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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

Diss Factsheets

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

The HYDROTOPES Category comprises the following 6 substances:
STS - Sodium toluene 4-sulphonate (CAS 657-84-1, EC 211-522-5)
SXS - Sodium (xylenes and 4-ethylbenzene) sulphonate (EC 701-037-1)
NH4XS - Ammonium (xylenes and 4-ethylbenzene) sulphonate (EC 943-024-5)
SCS - Sodium p-cumenesulphonate (CAS 15763-76-5, EC 239-854-6)
KCS - Potassium p-cumenesulphonate (CAS 164524-02-1, EC 629-764-9)
NH4CS - Ammonium p-cumenesulphonate (CAS 680972-33-2, EC 811-484-5) 
In addition CaXS (Calcium Xylenesulphonate, CAS 28088-63-3, EC 248-829-9) was evaluated for complete the assessment despite it is not registered under REACH.


From the available short-term toxicity results it can be concluded that aquatic organisms are of low sensitivity to Hydrotrope category substances. Most studies across the three trophic levels report no toxicity at the highest concentration tested. The studies relating to microbial activity (respiration) indicate low potential for toxicity at similar concentrations to fish, invertebrates and algae. The experimental available data on substances are consistent and confirms low eco-toxicity of the Hydrotropes to aquatic organisms including fish, invertebrates, algae and microorganisms. The density of the aquatic short term toxicity data is high enough to consider the hydrotropes as a category and the available information support a regular pattern of same absence of and type of effects with regard to aquatic toxicity.


The available studies on aquatic toxicity are:

Short term toxicity to fish
SXS (1993, no GLP): LC50 > 1000 mg/l (a.i.)    
CaXS (1994, GLP): LC50 > 1580 mg/l (a.i.)                  
SCS (2020, GLP): LC50 > 100 mg/l (a.i.)          
TSA (1981, no GLP): LC50 > 325 mg/l (a.i.)

Short term toxicity to aquatic invertebrates
STS (2020, GLP): EC50 = 217 mg/l (a.i.)          
STS (1995, GLP): EC50 = 54 mg/l  (disregarded)      
SXS (1993, no GLP): EC50 > 1000 mg/l
SXS (1995, GLP not specified): EC50 > 40.3 mg/l (a.i.) Limit test, highest concentration tested  
CaXS (1994, GLP): EC50 > 1020 mg/l (a.i.)      
SCS (1995, GLP not specified): EC50 > 40.3 (a.i.)         
SCS (2020, GLP): EC50 > 121 mg/l (a.i.)

Toxicity to aquatic plants (algae)
STS (1995, GLP): EC50 72 h = 150 mg/l (a.i.)
SXS (1993, no GLP): EC50 96 h > 230 mg/l (a.i.)
CaXS (1994, GLP): EC50 96 h = 758 mg/l (a.i.)
SCS (2020, GLP): EC50 72 h > 100 mg/l (a.i.)

Toxicity to micro-organism
STS (2009, GLP): EC10 3 h > 1000 mg/l (a.i.)
SCS (2009, GLP): EC10 3 h > 1000 mg/l (a.i.)