Guanidinium thiocyanate

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

194 µg/L

Assessment factor:

10

Extrapolation method:

assessment factor

PNEC freshwater (intermittent releases):

424 µg/L

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

19.4 µg/L

Assessment factor:

100

Extrapolation method:

assessment factor

PNEC marine water (intermittent releases):

424 µg/L

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

20 mg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

750 µg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

75 µg/kg sediment dw

Extrapolation method:

equilibrium partitioning method

Hazard for air

Air

Hazard assessment conclusion:

no hazard identified

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

37 µg/kg soil dw

Extrapolation method:

equilibrium partitioning method

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

no potential for bioaccumulation

Conclusion on classification

Conclusive experimental results are available from acute tests for fish, invertebrates (daphnia), algae and microorganism as well as chronic tests for fish and invertebrates (read-across from ammonium and potassium thiocyanate).

The lowest acute effect level was the EC50 of 42.4 mg/L from an acute study in daphnia. The lowest chronic effect level was the NOEC of 1.94 mg/L from a chronic study in daphnia (on ammonium thiocyanate and corrected for molecular weight difference). Guanidine Thiocyanate is inherently biodegradable and has a log Kow of -1.42.

 

The criterion of “rapid degradability” is not met as the biodegradation observed in an OECD 302B guideline study was 46 %. Guanidine Thiocyanate is inherently biodegradable.

Bioaccumulation is expected to be low based on inherently biodegradability a log Kow of -1.42. The lowest acute EC50/LC50 value from data of three trophic levels is the EC50 of 42.4 mg/L in invertebrates (daphnia).

 

Evaluation is based on classification categories for hazardous to the aquatic environment according to GHS Regulation EC No 1272/2008.

The following criteria are relevant for Guanidine Thiocyanate:

 

Acute (short-term) aquatic hazard:

Category Acute 1:

96 hr LC50 (for fish)                                                               = 1 mg/l and/or

48 hr EC50 (for crustacea)                                                       = 1 mg/l and/or

72 or 96 hr ErC50 (for algae or other aquatic plants)                   = 1 mg/l.

 

Chronic aquatic hazard: 

(iii) Substances for which adequate chronic toxicity data are not available

Category Chronic 3:

96 hr LC50 (for fish)                                                               > 10 to = 100 mg/l and/or

48 hr EC50 (for crustacea)                                                       > 10 to = 100 mg/l and/or

72 or 96 hr ErC50 (for algae or other aquatic plants)                   > 10 to = 100 mg/l

and the substance is not rapidly degradable and/or the experimentally determined BCF = 500 (or, if absent, the log Kow = 4).

 

(i) Non-rapidly degradable substances for which there are adequate chronic toxicity data available

Category Chronic 2:

Chronic NOEC or ECx (for fish)                                          = 1 mg/l and/or

Chronic NOEC or ECx (for crustacea)                                 = 1 mg/l and/or

Chronic NOEC or ECx (for algae or other aquatic plants)     = 1 mg/l.

 

The acute EC50/LC50 values are far above the cut off value for classification of = 1 mg/L for acute aquatic hazard, therefore no classification is required.

 

The acute EC50/LC50 values fall in the range > 10 to = 100 mg/l which require a classification for chronic aquatic hazard, therefore classification in category chronic 3 and labelling with H12 is required.

 

Based on the chronic NOEC values which fall in the range > 1 mg/L, a classification in category chronic 3, however, would not be required.

 

Nevertheless, the classification in category chronic 3 is in line with harmonised classification and labelling for salts of thiocyanic acid, (status 2016-09-09, ECHA homepage, https://echa.europa.eu/information-on-chemicals/annex-vi-to-clp).