EE, that are not completely broken down by wastewater treatment procedures. The input of artificial estrogens into freshwater ecosystems affects fish and amphibian populations. Chronic exposure to low levels of EE over seven years led to the collapse of fathead minnow populations in an experimental lake in Ontario, Canada. EE changed oogenesis in female fish and feminized male fish such that they produced a protein associated with egg maturation, vitellogenin, as well as early-stage eggs. In amphibians, exposure to EE can reduce hatching success and alter gonadal development. Exposure to hormones can change frogs' gonadal development even though it is encoded in their genes. A study of mink frogs found more intersex tadpoles in those experimentally exposed to EE than those not exposed to EE, and green frogs showed much lower rates of hatching success. Overdose Estrogens like EE are relatively safe in acute overdose. Interactions EE is metabolized by certain cytochrome P450 isoforms, including CYP3A4 and CYP2C9. Thus, inducers of enzymes such as CYP3A4 can decrease circulating concentrations of EE. Examples of inducers include anticonvulsants like phenytoin, primidone, ethosuximide, phenobarbital, and carbamazepine; azole antifungals like fluconazole; and rifamycin antibiotics like rifampin (rifampicin). Conversely, inhibitors of CYP3A4 and other cytochrome P450 enzymes may increase circulating levels of EE. An example is troleandomycin, which is a potent and highly selective inhibitor of CYP3A4. Paracetamol (acetaminophen) has been found to competitively inhibit the sulfation of EE, with pretreatment of 1,000 mg of paracetamol significantly increasing the AUC levels of EE (by 22%) and decreasing the AUC levels of ethinylestradiol sulfate (EE sulfate) in women. The same has been found for ascorbic acid (vitamin C) and EE, although the significance of the interaction has been regarded as dubious. In contrast to estradiol, it is unlikely that there is a pharmacokinetic interaction between smoking (which potently induces certain cytochrome P450 enzymes and markedly increases the 2-hydroxylation of estradiol) and EE. This suggests that estradiol and EE are metabolized by different cytochrome P450 enzymes. There is, however, an increased risk of cardiovascular complications with smoking and EE, similarly to the case of smoking and other estrogens. EE is known to inhibit several cytochrome P450 enzymes, including CYP1A2, CYP2B6, CYP2C9, CYP2C19, and CYP3A4, and is possibly an inducer of CYP2A6. As a result, it can affect the metabolism and concentrations of many other drugs. Examples of known interactions include bupropion, caffeine, mephenytoin, midazolam, nicotine, nifedipine, omeprazole,