Estrogen as an Environmental Pollutant.

Abstract

The paper ‘‘Estrogen as an Environmental Pollutant’’ appeared in the Bulletin of Environmental Contamination and Toxicology in 1993 (Shore et al. 1993). At the time it was one of the first papers to suggest that hormones excreted into the environment by humans and animals were present in sufficient quantities to disrupt the environment. Although originally an estrogen was defined as a compound that increase the uterine weight in the rats, in recent times, the ability to bind to the estrogen receptor has become the standard (Dorfman 1962; USEPA 1998). However, the receptor is also the site for chemicals to exert their anti-estrogenic actions. In nature there are some 300 natural compounds, and even more anthropogenic compounds, which have estrogenic or anti-estrogenic activity. These environmental estrogens can be categorized into four groups: (1) naturally occurring non-steroidal plant estrogens or phytoestrogens; (2) the steroid estrogens – 17b estradiol and estrone from animal and human sources; (3) the mycotoxins, zearalenone and zearalenol; (4) synthetic compounds with phenolic groups (Shemesh and Shore 1987; Lintelmann et al. 2003). In cows and sheep, the most important function of estrogen is to induce estrus behavior. However, too much estrogen, hyperestrogenism, can interfere with the function of the reproductive tract. Symptoms of hyperestrogenism in cattle include nymphomania (constant behavioral estrus), ovarian cysts and premature udder development (Shore and Bar-El Cohen 2010). Estrogens are also used in animal husbandry to increase growth in steers. In pigs, uterine prolapse caused by zearalenone is a common phenomenon. Phytoestrogens, in particular, are well documented to cause problems of infertility in cattle (Shemesh and Shore 1987). The function of the phytoestrogen in a legume is to signal the rhizobium to colonize the nodules. There is some evidence that the compounds may have evolved to be a mechanism to reduce fertility in foragers as well. A number of decades ago we noticed a rise in the level of coumestrol, a phytoestrogen, in alfalfa plants to levels associated with reproductive disorders. This was unrelated to any known trauma which we had previously described (Shemesh et al. 1969). It was found that the rise in coumestrol was correlated with irrigation by treated sewage water (Shore et al. 1995). When the treated sewage water was tested, estrone and 17b estradiol were readily detected. Furthermore, using experimental hothouse and hydroponic experiments, it was shown estrone and 17b estradiol in concentrations found in the irrigation water promoted vegetative growth (Shore et al. 1992). In separate line of investigation, it was observed that cattle, which were fed chicken manure silaged with wheat, developed premature udders. Examination of the chicken manure showed that the amount of steroidal estrogen ingested (1 mg/9 kg of feed/day) was high enough to explain the phenomenon (Shore et al. 1988; Shemesh and Shore 1994). Other reproductive disruptions could be attributed to the testosterone present in the manure (Shemesh and Shore 1994). These steroids were persistent in the environment as there was no decrease in either the content of testosterone or estrogen following 6 months of silaging (Shore and Shemesh 1993). In our 1993 paper in this journal, we focused on steroidal hormones since steroidal estrogens and testosterone from human and animal sources are constantly excreted & L. S. Shore laurenceshores@gmail.com