Effects of light on the cytotoxicity and Genotoxicity of Benzo(a)pyrene and an oil refinery effluent in the newt

Abstract

The genotoxicity and/or toxicity of benzo(a)pyrene (BaP) were evaluated under different lighting conditions in larvae and embryos of the newt Pleurodeles waltl. Visible light alone (1,220 lx; 2.1 mW/cm2), UVA alone (250 microW/cm2), or BaP alone (500, 50, 25, 12.5 ppb) had no toxic effects on the larvae. Conversely, toxic effects were observed in animals exposed to BaP (500 ppb)+daylight, or BaP (> or = 25 ppb)+UVA. BaP solutions (50 or 12.5 ppb) were irradiated for 24 hr (Irr BaP) prior to being assayed in the dark. The genotoxicity of BaP (50 ppb) as evaluated in the micronucleus test (on day 8) was halved by its previous exposure to UVA, and was abolished at the lowest concentration (12.5 ppb). In other experiments, the larvae were exposed alternatively to BaP or Irr BaP (18 hr in the dark) and UVA (6 hr in water), every day for 8 days. All animals that had accumulated non-irradiated BaP (50 ppb) showed signs of severe toxicity, and 90% died before the end of the test. On the other hand, irradiated BaP (50 ppb) was 4-fold less toxic and half as genotoxic as non-irradiated BaP. In addition, exposure of the animals to UVA alone for 4 days prior to treatment with BaP did not affect the genotoxicity or toxicity of this hydrocarbon. In the dark, the embryotoxicity of BaP was markedly attenuated by the presence of the jelly coats (10% vs. 24%). With dejellied embryos, comparable mortality (24%) was observed after exposure to 25 ppb BaP for 54 or 312 hr. Although UVA alone did not affect growth of the embryos, the toxicity of BaP was enhanced by the combined action of the two agents together or in succession (BaP+UVA or BaP then UVA). Larvae were treated with an oil refinery effluent (EF). At the concentration employed (125 ml/l), EF was not found to be genotoxic in the dark. However, in animals exposed to both EF and UVA, there was a progressive increase in level of micronucleated erythrocytes with increasing duration of daily exposure to UVA (9, 15, 24 hr). Moreover, the genotoxic potential of irradiated EF+UVA was systematically below that of non-irradiated EF+UVA for all durations of exposure to ultraviolet light. Irradiation of this type of effluent might help reduce its harmful effects on aquatic species. Our results also suggest that metabolic activation is not necessary for hydrocarbons to induce toxic effects.

Induction of micronucleated cells in the shed skin of salamanders (Ambystoma sp.) treated with colchicine or cyclophosphamide

“…Previous MN assays that used blood erythrocytes from amphibians required treatments that lasted over 2-3 months [Jaylet et al, 1986;Le et al, 1992;Fernandez and I'Haridon, 1994], and thus animals had a greater chance of dying during the long exposure period, and more test compound was required for the assay [Siboulet et al, 1984;Jaylet et al, 1986;Le et al, 1992;Fernandez and I'Haridon, 1994], which increases the cost of the trial. Furthermore, in the present assay, it was not necessary to sacrifice the animal to obtain the sample.…”

“…The use of non-human organisms to study genotoxic agents is rapidly increasing [Ruiz et al, 1992;Al-Sabti and Metcalfe, 1995;Burgeot et al, 1995;Choy et al, 1995;Jena and Bhunya, 1995;Ma et al, 1995;Zúñiga-González et al, 1998, 2001a, 2001b, and amphibians are of special interest in this regard due to their ecological niche [Jaylet et al, 1986;Krauter et al, 1987;Le et al, 1992;Rudek and Rozek, 1992;Fernandez and I'Haridon, 1994]. Urodela, which includes salamanders and newts, is one of the three surviving orders of the amphibian class.…”

Toxicity of coal-tar pavement sealants and ultraviolet radiation to Ambystoma Maculatum

“…Fernandez and l'Haridan (1994) found that mortalities resulted from exposing larvae of the Spanish ribbed newt (Pleurodeles waltl) to 25 lg/L of benzo(a)pyrene (BaP) in water under UVA radiation. Tadpoles of northern leopard frogs (Rana pipiens) experienced similar results when they were exposed to 30.6 lg/L of fluoranthene and 250 lg/L of anthracene.…”

“…Harmful effects in amphibian larvae and other aquatic organisms include cancerous growths and cellular abnormalities (Eisler 2000), genotoxicity and micronucleated erythrocytes (Jaylet 1971;Fernandez and l'Haridan 1992;Gauthier et al 1993), inhibition of growth and metamorphosis (Fernandez and l'Haridan 1994), edema and impaired gas exchange (McGrath and Alexander 1979), activation of mixed function oxidases or other cellular metabolic defense mechanisms (Schwen and Mannering 1982;Noshiro and Omura 1984), changes in activity, inability to swim properly, the appearance of skin lesions, and death (Hedtke and Puglisi 1982;Arfsten et al 1996;Lefcort et al 1997;Eisler 2000;Sparling 2000;and Blaustein et al 2003). Amphibians can bioaccumulate PAHs (Grinfield et al 1986;Vojinovic-Miloradov et al 1996) but there is evidence that amphibians can develop an equilibrium in body concentrations after several days of exposure (Garrigues et al 2004).…”

The Effects of Coal Tar Based Pavement Sealer on Amphibian Development and Metamorphosis

“…Benzo(a)pyrene, a frequently encountered PAH, was lethal to newt larvae at low levels (50 ppb) (Fernandez and Lharidon, 1994). Sadinski et al (1995) showed that Xenopus laevis had slower development and growth after exposure to 249 nM benzo(a)pyrene, a sublethal concentration equivalent to approximately 60 ppb.…”