Development of a bioavailability‐based risk assessment approach for nickel in freshwater sediments

To assess nickel (Ni) toxicity and behavior in freshwater sediments, a large‐scale laboratory and field sediment testing program was conducted. The program used an integrative testing strategy to generate scientifically based threshold values for Ni in sediments and to develop integrated equilibrium partitioning‐based bioavailability models for assessing risks of Ni to benthic ecosystems. The sediment testing program was a multi‐institutional collaboration that involved extensive laboratory testing, field validation of laboratory findings, characterization of Ni behavior in natural and laboratory conditions, and examination of solid phase Ni speciation in sediments. The laboratory testing initiative was conducted in 3 phases to satisfy the following objectives: 1) evaluate various methods for spiking sediments with Ni to optimize the relevance of sediment Ni exposures; 2) generate reliable ecotoxicity data by conducting standardized chronic ecotoxicity tests using 9 benthic species in sediments with low and high Ni binding capacity; and, 3) examine sediment bioavailability relationships by conducting chronic ecotoxicity testing in sediments that showed broad ranges of acid volatile sulfides, organic C, and Fe. A subset of 6 Ni‐spiked sediments was deployed in the field to examine benthic colonization and community effects. The sediment testing program yielded a broad, high quality data set that was used to develop a Species Sensitivity Distribution for benthic organisms in various sediment types, a reasonable worst case predicted no‐effect concentration for Ni in sediment (PNECsediment), and predictive models for bioavailability and toxicity of Ni in freshwater sediments. A bioavailability‐based approach was developed using the ecotoxicity data and bioavailability models generated through the research program. The tiered approach can be used to fulfill the outstanding obligations under the European Union (EU) Existing Substances Risk Assessment, EU Registration, Evaluation, Authorisation, and Regulation of Chemicals (REACH), and other global regulatory initiatives. Integr Environ Assess Manag 2016;12:735–746. © 2015 SETACKey PointsA comprehensive, representative sediment toxicity database is available to support risk assessment of Ni in freshwater sediments.Sediment Ni ecotoxicity data were gathered from studies that used spiking approaches that resulted in Ni‐enriched sediments resembling naturally contaminated sediments, thus increasing their relevance.Bioavailability of Ni in sediments, which is controlled by acid volatile sulfides (AVS), varies among different species, with actively bioturbating species showing a lower slope in the relationship between decreasing toxicity with increasing AVS.A bioavailability‐based, tiered approach is presented, where the first tier involves comparison of ambient total Ni concentrations with a RWC threshold value of 136 mg Ni/kg. Site‐specific AVS can be used to calculate a site‐specific threshold if ambient Ni is greater than 136 mg Ni/kg.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/134197/1/ieam1720.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/134197/2/ieam1720_am.pd

Impact of a district mental health care plan on suicidality among patients with depression and alcohol use disorder in Nepal

BACKGROUND:Large scale efforts to expand access to mental healthcare in low- and middle-income countries have focused on integrating mental health services into primary care settings using a task sharing approach delivered by non-specialist health workers. Given the link between mental disorders and risk of suicide mortality, treating common mental disorders using this approach may be a key strategy to reducing suicidality. METHODS AND FINDINGS:The Programme for Improving Mental Health Care (PRIME) evaluated mental health services for common mental disorders delivered by non-specialist health workers at ten primary care facilities in Chitwan, Nepal from 2014 to 2016. In this paper, we present the indirect impact of treatment on suicidality, as measured by suicidal ideation, among treatment and comparison cohorts for depression and AUD using multilevel logistic regression. Patients in the treatment cohort for depression had a greater reduction in ideation relative to those in the comparison cohort from baseline to three months (OR = 0.16, 95% CI: 0.05-0.59; p = 0.01) and twelve months (OR = 0.31, 95% CI: 0.08-1.12; p = 0.07), with a significant effect of treatment over time (p = 0.02). Among the AUD cohorts, there were no significant differences between treatment and comparison cohorts in the change in ideation from baseline to three months (OR = 0.64, 95% CI: 0.07-6.26; p = 0.70) or twelve months (OR = 0.46, 95% CI: 0.06-3.27; p = 0.44), and there was no effect of treatment over time (p = 0.72). CONCLUSION:The results provide evidence integrated mental health services for depression benefit patients by accelerating the rate at which suicidal ideation naturally abates over time. Integrated services do not appear to impact ideation among people with AUD, though baseline levels of ideation were much lower than for those with depression and may have led to floor effects. The findings highlight the importance of addressing suicidality as a specific target-rather than an indirect effect-of treatment in community-based mental healthcare programs

