2,6-dibromo-4-cyanophenyl octanoate

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

15 Feb - 08 Mar, 1991

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPP 72-4 (Fish Early Life-Stage and Aquatic Invertebrate Life-Cycle Studies)

Version / remarks:

1985

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

Sampling procedures included syphoning (using silicone tubing) from the midpoint of the test container into graduated cylinders for volumes greater than 200 mL, and pipetting (using volumetric pipets) from the midpoint ofthe test container for sample volumes less than or equal to 200 mL All sample volumes are transferred directly into 250-mL screw cap bottles.
It was deemed necessary to add 1 mL of 1M NaOH to the collection/reaction bottle immediately following collection of samples.

Vehicle:

yes

Remarks:

acetone

Details on test solutions:

A diluter stock solution of 2.9 mg a.i./mL was prepared by dissolving 0.150 grams (g) of test item (0.1458 grams as active ingredient) with acetone to a volume of 50 mL in a volumetric flask. The resulting stock solution was observed to be a clear, colorless solution with no visible signs of undissolved test material.
0.0066 ml of the stock solution was delivred into 385 mL of dilution water in the system's mixing chamber during each diluter cycle. The solution within the mixing chamber was continuously stirred with a magnetic stirrer. This 385 mL solution served as the highest treatment level (50 µg a.i./L, nominal) from which calibrated volumes were diluted to provide the 50% nominal concentration gradient (25 to 3.1 µg a.i./L). In addition to the five concentrations of test item, a dilution water control and a solvent control solution were maintained during the study. All treatments and controls were maintained in quadruplicate.
The solvent control solution contained the greatest amount of acetone present in any treatment level (0.017 mL/L)

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnids were cultured under static renewal conditions (20 ± 2 °C) in well water fortified.
Daphnids were fed daily a combination of green algae (Ankistrodesmus falcatus) and a trout food suspension. Food sources were considered to be acceptable since the total concentration of pesticides was less than 0.3 mg/kg.
Offspring produced during the 24-hour period prior to the start of the chronic exposure were used to initiate the study.

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

170 - 180 mg/L CaCO3

Test temperature:

21°C

pH:

7.9 - 8.3

Dissolved oxygen:

8.5 - 8.9 mg/L

Salinity:

not applicable

Conductivity:

500 µmhos/cm

Nominal and measured concentrations:

Nominal concentrations: 3.1, 6.3, 13, 25 and 50 µg a.i./L
Mean measured concentrations in phenol equivalents: 1.7, 2.5, 5.9, 12 and 23 µg a.i./L
Mean measured concentrations in octanoate equivalents: 2.5, 3.6, 8.6, 17.5 and 33.5 µg a.i./L

Details on test conditions:

Test vessels were glass battery jars having a volume capacity of 1.6 liters. Test solutions drained from each vessel through a 2 cm hole located approximately 15 cm from the bottom of the jars to maintain a solution volume of approximately 1.4 liters. Test solutions were delivered to the vessels at an approximate rate of 6 aquarium volumes per 24-hour period in order to provide a 90% test solution replacement rate of approximately 9 hours.
The test area was illuminated at an intensity of 24 to 56 footcandles and a photoperiod of 16 hours light and 8 hours darkness.
40 Daphnia magna (< 24 hours old) were impartially selected and distributed to each of the test concentrations and controls (10 per replicate).
During the exposure, the food was introduced at a rate of 2.0 mL of the trout food suspension (5 mg/mL), 3.0 mL of algal suspension.
Adult survival was recorded on days 1, 2, 4, 7, 10, 12, 14, 17, 19 and 21. Measurements of offspring production were recorded on days 7, 10, 12, 14, 17, 19 and 21. At each observation interval, the offspring were removed, counted and discarded. The total body length and dry weight of all surviving adult organisms was measured at test termination.

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

3.6 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

act. ingr.

Basis for effect:

reproduction

Remarks on result:

other:

Remarks:

Based on Bromoxynil octanoate recalculated from Bromoxynil phenol

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

2.5 µg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

other: Bromoxynil phenol

Basis for effect:

reproduction

Please refer to "overall remark/ attached background material" field for analytical tables.

