In a joint study, researchers at the Johns
Hopkins Bloomberg School of Public Health and Arizona State University found
evidence suggesting that a class of antibiotics previously banned by the U.S.
government for poultry production is still in use.
Results
of the study were published March 21 in Environmental Science & Technology.
The study, conducted by the Bloomberg School's Center for a Livable Future and
Arizona State's Biodesign Institute, looked for drugs and other residues in
feather meal, a common additive to chicken, swine, cattle and fish feed.
The
most important drugs found in the study were fluoroquinolones -- broad spectrum
antibiotics used to treat serious bacterial infections in people, particularly
those infections that have become resistant to old-er antibiotic classes. The
banned drugs were found in 8 of 12 samples of feather meal in a multi-state
study. The findings were a surprise to scientists because fluoroquinolone use
in U.S. poultry production was banned by the U.S. Food and Drug Administration
in 2005.
This is
the first time investigators have examined feather meal, a byproduct of poultry
production made from poultry feathers, to determine what drugs poultry may have
received prior to their slaughter and sale.
The
annual per capita human consumption of poultry products is approximately 100
lbs, greater than that of any other animal- or vegetable-derived protein source
in the U.S. To satisfy this demand, each year, the U.S. poultry industry raises
nearly 9 billion broiler chickens and 80 million turkeys, according to the U.S.
Department of Agriculture. A large percentage of the fresh weight of these
animals is inedible -- an estimated 33 percent for chickens, for example -- and
is recycled for other uses, including feather meal.
The
rendering industry, which converts animal byproducts into a wide range of
materials, processes poultry feathers into feather meal, which is often added
as a supplement to poultry, pig, ruminant, and fish feeds or sold as an
"organic" fertilizer. In a companion study, researchers found inorganic
arsenic in feather meal used in retail fertilizers.
"The
discovery of certain antibiotics in feather meal strongly suggests the
continued use of these drugs, despite the ban put in place in 2005 by the
FDA," said David Love, PhD, lead author of the report. "The public
health community has long been frustrated with the unwillingness of FDA to
effectively address what antibiotics are fed to food animals."
A
primary reason for the 2005 FDA ban on the use of fluoroquinolones in poultry
production was an alarming increase in the rate of the fluoroquinolone
resistance among Campylobacter bacteria. "In recent years, we've seen the
rate of fluoroquinolone resistance slow, but not drop," noted study
co-author Keeve Nachman, PhD, Farming for the Future Program Director at the
Johns Hopkins Center for a Livable Future. "With such a ban, you would
expect a decline in resistance to these drugs. The continued use of fluoroquinolones
and unintended antibiotic contamination of poultry feed may help ex-plain why
high rates of fluoroquinolone-resistant Campylobacter continue to be found on
commercial poultry meat products over half a decade after the ban."
In the
U.S., antibiotics are introduced into the feed and water of industrially raised
poultry, primarily to make them grow faster, rather than to treat disease. An
estimated 13.2 million kg of antibiotics were sold in 2009 to the U.S. poultry
and livestock industries, which represented nearly 80 percent of all antibiotic
sales for use in humans and animals in the U.S. that year.
In
conducting the study, researchers from the Johns Hopkins Bloomberg School of
Public Health and Arizona State University analyzed commercially available
feather meal samples, acquired from six U.S. states and China, for a suite of
59 pharmaceuticals and personal care products. All 12 samples tested had
between 2 and 10 antibiotic residues. In addition to antimicrobials, 7 other
personal care products, including the pain reliever acetaminophen (the active
ingredient in Tylenol), the antihistamine diphenhydramine (the active
ingredient in Benadryl) and the antidepressant fluoxetine (the active
ingredient in Prozac), were detected.
Researchers
also found caffeine in 10 of 12 feather meal samples. "This study reveals
yet another pathway of unwanted human exposure to a surprisingly broad spectrum
of prescription and over the-counter drugs," noted study co-author Rolf
Halden, PhD, PE, Co-Director of the Center for Health Information &
Research, and Associate Director of the Swette Center for Environmental
Biotechnology at Arizona State University.
When
researchers exposed several strains of E. coli bacteria to the concentrations
of antibiotics found in the feather meal samples, they also discovered the drug
residues could select for resistant bacteria. "A high enough concentration
was found in one of the samples to select for bacteria that are resistant to
drugs important to treat infections in humans," noted Nachman.
"We
strongly believe that the FDA should monitor what drugs are going into animal
feed," urged Nachman. "Based on what we've learned, I'm concerned
that the new FDA guidance documents, which call for voluntary action from
industry, will be ineffectual. By looking into feather meal, and uncovering a
drug banned nearly 6 years ago, we have very little confidence that the food
animal production industry can be left to regulate it-self."
Source:
Johns Hopkins University Bloomberg School of Public Health
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