A review of nickel toxicity to marine and estuarine tropical biota with particular reference to the South East Asian and Melanesian region

The South East Asian Melanesian (SEAM) region contains the world\u27s largest deposits of nickel lateritic ores. Environmental impacts may occur if mining operations are not adequately managed. Effects data for tropical ecosystems are required to assess risks of contaminant exposure and to derive water quality guidelines (WQG) to manage these risks. Currently, risk assessment tools and WQGs for the tropics are limited due to the sparse research on how contaminants impact tropical biota. As part of a larger project to develop appropriate risk assessment tools to ensure sustainable nickel production in SEAM, nickel effects data were required. The aim of this review was to compile data on the effects of nickel on tropical marine, estuarine, pelagic and benthic species, with a particular focus on SEAM. There were limited high quality chronic nickel toxicity data for tropical marine species, and even fewer for those relevant to SEAM. Of the data available, the most sensitive SEAM species to nickel were a sea urchin, copepod and anemone. There is a significant lack of high quality chronic data for several ecologically important taxonomic groups including cnidarians, molluscs, crustaceans, echinoderms, macroalgae and fish. No high quality chronic nickel toxicity data were available for estuarine waters or marine and estuarine sediments. The very sparse toxicity data for tropical species limits our ability to conduct robust ecological risk assessment and may require additional data generation or read-across from similar species in other databases (e.g. temperate) to fill data gaps. Recommendations on testing priorities to fill these data gaps are presented

Sediment Nickel Bioavailability and Toxicity to Estuarine Crustaceans of Contrasting Bioturbative Behaviors – An Evaluation of the SEM-AVS Paradigm

Robust sediment quality criteria require chemistry and toxicity data predictive of concentrations where population/community response <i>should</i> occur under known geochemical conditions. Understanding kinetic and geochemical effects on toxicant bioavailability is key, and these are influenced by infaunal sediment bioturbation. This study used fine-scale sediment and porewater measurement of contrasting infaunal effects on carbon-normalized SEM-AVS to evaluate safe or potentially toxic nickel concentrations in a high-binding <i>Spartina</i> saltmarsh sediment (4%TOC; 35–45 μmol-S^2–·g^–1). Two crustaceans producing sharply contrasting bioturbation -- the copepod <i>Amphiascus tenuiremis</i> and amphipod <i>Leptocheirus plumulosus</i> -- were cultured in oxic to anoxic sediments with SEM_[Ni]-AVS, TOC, porewater [Ni], and porewater DOC measured weekly. From 180 to 750 μg-Ni·g^–1sediment, amphipod bioturbation reduced [AVS] and enhanced porewater [Ni]. Significant amphipod uptake, mortality, and growth-depression occurred at the higher sediment [Ni] even when [SEM-AVS]/<i>f</i>_oc suggested acceptable risk. Less bioturbative copepods produced higher AVS and porewater DOC but exhibited net population <i>growth</i> despite porewater [Ni] 1.3–1.7× their aqueous [Ni] LOEC. Copepod aqueous tests with/without dissolved organic matter showed significant aqueous DOC protection, which suggests porewater DOC attenuates sediment Ni toxicity. The SEM_[Ni]-AVS relationship <i>was</i> predictive of acceptable risk for copepods at the important population-growth level

A Mystery Tale: Nickel Is Fickle When Snails Fail—Investigating the Variability in Ni Toxicity to the Great Pond Snail

