August 3, 2000

The Honorable Charles Fox
Assistant Administrator for Water
U.S. Environmental Protection Agency
401 M Street, SW
Washington, DC 20460

Dear Mr. Fox:

The undersigned health, environmental, and agricultural groups are writing to urge that the Agency include a limitation on the discharge of pathogens and antibiotics in the upcoming effluent guidelines for Confined Animal Feedlot Operations (CAFOs), which are due to be proposed in December 2000. It is our understanding that the Agency has begun to examine issues related to setting a limit for pathogens in CAFO effluents, which we strongly support. However, it appears that no consideration has been given thus far to setting a limit for antibiotics themselves in CAFO effluents. It is critical that this issue be addressed in light of the possible contribution of antibiotics in CAFO effluents to the worsening crisis of antibiotic resistance – a crisis that poses a particular threat to children, the elderly, and others that may be more susceptible to bacterial diseases.

Even loss of some treatment options can make once-treatable infections life threatening. Severely ill patients may die while physicians sequentially prescribe one antibiotic after another until they find one that is effective. Moreover, many people are allergic to certain antibiotics. If only one antibiotic remains to treat a disease and a person is allergic to it, the disease may be untreatable for that person.

About 40% of all antibiotics used in the United States are used in animal agriculture, with animal production increasingly concentrated in CAFOs. Given that total production of antibiotics in the U.S. now exceeds 50 million pounds annually, and given that a significant fraction of animals are produced in CAFOs, the usage of antibiotics in CAFOs is on the order of millions of pounds each year.

Although some antibiotics may be significantly metabolized, many are largely excreted intact and thus can be present in CAFO effluents. Indeed, as noted by the Ecological Exposure Research Division of EPA’s National Exposure Research Laboratory, "[i]n some cases as much as 80% of antibiotics administered orally pass through the animal unchanged into bacteria rich waste lagoons and is then spread on croplands as fertilizer leaving the antibiotics available for entry into ground water and runoff into surface waters carrying both the drugs and resistant bacteria or genetic material (R-plasmids) to other bacteria in soils and waterways."

Similarly, at a March 2000 symposium of the American Chemical Society on Pharmaceuticals and Personal Care Products in the Environment, scientists from the U.S. Geological Service noted that "antibiotics are transported into surface and ground water in areas with animal feeding operations." Scientists from USDA observed that "land disposal of animal manure could also introduce pharmaceuticals in surface water and in groundwater." In addition, a Swiss study found high levels of veterinary antibiotics in two lakes in the region of Switzerland with the highest density of animals; the large amounts of sulfonamides – antibiotics used in animal feed – suggested the source might be runoff from land adjacent to the lakes. (Abstracts of cited studies from the Symposium are contained in the Appendix to this letter.)

Recently, scientists from the U.S. Centers for Disease Control and Prevention investigated levels of antibiotics in CAFO lagoon wastewater, as well as in agricultural drainage wells, monitoring wells near the lagoons, and tile line inlets and outlets. For example, tetracyclines were measured at levels ranging from 11 to 540 micrograms per liter (m g/L), beta lactams at 2.1 to 3.5 m g/L, and macrolides at 15 to 275 m g/L.

Previously, other investigators had tested effluents from German sewage treatment works and groundwaters/surface waters for 18 antibiotics representing macrolides, sulfonamides, penicillins, and tetracyclines. The penicillins (which are susceptible to hydrolysis) and the tetracyclines (which can precipitate with calcium and similar cations) were not found, but the others were detected in the microgram per liter range. Since CAFO effluents do not enter sewage treatment works and thus may undergo less hydrolysis and precipitation, the penicillins and tetracyclines may also be present in CAFO effluents. Italian researchers have also reported the presence of tylosin and erthromycin in river water and sediments in Italy. In addition, oxytetracycline has been detected in sediments under fish farms.

Although the environmental persistence of antibiotics used in CAFOs varies, it is important to note that even those with short half-lives may be of concern. As noted by the Chief of the Environmental Chemistry Branch of EPA’s own National Exposure Research Laboratory, "chemicals continually infused to the aquatic environment essentially become ‘persistent’ pollutants even if their half-lives are short — their supply is continually replenished." The ongoing release of antibiotic-containing CAFO wastes thus means that even readily degraded antibiotics essentially act as persistent contaminants in the environment.

Finally, spillage of feed containing antibiotics may also contribute antibiotics to CAFO effluents directly, without passing through animals. The extent of this potential pathway apparently has not been studied to date.

Once antibiotics have entered CAFO effluents, they can enter waterways and spread through the environment in relatively low concentrations – thus killing susceptible bacteria and leaving resistant survivors to multiply. Those resistant bacteria can subsequently come into contact with people who contact that water through recreational activities, or whose drinking water becomes contaminated. Indirect transmission may also occur (e.g., if pets enter water and then carry resistant bacteria into the home on their fur).

In light of the data described above, we believe EPA is obliged to gather the data needed to support inclusion of a limitation on antibiotics in CAFO effluents, and to propose such a limitation as part of its current CAFO effluent guideline development.

We request an opportunity to meet with you at your earliest convenience to discuss this issue. To arrange such a meeting, please contact Tim Searchinger or Karen Florini at Environmental Defense, 202/387-3500, 1875 Connecticut Ave., NW, Suite 1016, Washington, DC 20008.

Very truly yours,

American Public Health Association, Washington, D.C.
Center for Science in the Public Interest, Washington, D.C.
Environmental Defense, Washington, D.C.
Global Resource Action Center for the Environment, New York, NY
Institute for Agriculture and Trade Policy, Minneapolis, MN
Natural Resources Defense Council, Washington, D.C.
Science and Environmental Health Network, Boston, MA
Sierra Club, Washington, D.C.
Union of Concerned Scientists, Washington, D.C.

APPENDIX

Occurrence of antibiotics in surface and ground water near confined animal feeding operations and waste water treatment plants using radioimmunoassay and liquid chromatography/electrospray mass spectrometry. M. Meyer, D.W. Kolpin, J.E. Bumgarner, J.L. Varns and J.V. Daughtridge. U.S. Geological Survey, 3916 Sunset Ridge Rd., Raleigh, NC 27607.

Concerns about pharmaceuticals in water reuse and animal waste. Herman Bouwer. U.S. Water Conservation Laboratory, USDA-ARS, 4331 E. Broadway Rd, Phoenix, AZ 85040.

Pharmaceuticals in sewage effluent could find their way into groundwater via seepage from contaminated streams and lakes, artificial recharge with sewage effluent, or drainage or deep-percolation from fields irrigated with sewage effluent. The latter is the most serious because contaminant concentrations in the deep-percolation water can be a multiple of those in the irrigation water. Land disposal of animal manure could also introduce pharmaceuticals in surface water and in groundwater.

Occurrence of macrolide and sulfonamide antibiotics in the aquatic environment of Switzerland. Norriel S. Nipales, Christa S. McArdell, Eva Molnar and Walter Giger. Swiss Federal Institute for Environmental Science and Technology (EAWAG) and Swiss Federal Institute of Technology, (ETH), Ueberlandstrasse 133, PO Box 611, Dübendorf, CH-8600, Switzerland, fax: 41-1-823-5028, mcardell@eawag.ch.