4-(α,α-dimethylbenzyl)phenol

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Study following OECD Test Guideline 202 and GLP.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes

Test material

Test material information

Constituent 1

Reference substance name:

4-(α,α-dimethylbenzyl)phenol

EC Number:

209-968-0

EC Name:

4-(α,α-dimethylbenzyl)phenol

Cas Number:

599-64-4

Molecular formula:

C15H16O

IUPAC Name:

4-(2-phenylpropan-2-yl)phenol

Constituent 2

Reference substance name:

290-968-0

IUPAC Name:

290-968-0

Details on test material:

p-Cumylphenol (PCP, CAS #599-64-4); Purity: 98-100%.

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Samples of the test and control solutions were collected for chemical analysis in 50-mL polypropylene centrifuge tubes at test initiation and termination.

Test solutions

Details on test solutions:

Test solutions were prepared from a stock solution containing 10 mg of the test substance in 1 L dilution water. The stock solution was serially diluted with laboratory dilution water to obtain the remaining test concentrations (5.0, 2.5, 1.3, 0.6, 0.3, and 0.2 mg/L; nominal concentrations). The control was laboratory dilution water. Four 50-mL volumes of each test solution were dispensed to replicate test vessels (100-mL glass beakers) and an additional 50 mL was archived for chemical analysis.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

The test organism was Daphnia magna. The test was initiated with young daphnids less than 24 hours old from in-house cultures. The culture vessels were incubated in a temperature-controlled room at 20 ± 1degrees C, under an 8 hours dark and 16 hours light photoperiod. Light intensity at the water surface was 410 to 460 lux provided by cool white florescent lights. Stock cultures were fed a 50:50 (volume to volume) mixture of a green alga and a solution of yeast, alfalfa powder, and fermented trout chow three times weekly. Culture vessels were cleaned on Monday and Friday and the culture turned over on Wednesday. On these days the number of adults and young were counted and recorded for each jar. Young for testing were collected from 3- to 4-week-old adults. Mortality in the stock culture was 2.5% in the week prior to test initiation.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Hardness:

Dilution water was dechlorinated City of Calgary tap water (charcoal filtered and aerated). The dilution water had a hardness of 196 mg CaCO3/L.

Test temperature:

20 ± 1 degree C

pH:

The pH was 8.1-8.2 at initiation and 8.2-8.3 at termination.

Dissolved oxygen:

The concentration of dissolved oxygen was between 7.7 and 8.2 mg/L (95 - 100 % saturation at the test temperature corrected for altitude).

Nominal and measured concentrations:

Nominal concentrations: 0.2, 0.3, 0.6, 1.3, 2.5, 5.0, and 10 mg/L
Measured concentrations: <0.2, 0.3, 0.6, 1.1, 2.2, 4.5, and 9.2 mg/L

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

1.6 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 1.4-1.8 mg/L

Effect concentrations 2

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.9 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Remarks on result:

other: 0.8-1.2 mg/L

Effect concentrations 3

Duration:

24 h

Dose descriptor:

NOEC

Effect conc.:

1.1 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 4

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

0.6 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

At test initiation, dissolved oxygen, temperature, and pH ranged from 7.7 to 8.2 mg/L, 19.0 to 20.0 degrees C, and 8.1 to 8.2 units, respectively. At test termination, dissolved oxygen and temperature were 7.9 mg/L and 20 degrees C in all test solutions, respectively. The pH ranged from 8.2 to 8.3.

Dead organisms were considered immobilized. The organisms in the two highest test concentrations (4.5 and 9.2 mg/L) were confirmed dead at 24 hours. Ninety percent of the organisms in the next lowest concentration (2.2 mg/L) were alive but immobile at 24 hours. There was an immobile daphnid in one replicate of the 1.1 mg/L concentration. The daphnids in the other replicates of this and the lower test concentrations and controls were all mobile. At test termination (48 hours), the daphnids in the 2.2 mg/L test concentration were immobile. Seventy percent of the daphnids in the 1.1 mg/L concentration were immobile. The daphnids in the lower test concentrations (<0.2, 0.3, and 0.6 mg/L) and controls were mobile.
The concentrations (and 95 % confidence limits) that immobilized 50% of the daphnids at 24 and 48 hours were 1.6 mg/L (1.4 to 1.8 mg/L) and 0.9 mg/L (0.8 to 1.2 mg/L), respectively.
The highest concentrations that produced no significant immobility relative to controls at 24 and 48 hours were 1.1 mg/L and 0.6 mg/L, respectively (NOEC).
The lowest concentrations that produced significant immobility relative to controls at 24 and 48 hours were 2.2 mg/L and 1.1 mg/L, respectively (LOEC). The lowest concentrations that produced 100 % immobility at 24 and 48 hours were 4.5 mg/L and 2.2 mg/L, respectively. The highest concentration that produced no immobility at 24 and 48 hours was 0.6 mg/L.

Any other information on results incl. tables

Average Number of Daphnia Immobilized After a

24- or 48-hour Exposure to p-Cumylphenol (p-Cumylphenol)

Nominal p-Cumylphenol Concentration (mg/L)	Measured p-Cumylphenol Concentration (mg/L)	Average Immobilization (%)
		24 h	48 h
Control	Control	0	0
0.2	Less than 0.2	0	0
0.3	0.3	0	0
0.6	0.6	0	0
1.3	1.1	5	70
2.5	2.2	90	100
5.0	4.5	100	100
10	9.2	100	100

Applicant's summary and conclusion

Conclusions:

Under the conditions of this study, the EC50 concentrations (and 95% confidence limits) at 24 and 48 hours were 1.6 mg/L (1.4 to 1.8 mg/L) and 0.9 mg/L (0.8 to 1.2 mg/L), respectively. The NOECs at 24 and 48 hours were 1.1 mg/L and 0.6 mg/L, respectively. The LOECs at 24 and 48 hours were 2.2 mg/L and 1.1 mg/L, respectively.