Faculty Bibliography

The relationship between childhood obesity and aspects of the built environment characterizing neighborhood social context is understudied. This study evaluates the association between 7 built environment domains and childhood obesity in Durham, North Carolina. Measures of housing damage, property disorder, vacancy, nuisances, and territoriality were constructed using data from a 2008 community assessment. Renter-occupied housing and crime measures were developed from public databases. The authors linked these measures to 2008-2009 Duke University Medical Center pediatric preventive care visits. Age- and sex-specific body mass index percentiles were used to classify children as normal weight (>5th and ≤85th percentile), overweight (>85th and ≤95th percentile), or obese (>95th percentile). Ordinal logistic regression models with cluster-corrected standard errors evaluated the association between weight status and the built environment. Adjusting for child-level socioeconomic characteristics, nuisances and crime were associated with childhood overweight/obesity (P < .05). Built environment characteristics appear important to childhood weight status in Durham, North Carolina.

Research on racial residential segregation (RRS) and birth outcomes has focused on RRS at a broad geographic scale, in an aspatial framework, and in northern US cities. We developed a spatial measure of neighborhood level racial isolation of blacks. We examined the association between this new measure and low birthweight, preterm birth, and birthweight in the southern state of North Carolina. Natality data were obtained from the North Carolina Detailed Birth Record 1998-2002 files. Using multiple regression with cluster corrected standard errors, infants born to black and white mothers living in black isolated neighborhoods had, on average, decreased birthweight, and increased odds of low birthweight and preterm birth compared to their counterparts in less isolated areas. White mothers in predominantly black neighborhoods experienced greater increases in odds of each poor birth outcome than did black mothers. Black isolation may be proxying concentrated socioeconomic disadvantage, including disamenities in the built environment.

BACKGROUND:Seasonal variation in poor pregnancy outcomes has not received the same level of research attention and rigor as has the well-established seasonal variation in births. METHODS:In this analysis of data from the 2001-2005 North Carolina Detailed Birth Record, we use season of conception as a proxy for environmental or other risk factors. We model the continuous pregnancy outcome of birth weight percentile for gestational age by use of linear regression. We use logistic regression to model the binary pregnancy outcomes of low birth weight (< 2500 g), preterm birth (< 37 weeks), and small for gestational age (< 10th percentile of birth weight for gestational age). RESULTS:We found significant seasonal patterns in poor pregnancy outcomes. Our results suggest that, in North Carolina, seasonal patterns are most pronounced among non-Hispanic white women living in urban areas. LIMITATIONS/CONCLUSIONS:The present study is limited by the restricted set of maternal and pregnancy variables available in this data set. Richer data, potentially including psychosocial and activity measures of the women, would allow us to more ably discern what is driving the seasonal patterns we observed. The pronounced increased risk associated with a spring season of conception provides an important clue for determining the true causative factors. CONCLUSIONS:Poor pregnancy outcomes in North Carolina follow a clear seasonal pattern based on timing of conception, with patterns most pronounced among non-Hispanic white women living in urban areas. These seasonal patterns are suggestive of causative environmental factors and certainly warrant additional research.

BACKGROUND:Polybrominated diphenyl ethers (PBDEs) are chemical additives used as flame retardants in commercial products. PBDEs are bioaccumulative and persistent and have been linked to several adverse health outcomes. OBJECTIVES/OBJECTIVE:This study leverages an ongoing pregnancy cohort to measure PBDEs and PBDE metabolites in serum collected from an understudied population of pregnant women late in their third trimester. A secondary objective was to determine whether the PBDEs or their metabolites were associated with maternal thyroid hormones. METHODS:One hundred forty pregnant women > 34 weeks into their pregnancy were recruited into this study between 2008 and 2010. Blood samples were collected during a routine prenatal clinic visit. Serum was analyzed for a suite of PBDEs, three phenolic metabolites (i.e., containing an -OH moiety), and five thyroid hormones. RESULTS:PBDEs were detected in all samples and ranged from 3.6 to 694 ng/g lipid. Two hydroxylated BDE congeners (4´-OH-BDE 49 and 6-OH-BDE 47) were detected in > 67% of the samples. BDEs 47, 99, and 100 were significantly and positively associated with free and total thyroxine (T4) levels and with total triiodothyronine levels above the normal range. Associations between T4 and PBDEs remained after controlling for smoking status, maternal age, race, gestational age, and parity. CONCLUSIONS:PBDEs and OH-BDEs are prevalent in this cohort, and levels are similar to those in the general population. Given their long half-lives, PBDEs may be affecting thyroid regulation throughout pregnancy. Further research is warranted to determine mechanisms through which PBDEs affect thyroid hormone levels in developing fetuses and newborn babies.

BACKGROUND:Aviation gasoline, commonly referred to as avgas, is a leaded fuel used in small aircraft. Recent concern about the effects of lead emissions from planes has motivated the U.S. Environmental Protection to consider regulating leaded avgas. OBJECTIVE:In this study we investigated the relationship between lead from avgas and blood lead levels in children living in six counties in North Carolina. METHODS:We used geographic information systems to approximate areas surrounding airports in which lead from avgas may be present in elevated concentrations in air and may also be deposited to soil. We then used regression analysis to examine the relationship between residential proximity to airports and North Carolina blood lead surveillance data in children 9 months to 7 years of age while controlling for factors including age of housing, socioeconomic characteristics, and seasonality. RESULTS:Our results suggest that children living within 500 m of an airport at which planes use leaded avgas have higher blood lead levels than other children. This apparent effect of avgas on blood lead levels was evident also among children living within 1,000 m of airports. The estimated effect on blood lead levels exhibited a monotonically decreasing dose-response pattern, with the largest impact on children living within 500 m. CONCLUSIONS:We estimated a significant association between potential exposure to lead emissions from avgas and blood lead levels in children. Although the estimated increase was not especially large, the results of this study are nonetheless directly relevant to the policy debate surrounding the regulation of leaded avgas.