Downstream Effects of Hormonal Contraceptives

When we wash dishes in the kitchen sink, take a shower, or flush the toilet, we don't generally think about where that water goes; out of sight out of mind. We are fortunate to have the luxury of clean water and not worrying about how our water waste will again become clean, all thanks to water waste treatment plants (WWTP). With all of the different things that we put into our bodies and eventually into the water system, is our treated waste water really as clean as we think it is when it returns to the streams or rivers?

Unfortunately, some endocrine-active chemicals (EAC) still manage to make their way into WWTP effluent, and with the increasing availability of hormonal-based contraceptives and normalization of their use, we aren't the only species experiencing their reproductive effects. Vajda et al. (2008) looked into white sucker fish in Boulder Creek and found some of the population to be intersex. More specifically, samplings of white sucker fish were taken from a site approximately 2km upstream of the Boulder WWTP, and approximately 200m downstream of the WWTP effluent site, but only found intersex fish in the sample taken below the effluent site (Vajda et al., 2008).  Fish were considered to be intersex if both ovarian and testicular tissue were present during histological examination (Vajda et al., 2008). Of several steroidal estrogens that were observed in Boulder Creek, a couple of the more commonly recognized estrogens that were found in a higher relative concentrations were 17β-estradiol (E2) and ethinylestradiol, two chemicals used in common forms of contraceptives (Vajda et al., 2008). Colorado is a relatively arid-state, meaning that during low-flow conditions, the effluent from WWTP can make up a large amount of the creek's water flow, increasing the EAC concentration in the creek water (Vajda et al., 2008). This is of importance because the period of time that white sucker fish undergo sexual differentiation after hatching falls at the same time that Boulder Creek experiences these low-flow conditions where EAC concentration is highest (Vajda et al., 2008). This is a significant threat to this population since EACs are able to interfere with estrogen signaling pathways at even low concentrations, hence the emergence of intersex fish (Vajda et al., 2008). 

The region of Boulder Creek located below the effluent site had a female to male ratio with a significant female bias (Vajda et al., 2008). This has significant ethical implications when it comes to the future of the white sucker population in Boulder Creek. The efficiency of WWTPs ought to be improved in order to rid effluent water from EACs on the basis of beneficence and non-maleficence. Non-maleficence applies here, because although this study doesn't necessarily represent the entire population of white sucker fish, there have been other incidences where EAC contamination has led to the collapse of fish populations (Kidd et al., 2007). We should not be causing any harm, intended or unintended, to other populations as a result of our own chemical use. Beneficence is also important here, because by removing harmful EACs from natural water sources like Boulder Creek, we would help to promote normal reproductive processes in these fish populations. Fortunately, upgrades to the Boulder WWTP have been made slowing the feminization of male fish, but there is still a long way to go (CU Boulder Today, 2010).

References:

Gender-Bending Fish Problem in Colorado Creek Mitigated by Treatment Plant Upgrade. (2010, June 21). Retrieved November 29, 2019, from CU Boulder Today website: https://www.colorado.edu/today/2010/06/21/gender-bending-fish-problem-colorado-creek-mitigated-treatment-plant-upgrade

Kidd, K. A., Blanchfield, P. J., Mills, K. H., Palace, V. P., Evans, R. E., Lazorchak, J. M., & Flick, R. W. (2007). Collapse of a fish population after exposure to a synthetic estrogen. Proceedings of the National Academy of Sciences, 104(21), 8897–8901. https://doi.org/10.1073/pnas.0609568104

Vajda, A. M., Barber, L. B., Gray, J. L., Lopez, E. M., Woodling, J. D., & Norris, D. O. (2008). Reproductive Disruption in Fish Downstream from an Estrogenic Wastewater Effluent. Environmental Science & Technology, 42(9), 3407–3414. https://doi.org/10.1021/es0720661