The environmental fate of synthetic and naturally produced hormones/growth promoters used in livestock production is not well understood. Two such compounds: tylosin, a macrolide antibiotic and progesterone, an estrogenic steroid are used as growth promoters. We conducted batch sorption experiments to measure the sorption of these two compounds to several different soils with varying sorbent properties. Our results show that tylosin sorption is linear to all soils with soil organic matter partition coefficients (KOC) consistent with previously reported values (390-1130 L/kg). Paradoxically the KOC values are much higher than the compound's octanol/water partition coefficient (KOW = 316), possibly due to adsorption of positively charged tylosin species to specific sites on the sorbent. Progesterone exhibited linear sorption with KOC's ranging from 471-1063 L/kg, but some of our isotherms also deviated from linearity. We are currently studying how both the sorbate and sorbent properties influences the sorption of our target compounds.

Sorption of tylosin and progesterone to Midwestern soils

243rd National Meeting (2012)

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