Well, I guess one of the advantages(?) of redefining "standards" is all of the additional work it creates for researchers! The definitive EPA Paper on defining RfDs from other factors is in the following reference. Chlorides and chlorine toxicity data have been around for a long time, so you should be able to tweak them to the EPA's liking.

https://www.epa.gov/iris/reference-dose-rfd-description-and-use-health-risk-assessments