Dynamics of uptake and elimination of 17α-ethinylestradiol in male goldfish (Carassius auratus)

We used male goldfish (Carassius auratus) as a model species to determine the uptake, elimination, and bioaccumulation of 17α-ethinylestradiol (EE2). Goldfish were exposed to EE2 via two different routes: water (135ng/L±12.8 standard deviation) for 72h, and food (231ng/g±42 SD) for 120h. We observed a rapid uptake of EE2 in goldfish, reaching 8.4ng/g±1.2 dry weight (dw) after the first hour of exposure with an uptake rate coefficient (k1) of 45h(-1). The elimination rate coefficient (k2) was determined by a depuration experiment to be 0.0786h(-1). In the feeding experiment, EE2 concentrations increased rapidly, reaching an average of 1.4ng/g after 3h following the first dietary exposure with an estimated absorption efficiency (α) of 0.106. An average of 2.66ng/g±0.87 (n=8) was determined in the 24-72h samples, whereas EE2 concentrations in fish fell below our method detection limits (0.67ng/g) for all samples after 72h, suggesting efficient elimination over time. The bioconcentration factor (BCF) for EE2 reached a maximum of 377, similar to BCFs measured for other pharmaceuticals like fluoxetine and sertraline. Our kinetic data were also used to model various scenarios of EE2 uptake in the aquatic environment. To our knowledge, this is the first report to describe aqueous and dietary EE2 uptake and elimination in fish, as well as providing important data to model EE2 kinetics in fish.

The occurrence of steroidal estrogens in south-eastern Ontario wastewater treatment plants

We measured steroidal estrogens in wastewater in Ottawa and Cornwall (Ontario, Canada) to determine removal efficiency of these steroids during the treatment process, and whether removal varies during a seasonal cycle. Estrone (E1), 17β-estradiol (E2) and 17α-ethinylestradiol (EE2) were found at maximum concentrations in raw sewage (RS), at 104, 66.9 and 5.7 ng L(-1), respectively. For the Ottawa wastewater treatment plant (WWTP), there was sufficient data to show that E1 concentrations in RS correlated with both ambient air temperature and mean daily flow of the WWTP (R(2)=0.792, p=0.003 and R(2)=0.757, p=0.005). E1 removal was correlated with the percent difference in cBOD from RS to FE (final effluent) (R(2)=0.435, p=0.075). However estrogenic potency, as determined by a sensitive in vitro reporter gene assay, did not decrease during the water treatment process, suggesting that many estrogenic chemicals are conserved in FE. E1 and EE2 were found in river water, both upstream and downstream of the WWTPs, and at much lower concentrations than in FE. Our study demonstrates the persistence of steroidal estrogens and estrogenic potency in Ontario WWTP effluents and surface waters, and has uncovered temporal patterns of release that may be used to help predict risks to aquatic organisms in these environments.

Lumiestrone is Photochemically Derived from Estrone and may be Released to the Environment without Detection

Endocrine disrupting chemicals are adversely affecting the reproductive health and metabolic status of aquatic vertebrates. Estrone is often the dominant natural estrogen in urban sewage, yet little is known about its environmental fate and biological effects. Increased use of UV-B radiation for effluent treatments, and exposure of effluents to sunlight in holding ponds led us to examine the effects of environmentally relevant levels of UV-B radiation on the photodegradation potential of estrone. Surprisingly, UV-B-mediated degradation leads to the photoproduction of lumiestrone, a little known 13α-epimer form of estrone. We show for the first time that lumiestrone possesses novel biological activity. In vivo treatment with estrone stimulated estrogen receptor (ER) α mRNA production in the male goldfish liver, whereas lumiestrone was without effect, suggesting a total loss of estrogenicity. In contrast, results from in vitro ER-dependent reporter gene assays indicate that lumiestrone showed relatively higher estrogenic potency with the zebrafish ERβ2 than zfERα, suggesting that it may act through an ERβ-selectivity. Lumiestrone also activated human ERs. Microarray analysis of male goldfish liver following in vivo treatments showed that lumiestrone respectively up- and down-regulated 20 and 69 mRNAs, which was indicative of metabolic upsets and endocrine activities. As a photodegradation product from a common estrogen of both human and farm animal origin, lumiestrone is present in sewage effluent, is produced from estrone upon exposure to natural sunlight and should be considered as a new environmental contaminant.

Environmental factors affecting ultraviolet photodegradation rates and estrogenicity of estrone and ethinylestradiol in natural waters

The environmental fate and persistence of steroidal estrogens is influenced by their photodegradation. This can potentially occur both in the presence of the ultraviolet (UV) portion of solar radiation and in tertiary wastewater treatment plants that use UV radiation for disinfection purposes. To determine patterns of UV photodegradation for estrone (E1) and 17α-ethinylestradiol (EE2), water samples containing these compounds were exposed to levels of UVB radiation that would simulate exposure to ambient sunlight. E1 degraded with a pseudo-first-order rate law constant that was directly proportional to UVB radiation intensity (R² = 0.999, P < 0.001) and inversely proportional to dissolved organic carbon (DOC) concentration (R² = 0.812, P = 0.037). DOC acted as a competitive inhibitor to direct photolysis of E1 by UV. In contrast to E1, EE2 was more persistent under similar UVB treatment. A reporter gene assay showed that the estrogenicity of UVB-exposed estrogens did not decrease relative to non-UVB-exposed estrogens, suggesting that some of the photoproducts may also have estrogenic potency. These results show that environmental degradation rates of steroidal estrogens are predictable from the UV intensity reaching surface waters, and the DOC concentrations in these surface waters.