Correspondence/Rebuttal pubs.acs.org/est
Comment on “Feather Meal: A Previously Unrecognized Route for Reentry into the Food Supply of Multiple Pharmaceuticals and Personal Care Products (PPCPs)”
T
feathers would contain in the neighborhood of 0.04 ppm using the same decay rates as reported by San Martin et al.3 This level is 300-fold below any use rate reported to select for FQ resistance in C. jejuni 4 and it represents a “worst case” scenario as it assumes a late in life use of FQ which was very uncommon. Let us assume again for a moment that contraband oral product has been stowed away for use today. Another important fact mitigates against the possibility of FQ recycling due to feather meal. That fact relates to the avian integumentary system. Most field treatments of poultry with FQ’s were generally done within the first 1−2 weeks of their life when systemic Colibacillosis tends to occur and cause mortality. Systemic Colibacillosis was in fact the only label indication for the approved poultry oral product. As broilers grow they shed (via molting) their juvenile feather coat into the litter and regrow new adult feathers by the time they go to market at roughly 5 weeks of age. As a result, any FQ positive feather pulp from early in life treatment would no longer be present in feathers of market age broilers. Even continuous feeding of heavily contaminated Chinese feather meal containing 1.0 ppm FQ at a 2−3% dietary inclusion rate would keep overall selection pressure at 0.03 ppm FQ in the diet; or 370-fold below know selection pressure rates.4 Any attempts to ascribe use of contraband FQ’s or contaminated feather meals to current levels of FQ-resistant Campylobacter sps. in broilers fails for lack of a biologically plausible explanation. Fluoroquinolones may be compounded into animal feeds in China, but they have never have been used in the U.S. in this fashion at any time. FQ’s have only been used by veterinary prescription for short-term water medication to treat severe, economically significant and welfare compromising outbreaks of E. coli (in poultry) in the U.S. The U.S. poultry industry and its veterinarians take seriously the charge to protect both animal welfare and the public health of U.S. citizens. In short, there are no scientific justifications for the “reintroduction” scheme hypothesized in Figure 1 of the article for recycling of significant FQ residues in animal feeds nor for the maintenance of FQ drug levels that could provide ongoing selection pressure to maintain an FQ-R Campylobacter sps. reservoir in commercial broilers.
he clear implication is made in this article that fluoroquinolone (FQ) residues found in feather meal samples from both the United States and China might serve as a selective pressure to maintain FQ resistant Campylobacter sps. in commercial U.S. broiler production. The main line of reasoning used is depicted in Figure 1 of the paper.1 The underlying assumptions are that there remain some illicit uses of banned fluoroquinolone (FQ) products in commercial broiler feed and/or water and sustained “recycling” of FQ residues because of their feather trophic distribution. Several important facts serve to mitigate against this being even a remote possibility. Feathermeal produced and imported from China, while apparently obtainable, is simply not used to feed domestically reared commercial poultry. Nearly all the feather meal produced by integrated poultry companies is sold as higher margin byproduct to other animal feeding enterprises and is sparingly used in poultry rations. Norfloxacin and ofloxacin have never been approved for use in any food animal species in the U.S. The presence of norfloxacin in U.S. sourced feather meal is not the result of norfloxacin use in commercial poultry. Extra label use of FQ’s in food animals has been forbidden since the 1995 approval of FQ’s in food animals and FDA reported in the 2000−2005 NOOH proceedings that they found no evidence of extra-label use of FQ’s in poultry. Upon the removal of FQ’s for use in poultry in the Fall of 2005 all approved products were the subject of a nationwide recall which took all products out of the marketplace and drug sponsors ceased their manufacture. It is noted that no U.S. produced feather meals were positive for ciprofloxacin and only two were “positive” for enrofloxacin near the assay’s limit of detection. The article cites two lab withdrawal studies in support of the contention that FQ’s are feather trophic and can be found in commercial feather meals at levels reported in the lab studies. The article is correct in stating that FQ’s are feather trophic as this propensity also extends to cartilaginous tissue and is a reason for use contraindications of FQ’s in young foals, long bone dog breeds and even children under the age of 16 years. The first citation2 is not informative as it deals with flumequine which is not a topic of this paper and it is pharmacokinetic and pharmacodynamic properties are different than enrofloxacin. The second reference3 is useful (however not a “feeding” study) to help extrapolate a very rough comparison from high level intramuscular (IM) dosing to that of a late grow-out administration of the previously approved oral enrofloxacin product sold in the US. The oral poultry product when used at its most common approved oral dose rate resulted in a dose of about 2.5 mg/kg in broilers. Assuming a roughly linear relationship, broilers would have about 2.0 ppm in the feather pulp when they started the mandatory one week drug withdrawal before they could go to market. At that time their © 2012 American Chemical Society
Barry J. Kelly*
■
AAAP Drugs & Therapeutics Committee, 12627 San Jose Boulevard, Suite 202, Jacksonville, Florida, United States
AUTHOR INFORMATION
Corresponding Author
*E-mail:
[email protected]. Notes
The author declares no competing financial interest. Published: October 22, 2012 13024
dx.doi.org/10.1021/es303433s | Environ. Sci. Technol. 2012, 46, 13024−13025
Environmental Science & Technology
■
Correspondence/Rebuttal
REFERENCES
(1) Love, D. C.; Halden, R. U.; Davis, M. F.; Nachman, K. E. Feather meal: A previously unrecognized route for reentry into the food supply of multiple pharmaceuticals and personal care products (PPCPs). Environ. Sci. Technol. 2012, 46 (7), 3795−3802. (2) Cornejo, J.; Lapierre, L.; Iraguen, D.; Pizarro, N.; Hidalgo, H.; San Martin, B. Depletion study of three formulations of flumequine in edible tissues and drug transfer into chicken feathers. J. Vet. Pharmacol. Ther. 2011, 34 (2), 168−175. (3) San Martin, B.; Cornejo, J.; Iraguen, D; Hidalgo, H.; Anadon, A. Depletion study of enrofloxacin and it metabolite ciprofloxacin in edible tissues and feathers of white leghorn hens by liquid chromatography coupled with tandem mass spectrometry. J Food Prot. 2007, 70 (8), 1952−1957. (4) Stapleton, K.; Cawthraw, S. A.; Cooles, S. W.; Coldham, N. G.; La Ragione, R. M.; Newell, D. G. Selecting for development of fluoroquinolone resistance in a Campylobater jejuni strain 81116 in chickens using various enrofloxacin treatment protocols. J. Appl. Microbiol. 2010, 109, 1132−1138.
13025
dx.doi.org/10.1021/es303433s | Environ. Sci. Technol. 2012, 46, 13024−13025
