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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

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Diss Factsheets

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Experimental data from tests investigating the toxicity of KDDC to aquatic organisms were not conducted since studies from similar analogues are considered suitable for this purpose, in accordance with the specifications listed in Regulation (EC) No. 1907/2006 Annex XI, 1.5 Grouping of substances and read across, on basis of structural similarity, physico-chemical properties, ecotoxicological profiles. There is no convincing evidence that any one of these chemicals might lie out of the overall profile of this analogue approach, respectively. Conclusions regarding this section have been drawn based on studies performed on SDDC (sodium dimethyldithiocarbamate, CAS No. 128-04-1) and Ziram (zinc bis(dimethyldithiocarbamate), CAS No. 137-30-4). KDDC, SDDC and Ziram represent salts of dimethyl dithiocarbamic acid (DDC) that are capable of dissociating into the respective ions when exposed to water. The main differences between Ziram and KDDC/SDDC are the solubility in water and partition coefficient, related to the rather covalent character of the zinc-sulphur bond with respect to the sodium-sulphur bond. The physico-chemical parameters of the three substances are listed in the table below.

Table 2. Physico-chemical parameters of KDDC, SDDC and Ziram

Parameter

KDDC

SDDC

Ziram

CAS no.

128-03-0

128-04-1

137-30-4

IUPAC Name

potassium dimethyldithiocarbamate

sodium dimethyldithiocarbamate

zinc bis(dimethyldithiocarbamate)

Molecular weight

159.3 g/mol

143.2 g/mol

305.8 g/mol

Molecular formula

C3H7NS2.K

C3H7NS2.Na

C6H12N2S4Zn

Melting point

Partial melting from 81.5 to 85.0°C followed by slow decomposition

Decomposition at
≥ 253°C

251.0 – 252.5°C
Colour change beginning at 238°C

Relative density at 20°C

1.51

1.4

1.7097

Vapour pressure at 25°C

8.76×10-5Pa

< 2×10–4Pa

1.8×10–5Pa

Log Pow at 20°C

read across to SDDC

pH 5: = –3.2
pH 7: < –2.28
pH 9: < –2.33

1.65

pH range: 7.4-8.6[1]

Water solubility

read across to SDDC

37.4 - 40% (w/w)
pH 10.5

9.67×10–4g/L
pH range: 7.2-7.41

* data are not presented within this dossier, but were subject to the respective REACh-registration of Ziram (CAS 137-30-4; EC 205-288-3)


Acute studies (fish, aquatic invertebrates, algae and aquatic microorganisms) are available for the analogue showing the highest similarity to KDDC, i.e. SDDC. For the chronic aquatic toxicity, data from Ziram were used to cover these endpoints. This approach implies a worst-case scenario, since acute values show generally a higher sensitivity of aquatic organisms to Ziram than to SDDC. The table below gives an overview on acute aquatic toxicity data of SDDC and Ziram.

Table 3. Ecotoxicological data of SDDC and Ziram in the aquatic compartment

Endpoint

SDDC

Ziram

Acute fish toxicity

Oncorhynchus mykiss,(semi static),
Van der Kerken (2003):
LC50(96h) = 0.76 mg a.i./L

 

Oncorhynchus mykiss,(semi static),
(1991):
LC50(96h) =1.7 mg a.i./L*

Lepomis macrochirus,(cont. renewal),
(1991):
LC50(96h) =0.0097 mg a.i./L*

Bluegill sunfish(Lepomis macrochirus),(cont. renewal),
Palmer (2007):
LC50(96h) =0.57 mg a.i./L*

Acute daphnia toxicity

Daphnia magna,(semi static),
Van der Kerken (2003):
LC50(48h) = 0.67 mg a.i./L

Daphnia magna, (static),
(1990):
EC50(48h) = 0.048 mg/L*

 

Acute algae toxicity

Selenastrum capricornutum,
Van der Kerken (2003):
EC50(growth rate) (96h) = 0.25 mg a.i./L

Selenastrum capricornutum,

Lopes Morandi (2007):
EC50(growth rate) (72h) = 0.5 mg a.i./L*

* data are not presented within this dossier, but were subject to the respective REACh-registration of Ziram (CAS 137-30-4; EC 205-288-3)

 

In accordance with Annex XI, 1.5 considering the similarities on structure, physico-chemical and ecotoxicological characteristics, the analogue approach from SDDC and ziram to KDDC is justified.

 

Based on the data presented, KDDC is considered to be very toxic to aquatic organisms. Lethal and/or sublethal effects at all trophic levels tested in the laboratory (fish, aquatic invertebrates, algae, and activated-sludge microorganisms) were observed after both acute and chronic exposure. The results from the short-term toxicity tests performed on the analogue SDDC showed that algae species are the most sensitive organisms (EC50 = 0.25 mg a.i./L). The evaluation of the chronic effects was carried out using toxicity data from Ziram, in which Daphnia magna showed the highest sensitivity (78 µg a.i./L). The toxic properties of KDDC as observed in fish, algae and daphnia tests, are supported by the low effect concentration as determined for SDDC in an activated sludge respiration test (EC50 = 3.65 mg a.i./L).