ABSTRACT Dissolved Ni concentrations inhibiting the growth of juvenile great pond snails (Lymnaea stagnalis) have been documented to vary from about 1 to 200 µg L−1 Ni. This variability makes L. stagnalis either a moderately sensitive or the most sensitive freshwater species to chronic Ni exposure tested to date. Given the role of sensitive species in environmental risk assessment frameworks, it is particularly important to understand this variability, i.e., to characterize the factors that modulate Ni toxicity and that may confound toxicity test outcomes when uncontrolled. In the present study, we tested if this variability was due to analytical (growth calculation: biomass versus growth rate), environmental (water quality), lab‐specific practices, and/or snail population differences among earlier studies. Specifically, we reanalyzed previously published Ni toxicity data and conducted additional measurements of Ni aqueous speciation, short‐term Ni uptake, and chronic Ni toxicity with test waters and snail cultures used in previous studies. Corrections for Ni bioavailability and growth calculations explained a large degree of variability in the published literature. However, a residual 16‐fold difference remained puzzling between 2 studies: Niyogi et al. (2014) (low ECxs) and Crémazy et al. (2018) (high ECxs). Indeed, differences in metal bioavailability due to water chemistry, lab‐specific practices, and snail population sensitivity could not explain the large variation in Ni toxicity in these 2 very similar studies. Other potentially important toxicity‐modifying factors were not directly evaluated in the present work: test duration, diet, snail holding conditions, and snail age at onset of testing. The present analysis highlights the need for further studies to elucidate 1) the mechanisms of growth inhibition in Ni‐exposed L. stagnalis and 2) the important abiotic and biotic factors affecting this biological response. Until these processes are understood, substantial uncertainties will remain about inclusion of this species in Ni environmental risk assessment. Integr Environ Assess Manag 2020;16:983–997. © 2020 SETAC KEY POINTS Nickel concentrations inhibiting the growth of Lymnaea stagnalis vary by 2 orders of magnitude (1–200 µg L−1) in the literature. The interstudy variability on EC20s was decreased by using specific growth rate instead of biomass as the response variable (by a factor of 5‐fold) and by bioavailability correction with the BLM (by a factor of 3‐fold). A remaining 7‐fold variation in reported EC20s could not be explained by differences in test waters, snail populations, and lab‐specific practices. Other potentially important toxicity‐modifying factors remain to be studied (e.g., test duration and snail age and diet)

Acute and chronic toxicity of nickel on freshwater and marine tropical aquatic organisms

© 2020 Elsevier Inc. Water quality guidelines and ecological risk assessment of chemical substances like nickel (Ni) in tropical regions such as South East Asia and Melanesia are often based on temperate information as a result of fewer Ni ecotoxicity data available for tropical species. This leaves an unknown margin of uncertainty in the risk assessment in the tropics. In order to fill this data gap, this study was designed to conduct standard toxicity tests on Ni with two freshwater species (acute tests) and three marine species (acute and chronic tests) originated from tropical Hong Kong. All tests were carried out using measured concentrations of Ni with control mortality below 15%. The median lethal concentrations (LC50s) were determined as 2520 (95% confidence interval: 2210, 2860) and 426 (351, 515) μg Ni L−1 for the freshwater gastropods Pomacea lineata (48 h) and Sulcospira hainanensis (96 h), respectively, while 96 h LC50s of 4300 (3610, 5090), 18,200 (6470, 51,200), 62,400 (56,800, 68,500), and 71,700 (68,200, 75,400) μg Ni L−1 were derived for the marine copepod Tigriopus japonicus, the gastropod Monodonta labio, juvenile and adult of the marine fish Oryzias melastigma, respectively. The chronic effect concentration of 10% (EC10) based on the intrinsic rate of increase of the population of T. japonicus was 29 (12, 69) μg Ni L−1. In terms of growth inhibition, the chronic EC10 for M. labio was 34 (17, 67) μg Ni L−1. The results also indicated that T. japonicus in maturation stage (LC10: 484 (349, 919) μg Ni L−1) was less sensitive than its nauplii stage (LC10: 44 (27, 72) μg Ni L−1). This study represents an important addition of high-quality toxicity data to the tropical Ni toxicity database which can be used for future ecological risk assessment of Ni and derivation of its water quality guidelines in tropical regions