Semicarbazide hydrochloride

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

This study was conducted between 31 August 2017 and 28 September 32017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 306 (Biodegradability in Seawater)

Version / remarks:

July 1992

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

Name: Semicarbazide-HCl
NIVA GLP substance number: G129
CAS: 563-41-7
Batch number: 55507861
Appearance: Crystalline, white
Purity: >99 %
Solubility in water: 100 g/L
Carbon content: 11%

Oxygen conditions:

aerobic

Inoculum or test system:

other: Sea water

Duration of test (contact time):

28 d

Initial conc.:

1.012 g/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

DOC removal

Details on study design:

Equipment
Test unit and incubator Erlendmeyer flasks (5L), shaking table, temperature controlled room K5
Refractometer ATAGO Hand refractometer
Volumetric cylinders 10 ± 0.2mL, 100 ± 0.75mL
Volumetric bottles 1000 ± 0.4mL
Balances Vekt 2, Vekt 10

 
Seawater quality
The seawater was pumped from a depth of 60 meter in the Oslofjord, from NIVA's Research Station at Solbergstrand, and collected in 30 L polyethylene containers. The temperature is logged at the research station and not measured according to GLP.

Appearance: Clear
Salinity: 35‰
Temperature: 8.1 ˚C

Dissolved organic carbon concentration was analyzed after storage (1.1 mg C/L). The concentration of heterotrophic bacteria was also determined (1.3x105 CFU/mL) by plating on marine agar and incubated for 8 days at 25 ± 2 °C.

Preparation of seawater test medium
The seawater was transported to NIVA in Oslo and stored at test temperature for three days in the dark. Water (7 L) was siphoned into new can and nutrient stock solutions A, B, C and D (OECD 306) were added (1 ml/L). The composition of the stock solutions is shown in Table 1.

Preparation of test bottles
Blank control bottles
Two Erlenmeyer flasks were filled with 1L each of test water by siphoning.

Test sample bottles
A stock solution of the test substance was made by dissolving 0.5058 g Semicarbazide hydrochloride in 500ml deionized water (MilliQ).

A 1L volumetric flask was added 90ml test substance stock and filled up to 1 L with test water by siphoning. Two Erlenmeyer flasks were filled with 1 L each.

Reference compound bottles (test control)
A stock solution of aniline (C6H5NH2, 99 %, Mw 93.13) was prepared as the reference (test control) by dissolving 0.2722 g aniline in 100 ml MilliQ water.

A 1 L volumetric flask was added 10ml reference stock and filled up to 1L with test water by siphoning. One erlendmeyer flaks was filled with 1 L.

Toxicity control
A 1 L volumetric flask was added 10ml reference stock and 90 ml test substance stock and filled up to 1 L with test water by siphoning. One erlendmeyer flaks was filled with 1 L.


Incubation and sampling
All bottles (blank, test and reference) were incubated under dark plastic in a temperature controlled room (21.2 ± 1.6˚C).

Samples were withdrawn for DOC measurements on days 0, 7, 14, 21 and 28.

Reference substance:

aniline

Key result

Parameter:

% degradation (DOC removal)

Value:

84

Sampling time:

28 d

Key result

Parameter:

COD

Value:

84 other: %

Results with reference substance:

Validity of test
Test control (reference compound)
Aniline was used as the reference compound in the test to assess the viability of the indigenous bacteria used to evaluate the biodegradability of the test compound. The biodegradability of this reference compound should be at least 50% after 14 days’ incubation at 20±1˚C.

The reference compound had 93% removal after 7 days and fulfilled the criteria of 50% biodegradability within 14 days.

Toxicity control

There was only 11% biodegradation in the toxicity control after 21 days incubation, see Figure 2. This would normally mean that the test substance is inhibitory to the bacteria. However, since the test substance alone was degraded it is assumed that the lack of biodegradation in the toxicity control might be caused by a combination effect of Semicarbazide-HCl and aniline.

Biodegradation of the test samples

The DOC values are shown in Table 1

Semicarbazide-HCl had an average biodegradation of 84% after 28 days (Table 2). The two parallel flasks had a similar degradation curve.

 Table 1 DOC Values

			DOC after n days (mg/L)
	flask no.		0	7	14	21	28
Test flasks	1	a1	10.0	6.8	4.7	2.8	2.0
		a2	10.2	6.8	4.6	3.0	2.2
		mean, Ca(t)	10.1	6.8	4.7	2.9	2.1
	2	b1	10.2	5.7	2.6	1.8	1.8
		b2	10.4	5.8	2.6	1.8	1.8
		mean, Cb(t)	10.3	5.8	2.6	1.8	1.8
Blank control	1	C1	1.1	0.9	1.0	1.0	1.0
		C2	1.0	0.9	1.1	1.0	0.9
		mean, Cc(t)	1.1	0.9	1.1	1.0	1.0
	2	d1	1.2	1.0	0.9	0.9	1.0
		d2	1.2	0.9	0.9	1.0	1.0
		mean, Cd(t)	1.2	1.0	0.9	1.0	1.0
	mean, C(bl(t)		1,1	0.9	1.0	1.0	1.0
	= (Cc(t) + Cc(t)) / 2
Controls	Reference	R1	20.6	2.3	2.2	1.9
		R2	20.6	2.4	2.4	2.1
		mean, Cr(t)	20.6	2.4	2.3	2.0
	Toxicity	X1	27.3	26.8	26.3	23.8
		X2	27.1	27.2	27.6	24.4
		mean, Cx(t)	27.2	27.0	27.0	24.1

Temperature range during test was maximum 22.7^oCand minimum 19.6^oC, resulting in a mean test temperature of21.2 ± 1.6˚C

Table 2 % Degradation after n days

Flask N o.	% Degradation after n days
	7	14	21	28
Test Flask 1	35	59	79	87
Test Flask 2	37	72	80	80
Mean	36	65	80	84
Reference Control	93	93	95
Toxicity Control	0	0	11

Validity criteria fulfilled:

yes

Interpretation of results:

readily biodegradable

Conclusions:

The results of the study indicate that Semicarbazide-HCl was biodegraded 84% in seawater over an incubation period of 28 days

Executive summary:

The biodegradability of Semicarbazide-HCl has been assessed in seawater at 21.2 ± 1.6^oC using the shake flask test method according to OECD Guidelines for Testing of Chemicals 306 (OECD, 1992).

 

The test compound was exposed to indigenous microorganisms in natural seawater.

 

Semicarbazide-HClwas tested at a concentration of 1000 mg/L.

 

Semicarbazide-HClwas 84% degraded.

 

The reference control, aniline, was 93% biodegraded after 7 days. The toxicity control did not degrade.

 

Description of key information

The biodegradability of Semicarbazide-HCl has been assessedin seawater at 21.2 ± 1.6^oC using the shake flask test method according to OECD Guidelines for Testing of Chemicals 306 (OECD, 1992).

 

The test compound was exposed to indigenous microorganisms in natural seawater.

 

Semicarbazide-HClwas tested at a concentration of 1000 mg/L.

 

Semicarbazide-HClwas 84% degraded.

 

The reference control, aniline, was 93% biodegraded after 7 days. The toxicity control did not degrade.

 

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

marine water