Recommended Reference Values for Risk Assessment of Oral Exposure to Copper

The U.S. Environmental Protection Agency's (EPA) Integrated Risk Information System (IRIS) database, the authoritative source of U.S. risk assessment toxicity factors, currently lacks an oral reference dose (RfD) for copper. In the absence of such a value, various health-based reference values for copper are available for use in risk assessment. We summarize the scientific bases and differences in assumptions among key reference values for ingested copper to guide selection of appropriate values for risk assessment. A comprehensive review of the scientific literature best supports the oral RfD of 0.04 mg/kg body weight/day derived by EPA from their Drinking Water Action Level. This value is based on acute gastrointestinal effects but is further supported by broader analysis of copper deficiency and toxicity.     

Changes in Racial Apathy Among White Young Adults: A Five-Year National Panel Study

This study investigates changes in racial apathy among white young adults using nationally representative panel survey data from the NSYR. Our regression models include social background, social values, and academic orientation variables specified as important correlates of racial apathy in prior cross-sectional studies. We also include interracial contact variables, which existing studies neglect. According to intergroup contact theory, interracial contact should predict decreases in racial apathy. We find variables specified as important correlates in prior cross-sectional studies do not explain changes in racial apathy across time. Surprisingly, interracial friendship associates negatively with increases and decreases in racial apathy. Further, interracial dating predicts increases in racial apathy across time. These findings suggest racial apathy may be dissimilar to other forms of white racial prejudice and interracial contact may be an ineffective method to reduce contemporary forms of white racial prejudice.     

There Goes the Neighborhood: How Racial Threat Shapes the Formation of Integrated and Segregated Neighborhoods

Neighborhoods in the United States are highly segregated by race. Black–white segregation is particularly acute. Although racial segregation has been declining in recent years, it remains extremely high—especially in the largest metropolitan areas. The historical pattern has been that as African Americans move into a neighborhood, whites move out and thus the neighborhood (gradually or rapidly) transitions from predominantly white to predominantly black. A seemingly contradictory pattern has recently been observed: integrated neighborhoods are becoming more common. Why do some neighborhoods transition from white to black and others become integrated? We use racial competition theory to answer this question. We examine the characteristics of stable, integrated neighborhoods and contrast them with segregated predominantly white, predominantly black, and rapidly transitioning neighborhoods in six large metropolitan areas. We find that the location of black neighborhoods is a key factor in whether an integrated neighborhood remains integrated. Specifically, we find integrated neighborhoods are spatially distant from majority black neighborhoods while transitioning neighborhoods are adjacent to them. Our findings support the “sense of threat” hypothesis of racial competition theory.