Since the inception of global industrialization, steroidal estrogens have become an emerging and serious concern. Steroid estrogens including estrone, estradiol and estriol, (Fig. 1) pose serious threats to soil, plants, water resources and humans. The world’s human population of about 7 billion discharges approximately 30,000 Kg/yr. of natural steroidal estrogens (E1, E2, and E3) and an additional 700 Kg/yr. of synthetic estrogens (EE2) solely from birth control pill practices. However, the possible release of estrogens to the environment from livestock is much higher (Fig. 2). Indeed, estrogens have gained notable attention in recent years, due to their rapidly increasing concentrations in soil and water all over the world. Concern has been expressed regarding the entry of estrogens into the human food chain which in turn relates to how plants take up and metabolism estrogens.
In comprehensive review study, authors have examined the effects of exogenous estrogens on animal and human health, on pollution of aquatic systems and on plant growth and development. Furthermore, study explore the environmental fate of estrogens highlighting their release through effluent sources, their uptake, partitioning and physiological effects in the ecological system. They draw attention to the potential risks of intensive modern agriculture and waste disposal systems on estrogen release and their effects on human health. Additionally, also highlight their uptake and metabolism in plants.
Estrogens at polluting levels have been detected at sites close to waste water treatment facilities and in groundwater at various sites globally (Fig. 3). Estrogens at pollutant levels have been linked with breast cancer in women and prostate cancer in men. Estrogens also perturb fish physiology and can affect reproductive development in both domestic and wild animals. Treatment of plants with steroid estrogen hormones or their precursors can affect root and shoot development, flowering and germination. However, estrogens can ameliorate the effects of other environmental stresses on the plant.
A series of recent papers describe estrogen uptake studies in plants. Batch and continuous flow tests involving waste water indicated that algae and duckweed play a crucial role in the removal of estrogens. The uptake of organic contaminants from the soil into plants is strongly affected by their concentration in the voids between soil and water (Fig. 4). Interestingly, several recent reports provide evidence that estrogens can alleviate some of the symptoms associated with toxic metal-induced oxidative damage. In maize and chickpea, exogenous androsterone treatment reduced significantly, oxidative damage caused from chilling stress by increasing the levels of antioxidant enzymes, including superoxide dismutase (SOD), guaicol peroxidase (POX), catalase, ascorbate peroxidase (APX) and glutathione reductase.
Review study have tried to raise critical awareness of the route of potentially harmful estrogens through the food chain. There is published evidence to establish a causal relationship between estrogens in the environment and breast cancer. However, there are serious gaps in our knowledge about estrogen levels in the environment and a call is required for a world wide effort to provide more data on many more samples sites. Of the data available, the synthetic estrogen, ethinyl estradiol, is more persistent in the environment than natural estrogens and may be a greater cause for environmental concern. Additionally, authors believe that there is an urgent requirement for inter-disciplinary studies of estrogens in order to better understand their ecological and environmental impact. At the end, authors have suggested very solid practical solution the overcome this mounting challenge for human health.
· Estrogen should be listed as a toxic organic pollutant which is confirmed by several studies;
· Many more data about estrogen levels in the natural environment from many more sites world-wide are urgently required;
· A greater data pool should enable tests that model the accumulation of natural as opposed to synthetic estrogens in the environment and in particular at those sites close to water treatment and sewage disposal systems;
· Estrogen pollution is becoming a vital environmental concern and has deleterious effects on human, animal and plant growth and development at significant levels. Attention to this issue is crucial and demands further in-depth investigation;
· Establishing a causal link between increased presence of environmental estrogens and increased incidences of breast cancer requires
more data;
· The role of estrogens in biological systems is also ambiguous. In addition, further studies are also required to determine tolerance, because still the impact of estrogen-toxicity in many ecosystems is not clear.
Reference
Adeel, Muhammad, et al. “Environmental impact of estrogens on human, animal and plant life: a critical review.” Environment international 99 (2017): 107-119. DOI: 10.1016/j.envint.2016.12.010
