4-chloro-o-cresol

Toxicity to microorganisms

Administrative data

Endpoint:

toxicity to microorganisms, other

Remarks:

determination of the inhibitory effect of water constituents on bacteria by Pseudomonas cell multiplication inhibition test

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: The study is in accordance with guidelines and is thought to be in accordance with GLP, however there is no evidence to support this.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

1990

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

DIN 38412-8 (Pseudomonas Zellvermehrungshemmtest)

GLP compliance:

not specified

Test material

Test material information

Constituent 1

Reference substance name:

4-chloro-o-cresol

EC Number:

216-381-3

EC Name:

4-chloro-o-cresol

Cas Number:

1570-64-5

Molecular formula:

C7H7ClO

IUPAC Name:

4-chloro-2-methylphenol

Test organisms

Test organisms (species):

Pseudomonas putida

Study design

Test type:

not specified

Water media type:

not specified

Total exposure duration:

17 h

Test conditions

pH:

The pH range was 7.0 - 7.2 at 0h, not inoculated.
The pH range was 7.1 -7.2 at 17 h not inoculated.
The pH range was 5.1 - 6.8 at 17 h inoculated for concentrations up to 156.26 mg/L, at concentration above this (312.5 - 5000m g/L) the pH range was 7.0 - 7.1.

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

17 h

Dose descriptor:

EC10

Effect conc.:

ca. 37 mg/L

Nominal / measured:

not specified

Conc. based on:

not specified

Basis for effect:

other: optical density

Effect concentrations 2

Duration:

17 h

Dose descriptor:

EC50

Effect conc.:

ca. 110 mg/L

Nominal / measured:

not specified

Conc. based on:

not specified

Basis for effect:

other: optical density

Effect concentrations 3

Duration:

17 h

Dose descriptor:

other: EC90

Effect conc.:

ca. 150 mg/L

Nominal / measured:

not specified

Conc. based on:

not specified

Basis for effect:

other: optical density

Any other information on results incl. tables

The optical density at 436nm was measured after 17 hours. The results are summarised in the table below.

Concentration, mg/L	Extinction Values
	1	2	3	4	5
C	0.611	0.637	0.639	0.643	0
15.53	0.579	0.589	0.599	0.612	0.001
39.06	0.559	0.55	0.577	0.578	0
78.13	0.491	0.489	0.515	0.501	0.001
156.25	0.016	0.01	0.012	0.016	0.0001
312.5	0.003	0.003	0.003	0.002	0.001
625	0.004	0.004	0.004	0.004	0.003
1250	0.009	0.009	0.008	0.008	0.006
2500	0.016	0.017	0.017	0.016	0.013
5000	0.046	0.048	0.046	0.046	0.038
625 n	0.003	0.003	0.004	0.002	0.001
5000 n	0.045	0.052	0.049	0.05	0.047

C = control

1 - 4 = parallel tests, inoculated

5 = parallel test, not inoculated

Applicant's summary and conclusion

Conclusions:

EC50 110mg/L

Executive summary:

A guideline study was performed to measure the effect on bacterial growth of 4-chloro-o-cresol. The study was performed using Pseudomonas putida (DSM 50026) and the effect determined by measuring the optical density at 436nm. Concentrations of 4-chloro-o-cresol in the range 15.53 - 5000mg/L were used.

The results showed at test concentration 15.53 mg/L, the optical density was 93.9 % of the control, at 39.06 mg/L the optical density was 89.5% of control, at 78.13 mg/L, 78.7% of the control, at 156.25 mg/L, 2.0%, 312.5mg/L 0.3%, 625mg/L 0.2%, 1250mg/L 0.4%, 2500mg/L 0.6% and 5000mg/L 1.3% of the control.

The results indicate that at doses above 156.25 mg/L 4-chloro-o-cresol is cytotoxic. Two additional tests were performed whereby the 4 -chloro-o-cresol was neutralised, doses of 625mg/L and 5000mg/L both showed growth of 0.3% of the control, indicating that the neutralised substance is also cytotoxic at these levels.

The EC 50 derived from the results is 110mg/L.