Registration Dossier

Diss Factsheets

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Read across for DTDMAC from structurally similar Quats DHTDMAC/DODMAC can be applied and the corresponding effect data form DHTDMAC/DODMAC used for DTDMAC as well.

SUMMARY ON TERRESTRIAL EFFECT DATA FOR DHTDMAC

This summary table is extracted from the EU Risk Assessment DODMAC (EU, 2002).

Species

Endpoint

Effect Conc.

Substance

Reference

Sinapis alba

 

Triticum aestivum

Linum utisatissimum

14d EC5

14d EC50

14d EC5

14d EC5

1400 mg/kg

3540 mg/kg

> 1000 mg/kg

> 1000 mg/kg

DHTDMAC

Pestemer et al, 1991

Sorghum bicolor

Helianthus annuus

28d EC50

NOEC

28d EC50

NOEC

2530 mg/kg

1000 mg/kg

2930 mg/kg

1000 mg/kg

DHTDMAC

Windeatt, 1987

Avena sativa

Brassica rapa

14d NOEC

14d NOEC

>1000 mg/kg

>1000 mg/kg

DHTDMAC

Stanley & Tapp, 1982

Eisenia fetida

14d NOEC

>1000 mg/kg

DHTDMAC

Coulson et al., 1989

Lycopersicum escul.

Lactuca sativa

Hordeum vulgare 

NOEC

(growth)

>40 g/kg (dw)

DHTDMAC

Topping & Waters, cited in ECETOC 1993

soil micro-organisms

14w NOEC


28d NOEC

>400 mg/kg


>365 mg/kg

DHTDMAC

DHTDMAC

Procter & Gamble, 1992

Täuber et al., 1986

SUMMARIZED DETAILS ON THE TESTS MENTIONED IN THE TABLE ABOVE (from EU Risk Assessment DODMAC)

As there is no terrestrial test with DODMAC results with DHTDMAC are cited below, because so far there is no proof that the toxicity of both substances varies significantly. The effect values are all nominal values and are not converted to a standard soil of a defined organic carbon content, because this does not seem to be adequate as the bioavailability of DODMAC/DHTDMAC is not determined by the organic matter content alone but also by other soil parameters e.g. ionic binding. The different test concentrations were prepared at maximum one day before the start of the test and adsorption was rapid.

The toxicity of DHTDMAC (75% purity; named DSDMAC in the reference) to plant seedlings was tested by Pestemer et al. (1991) in a loamy sandy soil (1.3% organic carbon, 9.9% clay, 54.3 sand, 35.7 silt). Seedlings with developed cotyledons were exposed for 14 days. Related to fresh weight reduction the most sensitive species wasSinapis albawith an EC5 of 1400 mg/kg dry weight and an EC50 of 3540 mg/kg dry weight. ForTriticum aestivumandLinum utisatissimumthe EC5-values were above 1000 mg/kg dw. In a germi­nation test DHTDMAC concentrations up to 3.2 g/l had no inhibiting effect onLepidium sativum(Pestemer et al. 1991).

In another study (Windeatt, 1987) the influence of DHTDMAC (76.1% active ingredient = quartenary ammonium) on the emergence of plant seedlings and the early growth stages ofSorghum bicolorandHelianthus annuuswere investigated. Potting compost with about 80% sand/gravel and 20% silt/clay including 4% organic matter was used as substrate. The highest test concentration of 10 g active ingredient of DHTDMAC per kg dry soil had no significant effect on the emergence of seeds after 7 days. After further 21 days the EC50 for fresh weight reduction of the seedlings was 2530 mg/kg forSorghum bicolorand 2930 mg/kg forHelian­thus annuus(active ingredient in dry soil). 1000 mg/kg was the highest test concentration with no growth effect. ForPhaseolus aureusthe 28 d EC50 was > 10 g/kg.

Similar results were reported forAvena sativaandBrassica rapa(Stanley & Tapp, 1982, cited in ECETOC, 1993). Plant seedlings exposed after germination for 14 days showed no reduc­tion of growth at 1000 mg DHTDMAC/kg dry soil (OECD draft guideline, 1981, no further details available).

Eisenia fetidawas exposed to DHTDMAC (solved in methanol, 76.1% active ingredient) incorporated into artificial soil consisting of 9.4% organic matter, 70% fine sand and 20% kao­linite clay (Coulson et al., 1989). At the only concentration of the definitive test with 1000 mg active ingredient/kg dry soil no mortality, no significant reduction in body weight nor any behavioral effects were observed after 14 days.

Concerning the toxicity of DHTDMAC to soil micro-organisms two studies are cited in the ECETOC report (1993) for which no test protocols are availble. However, they can give a rough indication on possible effects. Soil respiration was measured with soil samples amended with 12.3 g activated sludge and 365 mg DHTDMAC per kg standard soil (Täuber et al, 1986). After 28 days no depression of oxygen uptake could be measured. In a study of Procter & Gamble (1992) two different soils containing 400 mg DHTDMAC/kg produced 96 and 119% carbon dioxide compared to the controls over 14 weeks.

Assuming that two trophic levels are covered with long-term data for plants (Windeatt, 1987) and micro-organisms, an assessment factor of 50 could be applied and the following PNEC is calculated:

                    PNECsoil >/=1000 mg/kg / 50 >/=20 mg/kg

With this approach it was accepted that not every test could be validated, but if the terrestrial data are evaluated as a whole this seems to be acceptable in this special case. In case it would turn out that DHTDMAC might be more toxic than DODMAC the PEC/PNEC-ratio for DODMAC should be even saver.