2-ethylhexyl (4-chloro-2-methylphenoxy)acetate

Long-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

10.05.2004 - 31.05.2004

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Reason / purpose for cross-reference:

read-across source

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2004

Report date:

2004

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

(4-chloro-2-methylphenoxy)acetic acid

EC Number:

202-360-6

EC Name:

(4-chloro-2-methylphenoxy)acetic acid

Cas Number:

94-74-6

Molecular formula:

C9H9ClO3

IUPAC Name:

(4-chloro-2-methylphenoxy)acetic acid

impurity 1

Reference substance name:

Water

EC Number:

231-791-2

EC Name:

Water

Cas Number:

7732-18-5

Molecular formula:

H2O

IUPAC Name:

water

impurity 2

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 material form:

solid

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Effect concentrations 2

Key result

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Any other information on results incl. tables

Results and conclusion

Every validation criteria was met:

·        mortality of the parent animals did not exceed 20% at the end of the test; and

·        the mean number of alive offspring produced per parent animals at the end of the test was >= 60.

There was no significant effect ofMCPA tech.to survival of parent animal. There was 20% mortality (two parent animal) that occurred on day 14^thand 16^thin control and also in concentra­tion 10 mg/1 (18^thday of test), 56 mg/1 (14^thand 16^thday of test) and 100 mg/1 (9^thday of test). These mortalities however were statistically not significant as verified by Fisher's Exact Test. There were also dead young animals (offspring) found; one in control in 16^thday of test, and in concentration 100 mg/1, in total, thirty between 7^thand last day of test.

Total number of living offspring per parent animal (for each replicate) alive at the end of the test versus concentration of the test substance is presented on in Table 6

Table 6 Daphnia magna reproduction test – sum up of offspring of parent animals in all concentrations of MCPA tech. and control.

Table 6. Daphnia magna reproduction test — sum up of offspring of parent animals in all concentrations of MCPA tech. and control.

Replicate No	Number of live offspring after 21 days in concentrations
	Control	10 mg/l	18 mg/l	32 mg/l	56 mg/l	100 mg/l
1	178	173	159	152	153	118
2	82	89	166	144	196	53(12)
3	1(1)	*	158	79	127	85
4	162	59	185	161	*	79(6)
5	117	134	65	65	125	69(8)
6	145	143	159	70	177	82
7	141	84		156	*	*
8	*	*	102	153	187	96(3)
9	124	151	141	143	176	44
10	*	59	141	121	*	92(1)
Total	950	892	1276	1 244	1 141	718
Mean	118.75	111.5	141.7	124.4	163	79.7
Variance	3 115.93	1 945.14	1 348.7	1 467.4	811,7	502.4
t value

* parent animal died

( ) In brackets number of dead young animals.

 

Coefficient of variation for reproduction in control (based on total number of living offspring per living parent animal) = 3,8 %.

The Kolmogorov "D" Test for normality assumption of data distribution generated D⁺value of 0.0817 and D^-value of 0.1391. The final D* value = 1.0083 is lower than critical one (i.e. 1,035 at p₀,₀₁). Therefore the conclusion of the Kolmogorov"D"Test is that data are normally distrib­uted. Bartlett's Test used to estimate if variance is homogeneous or heterogeneous generated B value of 7.313. That is less than the critical one (15.086). Conclusion is that variance is homoge­neous.

T-Test with Bonferroni's Adjustment was performed to determine NOEC value. This test showed that all obtained t values for the consecutive concentrations were below the critical value (critical value is 2.404 at p₀.₀₅). It means that there is no statistical significant difference in reproduction between control and consecutive concentrations. The statistical values for each concentration are also given in Table 6.

 

In conclusion, taking into account the obtained results as well as statistical analysis the NOEC for MCPA tech. is above 100 mg/l measured concentration while LOEC also is above 100 mg/l measured concentration.

 

Applicant's summary and conclusion

Executive summary:

Daphnia magna (Crustacea, Cladocera) reproduction test was performed according to the OECD Guideline No 211 (adopted September 21, 1998) and Principles of Good Laboratory Practice (GLP, OECD 1997).

The aim of the study was determination of reproductive output of Daphnia magna exposed to the range of concentrations of MCPA technical (determination of NOEC after 21-day exposure). The test preparation was used in 5 concentrations in the range from 10 to 100 mg/l with separation factor of 1,8. Because the statistical analysis shown no significant differences between control and concentrations in reproduction levels hence the NOEC (21-day in mg/l) is above 100 mg/l while LOEC is also above 100 mg/l.