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Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Short-term toxicity to fish: Acute toxicity to freshwater fish, comparable to OECD 203, GLP,Oryzias latipes , 96 h semi-static: LC50 (96h) = 5.7 mg/L

Short-term toxicity to aquatic invertebrates: Acute Immobilization Test in Daphnia magna, 48 h, comparable to OECD Guideline 202, GLP, static, EC50 (48h) = 5.2 mg/L

Short-term toxicity to aquatic algae and cyanobacteria: Growth inhibition test in algae, Pseudokirchneriella subcapitata, 72h, comparable to OECD Guideline 201, GLP, static: ErC50 (72h) = 29 mg/L; NOECr (72h) = 5.00 mg/L

Additional information

Short-term toxicity to fish

A GLP compliant 96-hour acute toxicity test of 2,5-xylenol on Oryzias latipes (KS_Acute toxicity to freshwater fish_Oryzias latipes_96 h _2008) has been conducted in accordance with the acute toxicity test described in "Methods of Tests pertaining to New Chemical Substances, Etc" and comparable to OECD Guideline 203.

Ten fish per test concentration (10.00, 2.00. 4.00. 8.00 and 16.0 mg/L) were evaluated in a semi-static 96-hour acute toxicity test. Mortalities as well as symptoms of abnormal mobility has been evaluated. No symptoms of abnormal mobility, etc. were observed in the concentration area of 1.00 mg/L or lower. Abnormal mobility and death were observed 96 hours later in the 4.00 mg/L concentration area. Abnormal mobility or death were observed in some specimens 6 hours later in the 8.00 mg/L concentration area. All specimens died 24 hours later in the 16.00 mg/L concentration area.

Since the variations to the set concentration of the measured concentration of the test substance were all less than ± 20%, the set concentration was used as the concentration of the test substance in the test solution. The median lethal concentration (LC50), the highest concentration producing 0 percent death and the lowest concentration producing 100 percent deaths 24, 48, 72, and 96 hours after exposure were shown below.

Exposure period  LC50* (95% confidence limit)
(mg/L)
Highest concentration producing 0 percent death
(mg/L)
Lowest concentration producing 100 percent deaths
(mg/L)

24 hours 11* 4.00 16.0
48 hours 6.6* 4.00 16.0
72 hours 5.9* 4.00 16.0
96 hours 5.7** (4.4 - 7.2) 2.00 16.0

* Obtained by the plotting method.

** Obtained by Probit analysis

The median lethal concentration (LC50) after 96 hours was determined to be 5.7 mg/L.

Short-term toxicity to aquatic invertebrates

A GLP- acute immobilization test (static) of 2,5-xylenol on Daphnia magna in a 48-hour exposure (KS_

Acute Immobilization Test in Daphnia magna_48 h _2008) was carried out in accordance with the acute immobilization test described in "Methods of Tests pertaining to New chemical Substances, Etc" and comparable to OECD Guideline 202.

20 daphnids per concentration area (5 daphnids/ container) were exposed to 2,5-xylenol at static conditions and at test concentrations of 1.00, 2.00, 4.00, 8.00 and 16.0 mg/L.

The concentrations of the test substance in the test solutions were 1.00, 2.00, 4.00, 8.00, 16.0 mg/L and in set concentrations were 1.00, 2.10, 3.96, 8.08, and 15.6 mg/L at the start of exposure and 0.935, 1.95, 3.91, 7.91, and 15.8 mg/L 48 hours after exposure. The proportion with respect to the set concentration was in the range of 97.5 - 105% at the start of exposure and 93.5 - 98.9% 48 hours after exposure, and the variation was less than ± 20% in either case. Thereby, the median immobilization concentration (EC50) was calculated using the set concentration as the concentration of the test substance during the exposure period.

EC50 and its 95% confidence limit throughout the 24- and 48-hour exposure periods were shown below.

 

Exposure period

EC50(mg/L)

95% confidence limit (mg/L)

24 hours

9.0*

Not calculated due to plotting method

48 hours

5.2**

4.2-6.4

* Plotting method

** Probit analysis

The median immobilisation concentration (EC50) after 48 hours was determined to be 5.2 mg/L.

Short-term toxicity to aquatic algae and cyanobacteria

A GLP-growth inhibition test of 2,5-xylenol in algae throughout the 72-hour exposure period (KS_Growth inhibition test in algae_Pseudokirchneriella subcapitata_72h_2008) in accordance with the Growth Inhibition Test of in Algae described in "Methods of Tests pertaining to New Chemical Substances, Etc" and comparable to OECD Guideline 201 has been conducted. The test has been performed with the algae Pseudokirchneriella subcapitata at an initial cell concentration of 5005 cells/mL under static conditions and for 72 hours. The concentrations of the test substance in the test solutions having 5.00, 10.0, 20.0, 40.0, and 80.0 mg/L in set concentration were 4.75, 9.62, 18.6, 38.0, and 76.3 mg/L at the start of exposure and 4.78, 9.54, 17.9, 37.6, and 74.4 mg/L 72 hours after exposure. The proportion with respect to the set concentration was in the range of 93.0-96.2% at the start of exposure and became 89.5-95.6% 72 hours after exposure, with the variation less than ± 20%. Thereby, 50% growth inhibitory concentration (ErC50) was calculated using the set concentration as the concentration of the test substance during the exposure period.

50% growth inhibitory concentration (ErC50) and maximum no observed effect concentration (NOECr) obtained from the growth rate at the 72-hour exposure period were shown below.

Exposure period

ErC50

(mg/L)

95% confidence limit (mg/L)

NOECr

(mg/L)

0-72 hours

29

26-32

5.00