Dimethyloctadecyl[3-(trimethoxysilyl)propyl]ammonium chloride

Toxicity to aquatic algae and cyanobacteria

Description of key information

72 hrs aquatic toxicity study was predicted to assess toxic effects of the test compound (3-(Trimethoxysilyl)propyl)octadecyldimethylammonium chloride (CAS no. 27668 -52 -6) and the result were predicted (SSS QSAR Prediction Model, 2017). The study was based on the effects of the test compound on Pseudokirchneriella subcapitata in a static fresh watersystem. The predicted data suggests the effective concentration (EC50) for the test compound (3-(Trimethoxysilyl)propyl)octadecyldimethylammonium chloride (CAS no. 27668 -52 -6) was estimated to be 13.547 mg/l on the basis of growth rate.Thus, based on this value, it can be concluded that the test chemical (3-(Trimethoxysilyl)propyl)octadecyldimethylammonium chloride can be considered as toxic to aquatic organisms and thus can be classified as aquatic chronic category 3 as per the CLP criteria.

Key value for chemical safety assessment

EC50 for freshwater algae:

13.547 mg/L

Additional information

Various study and predicted data for the target chemical(3-(Trimethoxysilyl)propyl)dimethyloctadecylammonium chloride(CAS No. 27668-52-6) and the study for its read across substancewere reviewed to summarize the following information:

 

72 hrs aquatic toxicity study was predicted to assess toxic effects of the test compound (3-(Trimethoxysilyl)propyl)octadecyldimethylammonium chloride (CAS no. 27668 -52 -6) and the result were predicted (SSS QSAR Prediction Model, 2017). The study was based on the effects of the test compound on Pseudokirchneriella subcapitata in a static fresh watersystem. The predicted data suggests the effective concentration (EC50) for the test compound (3-(Trimethoxysilyl)propyl)octadecyldimethylammonium chloride (CAS no. 27668 -52 -6) was estimated to be 13.547 mg/l on the basis of growth rate.Thus, based on this value, it can be concluded that the test chemical (3-(Trimethoxysilyl)propyl)octadecyldimethylammonium chloride can be considered as toxic to aquatic organisms and thus can be classified as aquatic chronic category 3 as per the CLP criteria.

 

Long term toxicity study to Amphora coffeaeformis (fouling diatom)was carried out for 100 hrs (N Clarkson & L V Evans, 1993). Test chemical Dow Corning® 5700 (DC5700) (CAS no. 27668-52-5) was supplied by Dow Corning Ltd, Barry, Wales, as 42% active ingredient in methanol. It was recrystallised from methanol to obtain a solid which was dissolved in chloroform to give a 1% solution (w/v). Test organism used for the study was A. coffeaeformis. Cultures of A. Coffeaeformis were maintained in modified Guillard's F2 medium prepared with Instant Ocean Artificial Sea-water. Cultures were maintained in 1 dm3 Erlenmeyer flasks on a Gallenkamp orbital shaker (150 revs-min-1) under continuous illumination (PFD 400µmoles m2s-1) at 18° ± 1°C. All media were autoclaved (120°C, 20 min) and inoculated under aseptic conditions in a sterile laminar flow cabinet. Cultures were checked periodically for bacterial contamination under a microscope and by growing a small aliquot of cells on modified F2 medium in 1% agar.

The presence of DC5700 in leachates can be detected indirectly by gas chromatography (GC).The result of extraction and gas chromatographic separation of leachate samples showed the presence of volatile components of DC5700.

For determining the cell viability of test organism, glass microscope slides (76 x 26 mm) were placed in concentrated nitric acid for 1 h, removed, rinsed exhaustively in distilled water, placed in slide racks and dried (100°C, 1 h). The slides were then stored in sealed containers to prevent contamination. The slides were dipped in 1% DC5700 in chloroform for 1 min, then dried at room temperature, then placed in an oven (80°C, 5 h) to allow any residual solvent to evaporate. Control surfaces were (1) cleaned glass slides, and (2) hydrophobic slides coated with a 1% (v/v) solution of octadecyltrichlorosilane in chloroform.

Slides were leached by placing individually in "Stretton Young" jars containing seawater (50 cm3). Jars were sealed and placed on an orbital shaker. Slides were removed periodically, rinsed in distilled water and used for viability experiments. Leached slides and untreated control slides were placed in Petri dishes, and aliquots (30 cm3) of F2 medium containing A. coffeaeformis cells from a 4.8 h culture were added and the cells left to adhere. Slides were removed for staining over 24 h periods, starting approximately 30 min after addition of culture, which allowed time for cell settlement. An assessment of cell viability was carried out using Evans' blue (0.025% (w/v) in F2 medium),a mortal stain that renders organic material blue and which is excluded by cells with a functional plasma membrane. Stain solution was added to the F2 medium in the Petri dishes and after 5 min the medium and stain were carefully removed. Large cover slips were then placed over the slides trapping the cells onto the surfaces. This procedure was designed to minimise the number of cells washed from the surfaces during staining. Counts of viable and non-viable cells in 50 fields of view (magnification x630) were recorded for three replicates of each treatment and for each stain. From these data the percentage viability of cells on each surface was calculated. Leaching for 1 d resulted in an initial high cell viability followed by a relatively constant viability of around 38% from 24-96 h. Based on effect on the cell viability of test organism Amphora coffeaeformis, the 100 hrs LOEC value was determined to be 10,000 mg/l, respectively.

