RESUMO
In this study, the fate of steroid hormones in beef cattle manure composting is evaluated. The fate of 16 steroids and metabolites was evaluated in composted manure from beef cattle administered growth promotants and from beef cattle with no steroid hormone implants. The fate of estrogens (primary detected as estrone), androgens, progesterone, and the fusarium metabolite and implant α-zearalanol was monitored in manure compost piles. First-order decay rates were calculated for steroid half-lives in compost and ranged from 8 d for androsterone to 69 d for 4-androstenedione. Other steroid concentration data could not be fit to first-order decay models, which may indicate that microbial processes may result in steroid production or synthesis in composting systems. We demonstrate that composting is an effective strategy to remove steroid hormones from manure. Total steroid hormone removal in composted beef cattle manure ranged from 79 to 87%.