The Nickel Report

Everyone can agree that environmental assessments should be based on the best science. The “best” science, however, is an ever-advancing standard. Despite budget uncertainties and other hurdles, EPA scientists often pioneer new methods of assessment capable of detecting smaller and smaller increments of environmental impact. Although it may take years for EPA to develop and demonstrate a new method, stakeholders may benefit from paying attention to the development process and seeking opportunities to participate in it.

Scientists have been studying the sensitivity of fatmucket mussels (lampsilis siliquoidea) for at least a decade. The fatmucket mussel is native to much of the United States, including the Mississippi Basin, the Great Lakes, and Hudson Bay. Mussels in general are sensitive to water pollution because they are filter feeders (i.e., they remove nutrients from water by passing it through their gills) and are rather sedentary (i.e., unlike fish, they spend a large portion of their adult life attached to the substrate of a waterbody). But as it turns out, the fatmucket mussel is notable for being one of the most sensitive of mussels for certain contaminants, such as ammonia, chloride, sulfate, potassium, copper, nickel, and zinc. See, e.g., Wang, N., et al., Method development for conducting short-term effluent tests with freshwater mussel (Fatmucket, Lampsilis siliquoidea) (2018).

The sensitive nature of the fatmucket—combined with its large range—has attracted the attention of EPA scientists focusing on developing better whole effluent testing (WET) procedures. In a WET test, a test species is exposed to effluent for a set duration of time in controlled laboratory conditions to determine the likely effects of exposure on endpoints such as survival, growth, and reproduction. EPA scientists are studying the best practices for using the fatmucket in WET tests. For instance, they are evaluating the optimal laboratory feeding rates for juvenile mussels. Using this information and many other specific test procedures, EPA has evaluated its proposed mussel WET method in an interlaboratory study with volunteer laboratories. Once information gleaned from the interlaboratory study is taken into account, EPA will be one step closer to publishing its mussel WET test as an official test method. Even if your facility’s effluent routinely passes WET tests for common test species such as the fathead minnow (pimphales promelas), there is no guarantee that it will pass the new WET test.

Furthermore, toxicity testing using the fatmucket mussel (both in its own capacity and as a surrogate for threatened and endangered mussels) may result in more stringent water quality criteria by enabling the Agency to quantify the sensitivity of mussels to particular pollutants and, based on that information, develop or revise water quality criteria.

In this instance and many others where EPA is pushing science forward, stakeholders may benefit from participating in EPA interlaboratory studies or peer reviews. The stakeholders who make the effort to become involved help ensure accurate and reliable test methods. This involvement can also provide company laboratories with invaluable first-hand experience with new methods and access to expertise from peer laboratories.