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This article in JEQ

  1. Vol. 34 No. 3, p. 854-860
     
    Received: Aug 25, 2004
    Published: May, 2005


    * Corresponding author(s): toppe@agr.gc.ca
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doi:10.2134/jeq2004.0330

Persistence and Pathways of Testosterone Dissipation in Agricultural Soil

  1. Angela Lorenzen,
  2. Ralph Chapman,
  3. John G. Hendel and
  4. Edward Topp *
  1. Southern Crop Protection and Food Research Centre, Agriculture and Agri-Food Canada, 1391 Sandford Street, London, ON, Canada N5V 4T3

Abstract

The persistence and pathways of dissipation of testosterone in three agricultural soils were examined in laboratory microcosm incubations at different soil moistures (1.7–39%) and temperatures (4–30°C) using 14C- and 3H-labeled and unlabeled testosterone. Sterilized loam was also examined to assess possible abiotic pathways. Extractable 14C decreased rapidly for all three soils at 30°C with times to dissipate 50% of material (DT50) ranging from 8.5 to 21 h. Respired 14CO2 accounted for approximately 50% of the applied 14C after 120 h. Androgenic activity of soil extracts declined faster than the extractable 14C levels demonstrating that testosterone was not being converted to compounds with greater activity. Dissipation rates of nonvolatile, extractable 3H in loam at 7, 15, and 39% moisture were similar, but the rate in air-dried loam (1.7% moisture) was significantly reduced. High performance liquid chromatography (HPLC) analysis of extracts of 14C-testosterone-treated loam incubated at 30°C for 6 h revealed that the 14C was distributed among the remaining testosterone and three major metabolites (4-androstene-3,17-dione, 5α-androstane-3,17-dione, and 1,4-androstadiene-3,17-dione), which accounted for 48.7, 23.7, and 9.6% of the remaining 14C, respectively. Periodic analysis of soil incubated at 23, 12, and 4°C showed that the rates of testosterone dissipation and metabolite appearance and subsequent dissipation were temperature dependent with rates decreasing with decreasing temperature. In sterilized loam, 4-androstene-3,17-dione was the only metabolite detected. We conclude that testosterone is rapidly and thoroughly biodegraded in agricultural soils under a range of conditions typical of a temperate growing season and thus is unlikely to pose a long-term risk to adjacent aquatic environments.

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