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A CASE STUDY: CROP (LETTUCE, SPINACH, AND CARROTS) UPTAKE OF THREE MACROLIDE ANTIBIOTICS (AZITHROMYCIN, CLINDAMYCIN AND ROXITHROMYCIN) AND OTHER DRUGS
Citation:
JONES-LEPP, T. L. AND C. A. Sanchez. A CASE STUDY: CROP (LETTUCE, SPINACH, AND CARROTS) UPTAKE OF THREE MACROLIDE ANTIBIOTICS (AZITHROMYCIN, CLINDAMYCIN AND ROXITHROMYCIN) AND OTHER DRUGS. Presented at 6th International Micropol and Ecohazard 2009, San Francisco, CA, June 08 - 10, 2009.
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Presentaiton
Description:
It has been shown that human-use macrolide antibiotics (azithromycin, clindamycin, and roxithromycin) are environmentally available in wastewaters, source waters, and biosolids. In order to better understand the fate of these compounds into food crops via root migration, we conducted a controlled greenhouse study and then exposure studies on crops grown in soils that are watered with treated wastewater effluent from a medium population southwestern city (~ 1 million population, July 2008). A new analytical extraction method had to be developed to extract the antibiotics from the complex matrix of crop samples. We used a modified pressurized liquid extraction (PLE) technique, followed by a rigorous hexane clean-up. Subsequent PLE extracts were analyzed by liquid chromatography-electrospray-ion trap mass spectrometry (LC-ESI-ITMS/MS) in the positive ionization collision induced mode (CID) for greater specificity. Initially, under controlled greenhouse conditions, three crops (lettuce, spinach, and carrots) were watered with varying concentrations of the three macrolide antibiotics (azithromycin, clindamycin and roxithromycin). After harvest, the plants were dissected and separated into leaf and root, then freeze-dried. The freeze-dried samples were homogenized and 1-g subsamples were extracted and analyzed by LC-ESI-ITMS/MS. In order to groundtruth our methodology, we applied the methods to crop samples (carrots, watermelon, tomatoes, cantaloupe) that were grown in fields that use treated municipal wastewater effluent for watering. The treated wastewater effluent had previously been characterized, and was known to contain the macrolide antibiotic azithromycin, the over-the-counter drug pseudoephedrine, the illicit drug methamphetamine, and an industrial flavoring agent n,n-dimethylphenethylamine (n,n’- dmpea, an isomeric compound to methamphetamine). The results of the studies indicate the uptake of azithromycin, clindamycin, roxithromycin and n,n’-dmpea, albeit at very low-levels (low ppt), into several of the crops species.