness of discrimination against minorities, a more advanced education is not associated with greater support for racial preferences among any respondent group. Education is, however, related to more favorable attitudes toward race-targeted job training. These results are partly consistent with a revised group conflict perspective positing that education unevenly promotes different elements of the dominant racial ideology among nonwhite minorities, depending on their position in the racial hierarchy.

Neighborhood Effects in Temporal Perspective.

Theory suggests that neighborhood effects depend not only on where individuals live today, but also on where they lived in the past. Previous research, however, usually measured neighborhood context only once and did not account for length of residence, thereby understating the detrimental effects of long-term neighborhood disadvantage. This study investigates the effects of duration of exposure to disadvantaged neighborhoods on high school graduation. It follows 4,154 children in the PSID, measuring neighborhood context once per year from age 1 to 17. The analysis overcomes the problem of dynamic neighborhood selection by adapting novel methods of causal inference for time-varying treatments. In contrast to previous analyses, these methods do not "control away" the effect of neighborhood context operating indirectly through time-varying characteristics of the family, and thus they capture the full impact of a lifetime of neighborhood disadvantage. We find that sustained exposure to disadvantaged neighborhoods has a severe impact on high school graduation that is considerably larger than effects reported in prior research. Growing up in the most (compared to the least) disadvantaged quintile of neighborhoods is estimated to reduce the probability of graduation from 96% to 76% for black children, and from 95% to 87% for nonblack children.