Reuters | May 22, 2002 | Anne Harding |
SALT LAKE CITY (Reuters Health) - Methods now used by many swine farmers to dispose of pig manure may contaminate nearby groundwater with multiple-drug-resistant bacteria, North Carolina researchers report.
And while it is not known if this contamination is finding its way into drinking water, one of the researchers told Reuters Health, the E. coli contamination itself--let alone contamination with drug-resistant forms of this and other bacteria--would indeed be a public health concern.
Pigs raised for meat are treated with a number of antibiotics to boost growth and fight disease, notes Maren Anderson, a PhD candidate at the University of North Carolina at Chapel Hill and the study's lead author. The animals are known to shed bacteria--often resistant to antibiotics--in their feces.
To investigate whether swine manure disposal practices could be contaminating groundwater, Anderson and her colleagues tested groundwater near four farms. Two of the farms raised swine and dumped pig manure into lagoons or spread it over nearby land, and another did not raise swine but did apply swine manure to land as fertilizer. For comparison, the researchers looked at a fourth farm that raised only crops and used no swine manure.
The researchers tested water in 48 monitoring wells near the farms. One quarter of the wells tested positive for enterococci, and 17% contained E. coli. The enterococci the investigators found was associated with fecal contamination and capable of making people sick. And many of the bacteria they found were resistant to several drugs.
The most heavily contaminated water was found near the two farms that raised pigs and disposed of pig manure via lagoons and land application. Antibiotic resistance also was more prevalent at these sites.
Anderson told Reuters Health in an interview that lagoons and land application are the primary manure disposal methods used in North Carolina, and that a considerable amount of money is being spent on research to investigate less-polluting waste management techniques. She noted that older lagoons are probably leakier than newer ones, which use special liners to prevent contaminated water from seeping out.
Anderson presented her findings here Wednesday at the American Society for Microbiology's annual meeting.Reuters:
