Fate of Glucuronide Conjugated Estradiol in Soil.

The reproductive hormone, 17β-estradiol (E2), is polarized in the body with a glucuronide, facilitating urinary elimination. The fate of this potentially more mobile polar form of E2 is not well understood. Soil sorption studies were conducted using [14C] 17-β-estradiol-3-glucuronide (E2G) and a Hamar soil (Sandy, mixed, frigid typic Endoaquolls) for initial concentrations ranging from 0.364 to 28 mg/L. For initial concentrations of 2.8 to 28 mg/L, the aqueous concentrations of E2G rapidly decreased to 11-20% in the first 48 h, with first-order sorption rate constants ranging from 0.55 to 0.67. For the lowest initial concentration of 0.364 mg/L, a higher first-order rate constant of 0.90 was observed. Analysis of the aqueous phase with HPLC indicated that E2G degraded into E2 and other estrogen metabolites. For the first 8 h of the experiment, E2G composed 86-94% of the aqueous concentrations. Also, present in this first 8 h was an unknown polar compound. At 24 h, about 27% of the aqueous fraction was E2, 71% was estrone, and 2% was E2G. During the remainder of the study (up to 672 h) estrone concentrations were at least two times greater than E2 and little or no E2G or polar metabolite were present. Thus, the first 8 h after urinary elimination may be critical for E2G being transported to the receiving water systems. Acetone extraction of removable radiochemical mass from the soil yielded recoveries that ranged from 35% at 4 hr to 93% at 28 days. The acetone-extracted component was determined to be largely estrone, and no E2G was detected. Combustion analyses of residual soil extracts, which represented covalently bound radiochemical to the soil, resulted in recoveries ranging from 7 to 22% for 4 h to 28 d, respectively.