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Experimental data from tests investigating the toxicity of KDDC to terrestrial 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 were 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*

Molecular weight

159.3 g/mol

143.2 g/mol

305.8 g/mol

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 where subject to the respective REACh-registration of Ziram (CAS: 137-30-4, EC: 205-288-3)

An acute earthworm study is available for the analogue showing the highest resemblance to KDDC, i.e. SDDC. The remaining terrestrial endpoints were covered by data of Ziram. This approach can be considered as a worst-case scenario, since the comparison between SDDC and Ziram in a) aquatic toxicity tests (see technical dossier chapter 6.1) and b) for the terrestrial compartment (in acute earthworm studies),showed significantly lower effect concentrations for Ziram than those for SDDC (LC50(14d) = 140 mg a.i./kg soil (dw)* for Ziram and LC50(14d) = 787.6 mg a.i./kg soil (dw) for SDDC, respectively).

Based on the results from the studies performed on the analogue substances, KDDC may cause toxic effects to some terrestrial organisms (e.g. Eisenia fetida: NOEC of 4.053 mg a.i./kg dw soil).

The table below summarizes the effects of the analogue substances Ziram and SDDC to terrestrial organisms:

Table 4. Ecotoxicological data of SDDC and Ziram in the terrestrial compartment

Endpoint

Test duration

Effect value

Substance

Toxicity to soil macroorganisms except arthropods

14d

LC50 = 787.6 mg a.i./kg soil d.w.

SDDC

Toxicity to soil macroorganisms except arthropods

56d

NOEC = 4.053 mg a.i./kg soil d.w.

Ziram

Toxicity to terrestrial arthropods

48 h

LD50 > 100 µg per animal

Ziram

Toxicity to terrestrial plants

21 d

NOEC = 9 kg/ha

Ziram

Toxicity to soil microorganisms

56d

NOEC = 40 kg/ha

Ziram

Toxicity to birds

14 d

LD50 = 97 mg /kg bw

Ziram

Toxicity to birds

5 d

LC50 = 5156 mg/kg diet

Ziram

Toxicity to birds

20 wk

NOEC > 500 mg/kg diet

Ziram