Cyanamide

Toxicity to aquatic plants other than algae

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic plants other than algae

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2000-02-07 until 2000-02-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.4400 (Aquatic Plant Toxicity Test using Lemna spp. Tiers I & II))

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Mean measured concentrations of the 51.1 % (w/w) aqueous solution of cyanamide were 0.31, 0.86, 2.95, 10.18 and 34.5 mg /L, corresponding to 0.16, 0.44, 1.51, 5.20 and 17.63 mg ai/L and ranged from 76 to 109 % of nominal concentrations.

Vehicle:

no

Details on test solutions:

No vehicle

Test organisms (species):

Lemna gibba

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

7 d

Post exposure observation period:

No post exposure observation period

Hardness:

Not indicated

Test temperature:

All chemical and physical parameters (pH, temperature) in the definitive test were within expected ranges.

pH:

All chemical and physical parameters (pH, temperature) in the definitive test were within expected ranges.

Dissolved oxygen:

Not indicated

Salinity:

Freshwater

Nominal and measured concentrations:

Test concentrations of 0.32, 1.0, 3.2, 10.0 and 32.0 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L.
Mean measured concentrations of the 51.1 % (w/w) aqueous solution of cyanamide were 0.31, 0.86, 2.95, 10.18 and 34.5 mg /L, corresponding to 0.16, 0.44, 1.51, 5.20 and 17.63 mg ai/L and ranged from 76 to 109 % of nominal concentrations.

Details on test conditions:

The effects of SKW Cyanamid L500 (a 51.1 % (w/w) aqueous solution of cyanamide) on Lemna gibba G3 was determined in 20XAAP nutrient medium. Three replicates at test concentrations of 0.32, 1.0, 3.2, 10.0 and 32.0 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L, were incubated for 7 days and frond counts were taken on days 3, 5 and 7, corresponding to 0.16, 0.51, 1.64, 5.11 and 16.35 mg ai/L. Additionally, a control was tested in parallel. The samples of the test medium were analysed by a HPLC method using an UV/VIS-detector.

Reference substance (positive control):

no

Key result

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

2.33 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Key result

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

0.5 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

biomass

Key result

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

5.61 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Key result

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

0.5 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

growth rate

Duration:

7 d

Dose descriptor:

EC50

Effect conc.:

2.4 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: dry weight

Duration:

7 d

Dose descriptor:

NOEC

Effect conc.:

0.5 mg/L

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Basis for effect:

other: dry weight

Details on results:

The doubling time of fronds in the controls was 1.7 d (39.5 h) and thus less than 2.5 d (60 h), corresponding to an approximately 19-fold increase in 7 days.The test item had a statistically significant inhibitory effect on the growth of Lemna gibba after the exposure of 7 days first at the nominal concentration of 3.2 mg test item/L, corresponding to 1.63 mg ai/L. The 7-day NOEC was determined at the nominal concentration of 1 mg test item/L, corresponding to 0.51 mg ai/L, since up to and including this test concentration the mean biomass, mean growth rates and the dry weight of Lemna gibba were not significantly lower than in the control. At the nominal test concentrations of 0.32 to 3.2 mg/L, corresponding to 0.163 to 1.63 mg ai/l, the shape of fronds and colonies after the test period of 7 days was not different to those in the control. However, at the two highest test concentrations of 10.0 and 32.0 mg/L (5.1 and 16.35 mg ai/L), the fronds were pale and small.

Results with reference substance (positive control):

No positive control

Reported statistics and error estimates:

The test groups were significantly different from controls according to the Dunnett-test criteria, p < 0.05.

In the test medium the test item was sufficiently stable during the test period of 7 days. Therefore, all reported biological results are related to the nominal concentrations of the test item.

Analytical determination of concentrations tested:

Nominal concentrations of a 51.1 % (w/w) aqueous solution of cyanamide (mg/L)	Test concentration (% of nominal) samples taken after
	0 d	7 d
0.32	100.0	90.6
1.0	92.0	79.0
3.2	93.8	90.6
10.0	102.5	101.0
32.0	107.3	108.6

 

Effect of a 51.1 % (w/w) aqueous solution of Cyanamide on the growth and reproduction of Lemna gibba:

Nominal concentrations of a 51.1 % (w/w) aqueous solution of cyanamide (mg /L)	7-day mean frond number	7-day mean dry weight (mg)	Inhibition (%)
			Frond number	Dry weight	Area under the growth rate curve	Growth rate
Control	227.7	25.67	---	---	---	---
0.32	218.3	26.20	4.1	-2.2	3.1	1.4
1.0	205.7	25.87	5.8	-0.8	11.0	3.5
3.2	105.3	17.03	48.8	35.0*	47.7*	26.3*
10.0	50.0	6.33	52.5	78.4*	71.7*	51.5*
32.0	28.3	3.25	43.4	90.9*	88.0*	70.9*

 

Acute toxicity (7 d) of Cyanamide to Lemna gibba–Summary of endpoints:

Endpoint	Nominal concentration of a 51.1 % (w/w) aqueous solution of cyanamide
Biomass (area under growth curve):
EC50	4.56 mg/L (2.33 mg as/L)
No observed effect concentration (NOEC)	1.0 mg/L (0.5 mg as/L)
Growth rate:
EC50	10.98 mg/L (5.61 mg as/L)
No observed effect concentration (NOEC)	1.0 mg/L (0.5 mg as/L)
Dry weight:
EC50 4.7 mg/L	(2.4 mg as/L)
No observed effect concentration (NOEC)	1.0 mg/L (0.5 mg as/L)

