Rationale

Some content of Annex A5 “Guidance for Sediment Toxicity Tests with Juvenile Freshwater Mussels” in ASTM E1706-20 was based on ASTM E2455 Guide for Conducting Laboratory Toxicity Tests with Freshwater Mussels, which was originally developed in 2005 and reapproved in 2013. However, the E2455 has been revised and published in 2022. Some updates, such as starting toxicity tests with unform age and size of juvenile freshwater mussels and increased feeding rates in the revision (E2455-22) are important to be used for updating the guidance for the sediment tests with mussels (E1706-20).