Reaction mass of Limestone and calcium fluoride and calcium sulfate

Toxicity to aquatic algae and cyanobacteria

Description of key information

No studies have been conducted on the reaction mass of CaF₂, CaSO₄ and CaCO₃. Instead information is available on the 3 different constituents. 

Calcium sulfate and calcium carbonate, are ubiquitous in the environment and essential to living organims: no hazards have been identified for both constituents  in the available studies.

As no studies are available for calcium fluoride, studies on NaF were used as read-across source. The chosen key values were the lowest reported as EC50 for short term studies (up to 96 h) and NOECs for long term studies (up to 21 days). The values were drawn for the EU RAR 2001 review, which summaries different studies on a wide range of marine and freshwater algae. The lowest EC50 value among the freshwater algae was 43 mg/L F^- for Scenedesmus sp, which converts to 88.32 mg/L CaF₂. The lowest EC50 value among the marine algae was 81 mg/L F^- for Skeletonema costatum, which converts to 166.37 mg/L CaF₂. The lowest NOEC value among the freshwater and marine algae was 50 mg/L F^-, which converts to 102.7 mg/L CaF₂.

 

On the basis of the available effect levels for CaF₂, the values for the reaction mass can be concluded: 

EC50 freshwater algae: 176.64 mg/L RM

EC50 marine water algae: 332.74 mg/L RM

NOEC for fresh and marine water algae: 205.4 mg/L RM

 

These values are calculated by taking into account that the reaction mass contains only 50% of CaF₂ (ca. 47.5 w/w % CaF₂) and that the additional of Ca²⁺ through CaSO₄ and CaCO₃ would even further reduce the toxicity of CaF₂ as free F^- will be complexed.

Key value for chemical safety assessment

EC50 for freshwater algae:

176.64 mg/L

EC50 for marine water algae:

332.74 mg/L

EC10 or NOEC for freshwater algae:

205.4 mg/L

EC10 or NOEC for marine water algae:

205.4 mg/L