Increasing uranium exposure durations to the aquatic snail Amerianna cumingi does not result in lower toxicity estimates.
Reproductive inhibition (egg production) of the aquatic snail Amerianna cumingi over 4 d has been used to derive toxicity estimates for toxicants of concern in tropical Australia. Toxicity estimates from this test have been used as chronic data points in species sensitivity distributions (SSDs) for deriving site-specific guideline values. However, revised guidance for the Australian and New Zealand Water Quality Guidelines advises that test durations for adult macroinvertebrates should be ≥14 d to be considered chronic. Hence, to strengthen the data set underpinning the site-specific guideline value for uranium (U) in Magela Creek, which receives water from the Ranger Uranium Mine in northern Australia, the toxicity of U to A. cumingi was compared after 4 d, 9 d, and 14 d. Daily U concentrations were measured because of expected U loss during testing, providing extensive chemical analyses of the U exposure during the toxicity tests. Comparison of the U concentrations causing 50% reproductive inhibition (IC50) after 4 d, 9 d, and 14 d showed no difference in toxicity (4 d IC50 = 161 μg L-1, confidence interval = 133-195; 9-d IC50 = 151 μg L-1, confidence interval = 127-180; 14-d IC50 = 153 μg L-1, confidence interval = 29-180). The present study provides evidence that test durations of <14 d are suitable for assessing chronic toxicity to U for this species and supports the use of the 4-d toxicity estimate in the SSD for U. Environ Toxicol Chem 2016;35:2851-2858. © 2016 Commonwealth of Australia.
Environmental Research Institute of the Supervising Scientist, Department of the Environment, Darwin, Northern Territory, Australia. tom.mooney@environment.gov.au.
Thomas J
TJ
Mooney
Environmental Research Institute of the Supervising Scientist, Department of the Environment, Darwin, Northern Territory, Australia.
Andrew J
AJ
Harford
Environmental Research Institute of the Supervising Scientist, Department of the Environment, Darwin, Northern Territory, Australia.
Melanie A
MA
Trenfield
Environmental Research Institute of the Supervising Scientist, Department of the Environment, Darwin, Northern Territory, Australia.
Ceiwen J
CJ
Pease
Environmental Research Institute of the Supervising Scientist, Department of the Environment, Darwin, Northern Territory, Australia.
Alicia C
AC
Hogan
Environmental Research Institute of the Supervising Scientist, Department of the Environment, Darwin, Northern Territory, Australia.
Rick A
RA
van Dam
D000818:Animals; D001315:Australia; D005618:Fresh Water / Q000737:chemistry*; D007928:Lethal Dose 50; D012908:Snails / Q000187:drug effects*; D018675:Toxicity Tests; D014501:Uranium / Q000032:analysis / Q000633:toxicity*; D014875:Water Pollutants, Radioactive / Q000032:analysis / Q000633:toxicity*; D060753:Water Quality
D014875:Water Pollutants, Radioactive; D014501:Uranium
Chronic toxicity; Metal speciation; Uranium