Sulfaguanidine

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

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

comparable to guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Version / remarks:

1998

Deviations:

yes

Remarks:

Medium: ADaM; feed: S. dimorphus 8x10^5 cells/mL

GLP compliance:

not specified

Specific details on test material used for the study:

Sulfaguanidine (minimum purity: 99%) was purchased from Sigma–Aldrich.

Analytical monitoring:

yes

Details on sampling:

Sublethal effects on growth were determined as follows. Sixty haphazardly selected juveniles (<24 h old) were transferred in clean ADaM, fixed by progressively adding ethanol to a 70% concentration, and their length measured (from the top of the eye to the base of the tail spine) by means of a DMD108 digital microimaging device (Leica Microsystems, Milano, Italy). The same procedure was repeated on the surviving daphnids at the end of tests and the average daily growth rate calculated over the 21-days period.

Vehicle:

yes

Remarks:

ADaM medium

Details on test solutions:

Fresh stock solutions were prepared just before each experiment by diluting in the proper medium (ADaM) the compound to be tested. Where necessary, the solubilization was achieved by bringing back the pH of the medium to the original value using 1 M NaOH. The pH was measured using a BASIC 20 pH meter (CRISON, Carpi, Italy). All working solutions used in tests were prepared by appropriately diluting the stock solution with medium to the requested concentration.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna, <24-h old
- Strain/clone: Straus
- Source:from a single clone, cultured and maintained in ADaM medium and obtained from the second to fifth brood

FEEDING DURING TEST:
- Food type: S. dimorphus
- Amount: 8 x 10^5 cells mL-1
- Frequency: every other day

Test type:

semi-static

Water media type:

other: ADaM medium

Total exposure duration:

21 d

Hardness:

193 mg CaCO3 L-1

Test temperature:

20 ± 1°C

pH:

8.0–8.3

Dissolved oxygen:

6.2–6.8 mg/L

Salinity:

not specified

Conductivity:

1016–1170 µS/cm

Nominal and measured concentrations:

As the concentration of all the tested substances was maintained within ±20% of the initial concentration, test results were based on nominal values. The nominal values were: control, 0.098, 0.195, 0.395, 0.781 and 1.562 mg/L.

Details on test conditions:

The ADaM medium was used for the controls and the dilution of test solutions. For each of the five concentration tested and for the control, 10 young daphnids were allocated individually in 50 mL of solution and incubated at the same conditions (light, temperature) used for culturing. During the tests, solutions were renewed every other day, the neonates removed and counted, and the feed (S. dimorphus, 8 x 10^5 cells/mL) supplied. Old (48-h) solutions from each concentration level were then pooled and monitored for pH, conductivity and dissolved oxygen using YSI 85 multiparameter instrument (YSI Incorporated, Yellow Springs, OH, USA).

Reference substance (positive control):

no

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

0.395 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

LOEC

Effect conc.:

0.781 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

other: EC20

Effect conc.:

0.322 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

EC50

Effect conc.:

0.869 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

reproduction

Details on results:

Statistically significant effects were observed on reproduction at concentrations of sulfaguanidine (SGD) equal or above 0.781 mg L-1 and these were concentration dependent. At concentration of 1.562 mg/L significant effects on growth were also observed. No mortality was observed in the control, with an average of 97 neonates per survived female.

CONFIDENCE INTERVALS (95% confidence level):
EC20: 0.152 - 0.559 mg/L
EC50: 0.630 - 1.097 mg/L

Results with reference substance (positive control):

None

Nominal concentration (mg L^-1)	Survival rate (%)	Average daily growth (length, µm)	Total number of neonates	Neonates per female (mean ± sd)
1.562	20	125.2 a	17	8.50 a
0.781	90	147.7 ± 13.8	499	55.44 ± 31.70 a
0.395	80	145.5 ± 10.3	603	75.38 ± 36.79
0.195	100	154.3 ± 6.5	806	80.60 ± 30.63
0.098	100	152.9 ± 11.2	928	96.90 ± 16.86
Control	100	156.6 ± 10.6	974	97.40 ± 14.23
a Significantly different from the control (p< 0.05).

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity of the test item sulfaguanidine (SGD) to Daphnia magna was determined in a 21-day test, resulting in a 21-day 0.395 mg/L NOEC and 0.781 mg/L LOEC.
EC20 was calculated to be 0.3217 mg/L while EC50 was calculated to be 0.869 mg/L.

Executive summary:

The aquatic toxicity of sulfaguanidine (SGD) was evaluated on Daphnia magna reproduction in general accordance with OECD guideline 211 of 1998. Statistically significant effects were observed on reproduction at concentrations equal or above 0.781 mg/L and these were concentration dependent. At concentration of 1.562 mg/L significant effects on growth were also observed. Based on results from statistical analysis, 0.781 mg/L was taken as the LOEC and 0.395 mg/L was taken as the NOEC. The estimated EC50 of SGD for D. magna reproduction was 0.87 mg/L.

Description of key information

The aquatic toxicity of sulfaguanidine (SGD) was evaluated on Daphnia magna reproduction in general accordance with OECD guideline 211 of 1998. Statistically significant effects were observed on reproduction at concentrations equal or above 0.781 mg/L and these were concentration dependent. At concentration of 1.562 mg/L significant effects on growth were also observed. Based on results from statistical analysis, 0.781 mg/L was taken as the LOEC and 0.395 mg/L was taken as the NOEC. The estimated EC50 of SGD for D. magna reproduction was 0.87 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

0.395 mg/L