title: Radiation-induced bystander effects in the Atlantic salmon (salmo salar L.) following mixed exposure to copper and aluminum combined with low-dose gamma radiation.
abstract: Very little is known about the combined effects of low doses of heavy metals and radiation. However, such "multiple stressor" exposure is the reality in the environment. In the work reported in this paper, fish were exposed to cobalt 60 gamma irradiation with or without copper or aluminum in the water. Doses of radiation ranged from 4 to 75 mGy delivered over 48 or 6 h. Copper doses ranged from 10 to 80 μg/L for the same time period. The aluminum dose was 250 μg/L. Gills and skin were removed from the fish after exposure and explanted in tissue culture flasks for investigation of bystander effects of the exposures using a stress signal reporter assay, which has been demonstrated to be a sensitive indicator of homeostatic perturbations in cells. The results show complex synergistic interactions of radiation and copper. Gills on the whole produce more toxic bystander signals than skin, but the additivity scores show highly variable results which depend on dose and time of exposure. The impacts of low doses of copper and low doses of radiation are greater than additive, medium levels of copper alone have a similar level of effect of bystander signal toxicity to the low dose. The addition of radiation stress, however, produces clear protective effects in the reporters treated with skin-derived medium. Gill-derived medium from the same fish did not show protective effects. Radiation exposure in the presence of 80 μg/L led to highly variable results, which due to animal variation were not significantly different from the effect of copper alone. The results are stressor type, stressor concentration and time dependent. Clearly co-exposure to radiation and heavy metals does not always lead to simple additive effects.
authors.affiliation: Medical Physics and Applied Radiation Sciences Department, McMaster University, Hamilton, ON, L8S 4K1, Canada, mothers@mcmaster.ca.
authors.forename: Carmel
authors.initials: C
authors.lastname: Mothersill
authors.forename: Richard W
authors.initials: RW
authors.lastname: Smith
authors.forename: Lene Sørlie
authors.initials: LS
authors.lastname: Heier
authors.forename: Hans-Christian
authors.initials: HC
authors.lastname: Teien
authors.forename: Ole Christian
authors.initials: OC
authors.lastname: Lind
authors.forename: Ole Christian
authors.initials: OC
authors.lastname: Land
authors.forename: Colin B
authors.initials: CB
authors.lastname: Seymour
authors.forename: Deborah
authors.initials: D
authors.lastname: Oughton
authors.forename: Brit
authors.initials: B
authors.lastname: Salbu
mesh_terms: D000535:Aluminum / Q000633:toxicity*; D000818:Animals; D024201:Bystander Effect / Q000187:drug effects* / Q000528:radiation effects*; D003300:Copper / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004785:Environmental Pollutants / Q000633:toxicity*; D005720:Gamma Rays / Q000009:adverse effects*; D020317:Salmo salar
chemical_list: D004785:Environmental Pollutants; D003300:Copper; D000535:Aluminum