Pirimiphos-methyl

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:

16 Nov 1990 to 7 Dec 1990

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Version / remarks:

according to OECD 202, part II.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Each of the freshly prepared test solutions and the old test solutions on study days 2, 7, 9, 14, 16 and 21 were analysed for the test substance.

Vehicle:

yes

Remarks:

Acetone

Details on test solutions:

The top concentration was prepared by adding an aliquot of a stock solution of the test substance in acetone to hard, blended water to give the required nominal concentration of the test substance and 40 µL acetone per L. Lower concentrations were prepared from the top concentration by serial dilution using hard, blended water containing 40 µL acetone per L. The solvated control contained 40 µL acetone per L, the untreated control was hard and blended water only.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Age at study initiation: Less than 24 hours old
- Source: From cultures maintained at Jealotts Hill
- Food type: Diet of yeast and Chlorella vulgaris
- Feeding during test: The Daphnia were fed daily with suspensions of Chlorella vulgaris (4 E+07 cells per vessel) and dried yeast (0.25 mg per vessel)

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

176 - 177 mg/L as CaCO3

Test temperature:

19-21°C

pH:

7.2 - 8.4

Dissolved oxygen:

> 5.3 mg/L

Conductivity:

355 - 390 μS cm/L

Nominal and measured concentrations:

- Nominal concentrations: 0.025, 0.05, 0.1, 0.2, 0.4 µg/L of the test substance
- Mean measured concentrations: 0.028, 0.050, 0.09, 0.19, 0.36 µg/L of the test substance, respectively.
See Table 1 in "Any other information on materials and methods incl. tables"

Details on test conditions:

TEST SYSTEM
- No. of organisms per vessel: 1
- No. of vessels per concentration: 10
- No. of vessels per control: 1
- No. of vessels per vehicle control: 1

TEST MEDIUM / WATER PARAMETERS
- Alkalinity: 140 mg/L

EFFECT PARAMETERS MEASURED:
Mortality of the P0 generation was recorded daily for each test vessel. Fresh test solutions were prepared every Monday, Wednesday and Friday. Surviving P0 generation were transferred to the new solutions using a wide bore pipette. Old test solutions were examined, from study day 7, for young Daphnia (termed the F1 generation). Any offspring present, both live and dead, were counted and then discarded. At the end of the test (day 21) the length (from apex of helmet to base of spine) of the surviving P0 Daphnia was measured, using a microscope with a calibrated eyepiece graticule.

Reference substance (positive control):

no

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.05 µg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

reproduction

Details on results:

- Mortality: The LC50 values at days 7, 14 and 21 were 0.24, 0.08 and 0.08 µg/L respectively based on nominal concentration
- Growth: The lengths of the surviving P0 Daphnia at the end of the test are given in Table 1 together with the mean values for each treatment. In all the concentrations with Daphnia surviving at day 21 (nominally 0.1 µg/L and below) there was no significant difference between the treatments and either control.
- Reproduction: The total numbers of young produced in each replicate vessel are shown in Table 4, together with the mean values for each treatment. At nominally 0.4 μg/L there were no young produced as all the P0 generation Daphnia died before reproduction began (day 6-7). At 0.2 and 0.1 μg/L the mean number of young produced was significantly reduced from the controls. At 0.1 μg/L there were 3 P0 Daphnia surviving at day 21 and these produced a mean number of young of 110, compared to a solvent control value of 176. At concentrations of 0.05 and 0.025 μg/L there was no significant difference between the mean number of young produced per replicate and the controls. Therefore based on nominal concentrations the 21 day NOEC was 0.05 μg/L
See table 1 and table 2 in 'Any other information on results incl. tables'

Results with reference substance (positive control):

Not reported

Reported statistics and error estimates:

Estimates of the LC50 and its 95% confidence intervals on days 7, 14 and 21 were produced analysing the data by iteratively reweighted linear regression of the probit transformation of % mortality on log (nominal concentration). Furthermore, the number of young produced and Daphnia length, day 21, were analysed for significant differences from the controls.

table 1. Daphnia lengths, day 21

Replicate	Length in mm
	Nominal Concentration (µg/L)^a
	Control	Solvent Control	0.025	0.05	0.1
a b c d e f g h i j	4.42 5.03 4.69 4.62 4.62 4.83 4.76 4.62 4.56 4.62	4.42 4.56 4.76 4.62 4.49 4.90 4.42 4.96 4.83 4.76	4.62 4.69 5.03 4.90 4.69 4.56 4.69 4.69 4.76 4.28	4.42 4.42 4.69 4.76 4.69 4.56 4.62 4.69 4.62 4.56	- b - - 4.56 - 4.35 4.69 - - -
Mean	4.68^c	4.67^c	4.65^c	4.60^c	4.53^c

