August 2007

Grant Results

SUMMARY

From 2000 to 2002 researchers at the State of North Carolina Department of Health and Human Services, Raleigh, N.C., conducted a study in eastern North Carolina to assess the extent to which bacteria, antibiotics-resistant bacteria, antibiotic residues and nitrates are released from animal-feeding operations into groundwater aquifers and drinking-water supplies.

This study was done after extensive flooding occurred in eastern North Carolina in September 1999 due to Hurricane Floyd.

Researchers collaborated with staff from the University of North Carolina School of Public Health and the University of Maryland School of Medicine.

Key Findings

  • The results of the study showed that E. coli and Enterococci (enteric indicator bacteria) were present in groundwater on or near two swine farms in eastern North Carolina that have conventional anaerobic lagoon and sprayfield land application systems for swine waste management, as well as an alternative technology of compacting the swine waste solids and land — applying them as biosolids.
  • Multidrug-resistant E. coli and Enterococci were detected in groundwater on or near two swine farms in eastern North Carolina.
  • This study also detected elevated concentrations of nitrogen nutrients in the groundwater near swine farms.
  • Antibiotic residue analysis indicated that antibiotics were detectable in swine wastes and in some groundwater and surface-water samples at the swine farm testing sites, but rarely or not at all at the non-swine farm sites.
  • Overall, the data from this study show that the current practices at the two swine farms that were studied are negatively impacting groundwater by the introduction of fecal bacteria and elevated levels of nitrogenous nutrients.

Funding
The Robert Wood Johnson Foundation (RWJF) supported the project with a $398,881 grant between July 2000 and September 2002.

 See Grant Detail & Contact Information
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THE PROBLEM

In 1999, flooding in eastern North Carolina caused by Hurricane Floyd resulted in runoff from the region's concentrated animal feeding operations into the area's groundwater and drinking-water wells. Many of the area's confined animal feeding operations, primarily swine farms, manage their animal waste with systems using anaerobic holding lagoons followed by land application of the liquid waste.

Potential contamination of the region's drinking-water supply by these lagoon systems during heavy rain or flood conditions may pose long-term disease and health risks for residents of the region. However, in 1999 no scientific data existed to determine the public health impact of groundwater contamination resulting from flooding near animal-feeding operations.

At the same time, public health officials in North Carolina were concerned that antibiotics used in the region's concentrated animal-feeding operations could result in the release into the water supply of bacteria that are resistant to antibiotics. Research conducted in Belgium by Butaye, Devriese and Haesebrouck in 1998 and 1999 demonstrated that the use of antibiotics in animal production has resulted in multidrug-resistant bacterial pathogens in animals, contributing to the emerging public health threat of bacterial resistance to antimicrobials.

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RWJF STRATEGY

RWJF has made a number of grants to support research on the effects of natural disasters in states and communities. Grant ID# 032720 to the North Dakota State Department of Health and ID# 037385 to the Altru Health Foundation supported a study of sentinel health conditions associated with flooding in North Dakota.

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THE PROJECT

The State of North Carolina Department of Health and Human Services and staff from the University of North Carolina School of Public Health and the University of Maryland School of Medicine collaborated to understand the relationship between the presence of swine farms and groundwater quality.

The project focused in particular on the release of antibiotically resistant and pathogenic bacteria into the environment from lagoon wastewater systems used by commercial swine producers. The study team from the North Carolina School of Public Health and the University of Maryland School of Medicine set out to answer the following questions:

  • To what extent do swine farms contaminate groundwater with fecal bacteria?
  • Do swine farms contaminate groundwater with bacteria that are antimicrobial (antibacterial) resistant or pathogenic?
  • How do rain and flooding events affect the fate and transport of swine bacteria into the environment?
  • What are the factors that contribute to groundwater contamination (e.g., well depth, distance to swine anaerobic lagoon wastewater system)?
  • How much or what proportion of groundwater contamination is attributable to swine farm bacteria as opposed to other sources of these bacteria, such as human wastewater or other land uses?

This study did not include an epidemiological assessment of the health effects of flooding on residents of the study area.

