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Ecotoxicological information

Short-term toxicity to fish

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Description of key information

Two acute toxicity studies have been conducted on fish, one using Rainbow Trout and one using Bluegill sunfish. 
Acute Toxicity to Rainbow Trout: The results of the 96 hour static fish (Rainbow Trout) toxicity study gave a 96 hour LC50 of 360 mg/l (total compound). The 96 hour LC50 based on active ingredient (based on aqueous solution of carbohydrazide) was 23.47 mg ai/l.
Acute Toxicity to Bluegill sunfish: The results of the 96 hour static fish (Bluegill sunfish) toxicity study gave a 96 hour LC50 of 190 mg/l (total compound). The 96 hour LC50 based on active ingredient (based on aqueous solution of carbohydrazide) was 12.39 mg ai/l.

Key value for chemical safety assessment

LC50 for freshwater fish:
12.39 mg/L

Additional information

Acute Toxicity to Rainbow Trout

The acute toxicity of an aqueous solution of carbohydrazide to rainbow trout (Salmo gairdneri) was assessed.

Water quality parameters of temperature, dissolved oxygen, pH and ammonia were measured throughout the test and were within acceptable limits.

The study was conducted at the following nominal concentrations (total compound): 100, 180, 320, 560 and 1000 mg/l. A dilution water control was also included. Ten fish were exposed to each test concentration and control.

The results of the four day static fish toxicity study are summarised below:

96 hours LC50(based on total compound): 360 mg/l (95% CL: 180 - 560 mg/l)

96 hours LC50(based on active ingredient): 23.47 mg ai/l

There was 0% mortality in the control, 100 and 180 mg/l test concentrations. There was 30% mortality at 96 hours in the 320 mg/l test concentration. There was 10% mortality at 48 hours and 100% mortality at 96 hours in the 560 mg/l test concentration. There was 100% mortality at 48 hours in the 1000 mg/l test concentration.

Behavioral effects (erratic behavior and surfacing, loss of equilibrium) were observed in some fish at 48 and 72 hrs at the 320 mg/l and 560 mg/l test concentration. Surfacing was observed in some fish at 96 hours in the 100, 180 and 320 mg/l test concentration.

Acute Toxicity to Bluegill sunfish

The acute toxicity of an aqueous solution of carbohydrazide to bluegill sunfish (Lepomis macrochirus) was assessed.

Water quality parameters of temperature, dissolved oxygen, pH and ammonia were measured throughout the test and were within acceptable limits.

The study was conducted at the following nominal concentrations (total compound): 100, 180, 320, 560 and 1000 mg/l. A dilution water control was also included. Ten fish were exposed to each test concentration and control.

The results of the four day static fish toxicity study are summarised below:

96 hours LC50(based on total compound): 190 mg/l (95% CL: 130 - 250 mg/l)

96 hours LC50(based on active ingredient): 12.39 mg ai/l

The following mortality rates were observed:

Control: 0%

100 mg/l test concentration: 10% at 48 hr and 20% at 96 hr

180 mg/l test concentration: 40% at 96 hr

320 mg/l test concentration: 80% at 96 hr

560 mg/l test concentration: 20% at 24 hr, 60% at 48 hr and 100% at 96 hr

1000 mg/l test concentration: 80% at 24 hr and 100% at 48 hr

Behavioral effects were observed in some fish at 24 hrs in the 560 and 1000 mg/l test concentrations, at 48 hrs in the 180, 320 and 560 mg/l test concentrations, at 72 hrs in the 100, 180 and 320 mg/l test concentration and at 96 hrs in the 100, 180 and 320 mg/l test concentrations.