Registration Dossier
Registration Dossier
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EC number: 204-375-3 | CAS number: 120-18-3
Biodegradation in water: screening tests
Administrative data
Link to relevant study record(s)
Description of key information
readily biodegradable (according to OECD criteria)
Key value for chemical safety assessment
Additional information
The registration item contains ca. 78.89% of naphthalene-2-sulphonic acid (CAS # 120-18-3) and ca. 6.5 % of naphthalene-1-sulphonic acid (CAS # 85-47-2). These two substances have the same molecular weight and are structurally almost identical. Therefore naphthalene-2-sulphonic acid and naphthalene-1-sulphonic acid and their respective salts are suitable for read across in order to fulfill the data requirements.
Several studies on the biodegradability of single components of the substance are available. One study testing the biodegradability of naphthalene-1-sulphonic acid in different test systems is available. Within the test systems the test substance concentration and the type of inoculum was varied. The substance was traced by radio labeling. The degradation rates varied with the different test methods.The substance was degraded by >90 % when tested in compliance with OECD guideline 301A using activated sludge as inoculum.
In a second part of the study a test was set up according to OECD guideline 301E. Either effluent of a WWTP alone or a mixture of effluent and pond water was used as inoculum. Higher degradation rates were obtained when the test was inoculated with the effluent alone. The degradation rate decreased with increased test substance concentration. After 28 days a degradation rate of 70-80 % was determined at an initial test substance concentration of 50 µg/l and effluent as inoculum, whereas at 50000 µg/l the degradation rate was reduced to 20-30 % (effluent+pond water:. At 5 µg/l 10-20 %; at 50000 µg/l <10 %) (Koziollek, 1996).
In a study on the inherent biodegradability of 2 -NSA sodium salt following OECD 302B a degradation rate of 90-100 % based on DOC removal was determined (BASF AG, 1991). A comparable result was recorded by a study on the biodegradability of naphthalene-1-sulphonic acid. The study was conducted according OECD 302B. After 14 days the substance was degraded by 90 - 100 %
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