Environmental Toxicology and Chemistry, Vol. 33, No. 3, pp. 560–566, 2014 # 2013 SETAC Printed in the USA
PHYTOESTROGENS IN THE ENVIRONMENT, II: MICROBIOLOGICAL DEGRADATION OF PHYTOESTROGENS AND THE RESPONSE OF FATHEAD MINNOWS TO DEGRADATE EXPOSURE MEGAN M. KELLY,y NATHAN T. FLEISCHHACKER,z DANIEL C. REARICK,x WILLIAM A. ARNOLD,yz HEIKO L. SCHOENFUSS,x and PAIGE J. NOVAK*yz yWater Resources Science Graduate Program, University of Minnesota, St. Paul, Minnesota, USA zDepartment of Civil Engineering, University of Minnesota, St. Paul, Minnesota, USA xAquatic Toxicology Laboratory, St. Cloud State University, St. Cloud, Minnesota, USA (Submitted 16 August 2013; Returned for Revision 23 September 2013; Accepted 8 November 2013) Abstract: Phytoestrogens are endocrine active compounds derived from plants, including the isoflavones genistein and daidzein, and their
methylated derivatives biochanin A and formononetin. These compounds have been detected at the mg/L level in the effluents of plantprocessing industries and municipal treatment plants and at the ng/L level in surface waters worldwide. The present study assessed the persistence of genistein and daidzein in natural aquatic systems, specifically riverine samples. Initial concentration, temperature, sample location, and time of sample collection varied. Genistein and daidzein were found to be readily biodegradable at all tested concentrations, at both 10 8C and 20 8C, in samples collected during different seasons, and in samples from 3 different rivers. In addition, organismal responses in larval and sexually mature fathead minnows (Pimephales promelas) were quantified following exposure to microbiologically degraded phytoestrogens (genistein, daidzein, and formononetin). Products of the microbiological degradation of parent phytoestrogens did not affect larval survival, growth, or predator avoidance. Female adult fathead minnows exposed to these degradation products produced significantly fewer eggs than those exposed to a control, but no other morphological, physiological, or behavioral changes were observed with male or female minnows. The present research suggests that although phytoestrogens are not likely to persist in aquatic systems, they may pseudo-persist if discharges are continuous; in addition, caution should be exercised with respect to high-concentration effluents because of the potentially antiestrogenic effects of phytoestrogen degradates. Environ Toxicol Chem 2014;33:560–566. # 2013 SETAC
Keywords: Environmental fate
Endocrine disrupting compounds
Emerging pollutants
Phytoestrogens
Biodegradation
phytoestrogens (e.g., Mahmood-Khan & Hall, [18]), with a study measuring genistein concentrations in pulp and paper mill effluent at 10.1 mg/L [19]. In addition to industrial processes, humans are capable of excreting up to several milligrams of phytoestrogens per day depending on diet. This points to the likely presence of these compounds in municipal wastewater treatment plant (WWTP) effluents [20,21]. Studies conducted on municipal WWTP effluents have detected the presence of phytoestrogens at a range of concentrations (
PHYTOESTROGENS IN THE ENVIRONMENT, II: MICROBIOLOGICAL DEGRADATION OF PHYTOESTROGENS AND THE RESPONSE OF FATHEAD MINNOWS TO DEGRADATE EXPOSURE MEGAN M. KELLY,y NATHAN T. FLEISCHHACKER,z DANIEL C. REARICK,x WILLIAM A. ARNOLD,yz HEIKO L. SCHOENFUSS,x and PAIGE J. NOVAK*yz yWater Resources Science Graduate Program, University of Minnesota, St. Paul, Minnesota, USA zDepartment of Civil Engineering, University of Minnesota, St. Paul, Minnesota, USA xAquatic Toxicology Laboratory, St. Cloud State University, St. Cloud, Minnesota, USA (Submitted 16 August 2013; Returned for Revision 23 September 2013; Accepted 8 November 2013) Abstract: Phytoestrogens are endocrine active compounds derived from plants, including the isoflavones genistein and daidzein, and their
methylated derivatives biochanin A and formononetin. These compounds have been detected at the mg/L level in the effluents of plantprocessing industries and municipal treatment plants and at the ng/L level in surface waters worldwide. The present study assessed the persistence of genistein and daidzein in natural aquatic systems, specifically riverine samples. Initial concentration, temperature, sample location, and time of sample collection varied. Genistein and daidzein were found to be readily biodegradable at all tested concentrations, at both 10 8C and 20 8C, in samples collected during different seasons, and in samples from 3 different rivers. In addition, organismal responses in larval and sexually mature fathead minnows (Pimephales promelas) were quantified following exposure to microbiologically degraded phytoestrogens (genistein, daidzein, and formononetin). Products of the microbiological degradation of parent phytoestrogens did not affect larval survival, growth, or predator avoidance. Female adult fathead minnows exposed to these degradation products produced significantly fewer eggs than those exposed to a control, but no other morphological, physiological, or behavioral changes were observed with male or female minnows. The present research suggests that although phytoestrogens are not likely to persist in aquatic systems, they may pseudo-persist if discharges are continuous; in addition, caution should be exercised with respect to high-concentration effluents because of the potentially antiestrogenic effects of phytoestrogen degradates. Environ Toxicol Chem 2014;33:560–566. # 2013 SETAC
Keywords: Environmental fate
Endocrine disrupting compounds
Emerging pollutants
Phytoestrogens
Biodegradation
phytoestrogens (e.g., Mahmood-Khan & Hall, [18]), with a study measuring genistein concentrations in pulp and paper mill effluent at 10.1 mg/L [19]. In addition to industrial processes, humans are capable of excreting up to several milligrams of phytoestrogens per day depending on diet. This points to the likely presence of these compounds in municipal wastewater treatment plant (WWTP) effluents [20,21]. Studies conducted on municipal WWTP effluents have detected the presence of phytoestrogens at a range of concentrations (
