This rule was remanded by the U.S. Circuit Court of Appeals and the limits are not currently in force.
Trichloroacetic acid is a relatively strong acid that forms deliquescent crystals.
In the final rule, OSHA is establishing an 8-hour TWA limit for trichloroacetic acid of 1 ppm. This limit is based on analogy to the toxicity of 2,2-dichloropropionic acid.