 

Validity criteria fulfilled:

yes

Conclusions:

Growth inhibition values obtained with the 51.1 % (w/w) aqueous solution of cyanamide on Lemna gibba were as follows: Considering the area under the growth curve (biomass), a 7-day EC50 of 4.56 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (2.33 mg as/L) was calculated, the corresponding NOEC was 1.0 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (0.5 mg as/L). With respect to the growth rate, the 7-day EC50 was 10.98 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (5.61 mg as/L) and the respective NOEC was 1.0 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (0.5 mg as/L). Finally, for the dry weight a 7-day EC50 of 4.7 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (2.4 mg as/L) was determined with a corresponding NOEC of 1.0 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (0.5 mg as/L).

Executive summary:

The effects of SKW Cyanamid L500 (a 51.1 % (w/w) aqueous solution of cyanamide) on Lemna gibba G3 was determined in 20XAAP nutrient medium. Three replicates at test concentrations of 0.32, 1.0, 3.2, 10.0 and 32.0 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L, were incubated for 7 days. All chemical and physical parameters (pH, temperature) in the definitive test were within expected ranges. In the test medium the test item was sufficiently stable during the test period of 7 days. Therefore, all reported biological results are related to the nominal concentrations of the test item. The test item had a statistically significant inhibitory effect on the growth of Lemna gibba after the exposure of 7 days first at the nominal concentration of 3.2 mg test item/L, corresponding to 1.63 mg ai/L. The 7-day NOEC was determined at the nominal concentration of 1 mg test item/L, corresponding to 0.51 mg ai/L, since up to and including this test concentration the mean biomass, mean growth rates and the dry weight of Lemna gibba were not significantly lower than in the control. At the nominal test concentrations of 0.32 to 3.2 mg/L, corresponding to 0.163 to 1.63 mg ai/l, the shape of fronds and colonies after the test period of 7 days was not different to those in the control. However, at the two highest test concentrations of 10.0 and 32.0 mg/L (5.1 and 16.35 mg ai/L), the fronds were pale and small. A 7-day EC50 of 4.56 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (2.33 mg as/L) was calculated, the corresponding NOEC was 1.0 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (0.5 mg as/L). With respect to the growth rate, the 7-day EC50 was 10.98 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (5.61 mg as/L) and the respective NOEC was 1.0 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (0.5 mg as/L). Finally, for the dry weight a 7-day EC50 of 4.7 mg of a 51.1 % (w/w) aqueous solution of Cyanamide/L (2.4 mg as/L) was determined with a corresponding NOEC of 1.0 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (0.5 mg as/L).

Description of key information

The toxicity of cyanamide to aquatic plants (Lemna gibba G3) was examined in one available study. The effects of cyanamide were investigated in Lemna gibba G3 in a 7 day test. The calculated endpoint values were as follows: 7 day EC50 (dry weight) = 2.4 mg ai/L and a corresponding NOEC = 0.5 mg ai/L, a 7 day EC50 (biomass) = 2.33 mg ai/L and a corresponding NOEC = 0.5 mg ai../L, a EC50 (growth rate) = 5.61 mg ai/L and a corresponding NOEC = 0.5 mg ai/L.

Key value for chemical safety assessment

EC50 for freshwater plants:

5.61 mg/L

EC10 or NOEC for freshwater plants:

0.5 mg/L

Additional information

Toxicity of cyanamide (SKW Cyanamid L500 (a 51.1 % (w/w) aqueous solution of cyanamide)) to aquatic plants was examined in one available study. The effects of cyanamide were investigated in Lemna gibba G3 and determined in 20XAAP nutrient medium. Three replicates at test concentrations of 0.32, 1.0, 3.2, 10.0 and 32.0 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L, were incubated for 7 days. All chemical and physical parameters (pH, temperature) in the definitive test were within expected ranges. In the test medium the test item was sufficiently stable during the test period of 7 days. Therefore, all reported biological results are related to the nominal concentrations of the test item. The test item had a statistically significant inhibitory effect on the growth of Lemna gibba after exposure of 7 days first at the nominal concentration of 3.2 mg test item/L, corresponding to 1.63 mg ai/L. The 7-day NOEC was determined at the nominal concentration of 1 mg test item/L, corresponding to 0.51 mg ai/L, since up to and including this test concentration the mean biomass, mean growth rates and the dry weight of Lemna gibba were not significantly lower than in the control. At the nominal test concentrations of 0.32 to 3.2 mg/L, corresponding to 0.163 to 1.63 mg ai/l, the shape of fronds and colonies after the test period of 7 days was not different to those in the control. However, at the two highest test concentrations of 10.0 and 32.0 mg/L (5.1 and 16.35 mg ai/L), the fronds were pale and small.

 

A 7-day EC50 of 4.56 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (2.33 mg ai/L) was calculated, the corresponding NOEC was 1.0 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (0.5 mg ai/L). With respect to the growth rate, the 7-day EC50 was 10.98 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (5.61 mg ai/L) and the respective NOEC was 1.0 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (0.5 mg ai/L). Finally, for the dry weight a 7-day EC50 of 4.7 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (2.4 mg ai/L) was determined with a corresponding NOEC of 1.0 mg of a 51.1 % (w/w) aqueous solution of cyanamide/L (0.5 mg ai/L).