What are TELs and PELs?
A. These benchmarks are similar to ERL/ERMs, but have distinct differences in their derivation. Like ERL/ERMs, their derivation is based upon a database of synoptic contaminant concentrations and sediment toxicity bioassays or benthic community metrics. The database for TEL/PELs however is much larger. Also, the freshwater TEL/PELs in particular are more robust because the database is roughly split between toxicity bioassays and benthic community metrics. Most importantly though, unlike ERL/ERMs, TEL and PEL calculations do make use of the non-toxic samples: these benchmarks are calculated as a geometric mean using the full suite of information from the database (see their original publication for the full equations).
