Method Development for a Short-Term 7-Day Toxicity Test with Unionid Mussels.

The US Environmental Protection Agency's short-term freshwater effluent test methods include a fish (Pimephales promelas), a cladoceran (Ceriodaphnia dubia), and a green alga (Raphidocelis subcapitata). There is a recognized need for additional taxa to accompany the three standard species for effluent testing. An appropriate additional taxon is unionid mussels because mussels are widely distributed, live burrowed in sediment and filter particles from the water column for food, and exhibit high sensitivity to a variety of contaminants. Multiple studies were conducted to develop a relevant and robust short-term test method for mussels. We first evaluated the comparative sensitivity of two mussel species (Villosa constricta and Lampsilis siliquoidea) and two standard species (P. promelas and C. dubia) using two mock effluents prepared by mixing ammonia and five metals (cadmium, copper, nickel, lead, and zinc) or a field-collected effluent in 7-day exposures. Both mussel species were equally or more sensitive (more than two-fold) to effluents compared with the standard species. Next, we refined the mussel test method by first determining the best feeding rate of a commercial algal mixture for three age groups (1, 2, and 3 weeks old) of L. siliquoidea in a 7-day feeding experiment, and then used the derived optimal feeding rates to assess the sensitivity of the three ages of juveniles in a 7-day reference toxicant (sodium chloride [NaCl]) test. Juvenile mussels grew substantially (30%-52% length increase) when the 1- or 2-week-old mussels were fed 2 ml twice daily and the 3-week-old mussels were fed 3 ml twice daily. The 25% inhibition concentrations (IC25s) for NaCl were similar (314-520 mg Cl/L) among the three age groups, indicating that an age range of 1- to 3-week-old mussels can be used for a 7-day test. Finally, using the refined test method, we conducted an interlaboratory study among 13 laboratories to evaluate the performance of a 7-day NaCl test with L. siliquoidea. Eleven laboratories successfully completed the test, with more than 80% control survival and reliable growth data. The IC25s ranged from 296 to 1076 mg Cl/L, with a low (34%) coefficient of variation, indicating that the proposed method for L. siliquoidea has acceptable precision. Environ Toxicol Chem 2021;40:3392-3409. © 2021 SETAC.

Development of bioassessment-based benchmarks for iron.

Current water-quality criteria for metals typically are derived from toxicity tests with the metal dissolved in clean laboratory water. Estimating the toxicity of iron from such tests, however, is extremely difficult because of the complex solubility and toxicity characteristics of the ferrous and ferric forms of the metal in freshwater. Consequently, a criterion for dissolved iron in freshwater derived from standard laboratory bioassays may not accurately describe the actual bioavailability and toxicity of this metal. A new approach is necessary to adequately protect aquatic life from the direct (toxic) and indirect (physical) negative effects of iron. We present a novel methodology to derive bioassessment-based benchmarks for total iron. This approach involves the use of quantile regression to model the decline in maximum abundance of taxa along a gradient of increasing iron concentrations. The limiting function (e.g., 90th quantile) is used to project the iron concentration associated with a selected reduction in maximum number of organisms (e.g., 20%). The projected declines in abundance of aquatic organisms are interpreted within the larger context of biological responses to increasing levels of stress (i.e., a biological condition gradient). Projections of iron concentration associated with multiple levels of reduction are selected to establish acceptable levels of change in the various tiers of a biological community. The bioassessment-based benchmarks that we establish for total iron (0.21 and 1.74 mg/L) are based on the assumption that if ecological effects-based criteria for total iron are derived and applied, the structure and function of the aquatic community will be protected.

Integrating chemical and biological criteria.

We present a system to derive benchmarks for protection of aquatic organisms that, as chemical criteria, promotes regulation of contaminants and, as biological criteria, focuses on an endpoint that adequately represents species abundance. The proposed method utilizes quantile regression to quantify the decline in maximum number of organisms with increasing contaminant concentrations. This limiting function then is applied to project the contaminant concentration associated with a threshold number of organisms. The threshold value is defined according to the study's objective and level of desired protection. Here, we defined it as 0.8 x 90th quantile of the number of organisms in samples from reference sites. We use the proposed system to derive taxon-specific, field-based effect concentrations (FECs) for copper and zinc in Ohio, USA, rivers and streams. Comparisons of results with respective chronic values suggest that only the draft criteria for copper are adequately protective. Projected zinc FECs were far lower than respective estimates of chronic values. The FECs likely are less sensitive to impacts of confounding factors because high numbers of organism in samples are observed when negative effects of other stressors are absent or minimal. We discuss other advantages, limitations, and potential applications of the proposed system.

Overview, History, and Objectives of Performance Measurement.

This article provides an overview of health care performance measurement, including a chronological history of the major developments in the performance measurement field. It is not intended to be all-encompassing in its descriptions of events and organizations but, rather, its purpose is to provide a broad historical context for describing health care performance measurement activities of the past 50 years. The article also highlights the key constituents driving performance measurement (government payers, private sector regulators, business coalitions, health care providers, and health care consumers), how they have influenced what is measured (the content of performance measurement), and why. The article concludes by establishing the commonalities among constituents and forecasts what the foreseeable future may hold regarding performance measurement.