Phenyl 4-hydroxybenzoate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

The source compound Benzyl 4-hydroxybenzoate (EC 202-311-9, CAS 94-18-8) is considered a suitable read across partner for the target substance Phenyl 4-hydroxybenzoate (EC 241-698-9, CAS 17696-62-7). This read-across is based on the hypothesis that source and target substances have similar toxicological properties because:

- structural similarity of the target and the source substances (the presence or absence of additional functional groups or substituents that could influence the behaviour of a chemical),
- similarity in physico-chemical profile of the source and target substances (water solubility, partitioning behaviour (log Kow value))
Both substances are structural homologues regarding the functional groups at the ester (phenyl vs benzyl group). Both esthers have similar physico-chemical properties. Both are moderately/poorly water soluble (108 g/L vs 0.05 mg/L), exhibit similar log Kow values (3.97 vs 3.21), have similar boiling points (355 °C vs 241 °C) and vapour pressure (3.37x10-6 mm Hg vs 8.17x10-6 mm Hg).

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

1.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.52 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Validity criteria fulfilled:

not specified

Conclusions:

In a 72-h growth inhibition test wit Pseudokirchneriella subcapitata the following effect concentrations for benzyl 4-hydroxybenzoate (CAS # 94-18-8) were determined:

EC50 = 1.2 mg/L
LOEC = 1.0 mg/L
NOEC = 0.52 mg/L

Executive summary:

In a 72-hour acute toxicity study, the cultures of Pseudokirchneriella subcapitata were exposed to benzyl 4-hydroxybenzoate at five different concentrations under static conditions in accordance with the OECD guideline 201 (version 2006).  The NOEC or EC₀₅and EC₅₀/IC₅₀values based on cell number were 0.52 and 1.2 mg a.i./L, respectively. 

No abnormalities are reported.

This toxicity study is classified as acceptable and satisfies the guideline requirements for aquatic algae toxicity studies.

 

Results Synopsis

 

Test Organism: Pseudokirchneriella subcapitata

Test Type (Flowthrough, Static, Static Renewal): Static

 

72 hr EC₀₅:  1.2 mg a.i./L

72 h LOEC: 1.0 mg a.i./L

72 hr NOEC:  0.58 mg a.i./L                   

Endpoint(s) Effected: number of algae cells

Description of key information

In a 72-h growth inhibition test with Pseudokirchneriella subcapitata conducted according to the OECD guideline 201, the following effect concentrations for benzyl 4-hydroxybenzoate (CAS # 94-18-8) were determined:

EC50 = 1.2 mg/L

LOEC = 1.0 mg/L

NOEC = 0.52 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

1.2 mg/L

EC10 or NOEC for freshwater algae:

0.52 mg/L