Methodology

Ground and surface water samples were collected and analyzed at four study sites, all located in the Neuse River Basin in eastern North Carolina and representative of areas affected by Hurricane Floyd. Two sites were swine farms that use lagoons as the primary treatment of swine waste, and then apply this wastewater to land for disposal and recycling. Two sites were agricultural crop sites (non-swine farm sites) which did not use land application of animal waste and on which there were no animals present. Wells were tested at the four study sites during four distinct sampling periods selected to reflect seasonal events.

Groundwater samples were screened for E. coli, Enterococci, Salmonella and male-specific and somatic coliphages (viral indicators of fecal contamination). Salmonella and coliphages were rarely found in groundwater. For this reason, E. coli and Enterococci are useful indicators of groundwater contamination from swine waste, while Salmonella and coliphages are not.

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FINDINGS

Researchers reported the following findings to the State of North Carolina Department of Health and Human Services:

  • The results of the study showed that E. coli and Enterococci (enteric indicator bacteria) were present in groundwater on or near two swine farms in eastern North Carolina that have conventional anaerobic lagoon and sprayfield land application systems for swine waste management, as well as an alternative technology of compacting the swine waste solids and land-applying them as biosolids.
  • Multidrug-resistant E. coli and Enterococci were detected in groundwater on or near two swine farms in eastern North Carolina.
  • This study also detected elevated concentrations of nitrogen nutrients in the groundwater near swine farms.
  • Antibiotic residue analysis indicated that antibiotics were detectable in swine wastes and in some groundwater and surface-water samples at the swine farm testing sites, but rarely or not at all at the non-swine farm sites.
  • Overall, the data from this study show that the current practices at the two swine farms that were studied are negatively impacting groundwater by the introduction of fecal bacteria and elevated levels of nitrogenous nutrients.

Limitations

Researchers reported the following limitations:

  • The original intention of the study was to assess the relationship between heavy rainfall and flooding events and the movement of swine farm contaminants into the groundwater. However, while there was flooding caused by Hurricane Floyd prior to the study, the combination of too few samples over time and the lack of a major precipitation event during the study period hindered the ability of researchers to properly address this question.
  • Although the study determined that groundwater on or near swine farms is contaminated by bacterial contaminants, more sampling and analysis are needed to conclusively link the bacteria found in groundwater to the bacteria found in swine lagoon wastewater systems.

Communications

Researchers submitted a report, Detection and Occurrence of Antimicrobially Resistant Enteric Bacteria on or near Swine Farms in Eastern North Carolina, to the State of North Carolina Department of Health and Human Services in May 2003 (see the Bibliography).

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SIGNIFICANCE TO THE FIELD

William Pate, of the North Carolina Department of Health and Human Services, Division of Public Health, states: "Very little research has been reported on the impacts of swine operations on the microbiological quality of groundwater. This study expanded on the existing research by investigating two bacterial indicators of fecal contamination, E. coli and Enterococcus species." It should be noted that in 1999 the potential health risks associated with animal-feeding operations were, and remain, a public health concern in states with large numbers of such operations, including North Carolina. This situation increased interest in conducting a study that could produce objective scientific data.

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AFTER THE GRANT

The State of North Carolina Department of Health and Human Services has received funding from the Centers for Disease Control and Prevention for a related study to investigate the presence of antibiotic-resistant organisms in swine waste and in people who work on swine farms.

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GRANT DETAILS & CONTACT INFORMATION

Project

Studying the Public Health Consequences of Hurricane Floyd

Grantee

State of North Carolina Department of Health and Human Services (Raleigh,  NC)

  • Amount: $ 398,881
    Dates: July 2000 to September 2002
    ID#:  038787

Contact

William J. Pate
(919) 715-6432
Bill.Pate@ncmail.net

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BIBLIOGRAPHY

(Current as of date of this report; as provided by grantee organization; not verified by RWJF; items not available from RWJF.)

Reports

Anderson ME and Sobsey MD. "Detection and Occurrence of Antimicrobially Resistant E.coli in Groundwater on or near Swine Farms in Eastern North Carolina." Water Science and Technology, 54(3): 211–218, 2006. Abstract available online.

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Report prepared by: Karyn Collins
Reviewed by: James Wood
Reviewed by: Molly McKaughan
Program Officer: Pamela Russo

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