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Feminisation of fish 14. Possible non-sewage effluent related sources of estrogens to the aquatic environmentThe possibility that other sources to estrogens in the aquatic environment exist besides direct release with sewage effluent also has to be considered when evaluating the exposure risk for the aquatic fauna towards exposure to estrogens. A source which has been considered is the manure from cattle, pigs, poultry and other domestic animals (258-261). Runoff from spreading of manure on fields for fertilisation might take place and has been demonstrated for poultry manure (259-261). The concentration of estrogens in manure from domestic animals has been estimated in a report by the Dutch Association of River Waterworks (258). Estrogen emission from pregnant cows in faeces and urine as both conjugated and unconjugated estrogens has been estimated to 37.3 mg/day based on an average concentration during gestation of 54 µg/kg manure (in (258)). In non-pregnant cows the daily excretion was assessed to 1.1 mg/day or 30 µg/kg. A dutch study has reported concentration of estrogens (DW) in manure from cattle to 46 – 50 µg/kg 17ß-estradiol, 28 – 72 µg/kg estrone and <1 µg/kg ethinylestradiol (6). The estrogen emission from breeding and non-breeding sows as manure and urine has been estimated to 6.8 mg/day (1.13 mg/kg manure) and 31.7 µg/day, respectively. From chicken the emission of estrogens by urine is negligible compared to emission by manure in which a total content between 14 µg/kg dry weight for male chicks and 533 µg/kg for laying hens (262). One experiment with application of 5000 kg/ha of chicken manure to fields yielded runoff concentrations of 3.5 µg E2/l and 1413 mg/ha after simulated rainfall (50 mm/h) (261). The runoff was generated immediately after litter application and designed to represent worst case scenario. Another study by Nichols et al. has demonstrated first runoff concentrations of 1.28 µg/l and 198.8 mg/ha after application of 7050 kg/ha (260). Second runoff concentrations were 66 and 69 % less than that of first runoff. Part of the estrogens applied with manure will bind to the soil. Experiments in which heavy soil from a field was irrigated for several months with sewage water indicated that 56 ± 2 % of the estradiol and 59 ± 2 % of estrone was strongly bound by the soil and only extractable by organic solvents. Testosterone, on the other hand, was readily washed out by aqueous solutions (262). In general, however, not much literature exists on the subject of manure as a potential risk source for estrogens to the aquatic environment and it is yet difficult to estimate the importance of this as a possible contributor to stream and river contents of estrogens. Sludge from sewage treatment plants are besides manure also used to fertilise fields in Denmark. As mentioned in chapter 5 estrogens and xenoestrogens have a high log Kow and therefore a strong absorbance to organic material. In the sewage treatment process a proportion of the estrogens will therefore accumulate in sludge (see chapter 11) and estrogens have been demonstrated to persist during sludge digestion (263). In activated and digested sewage sludge from a German study, estrone and 17ß-estradiol have been detected at concentrations up to 37 ng/g and 49 ng/g, respectively. Ethinylestradiol was detected at concentrations up to 17 ng/g (263). Nonylphenol has been detected at concentrations of 137 ± 7.7 and 470 ± 22 µg/g in measurements of sludge from two Canadian STPs (264), 172 µg/g in sludge fra a Spanish STP (265) and < 0.125 – 4.59 ± 0.11 µg/g in sludge from two German STPs (266). In Denmark in 1995 alkylphenols were reported in the range of 0.3 – 67 µg/g with a median concentration of 8 µg/g. The cut off value for using sludge as fertiliser on fields was in 2000 set to 10 µg/g (267). Octylphenol has been detected at concentrations of 9.2 ± 0.4 and 12.1 ± 0.5 µg/g and 7.5 µg/g in sludge from two Canadian and one Spanish STP, respectively. Bisphenol A seems to be present in even lower concentrations and has been reported to < 0.125 – 0.078 – 0.09 µg/g in sludge from two German STPs. Again, however, little information exist on the runoff of estrogenic compounds from the sludge once deposited on the field. An experiment in which sewage sludge was applied to sandy soil in lysimeters, few leachate samples induced growth of human breast cancer cells (MCF-7) cells in the E-screen. The highest estrogenic activity in leachate samples, detected as estrogen equivalents, was 2.94 ng/l (268). The measured concentrations of various estrogenic compounds in the sewage sludge were: nonylphenol, 1.51 mg/g; bisphenol A, 0.38 µg/g; 17a -estradiol, < 2 ng/g and 17 ß-estradiol, 3.5 ng/g. Most leachate and soil extract samples gave no response in the E-screen. Conclusively, too little is known about runoff of estrogenic compounds from both manure and sludge, used as fertiliser on fields and it is not possible yet to assess whether these are considerable sources of estrogenic activity to the surface waters.
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