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Environmental fate & pathways

Additional information on environmental fate and behaviour

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additional information on environmental fate and behaviour
Type of information:
experimental study
Adequacy of study:
supporting study
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Study conducted according to well documented methods.

Data source

Reference Type:
Degradation Kinetics of Testosterone by Manure-Borne Bacteria: Influence of Temperature, pH, Glucose Amendments, and Dissolved Oxygen
Yun-Ya Yang, Thomas Borch,* Robert B. Young, Lawrence D. Goodridge, and Jessica G. Davis
Bibliographic source:
J. Environ. Qual. 39 (2010)

Materials and methods

Test material

Constituent 1
Chemical structure
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Results and discussion

Applicant's summary and conclusion

These results indicate that testosterone is rapidly degraded by manure-borne bacteria under a wide range of environmentally relevant conditions.
Executive summary:

Land application of manure may contribute endocrine disrupting compounds (EDCs) such as steroid hormones to the environment. Little attention has been paid to the potential for degradation of steroid hormones by manure-borne bacteria and their degradation kinetics and pathways. In a laboratory study, the potential for biodegradation of testosterone, 17b-estradiol (E2) and progesterone by swine (Sus scrofa) manure-borne bacteria was examined. In addition, the impact of temperature, pH (6, 7, and 7.5), glucose amendments (0, 3, and 22 mmol L–1), and presence of oxygen on testosterone degradation kinetics was determined. Testosterone, 17b-estradiol and progesterone were biodegraded within 25 h of reaction initiation under aerobic conditions. The degradation of testosterone followed pseudo first-order and zero-order reaction kinetics under aerobic and anaerobic conditions, respectively, in tryptic soy broth (TSB) pre-enriched systems. The half-life (t1/2) for the degradation of testosterone under anaerobic conditions was six times longer than aerobic conditions. Testosterone degradation was found to significantly increase (~ 17%) when incubated at 37°C vs. 22°C. The impact of pH (t1/2 ranged from 4.4–4.9 h) and glucose amendments (t1/2 ranged from 4.6–5.1 h) on the testosterone degradation rate were found to be small. Testosterone was transformed to dehydrotestosterone (DHT) (major degradation product), androstenedione (AD), and androstadienedione (ADD) under aerobic conditions as revealed by liquid chromatography-time-of-flight mass spectrometry (LC/TOF-MS). These results indicate that testosterone is rapidly degraded by manure-borne bacteria under a wide range of environmentally relevant conditions.