Troclosene sodium

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0 mg/L

Assessment factor:

1 000

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

0.002 mg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

1.52 mg/L

Assessment factor:

50

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

0.59 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

7.56 mg/kg sediment dw

Assessment factor:

100

Extrapolation method:

assessment factor

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

0.756 mg/kg soil dw

Assessment factor:

1 000

Extrapolation method:

assessment factor

Additional information

The chlorinated isocyanurates produce free available chlorine, in the form of hypochlorous acid (HOCl) as they dissolve in water. As the equilibria involve all of the possible chlorinated isocyanurates, the toxicity of trichloroisocyanuric acid (TCCA), sodium dichloroisocyanurate (NaDCC) and sodium dichloroisocyanurate dihydrate (NaDCC.2H₂O) will be virtually equivalent at the same available chlorine concentration. The parent compound for all chlorinated isocyanurates is isocyanuric acid (cyanuric acid). All of the chlorinated isocyanurates are essentially equivalent, once they are dissolved in water at the low concentrations at which they are used.Based upon the available chlorine content and the dissociation constants for the chlorinated isocyanurate species, TCCA is considered to be the most toxic, or reactive form. Therefore test results for this species will be considered as the "worst-case" for the chlorinated isocyanurates allowing read-across for the less reactive dichlorinated forms.

TCCA exhibited toxicity in acute aquatic toxicity studies in fish invertebrates and algae (LC₅₀fish = 0.23 mg/L, EC₅₀daphnia = 0.17 mg/L, EC₅₀algae = 0.5 mg/L). NaDCC showed a similar toxicity to TCCA with daphnia (EC₅₀= 0.196 mg/l) indicating toxicity of the chlorinated isocyanurates is related to the release of available chlorine and is not substance specific.

NaDCC is unstable in the environment, because the free available chlorine is rapidly reduced. CYA, or its salt, is the stable degradation product. Therefore, CYA, or its sodium salt, is the substance of interest for chronic ecotoxicity studies and NaDCC for acute toxicity data. Derivation of PNECs have therefore been calculated for both NaDCC and the stable degradation substance CYA.

Conclusion on classification

Three acute fish toxicity studies with TCCA gave an LC50 < 1 mg/L. 96 h LC50 in rainbow trout was 0.24 mg/L and in the two studies with bluegill sunfish were 0.23 mg/L and 0.4 mg/L..

Acute daphnia studies were performed with NaDCC dihydrate which gave a 48 h LC50 of 0.196 mg/L and with TCCA 48 h LC50s were 0.21 mg/L and 0.17 mg/L.

 

The algal study with TCCA against algae clearly demonstrated toxic effects with an LC50 of 0.5 mg/L.

Taking into account the results for both NaDCC and the read across substance TCCA it is clear that the chlorinated isocyanurates exhibit toxic effects on aquatic organisms. LC50s are ≤ 1 mg/L for all trophic levels which results in a classification of aquatic acute category 1 with the hazard phrase H400: Very toxic to aquatic life.