Docosyltrimethylammonium methyl sulphate

Endpoint summary

Additional information

A. BIODEGRADATION IN WATER - STATIC TESTS

1. General remark on Biodegradation Testing

The supporting substance C20/22 ATQ (CAS 68607-24-9) inhibts sludge respiration at concentrations which are normally used in Screening test on biodegradation (ready and inherent tests). From an OECD 209 test the EC10 (3h) is 9.5 mg/L and the EC50 (3h) 43 mg/L which makes clear that the test concentration has to be selected carefully not to interfere with toxicity.

2. OECD 301 Type Screening tests

An OECD 301B CO₂Evolution test was carried out for the supporting substance C20/22 ATQ (CAS 68607 -24 -9) at 10 and 5 mg/L test concentration for 28d. The biodegradation rate was higher at the lower concentration (see Table 5.2-1) but at these test concentrations the test criteria for ready biodegradation was not achieved. When carrying out the OECD 301B with [14C]-labelled supporting substance C22 ATQ (CAS 17301-53-0) at a test concentration of 0.2 mg/L the formation of CO₂ reached 80% after 28d.

 

Table 5.2-1  OECD 301 B Biodegradation results for the supporting substance (see IUCLID Chapter 5.1.2) after 28d

Test material	Test conc. (mg/L)	Formation of CO2 (%)
C20/22 ATQ	10	21
C20/22 ATQ	5	40
[14C] C22 ATQ	0.2	80

 

The supporting substance C20/22 ATQ is readily and ultimately biodegradable at a concentration of 0.2 mg/L covering relevant STP influent concentrations e.g. for manufacturing and cosmetic use of the submission substance.

In an Enhanced OECD 301D Closed bottle test (see REACH Guidance Document) at 0.5-2 mg/L different test settings were applied. For example humic acid and river water with silica gel was used and the exposure time expanded up to 60 days. In two of the four test settings biodegradation exceed the test criteria of 60% but only after 60d.

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3.OECD 314D River Die Away Test

According Annex IX, Section 9.1.2.1 column 2 of the REACH Regulation 1907/2006/EC a Simulation test on ultimate biodegradation in surface water need not to be carried out if the substance is readily biodegradable. Nevertheless information is provided using read across. Read across from a similar Quat (HYEQS N,N’-Dimethyl-N’’-2-Hydroxyalkyl-N’’’ (C12-14 alkyl) quat (CASNo. 85736-63-6) can be applied. The test system for HYEQS consisted of: 89% river water, 10% sewage effluent, and 1% combined activated sludge liquor. Biodegradation was determined by Liquid Scintillation Counting of 14C-HYEQS over a 21 day test duration. HYEQS degraded rapidly with a half-life of 0.61 days for loss of parent. No parent compound remained by day 5.The half-life of mineralization was 7.7 days (CO2 evolved), and by day 21 80% of the test substance had evolved as CO2. After 21 days, 0% remained as parent, 11.6% was present as metabolites, 8.4% was present in the solids, and 80% was evolved CO2.

4. Biodegradation in Sediment

According Annex IX, Section 9.2.1.4 column 2 of the REACH Regulation 1907/2006/EC a Sediment simulation test need not to be carried out if the substance is readily biodegradable. Nevertheless available information is provided using read across. Based on EChA REACH Guidance R.16 Environmental Exposure Assessment, Section R.16.4.4.5 (May 2008) soil half-life may also be applied for aerobic sediment if no other data are available. From the supporting substance C22-ATQ (CAS 17301-53-0) it can be concluded that also the submission substance is rapidly biodegraded/transformed in soils. The half-lifes determined from three different soils for C22-ATQ were 23.2 to 41.4 days. This is corroborated from read across to the Quat HYEQS (N,N’-Dimethyl-N’’-2-Hydroxyalkyl-N’’’ (C12-14 alkyl) quat, CAS No. 85736-63-6; supporting study). The median half-life for HYEQS in soils was determined as 6.2 days (for both studies see IUCLID Section 5.2.3).

B. BIODEGRADATION IN SEWAGE TREATMENT PLANT - DYNAMIC TEST
OECD 303A C20/22 ATQ Simulation Test Activated Sludge Unit -Aerobic Sewage Treatment
The supporting substance C20/22 ATQ (CAS 68607-24-9) was continuously dosed into the activated sludge unit resulting in an influent concentration of 300 µg/L (41 µg/L C20 isomer, 243 µg/L C22 isomer). Influent and effluent concentration of C20/22 ATQ were measured daily using LC MS MS (LOQ C20 influent= 4.1 µg/L, C22 24.3 µg/L; LOQ C20 effluent= 2.1 µg/L, C22 12.1 µg/L). Already one day after the start of the test the elimination of C20/22 ATQ was > 99% (C20 and C22 fraction). Biodegradation of C20/22 ATQ has started immediately and reached a maximum of 98% during the plateau phase. Biodegradation of the C20 fraction was 94-98% (median 96%) and of the C22 fraction 87-93% (median 91%).

C. BIODEGRADATION IN SOIL

OECD 307 Aerobic Transformation in Soil, Key study

According Annex IX, Section 9.2.1.3 column 2 of the REACH Regulation 1907/2006/EC a Soil simulation test need not to be carried out if the substance is readily biodegradable. Nevertheless available information is provided using read across from the supporting substance C22-ATQ (CAS 17301-53-0). The degradation rate of 14C-C22 -ATQ in three aerobic soils was investigated during 124 days. The 14C-labelled substance was applied at a rate of 0.2 mg a.i./kg soil dw. using sewage sludge as carrier. The application rate was determined from an exposure modelling using realistic use rates. Soil sampling was done after 3, 7, 14, 29, 62 and 124 days. Significant amounts of radioactive carbon dioxide and bound residues were formed. The total mean recoveries of radioactivity were in the range of 105 to 107% for the three soils. From the measurements the following DT50 for biotransformation were calculated:

DT50 soil 1: 23.2 d;

DT50 soil 2: 24.9 d;

DT50 soil 3: 41.4 d;

These results are further corroborated by the supporting study:

OECD 307 Aerobic Transformation in Soil, supporting study

According Annex IX, Section 9.2.1.3 column 2 of the REACH Regulation 1907/2006/EC a Soil simulation test need not to be carried out if the substance is readily biodegradable. Nevertheless available information is provided using read across from a similar compound.

The quaternary ammonium compound "Quaternary ammonium compounds, C12-18-alkyl(hydroxyethyl)dimethyl, chlorides", (CASNo. 85736-63-6) is deemed sufficiently similar to yield supporting information on biodegradability of the submission substance. The degradation rate of 14C-"Quaternary ammonium compounds, C12-18-alkyl(hydroxyethyl)dimethyl, chlorides" in three aerobic soils was investigated during 62 days. The 14C-labelled substance was applied at a rate of 0.45 mg a.i./kg soil dw. using sewage sludge as carrier. The application rate was determined from an exposure modelling using realistic use rates. Soil sampling was done after 2, 4, 8, 15, 28 and 62 days. Further sampling up to 120 days was not necessary due to rapid biodegradation/biotransformation. Significant amounts of radioactive carbon dioxide and bound residues were formed. The total mean recoveries of radioactivity were in the range of 91.2 to 94.9% for the three soils. From the measurements the following DT50 for biotransformation were calculated:

DT50 soil 1 6.2 d (also the median of all 3 soils),
DT50 soil 2 6.0 d,
DT50 soil 3 13.6 d.