Table 1: Cumulative mean percentage survival for parental daphnids (Daphnia magna) during the 21 day chronic exposure to Bromoxynil octanoate 

Concentration [µg/L]			% mean cumulative survival
nominal	mean measured		Day
octanoate equivalents	phenol equivalents^a	octanoate equivalents^b	1	2	4	7	10	12	14	17	19	21
50	23	33.5	100	100	100	100	95	88	85	85	85	85^*
25	12	17.5	100	100	100	98	98	98	93	93	93	93
13	5.9	8.6	100	93	93	90	90	90	90	88	88	88
6.3	2.5	3.6	100	100	100	100	100	98	98	98	98	98
3.1	1.7	2.5	100	100	100	100	100	98	98	98	98	98
solvent control			100	100	100	100	100	100	100	100	100	100
control			100	100	100	98	95	95	95	95	95	95
pooled control			100	100	100	99	98	98	98	98	98	98

^aas originally reported (without reconversion into octanoate equivalents

^bafter reconversion into octanoate equivalents with factor 1.455

^*statistically different (p <0.05) as compared to pooled control

Table 2: Cumulative number of offspring produced per female daphnid during the 21 day chronic exposure to Bromoxynil octanoate

Concentration [µg/L]			% mean cumulative number of offspring/female^a
nominal	mean measured		Day
(octanoate equivalents)	(phenol equivalents)^a	(octanoate equivalents)^b	7	10	12	14	17	19	21
50	23	33.5	0	5	17	31	40	46	51^d
25	12	17.5	0	1	7	38	64	67	87^*
13	5.9	8.6	1	9	38	74	126	130	180^*
6.3	2.5	3.6	1	20	48	104	175	182	246
3.1	1.7	2.5	0	16	41	93	170	172	246
solvent control			0	15	45	104	174	174	246
control			0	14	44	104	168	170	246
pooled controls^c			0	15	45	104	171	172	246

^aas originally reported (without reconversion into octanoate equivalents

^bafter reconversion into octanoate equivalents with factor 1.455

^cno statistically significant difference between the control and solvent control, therefore effects on reproduction evaluated against the pooled control and solvent control data.

^dSince survival was adversely affected for this treatment level , reproduction data was not statistically evaluated
^*Significantly (p ≤ 0.05) different as compared to the pooled control organisms.

Table 3: Length and weight of parental daphnids after the 21 day chronic exposure to Bromoxynil octanoate

Concentration [µg/L]			mean length [mm] (S.D)	mean weight [mg] (S.D)
nominal	mean measured
(octanoate equivalents)	(phenol equivalents)^a	(octanoate equivalents)^b
50	23	33.5	4.0 (0.4)^d	0.66 (0.17)^d
25	12	17.5	4.9 (0.2)^*	1.32 (0.14)^*
13	5.9	8.6	5.2 (0.2)^*	1.74 (0.14)^*
6.3	2.5	3.6	5.5 (0.1)	1.88 (0.12)
3.1	1.7	2.5	5.6 (0.1)	1.95 (0.14)
solvent control^c			5.6 (0.1)	1.91 (0.09)
control			5.5 (0.1)	1.84 (0.13)
pooled controls^c			NA	1.88 (0.12)

^a as originally reported (without reconversion into octanoate equivalents

^b after reconversion into octanoate equivalents with factor 1.455

^c Statistical analysis compared treatment levels to the solvent control for length measurements, and to the pooled control for weight measurements.

^d Since survival was adversely affected at this treatment level length and weight data was not statistically evaluated

^*Significantly (p ≤ 0.05) different compared to the solvent control (length) or the pooled control (weight)

 

Validity criteria fulfilled:

yes

Remarks:

mentioned in the report according to EPA 72-4

Conclusions:

The present guideline study was conducted in compliance with GLP. Under the test conditions used, the NOEC 21-day for Daphnia magna was 3.6 µg a.i./L.

Description of key information

From long-term key study, the 21-day NOEC for aquatic invertebrates exposed to the present test material was 0.0036 mg a.i./L in freshwater.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Effect concentration:

ca. 0.004 mg/L

Additional information

The long-term effects of the substance towards aquatic invertebrates were examined in a 21-day toxicity test with Daphnia magna under flow-through conditions (1991). The study was carried out according to GLP and EPA OPP 72-4 guidelines. Daphnia were exposed to mean measured concentrations of 0.0025, 0.0036, 0.0086, 0.0175 and 0.0335 mg a.i./L, alongside with a control. Based on this study, the 21d NOEC reproduction for aquatic invertebrates exposed to test substance in the freshwater was 0.0036 mg a.i./L.