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Endpoint summary

Description of key information

Short-term toxicity to aquatic invertebrates

This study was performed to assess the potential toxic effects of the test item to Daphnia magna, under static conditions (Test Guideline OECD 202).

Based on results of the preliminary range finding study, concentration levels selected for the main study were 0.05, 0.09, 0.16, 0.28, and 0.50 mg test item/L, along with control and vehicle control. In the main study, 48-h static toxicity test procedure was followed, comprising six groups. Each group consisted of four replicates with 5 daphnids per replicate. Daphnids were exposed to 16h light and 8h dark cycle. Temperature, pH, and dissolved oxygen content of reconstituted water were recorded at 0 h and 48 h. Total hardness of reconstituted water was measured once during the acclimatisation and test period. 

Test item in the test media was found to be stable up to 48 h (>80% of the nominal concentration). Test media was analysed for concentration and stability at 0 and 48 h during the main study and was within the acceptable limit (>80% of the nominal concentration).

The highest tested concentration level of the test item causing no immobilisation was 0.09 mg/L and the lowest tested concentration causing 100% immobilisation within the 48 h test period was 0.50 mg/L.

EC₅₀ (48h) = 0.262 mg/l (nominal).

 

Toxicity to aquatic algae and cyanobacteria

OECD 201 was performed to assess the inhibitory effects of the test item on the growth of alga Pseudokirchneriella subcapitata, under static condition.

Exponentially growing cultures of P.subcapitata were exposed to 0.0 (control), 0.0 (vehicle control),  0.008, 0.018, 0.039, 0.085, 0.187, and 0.412 mg test item/L. Algal cultures were assessed for growth by visual cell count at 24, 48, and 72 h.

The stability test of the substance in the test media was performed during the method validation, and the test item in the test media was stable up to 72 h (>80% of the nominal concentration). The test media was analysed for active ingredient concentration and stability of the test solution at 0 and 72 h during the main study. The active ingredient concentration of ZnDBM – Dibenzoylmethanate zinc salt in the test media was within the acceptable limit (>80% of the nominal concentration).

A concentration-effect relationship was observed and statistically analysed to obtain effect concentrations. The effect concentration with its respective 95% lower and upper confidence limits for the inhibition of growth rate was E_rC₁₀ = 0.065 (0.041 – 0.105) mg/L, E_rC₂₀ = 0.109 (0.075 – 0.160) mg/L and E_rC₅₀ = 0.295 (0.188 – 0.463) mg/L.

The effect concentration with its respective 95% lower and upper confidence limits for the biomass inhibition was E_bC₁₀ = 0.019 (0.011 – 0.033) mg/L and E_bC₂₀ = 0.032 (0.021 – 0.050) mg/L and E_bC₅₀ = 0.089 (0.063 – 0.126) mg/L.

The effect concentration with its respective 95% lower and upper confidence limits for the yield was E_yC₁₀ = 0.019 (0.009 – 0.038) mg/L and E_yC₂₀ = 0.032 (0.019 – 0.055) mg/L and E_yC₅₀ = 0.089 (0.058– 0.136) mg/L.

There was a no significant change observed when data of mean biomass, growth rate, and yield of vehicle control group were compared with that of control group. Based on these results of statistical analysis, the value of NOEC and LOEC for biomass (cell growth) and yield were 0.008 and 0.018 mg test item/L, respectively and for growth rate were 0.018 and 0.039 mg test item/L, respectively.

ErC10 (72h) = 0.065 mg/L (nominal)
ErC20 (72h) = 0.109 mg/L (nominal)
ErC50 (72h) = 0.295 mg/L (nominal)
LOEC (72h) = 0.039 mg/L (nominal)
NOEC (72h) = 0.018 mg/L (nominal)

 

Justification of classification or non-classification

For the classification for short-term (acute) aquatic hazard, EC₅₀ (48h) = 0.262 mg/l (nominal) evaluated in the short-term toxicity test to aquatic invertebrates has been considered. According to the CLP Regulation EC 1272/2008, table 4.1.0., the EC50 ≤ 1 mg/l classify the substance for aquatic acute 1 (H400).

For the classification for long-term (chronic) aquatic hazard, the substance biodegradation in water (not biodegradable) and the ErC50 (72h) = 0.295 mg/L (nominal) / NOEC (72h) = 0.018 mg/L (nominal) evaluated in the toxicity to aquatic algae test have been considered. According to the CLP Regulation EC 1272/2008, table 4.1.0. (iii), the chronic NOEC or EC50 for algae or other aquatic plants ≤ 1 mg/l classify the substance for aquatic chronic 1 (H410).