title: Screening breeding sites of the common toad (Bufo bufo) in England and Wales for evidence of endocrine disrupting activity.
abstract: Anuran amphibians are often present in agricultural landscapes and may therefore be exposed to chemicals in surface waters used for breeding. We used passive accumulation devices (SPMD and POCIS) to sample contaminants from nine breeding sites of the Common toad (Bufo bufo) across England and Wales, measuring endocrine activity of the extracts in a recombinant yeast androgen screen (YAS) and yeast estrogen screen (YES) and an in vitro vitellogenin induction screen in primary culture of Xenopus laevis hepatocytes. We also assessed hatching, growth, survival, and development in caged larvae in situ, and sampled metamorphs for gonadal histopathology. None of the SPMD extracts exhibited estrogen receptor or androgen receptor agonist activity, while POCIS extracts from two sites in west-central England exhibited concentration-dependent androgenic activity in the YAS. Three sites exhibited significant estrogenic activity in both the YES and the Xenopus hepatocyte. Hatching rates varied widely among sites, but there was no consistent correlation between hatching rate and intensity of agricultural activity, predicted concentrations of agrochemicals, or endocrine activity measured in YES/YAS assays. While a small number of intersex individuals were observed, their incidence could not be associated with predicted pesticide exposure or endocrine activitity measured in the in vitro screens. There were no significant differences in sex ratio, as determined by gonadal histomorphology among the study sites, and no significant correlation was observed between proportion of males and predicted exposure to agrochemicals. However, a negative correlation did become apparent in later sampling periods between proportion of males and estrogenic activity of the POCIS sample, as measured in the YES. Our results suggest that larval and adult amphibians may be exposed to endocrine disrupting chemicals in breeding ponds, albeit at low concentrations, and that chemical contaminants other than plant protection products may contribute to endocrine activity of surface waters in the agricultural landscape.
authors.affiliation: Institute for the Environment, Brunel University, Kingston Lane, Uxbridge, Middlesex UB8 3PH, United Kingdom. Electronic address: dan.pickford@syngenta.com.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Pickford
authors.affiliation: Institute for the Environment, Brunel University, Kingston Lane, Uxbridge, Middlesex UB8 3PH, United Kingdom.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Jones
authors.affiliation: Institute for the Environment, Brunel University, Kingston Lane, Uxbridge, Middlesex UB8 3PH, United Kingdom.
authors.forename: Alejandra
authors.initials: A
authors.lastname: Velez-Pelez
authors.forename: Frances
authors.initials: F
authors.lastname: Orton
authors.affiliation: National Institute for Basic Biology, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi 444-8787, Japan.
authors.forename: Taisen
authors.initials: T
authors.lastname: Iguchi
authors.affiliation: Environmental Risk Research Center, Institute of Environmental Ecology, IDEA Consultants, Inc., 1334-5 Riemon, Yaizu, Shizuoka 421-0212, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Mitsui
authors.affiliation: Environmental Risk Research Center, Institute of Environmental Ecology, IDEA Consultants, Inc., 1334-5 Riemon, Yaizu, Shizuoka 421-0212, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Tooi
mesh_terms: D000383:Agriculture; D000728:Androgens / Q000032:analysis; D000818:Animals; D001681:Biological Assay; D001947:Breeding; D002023:Bufo bufo / Q000254:growth & development*; D017753:Ecosystem; D052244:Endocrine Disruptors / Q000032:analysis*; D004739:England; D004967:Estrogens / Q000032:analysis*; D005260:Female; D006066:Gonads / Q000033:anatomy & histology; D022781:Hepatocytes; D006801:Humans; D007814:Larva / Q000254:growth & development; D008297:Male; D010575:Pesticides; D061005:Ponds / Q000737:chemistry*; D011960:Receptors, Estrogen; D012744:Sex Ratio; D014819:Vitellogenins; D014852:Wales; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014981:Xenopus; D015003:Yeasts
chemical_list: D000728:Androgens; D052244:Endocrine Disruptors; D004967:Estrogens; D010575:Pesticides; D011960:Receptors, Estrogen; D014819:Vitellogenins; D014874:Water Pollutants, Chemical
keywords: Amphibian; Bufo bufo; Endocrine active substance; Pesticide; Recombinant yeast assay; Vitellogenin