Naturally produced steroid hormones and their release into the environment

Steroidal hormones produced by humans and animals are constantly excreted into the environment in their active forms. The primary steroid hormones are progesterone, estrone, estradiol, testosterone, and cortisol, all of which are lipophilic and poorly soluble in water. The steroids of major concern are estrone and estradiol-17beta, since they exert their physiological effects at a lower concentration than other steroids and can be found in the environment in concentrations above their lowest observable effect level for fish and plants (10 ng/l). The steroid hormones can be readily measured in run-off, soil, and groundwater, but each steroid has its distinct pathway of transport. Since the major source of steroids in the environment appears to be cattle and chickens, the hormonal steroid input into the environment could be drastically reduced by well-established techniques such as buffer strips and composting.