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Toxicity to aquatic algae and cyanobacteria

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Description of key information

Toxicity to aquatic algae Chlorella pyrenoidosa with Chlorocresol was tested for 72 hours on the basis of growth inhibition effect. Different Effect Concentration for this study was found as follows:

EC 10 = 2.3 mg/L

EC 50 = 15 mg/L

LOEC = 5.7 mg/L

NOEC =  1.9 mg/L

But the BCF value of Chlorocresol reported was not >= 2000 as well as the substance was found to be rapidly degradable. Thus according to CLP criteria of aquatic classification it is concluded that the substance Chlorocresol is not toxic to aquatic algae Chlorella pyrenoidosa

Key value for chemical safety assessment

EC50 for freshwater algae:
15 mg/L
EC10 or NOEC for freshwater algae:
1.9 mg/L

Additional information

Based on the various studies available with Klimish rating 2 for the target substance CAS NO 59-50-7 The results is summarized as follows

 

Sr.No

Endpoint

Effect values

Basis for effects

Duration

Species

Remarks

1

EC50

EC10

NOEC

LOEC

15 mg/l

2.3 mg/l

1.9 mg/l

5.7 mg/l

growth inhibition

72 hrs

Chlorella pyrenoidosa

Data from publication for target chemical

2

EC50

EC10

>10 mg/l

5.2 mg/l

growth inhibition

96 hrs

Scenedesmus subspicatus

Data from publication for target chemical

 

By applying weight of evidence approach to the studies summarized in the above table it can be observed that EC50 value is expected to be in range of10 to15 mg/l and EC10 value was found to be in range of 2.3 – 5.5 mg/l and LOEC And NOEC is 5.7 mg/l and 1.9 mg/l in 96 study on the basis of growth inhibition effect. But the BCF value of Chlorocresol reported was not >= 2000 as well as the substance was found to be rapidly degradable. Thus according to CLP criteria of aquatic classification it is concluded that the substance Chlorocresol is not toxic to to aquatic algae Chlorella pyrenoidosa and Scenedesmus subspicatus

However, since this chemical has a harmonized classification as "Aquatic acute 1 " category, for the pupose of chemical safety assessment, this classification shall be considered