Study Points to Improved Methodology for Chronic Sediment Toxicity Testing Using Leptocheirus plumulosus

WAREHAM, MA, USA  – Smithers Viscient, a global contract research organization (CRO), announced that its recent independent method study around the use of Leptocheirus plumulosus in 28-day chronic sediment toxicity tests has resulted in a revised methodology capable of producing more reliable and robust data with fewer failures. This type of study, which historically has been known to pose challenges in terms of variability of growth and reproduction in the test amphipods, as well as achieving survival criteria, is one of the primary methods for testing sediment toxicity.
Since implementation of these technical changes, Smithers Viscient has submitted a revised standard protocol to EPA and received approval of the modifications for the purpose of supporting pesticide registration under the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA). Smithers Viscient has now successfully completed multiple exposures since the end of 2016 and is actively reporting for EPA submission.
“Sediment toxicity testing is a key tool for bringing a new chemical product to market, but these types of studies are complex,” said Ron Biever, Chief Scientific Officer, Smithers Viscient. “We recognized an opportunity to invest in troubleshooting the Leptocheirus methodology so that we can improve on the success rate of these studies for our clients. Not only did we see the amphipod survival rate increase, the changes we made resulted in significantly better growth and amphipod reproduction, which are the critical endpoints in the study.”
Smithers Viscient’s announcement describes the latest in a series of independent studies seeking to solve methodology challenges and improve results for clients. The company announced in 2016 the results of a study that resulted in shorter duration for fish full life-cycle testing, another common and often challenging environmental ecotoxicology test.
The Smithers Viscient team performed a series of investigations, dating back to 2013, into why poor survival was occurring with the Leptocheirus plumulosus across multiple studies. After finding that survivability was not immediately related to the sediment characteristics, the prescribed diet, nor the source of the organism, independent testing continued. The team discovered that the quality of the water in the exposure system was the primary issue. After increasing the frequency of water exchange, along with modification to the feeding regimen, the team began seeing positive results. Survivability climbed beyond the 80% acceptability criteria, and reproduction was abundant.

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