4-chlorophenol

Toxicity to aquatic algae and cyanobacteria

Description of key information

4-chlorophenol is harmful to algae.

Key value for chemical safety assessment

EC50 for freshwater algae:

17 mg/L

EC10 or NOEC for freshwater algae:

5.8 mg/L

Additional information

Two studies investigating the toxicity of 4-chlorophenol (CAS No. 106-48-9) to algae are available. Additionally, further results were found by screening relevant data bases. These supporting data are listed in the given table.

The key study was conducted similar to OECD guideline 201, under static conditions and testing concentrations of 0.16 to 20 mg/L (Kühn and Pattard, 1990). The toxicity values for an exposure time of 72 h were used for the toxicity assessment, as (i) this is recommended in current guidelines and (ii) the growth curve of the control pass into the stationary phase between 72 and 96 h test duration. An IC50 (72 h) value of 17 mg/L and an EC10 (72 h) value of 5.8 mg/L were recorded for Scenedesmus subspicatus based on growth rate and nominal concentrations. A slightly lower IC50 (72 h) value = 8.3 mg/L was recorded with for biomass inhibition. The results indicate that the test substance is toxic to freshwater algae.

A further study assessed the toxicity of the test substance to the marine alga Skeletonema costatum (Cowgill et al., 1989). The study did not follow a specific guideline; however, was conducted similar to OECD guideline 201. The test organism was applied in an initial cell density of 100,000 cells/mL. An IC50 (96 h) value of 13.8 mg/L and an NOEC (96 h) value of 1.08 mg/L were recorded for Skeletonema costatum based on cell number and nominal concentrations. With this, the study confirmed the acute toxicity of the test substance based on the study by Kühn and Pattard (1990); however, it also indicates a distinct chronic toxicity of the test substance to algae as similarly found for aquatic invertebrates (see 6.1.4).

 

The additional studies listed in the table support the assumption that 4-Chlorophenol is toxic to algae.

Species	Exposure time [h]	Test parameter	Effect measurement	Effective concentration [mg/L]	Reference
Chlorella protothecoides	72	EC50	growth rate	44.9	[1]
Nitzschia closterium	72	EC50	growth rate	8.1	[1]
Pseudokirchneriella subcapitata	72	EC50	chlorophyll concentration	7.63	[2]
Chlorella vulgaris	96	EC50	growth rate	29	[3]
Pseudokirchneriella subcapitata	96	EC50	growth rate	38	[3]
Selenastrum capricornutum	96	EC50	cell production	4.79	[2]
Chlorella vulgaris	96	NOEC	growth rate	> 1	[5]
Chlorella pyrenoidosa	72	NOEC	chlorophyll concentration	10	[4]

References

[1] Stauber J.L. 1995. Toxicity testing using marine and freshwater unicellular algae. Australas. J. Ecotoxicol. 1(1): 15 -24

[2] US-EPA. 1978. In-depth studies on health and environmetal impacts of selected water pollutants. US-EPA contract No. 68 -01 -4646, Duluth, MN: 9p.

[3] Shigeoka T., Sato Y., Takeda Y., Yoshida K. and F. Yamauchi. 1988. Acute Toxicity of chlorophenols to green algae, Selenastrum capricornutum and Chlorella vulgaris, and Quantitative Structure-Activity Relationships. Environ. Toxicol. Chem. 7(10): 847-854

[4] Huang J.C. and E.F. Gloyna. 1967. Effects of toxic organics on photosynthetic reoxygenatioin. Contract No. WP-00688 -03. Tech. Rep. to Fed. Water Pollut. Control Admin., U.S.D.I., Center for Res. Water Resour, Uni of Texas, Austin, TX: 163 p.

[5] Gokcen J.E. 1998. Investigating the potential impacts of chlorophenols on the Lake Baikal (Siberia, Russia) food web by employing Daphnia grazing bioassays and a Chlorella growth bioassay. Arch. Environ. Contam. Toxicol. 34(3): 241 -247