Unexpected effects of zinc pyrithione and imidacloprid on Japanese medaka fish ( Oryzias latipes)

• Published in: Aquatic toxicology 2005-09, Vol.74 (4), p.285-293
• Main Authors: Sánchez-Bayo, Francisco, Goka, Kouichi
• Format: Article
• Language: English
• Subjects: abnormal development; Agnatha. Pisces; animal stress; Animal, plant and microbial ecology; Animals; Applied ecology; Biocides; Biological and medical sciences; Body Size - drug effects; chemical substances; Chronic exposure; contaminants; Ecotoxicology, biological effects of pollution; Ectoparasitic Infestations - etiology; Ectoparasitic Infestations - veterinary; Fish Diseases - chemically induced; Fish parasites; flooded conditions; Freshwater; Fundamental and applied biological sciences. Psychology; General aspects; imidacloprid; Imidazoles - toxicity; Japan; Neonicotinoids; Nitro Compounds; Oligohymenophorea; Organometallic Compounds - chemistry; Organometallic Compounds - toxicity; Oryza sativa; Oryzias - growth & development; Oryzias latipes; parasites; Physiological stress; Pyridines - chemistry; Pyridines - toxicity; Rice; rough rice; Stress, Physiological - chemically induced; Stress, Physiological - complications; Stress, Physiological - veterinary; Tail - drug effects; Tail - growth & development; toxicity; Trichodina; Vertebrates: general zoology, morphology, phylogeny, systematics, cytogenetics, geographical distribution; water pollution; zinc pyrithione
• ISSN: 0166-445X; 1879-1514
• DOI: 10.1016/j.aquatox.2005.06.003

Biological effects of the biocide zinc pyrithione (Zpt), used in anti-dandruff shampoos and antifouling paints and the agricultural insecticide imidacloprid on Japanese medaka fish ( Oryzias latipes) were assessed in experimental rice fields. Both chemicals are toxic to medaka, in particular Zpt, which also causes teratogenic effects such as spinal cord deformities in embryos at very low, sublethal concentrations. Rates of malformation in medaka fry from paddies treated twice a week with anti-dandruff shampoo (0.18–0.37 μL/L each time) over a period of 4 months were within the natural background, perhaps due to the quick dissipation rate of this chemical in the environment. Both Zpt and imidacloprid caused stress syndrome in juvenile medaka, with fish from Zpt-shampoo fields having a significantly lower weight to body length ratio than those from control fields. As it often happens with stressed fish, a massive infestation by a Trichodina ectoparasite was observed in medaka from imidacloprid fields. However, despite their high stress levels, fish from the Zpt fields did not suffer such infestation, supposedly because the disinfectant action of this biocide.