LSD  5% = 0.166

LSD  1% = 0.224

a: All Daphnia at nominal concentrations 0.2 and 0.4 µg/L were dead before day 21

b: Daphnia dead at or before day 21

c: Means not significantly different

Table 2. Total number of young produced Daphnia

Replicate	Total Number of Live Young
	Nominal Concentration in µg/L
	Control	Solvent Control	0.025	0.05	0.1	0.2	0.4
a	181	170	190	174	21	0	0
b	162	184	181	157	26	14	0
c	182	163	187	163	28	14	0
d	177	179	172	175	80	17(2)^a	0
e	171	165	177	170	60(2)^a	6	0
f	159	196	174	159	125	17	0
g	162	158	191	167	123	20(3)^a	0
h	174	185	167	169	28	0	0
i	176	174	176	171	43	20	0
j	165	181	177	161	71	25(2)^a	0
Means	172	176	179	167	60	11	0
Detransformed means	170	175	179	167	50^b	8^b	o^b

* na = Not analysed

^a +: Sample lost during analysis

^b-: Sample not analysed/prepared as Daphnia had died

^c: Approximate limit of determination under the conditions used

Validity criteria fulfilled:

not specified

Conclusions:

The 21 day NOEC was determined at 0.05 µg/L

Executive summary:

The long-term toxicity to aquatic invertebrates was determined in a study in accordance with OECD TG 211 and in compliance with GLP criteria. Daphnia magna were exposed to a series of concentrations of the test substance of 0.025, 0.05, 0.1, 0.2, 0.4 µg/L in water containing 0.01% acetone at 20 ± 1°C; including solvent and blank controls for 21 days. Each test concentration consisted of 10 replicate chambers, originally containing a single daphnid. Daphnids were transferred to freshly prepared test solutions three times weekly. Analysis by gas liquid chromatography of freshly prepared test solutions for the test substance gave mean measured concentrations in the range 90-112% of the nominal. Analysis of aged (2-3 day old) test solutions after the transfer of the daphnids showed the test substance to be in the range of 44-138% of the same solutions analysed when freshly prepared, indicating little, if any loss of the test substance over the period of use of each test solution. The mean measured concentrations were determined to be 0.028, 0.050, 0.09, 0.19, 0.36 µg/L, respectively. The test was carried out under the following conditions: temperature 19 - 21 °C, pH 7.2 – 8.4, dissolved oxygen concentration >5.3 mg O2/L (>60% of saturation). The water parameters were measured at the start and end of the test. Mortality of the parent generation was recorded daily for each test vessel. After renewals, old test solutions were examined, for young daphnids. Any offspring present, both live and dead, were counted and then discarded. At the end of the test, the length of the surviving parent daphnids was also measured.

 

At nominal concentrations of 0.4 and 0.2 µg/L, all the daphnids were completely immobilized after 5 and 12 days, respectively. At 0.1 µg/L, there were 3 out of the parent 10 daphnids surviving at 21 days. At lower concentrations and in the controls, all the daphnids survived. There was no significant difference in the adult daphnid length between any of the surviving parent daphnids. At 0.1 µg/L, however, the mean number of young produced per replicate was significantly reduced from the controls, whereas at 0.05 and 0.025 µg/L there was no significant difference. Therefore, based on the findings, the 21-d NOEC, based on reproduction, was determined to be 0.05 µg/L.

Description of key information

28-d NOEC = 0.05 µg/L, Daphnia magna, semi-static regime, OECD TG 211, Rapley & Hamer 1991

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Effect concentration:

0.05 µg/L

Additional information

The long-term toxicity to aquatic invertebrates was determined in a study in accordance with OECD TG 211 and in compliance with GLP criteria. Daphnia magna were exposed to a series of concentrations of the test substance of 0.025, 0.05, 0.1, 0.2, 0.4 µg/L in water containing 0.01% acetone at 20 ± 1°C; including solvent and blank controls for 21 days. Each test concentration consisted of 10 replicate chambers, originally containing a single daphnid. Daphnids were transferred to freshly prepared test solutions three times weekly. Analysis by gas liquid chromatography of freshly prepared test solutions for the test substance gave mean measured concentrations in the range 90-112% of the nominal. Analysis of aged (2-3 day old) test solutions after the transfer of the daphnids showed the test substance to be in the range of 44-138% of the same solutions analysed when freshly prepared, indicating little, if any loss of the test substance over the period of use of each test solution. The mean measured concentrations were determined to be 0.028, 0.050, 0.09, 0.19, 0.36 µg/L, respectively. The test was carried out under the following conditions: temperature 19 - 21 °C, pH 7.2 – 8.4, dissolved oxygen concentration >5.3 mg O2/L (>60% of saturation). The water parameters were measured at the start and end of the test. Mortality of the parent generation was recorded daily for each test vessel. After renewals, old test solutions were examined, for young daphnids. Any offspring present, both live and dead, were counted and then discarded. At the end of the test, the length of the surviving parent daphnids was also measured.

 

At nominal concentrations of 0.4 and 0.2 µg/L, all the daphnids were completely immobilized after 5 and 12 days, respectively. At 0.1 µg/L, there were 3 out of the parent 10 daphnids surviving at 21 days. At lower concentrations and in the controls, all the daphnids survived. There was no significant difference in the adult daphnid length between any of the surviving parent daphnids. At 0.1 µg/L, however, the mean number of young produced per replicate was significantly reduced from the controls, whereas at 0.05 and 0.025 µg/L there was no significant difference. Therefore, based on the findings, the 21-d NOEC, based on reproduction, was determined to be 0.05 µg/L.