Mar. 11, 2002 CHAPEL HILL – Flooding from hurricanes such as Floyd, which dumped up to 20 inches of water on parts of eastern North Carolina, poses a significant threat to both environmental and human health by washing industrial animal operation wastes into areas with vulnerable populations, according to a new study.
The study, conducted by University of North Carolina at Chapel Hill researchers, involved analyzing satellite images of the region recorded a week after the 1999 hurricane to see how many animal operations appear to have been affected. Researchers say their findings suggest that many more livestock operations were flooded than previous N.C. Division of Water Quality records had indicated.
Significant chemical and biological contamination of wells, the chief source of drinking water for many area residents, is a particular concern when contamination from fecal waste pits, spray fields and animal confinement structures reaches nearby communities, researchers said. No good data on the extent of any adverse health effects exist, however.
A report on the research will appear in the April issue of Environmental Health Perspectives, a scientific journal published by the National Institute of Environmental Health Sciences. Authors are Dr. Steven B. Wing, associate professor of epidemiology at the UNC School of Public Health; former graduate student Stephanie Freedman; and Dr. Lawrence Band, Voit Gilmore distinguished professor of geography.
“In the area we studied, state inspectors found 46 flooded or breached waste pits, but in our interactions with various communities and environmental groups, people had the impression that there were potentially many more than that,” Wing said. “When the N.C. Division of Emergency Management obtained digitized satellite imagery of eastern North Carolina taken in 1999 a week after the rains fell, we had an opportunity to investigate. We already had data on where the state had issued permits for swine, cattle and poultry operations so we could combine those two sources of information to create a fuller picture of what really happened.”
Using the satellite imagery, researchers estimated that 241 N.C. livestock operations were flooded or partially flooded by the rising waters. By linking that information to the 2000 Census, they found that 171,498 people lived in neighborhoods, known as block groups, where the 241 operations were located. In contrast, only 46,800 people lived in areas where the state found flooded waste pits, Wing said.
“We also were interested in well water and residents’ racial and economic characteristics because from past research we knew that swine operations are disproportionately located in low-income communities and communities of color,” Wing said.
Blacks were 16 percent more likely than whites to live in areas with flooded animal operations, according to estimates based on satellite data, researchers found. In contrast, blacks were 8 percent less likely to live in areas where state officials inspected flooded waste pits.
Almost 60 percent of N.C. households in neighborhoods with flooded livestock operations depended on well water according to 1990 census figures, the team found.
The strength of the state tally was that every one of the waste pits they reported as breached or flooded was physically inspected, Wing said. The weakness was that inspectors could not inspect every animal operation. Moreover, half of their reports were confined to the Northeast Cape Fear and Neuse River watersheds.
“Advantages of satellite images are that they covered most of the eastern part of the state,” Wing said. “An important disadvantage was that we only had a single coordinate location for each animal facility. Information on the boundaries of the animal operations will be needed to get better estimates of the impact of flooding.”
Also, satellite images were not available for the western edge of the flooded region, he said.
Of the 2,286 animal operations holding state permits in the area the UNC scientists studied, 2,245 involved swine, Wing said. The swine operations with geographic coordinates in areas that were inundated according to satellite images were permitted to have 736,000 hogs.
“North Carolina’s industrial animal operations are currently permitted as non-discharge facilities under the assumption that all waste is contained on site,” Wing said. “Our analyses emphasize that this is not the case. Flood conditions occur periodically in the state. As long as there are industrial livestock operations in flood plains, flooding will lead to environmental contamination from chemicals and disease-causing organisms.”
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