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Biodegradation in soil

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Description of key information

No biodegradation is expected in soil.

Key value for chemical safety assessment

Additional information

There are no experimental data available on the Leucophor 1111X, nevertheless a field study at a full-scale STP on the analogous substance 04 gave no evidence of biodegradation when the mass flow was monitored (Poiger, 1994. IUCLID section 5.5.2).

A biological degradation study was conducted with analogous substance 04 in soil. Unfortunately, the complete translation of the publication is not available, thus only an abstract can be consulted. Biodegradation by soil microorganisms was investigated perfusing the substance in soil in dark condition. During the first 2 weeks of soil perfusion optical density at 348 nm (λmax of both agents) and TOC values of the perfusion solution parallel decreased due to test item adsorption into soil particles. The perfusion soil was oversaturated with the SFWA agent which was added repeatedly during next 8 weeks.After 10 weeks of perfusion the optical densities of the perfusion solution decreased rapidly with no change in TOC values upon addition of 10 ppm of SFWA.The UV spectra of the substance solution after soil perfusion and UV exposure were respectively closely similar to each other. The UV spectrum after soil perfusion was closely similar to that of the cis-isomer of the agent. It was concluded that the results suggested that the substance was partially degraded to organic intermediates by soil microorganisms [2].

The analogous substance 04 has been submitted to the voluntary industry programme to carry out Human and Environmental Risk Assessments on ingredients of household cleaning products, known as HERA project. In the review document it is reported that EAWAG (Swiss Federal Institute for Water Resources and Water Pollution Control) designed a soil study on behalf of Ciba Specialty Chemicals Inc., which was conducted from 1999 to 2003. On two sites open air plots of 1 m2 each were prepared. Each plot was treated with stabilized sludge from a communal sewage treatment plant in different amounts based on the maximum permissible amount of dry sludge allowed according to the Swiss law. Soil samples were taken after 1, 4, 7, 12, 20, 29 and 45 months and analyzed on test item. Analogous substance 04 could only be traced in the top layer of 2.5 cm depth. The concentrations scattered over time [3].

Leucophor 1111X is a Stilbene Fluorescent Whitening Agent (SFWA), 4,4’-bis(1,3,5-triazinyl-2-yl)amino)stilbene-2,2’-disulfonic acid (DAS) derivative. This class of substances have been available since 1941 and remain the most important class of optical brighteners in terms of quantity [1]. Extensive work has been done to characterize aquatic toxicity and photo- and biodegradation: many data are available in the contexts of IUCLID dataset, OECD SIDS, HPV, HERA projects and some DAS derivatives have been registered under the REACH Regulation. In general, they are considered as not significantly biodegradable.

It is assumed that Leucophor 1111X is not biodegradable in soil tests either.

Further biotic degradation testing shall be proposed only if the Chemical Safety Assessment according to Annex I indicates the need to investigate further degradation of the substance and its degradation products. Based on the Chemical Safety Assessment the exposure of sediment and soil results to be negligible, since the substance and its formulations are produced and used in plants equipped with industrial STP which filter the waste waters before discharging in the municipal net. There are no direct releases involving air and soil compartments. No further tests on biodegradation are proposed.


[1] AAVV 2003. Industrial dyes. Chemistry, Properties, Applications. Edited by Klaus Hunger. Wiley-vch.

[2] Katayama M. 1984. Biological Degradation of Detergent Fluorescent Whitening Agents by Soil Perfusion. Nippon Nogeakagaku Kaashi Vo1. 58, No. 5, PP. 449~445.

[3] HERA, 2004. Human & Environmental Risk Assessment on ingredients of European household cleaning products. Substance: Fluorescent Brightener FWA-1 (CAS 16090-02-1) - Draft - Version October 2004