Characteristics of Solid Waste Facilities
Permit records were reviewed and electronically recorded for 536 facilities. Ninety-three facilities were excluded because they were not classified as an eligible facility type; 24 other facilities were excluded because they received a permit to operate after the end of the study period (n = 8) or because they had not been constructed by the end of the study period (n = 16). Therefore, 419 solid waste facilities were eligible to be included in the study.
The number, type, operation status, permit period, and owner/operator of these 419 solid waste facilities are provided in Table 1 . MSWLs comprise the largest solid waste facility category (48%), followed by TRANSFERs (22%), CDLFs (18%), INDUSLFs (12%), and TIRELFs (1%). There were 194 facilities open to accept waste for disposal or transfer on 31 December 2003. TRANSFERs had the largest proportion of open facilities (86%), followed by CDLFs (84%), TIRELFs (67%), INDUSLFs (21%), and MSWLs (20%). Permits were issued to 207 solid waste facilities to construct and/or operate after 1 January 1990. TRANSFERs comprise the largest category of solid waste facilities issued permits during this period (42%) followed by CDLFs (35%), MSWLs (19%), INDUSLFs (3%), and TIRELFs (< 1%).
MSWLs were widely distributed in North Carolina, located in 97 of 100 counties; 251 block groups (4.8%) contained at least one solid waste facility. MSWLs were present in 3.2% of block groups, TRANSFERs in 1.6%, CDLFs in 1.4%, and INDUSLFs in 0.8%.
Race and Wealth of Block Groups
The spatial distribution of race in 2000 is shown in Figure 1. The highest percentages of populations of color, primarily African Americans, are in the Coastal Plain and in the large Piedmont cities of Charlotte, Winston-Salem, Greensboro, Durham, and Raleigh. In the Mountain region, many American Indians reside on and near the Cherokee Indian Reservation in Swain and Jackson Counties. The population of Robeson County, at the southern border of the Coastal Plain, is roughly evenly divided between African American, American Indian, and white.
The spatial distribution of house values is shown in Figure 2. Housing values are highest in the Piedmont, with notably high values in some areas of the Mountain and Tidewater regions. The lowest housing values are in the Coastal Plain.
We quantified relationships of race and house value with solid waste facility locations, with adjustment for other predictors of facility location. The presence of one or more permitted solid waste facilities in 2003 showed a strong inverse relationship with population density. This was modeled using a cubic polynomial for the natural log of population density (the likelihood ratio test for addition of these terms to an intercept-only logistic model was 190.9; 2 degrees of freedom). Additional polynomial terms did not contribute substantially to model fit. The prevalence of any solid waste facility was highest in the Tidewater region (8.4% of 513 block groups), followed by the Mountain region (6.5% of 835 block groups), Coastal Plain (4.4% of 1,087 block groups), and the Piedmont (3.8% of 2,826 block groups). Compared with the Piedmont, the prevalence odds of any solid waste facility, adjusted for population density, were 1.8 (95% CI, 1.2-2.7) times higher in the Tidewater region. Adjusted PORs were slightly higher for the Mountain region (POR = 1.1; 95% CI, 0.8-1.6) and slightly lower for the Coastal Plain (POR = 0.9; 95% CI, 0.6-1.2), compared with the Piedmont. After adjustment for population density, distances from urban areas and major roads were not associated with prevalence of solid waste facilities. These variables did not affect estimated relationships of waste facility locations with race and house value and therefore were not included in subsequent models.
Table 2 provides adjusted PORs for solid waste facility types by race and house value. Results are not provided separately for TIRELFs or INDUSLFs because of small numbers. The adjusted PORs of any solid waste facility, and of each facility type, were approximately 2-3 times higher in block groups with ≥20% people of color compared with block groups with <10% people of color. Adjusted PORs in block groups with 10 to <20% people of color were between unity and 2, compared with block groups with <10% people of color. Table 2 also provides summary values for block groups with ≥10% people of color compared with block groups with <10%; these ranged from 2.1 for any solid waste facility to 2.5 for TRANSFERs.
Compared with block groups with median house values >$100,000, adjusted PORs ranged from 1.2 to 1.8 for any solid waste facility and any MSWL. Adjusted PORs were less than unity for construction and demolition landfills, and between 0.8 and 1.5 for TRANSFERs. Summary PORs comparing block groups with median house values <$100,000 with those with greater values ranged from 0.9 for construction and demolition landfills to 1.5 for MSWLs.
Adjusted PORs for cross-classified levels of race and house value are presented in Table 3 . The prevalence odds of any solid waste facility increased as median house value decreased among white block groups. Among high-wealth (≥ $100,000) and medium-wealth ($60,000 to < $100,000) block groups, the prevalence odds of any solid waste facility increased as the percentage of people of color in the population increased. PORs ranged between 3.0 and 5.6 for block groups with ≥ 10% people of color and house values < $100,000, and for block groups with < 10% people of color and house values < $60,000.
Of the block groups that received at least one permitted solid waste facility between 1990 and 2003, most (93/146) also contained at least one solid waste facility permitted before 1 January 1990. To account for the difference in the baseline risk of new permitted solid waste facilities, we conducted a stratified analysis based on the presence of any previously permitted solid waste facility in the block group.
Table 4 provides adjusted HRs for solid waste facilities newly permitted between 1990 and 2003 by race and house value, stratified by the presence of any previously permitted solid waste facility. Because of small numbers, results are not presented separately by facility type. Among block groups that did not have a permitted solid waste facility eligible to be included in the study before 1 January 1990, the hazards of any new solid waste facility were 1.6-3.0 times higher in block groups with ≥10% people of color compared with block groups with <10% people of color. Among block groups that contained a previously permitted solid waste facility eligible to be included in the study, race was not strongly associated with the hazard of any new solid waste facility (HRs ranged from 0.8 to 1.1).
Among block groups that did not have a previously permitted solid waste facility (compared with block groups with median house values ≥$100,000), adjusted HRs for medium wealth block groups, median house values $60,000 to <$75,000 and $75,000 to <$100,000, respectively, were 0.6 and 0.5 times as high. Among block groups with a previously permitted solid waste facility (compared with block groups with median house values ≥$100,000), adjusted HRs for medium wealth block groups (median house values $60,000 to <$75,000 and $75,000 to <$100,000, respectively) were 1.3 and 1.4 times higher.
Table 5 presents adjusted HRs by owner/operator of the first solid waste facility newly permitted between 1990-2003. Privately owned and/or operated facilities were permitted at a 2.4 times higher rate in block groups with ≥10% people of color, compared with block groups with <10%. Permitting of publicly owned and operated solid waste facilities was not related to race (HR = 1.0). Compared with block groups with median house values ≥$100,000, the hazard of any new solid waste facility in block groups with median house values <$100,000 was similar for private and public facilities (HR = 0.9 and 0.8, respectively).
Environ Health Perspect. 2007;115(9):1344-1350. © 2007 National Institute of Environmental Health Sciences
Cite this: Race, Wealth, and Solid Waste Facilities in North Carolina - Medscape - Sep 01, 2007.