Tar acids, xylenol fraction

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

fish early-life stage toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

other: Benoit et al. 1982. A fathead minnow, Pimephales promelas, early life stage toxicity test method evaluation and exposure to four organic chemicals. Environ. Pollute 28: 189-297.

Qualifier:

according to guideline

Guideline:

other: U.S. EPA. 1982. Wildlife aquatic organism data requirements. U.S. Government Printing Office, Washington, D.C. Federal Register 47: 53212.

GLP compliance:

no

Analytical monitoring:

yes

Details on sampling:

- Sampling: weakly

Vehicle:

not specified

Test organisms (species):

Pimephales promelas

Details on test organisms:

TEST ORGANISM
- Common name: fathead minnow embryos and larvae

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 d

Nominal and measured concentrations:

control, solvent control, 0.75, 1.5, 3.2, 7.4, and 15.0 (mean measured)

Details on test conditions:

TEST SYSTEM
- Type of flow-through (e.g. peristaltic or proportional diluter): Mount and Brungs (1967) type proportional diluters

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): hatching of embryos, survival and growth of larvae

Duration:

30 d

Dose descriptor:

NOEC

Effect conc.:

1.5 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

30 d

Dose descriptor:

NOEC

Effect conc.:

3.2 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality

Table 1: The effects on the embryos and larvae

Measured Concentration (mg/L)*	Hatch (%)*	30 days post hatch
		Survival (%)*	Length (mm)*	Weight (mg)*
15(1)	56(31)**	0(0)**	-	-
7.4(0.9)	66(20)**	12(5)**	14(1)**	20(2)**
3.2(0.3)	84(6)	69(1)	19(2)**	53(3)**
1.5(0.3)	68(12)	62(2)	21(3)	78(8)
0.75(0.2)	98(1)	58(25)	22(2)	90(22)
Solvent Control	96(2)	86(2)	21(2)	80(6)
Control	94(6)	93(10)	21(2)	70(1)

* Mean (standard deviation)

** Significantly (p = 0.05) different from controls

Exposure to 7.4 and 15 mg/L 2,4-xylenol significantly reduced the hatching of fathead minnow embryos. No fathead minnow larvae survived exposure to 15 mg/L and survival of larvae was significantly reduced at 7.4 mg/L. Larvae survival was not affected at concentrations as high as 3.2 mg/L. Larvae growth was significantly reduced at concentrations of 3.2 and 7.4 mg/L , but was not affected at 0.75 and 1.5 mg/L.

Validity criteria fulfilled:

not specified

Reference 2

Endpoint:

fish early-life stage toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 210 (Fish, Early-Life Stage Toxicity Test)

Principles of method if other than guideline:

Early life stage test

GLP compliance:

no

Analytical monitoring:

not specified

Test organisms (species):

Pimephales promelas

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

32 d

Hardness:

soft water from lake Superior

Test temperature:

25 ± 0.2 °C

Dissolved oxygen:

≥ 6.1 mg/L

Details on test conditions:

- Fluorescent lights provided 16h light per day
- Water chemistry data was recorded at the Environmental Research  Laboratory, Duluth, MN
- Fish were fed newly hatched brine shrimp ad libitum twice per day so that moderate accumulation occured.

Duration:

32 d

Dose descriptor:

NOEC

Effect conc.:

1.35 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

larval development

Duration:

32 d

Dose descriptor:

LOEC

Effect conc.:

2.57 mg/L

Nominal / measured:

not specified

Conc. based on:

test mat.

Basis for effect:

larval development

NOEC for macromolecular content (nucleic acid, protein) was 2.57 mg/L (LOEC 4.20 mg/L). NOEC for growth was >4.2 mg/L

Validity criteria fulfilled:

not specified

Executive summary:

The chronic toxicity of p-cresol to fish was tested with Pimephales promelas in an Early-Life Stage Toxicity Test equivalent to OECD Guideline 210. The 32d NOEC is 1.35 mg/L.

Description of key information

Based on all available information and following an analogue read-across and worst case approach the freshwater NOEC (32d) of 1.35 mg/L determined for Pimephales promelas (Barron & Adelman, 1984) for p-cresol represent the most sensitive effect value for chronic toxicity to fish for Tar acids, Xylenol fraction (CAS 84989-06-0) and is considered as key value for the chemical safety assessment.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

1.35 mg/L

Additional information

Data on chronic toxicity to fish are available for two constituents of Tar acids, Xylenol fraction (CAS 84989-06-0) (p-cresol and 2,4 -xylenol). These data are used to determine the long-term hazard on fish by applying an analogue read-across approach. The studies were conducted with Pimephales promelas as test species. The resulting NOEC values of the two studies are in the same range with 1.35 mg/L for p-cresol (Barron & Adelman, 1984) and 1.5 mg/L for 2,4-xylenol (Le Blanc, 1984). The lower NOEC value of 1.35 mg/L for p-cresol was considered for PNEC derivation and risk assessment and for deriving environmental classification. For details on the read-across approach please refer to the analogue justification provided in IUCLID section 13.

Chronic effect values determined in the available studies are listed in the table below:

Source	*	Species	p-cresol	m-cresol	o-cresol
Barron & Adelman, 1984	f	Pimephales promelas	NOEC (32d) = 1.35 mg/L	-	-
			2,3-xylenol	2,4-xylenol	2,5-xylenol
Le Blanc, 1984	f	Pimephales promelas	-	NOEC (30d) = 1.5 mg/L	-

* f = freshwater