“Toxic unit chronic (TUc)” means the reciprocal of the effluent dilution that causes no unacceptable effect to the test organisms by the end of the chronic exposure period, which can be calculated by dividing 100 by the chronic NOEC value.

Source. (See Revision Notes #1, #2, and #3 at chapter heading for Env-Wq 1700) #12042, eff 12-1-16; ss by #14203, eff 2-26-25 (formerly Env-Wq 1702.48)