17 β-estradiol mineralization in human waste products and soil in the presence and the absence of antimicrobials.
Summary (2 min read)
INTRODUCTION
- Estrogens are excreted by vertebrates in both urine and feces with an estimated global rate of 29,500 kg of natural estrogens being excreted by humans each year. [1].
- Drinking water contaminated with estrogens could pose health risk to humans. [7, 12].
- Antimicrobial additions to soil and other media has shown to reduce reduced E2 mineralization in some cases. [20, 23, 26].
- Doxycycline is commonly used to treat wide array of infections in humans (urinary tract, intestine and eye) and is also increasingly used as an anti-cancer therapeutic. [28].
- Tetracycline has shown to decrease soil bacterial diversity following its application to a plantsoil system. [24].
Chemicals and Media
- Analytical grade 17 β-estradiol (≥98% pure), doxycycline (≥98% pure) and norfloxacin (≥98% pure) were purchased from Sigma-Aldrich Chemical Company (Saint Louis, MO, USA).
- Sewage sludge was obtained from facultative lagoon-based sewage treatment facility in southern Manitoba, Canada that services approximately 8000 people.
- The soil was sampled (0-15 cm) from the Ap-horizon of a Newdale Clay Loam, which is recognized as the provincial soil of Manitoba and represents a large area of agricultural land in this province.
- Hormones were below detection limits in both samples.
Microcosm Experiments
- The impact of antibiotics on E2 mineralization in these media was quantified using a factorial design of antimicrobial additions plus controls without antimicrobials.
- Both radiolabeled and analytical grade E2 was applied and the E2 experiment was terminated at 189 days at which time E2 mineralization had slowed to <0.1% per day for all treatments.
- In a parallel experiment, only analytical E2 was applied, but the same factorial design plus control was utilized to quantify the impact of antibiotics on microbial respiration (CO 2 production) over 189 days.
- Microcosms were pre-incubated at 20˚C for seven days prior to E2 applications.
- Antibiotic stock solutions were prepared in milli-Q water that was acidified with 0.5 M HCl (pH 4) to help dissolve doxycycline and/or norfloxacin.
Statistical Analyses
- The effect of media and antibacterial treatment on total E2 mineralization or total respiration was analyzed by ANOVA using PROC MIXED in SAS ver. 9.4 (SAS Institute Inc., 2013).
- All data respected normality based on Shapiro-Wilks statistic ≥ 0.9.
- Dissipation kinetics of E2 for each media was generated and compared using PROC NLIN in SAS.
- The calculated half-life is equivalent to the time that 50% of the radioactivity would have been mineralized in a media.
- The Tukey multiple comparison procedure was used for pairwise comparisons of treatment means.
RESULTS AND DISCUSSION
- Specifically, when norfloxacin or doxycycline were applied together, or when no antimicrobials were added, cumulative respiration was significantly greater in the sewage sludge than soil; however, when either norfloxacin or doxycycline were applied alone, sewage sludge and soil had a similar cumulative respiration (Fig. 3 ).
- Regardless of whether norfloxacin or doxycycline was applied alone or in combination, the antimicrobials did not supress microbial respiration and, consistently, antimicrobial applications had no pronounced effect on E2 mineralization.
- Biosolid showed a very small total E2 mineralization relative to sewage sludge and soil, yet this medium had a much greater microbial respiration.
- 3 LECO model CHN 600 carbon-hydrogen-nitrogen determinator.
- 8 Aqua regia digestion followed by Inductively Coupled Plasma Optical Emission Spectroscopy.
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Cites background from "17 β-estradiol mineralization in hu..."
...recovery of (14)CO2 indicates that the steroid molecule has been inactivated because of ring cleavage.([17]) The time that 50% of the applied E2 is mineralized (E2-(1)/2) can be calculated from these laboratory data....
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References
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"17 β-estradiol mineralization in hu..." refers background in this paper
...to soil and other media has shown to reduce E2 mineralization in some cases.([20,23,26]) For example, the addition of 40 mg kg¡1 tetracycline to manure decreased total E2 mineralization by...
[...]
...In another laboratory experiment of shorter duration (7 days), [23] the presence of a single antimicrobial (chlortetracycline, sulfamethazine, or tylosin) in a loam soil reduced the transformation of E2 to estrone (E1) when the antimicrobial was applied at 2 or 200 mg kg¡1....
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...zine, and tylosin applied to soil at concentrations as low as 2 mg kg¡1 significantly reduced the transformation of E2 to estrone (E1).([23]) Antimicrobials affect bacterial compositions with the...
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...and hence has a strong affinity for organic matter substances in biosolid.([44]) Desorption of E2 from biosolid has been reported to be low (e....
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