The mechanisms of nickel toxicity in aquatic environments: An adverse outcome pathway analysis

Although metal mixture toxicity has been studied relatively intensely, there is no general consensus yet on how to incorporate metal mixture toxicity into aquatic risk assessment. We combined existing data on chronic metal mixture toxicity at the species level with species sensitivity distribution (SSD)-based in silico metal mixture risk predictions at the community level for mixtures of Ni, Zn, Cu, Cd, and Pb, to develop a tiered risk assessment scheme for metal mixtures in freshwater. Generally, independent action (IA) predicts chronic metal mixture toxicity at the species level most accurately, whereas concentration addition (CA) is the most conservative model. Mixture effects are noninteractive in 69% (IA) and 44% (CA) and antagonistic in 15% (IA) and 51% (CA) of the experiments, whereas synergisms are only observed in 15% (IA) and 5% (CA) of the experiments. At low effect sizes (∼ 10% mixture effect), CA overestimates metal mixture toxicity at the species level by 1.2-fold (i.e., the mixture interaction factor [MIF]; median). Species, metal presence, or number of metals does not significantly affect the MIF. To predict metal mixture risk at the community level, bioavailability-normalization procedures were combined with CA or IA using SSD techniques in 4 different methods, which were compared using environmental monitoring data of a European river basin (the Dommel, The Netherlands). We found that the simplest method, in which CA is directly applied to the SSD (CA ), is also the most conservative method. The CA has median margins of safety (MoS) of 1.1 and 1.2 respectively for binary mixtures compared with the theoretically more consistent methods of applying CA or IA to the dose-response curve of each species individually prior to estimating the fraction of affected species (CA or IA ). The MoS increases linearly with an increasing number of metals, up to 1.4 and 1.7 for quinary mixtures (median) compared with CA and IA , respectively. When our methods were applied to a geochemical baseline database (Forum of European Geological Surveys [FOREGS]), we found that CA yielded a considerable number of mixture risk predictions, even when metals were at background levels (8% of the water samples). In contrast, metal mixture risks predicted with the theoretically more consistent methods (e.g., IA ) were very limited under natural background metal concentrations (<1% of the water samples). Based on the combined evidence of chronic mixture toxicity predictions at the species level and evidence of in silico risk predictions at the community level, a tiered risk assessment scheme for evaluating metal mixture risks is presented, with CA functioning as a first, simple conservative tier. The more complex, but theoretically more consistent and most accurate method, IA , can be used in higher tier assessments. Alternatively, the conservatism of CA can be accounted for deterministically by incorporating the MoS and MIF in the scheme. Finally, specific guidance is also given related to specific issues, such as how to deal wit...

Section: Q1: Which Reference Model Is Most Accurate For Predicting Chmentioning

confidence: 99%

A framework for ecological risk assessment of metal mixtures in aquatic systems

Nys

Regenmortel

Janssen

et al. 2018

“…This difference from the acute studies may be explained by the lack of an acclimation period in the acute studies, which is necessary to reach a homeostatic balance to the new temperature environment (Williams et al 2012) or to reach full sequestration capacity. The exact mechanisms of uptake, elimination, sequestration, and detoxification of Ni in Daphnia remain unclear (Brix et al 2017;Pyle and Couture 2011). For instance, the metallothionein proteins are known to be involved in the regulation of some intracellular metal concentrations such as those of Cu and Zn (Asselman et al 2013;Fan et al 2009), but this is unlikely in the case of Ni (Asselman et al 2012;Denkhaus and Salnikow 2002;Pyle and Couture 2011).…”

Section: Different Multigenerational Ni Effects On D Magna Reproductionmentioning

confidence: 99%

Multigenerational effects of nickel on Daphnia magna depend on temperature and the magnitude of the effect in the first generation

Pereira

Everaert

Blust

et al. 2018

Ecological risk assessment is commonly based on single-generation ecotoxicological tests that are usually performed at one standard temperature. We investigated the effects of nickel (Ni) on Daphnia magna reproduction at 15, 20, and 25 °C over 4 generations. Multigenerational Ni effects on D. magna reproduction depended on the magnitude of the effect in the first generation (F0) and showed very different patterns at different temperatures. At low effect level concentrations (<10% effect concentration [EC10] in F0), chronic Ni toxicity at 15 and 20 °C did not increase over 4 generations, and the increase in Ni toxicity at 25 °C observed in F1 and F2 in some Ni treatments did not persist into F3, where complete recovery of reproduction was observed. At higher effect level concentrations, the multigenerational Ni effects depended on the test temperature. In F0, Ni toxicity was 6.5-fold lower at 25 °C than at 15 °C (based on the median effect concentration), but the temperature effect on Ni toxicity was not explained by differences in Ni accumulation. At a lower temperature, lower internal Ni concentrations in D. magna were necessary to induce the same Ni toxicity as at a higher temperature. Overall, our results indicate that low single-generation chronic effect concentrations of Ni in D. magna (EC10 in the present study) are also protective in a long-term, multigenerational context and that temperature should be taken into account in the ecological risk assessment of Ni. Environ Toxicol Chem 2018;37:1877-1888 © 2018 SETAC.

“…In the present study, the body condition of wood frog tadpoles declined with an increase in aqueous Ni concentration. The potential mechanisms of Ni toxicity are disruption of iron (Fe) 2þ/3þ , Mg 2þ , and Ca 2þ homeostasis and oxidative stress that result in reduced growth, metabolic activity, and reproductive success at the organismal level (Brix et al 2017). Because food consumption did not vary with Ni concentration, tadpoles exposed to Ni were under stress and possibly not processing food efficiently, or diverting energetic resources toward FIGURE 1: Wood frog tadpoles accumulated more nickel (Ni) in their whole bodies (mg/g; n ¼ 3) with increased aqueous Ni concentration (mg/L; y ¼ 12.7 Ã x 0.7 ; r 2 ¼ 0.93; p < 0.001).…”

Section: Discussionmentioning

confidence: 99%

Nickel toxicity in wood frog tadpoles: Bioaccumulation and sublethal effects on body condition, food consumption, activity, and chemosensory function

Klemish

Bogart

Luek

et al. 2018

Nickel (Ni) concentrations in aquatic ecosystems can be amplified by anthropogenic activities including resource extraction. Compared with fish and invertebrates, knowledge of Ni toxicity in amphibians is limited, especially for northern species. We examined the effect of Ni on wood frog (Lithobates sylvaticus) tadpoles, the species with the widest and most northern distribution of any anuran in North America. Wood frog tadpoles were exposed to a Ni concentration gradient (0.02-5.5 mg/L of Ni at 164 mg/L as CaCO water hardness) for 8 d and examined for lethality, Ni bioaccumulation, and several sublethal endpoints including body condition, food consumption, activity, and chemosensory function. Nickel induced a sublethal effect on body condition (8-d 10 and 20% effect concentrations [EC10 and EC20] of 1.07 ± 0.38 and 2.44 ± 0.51 mg/L of Ni ± standard error [SE], respectively) but not on food consumption, activity, or chemosensory function. Nickel accumulation in tadpole tissues was positively related to an increase in aqueous Ni concentration but was not lethal. Both the acute and chronic US Environmental Protection Agency water quality guideline concentrations for Ni (0.71 and 0.08 mg/L at 164 mg/L as CaCO water hardness, respectively) were protective against lethal and sublethal effects in wood frog tadpoles. In the present study, wood frog tadpoles were protected by current water quality guidelines for Ni and are likely not as useful as other taxa for environmental effects monitoring for this particular metal. Environ Toxicol Chem 2018;37:2458-2466. © 2018 SETAC.