 

Long term toxicity study to Amphora coffeaeformis (fouling diatom) was carried out for 100 hrs (N Clarkson & L V Evans, 1993). Test chemical Dow Corning® 5700 (DC5700) (CAS no. 27668-52-5) was supplied by Dow Corning Ltd, Barry, Wales, as 42% active ingredient in methanol. It was recrystallised from methanol to obtain a solid which was dissolved in chloroform to give a 1% solution (w/v). Test organism used for the study was A. coffeaeformis. Cultures of A. coffeaeformis were maintained in modified Guillard's F2 medium prepared with Instant Ocean Artificial Sea-water. Cultures were maintained in 1 dm3Erlenmeyer flasks on a Gallenkamp orbital shaker (150 revs-min-1) under continuous illumination (PFD 400µmoles m2s-1) at 18° ± 1°C. All media were autoclaved (120°C, 20 min) and inoculated under aseptic conditions in a sterile laminar flow cabinet. Cultures were checked periodically for bacterial contamination under a microscope and by growing a small aliquot of cells on modified F2 medium in 1% agar.

The presence of DC5700 in leachates can be detected indirectly by gas chromatography (GC).The result of extraction and gas chromatographic separation of leachate samples showed the presence of volatile components of DC5700.

For determining the chorophyll measurement and cell growth, acid washed glass slides coated on both sides with DC5700 (1%) were fixed in "Stretton Young" jars and sterile F2 medium (50 cm3) was added. The jars were then sealed and placed in an orbital shaker for 1,7 and 14 d. the leachates were removed and aliquots (100 cm3) were placed in flasks which were inoculated with A. coffeaeformis cells (10 cm3). The flasks were placed on an orbital shaker at 18°C ± 1°C under continuous illumination. At 24 h periods aliquots (5 cm3) were removed for chlorophylla (chla) determinations, as an indirect measure of cell growth. Leachate from both two and four slides caused a significant (p = 0.0095 and p = 0.0001 respectively) decrease in the chla concentration of A. coffeaeformis cells compared to the control. Increasing the number of leached slides also increased the effect on the chla values of the cells. At 120 h leachate from two slides caused a 32% decrease and leachate from four slides a 51% decrease in the chla concentration compared to the control value. Based on effect on the chlorophyll a concentration of test organism Amphora coffeaeformis, the 100 hrs LOEC value was determined to be 10,000 mg/l, respectively.

 

Short term toxicity study to Gymnodinium breve was carried out for 48 hrs (E.C. Kutt and D.F. Martin, 1974) (CAS no. 68783-78-8). Samples were prepared as standard solution, 1000 ppm of (100%) active material in triple-distilled water, and then secondary-stock solutions (100 ppm) were prepared just prior to use. Fresh standard solutions were prepared for each study. Gymnodinium breve was used as a test organism. Bacteria-free, unialgal cultures of Gymnodinium breve were obtained from S.M. Ray and W.B. Wilson, Texas A & M Marine Station, Galveston. The cells were maintained in enriched seawater. B-5 medium was used to culture cells. All inoculations were aseptically transferred when the parent culture had reached the stationary phase of growth after approximately 3 weeks.

A modification of the Flask Test of the Provisional Algal Assay Procedure was used for assaying the effect of test chemical. Aged seawater that has been used for the study was stirred with charcoal (0.13 g/l), filtered through sand, 0.45µ Millipore membrane filters, autoclaved (15 min, 15 psi) and allowed to stand for 3 days before inoculation. All inoculations were aseptically transferred, and all enrichments were added aseptically using a disposable Millipore Swinnex filter unit with a 0.22µmembrane filter. Inoculated flasks (initial cell counts ca. 150/mi) were maintained at 25~ under constant illumination of approximately 600 ft-candles, provided by dual banks of 40-watt cool-white fluorescent lamps. Cell counts were determined with a Coulter Counter (Model B) equipped with Model C-IO00 Channelyzer and x-y recorder after sterile removal of an aliquot of culture. Counts were obtained from duplicate cultures that were counted every 2 to 3 days. Aliquots were counted 5 to 7 times, and all results were used to calculate the mean cell count and standard deviation of the mean using a Wang C 62 calculator. Cell viability was confirmed visually by noting motility of a slide sample at 100X with a monocular scope.

The comparison of mean cell count after 2 days incubation generally showed a decrease in cell numbers. Ditallow-dimethyl ammonium chloride (3 concentrations), however, showed an increase of about 200%, that was not statistically significantly different from control. Finally, the ditallow-dimethyl ammonium chloride had growth constants similar to those for control values.

Based on the effect on the growth rate of test organism Gymnodinium breve, the 48 hrs NOEC and LOEC value was determined to be16.67 and 66.67 mg/l, respectively. Thus, based on this value, it can be concluded that the read across chemical Ditallow dimethyl ammonium chloride can be considered as toxic to aquatic organisms and thus can be classified as aquatic chronic category 3 as per the CLP criteria.

 

Based on the overall reported results for target and its read across substance, it can be concluded that the test substance (3-(Trimethoxysilyl)propyl) dimethyloctadecylammonium chloride can be considered as toxic to aquatic organisms and thus can be classified as aquatic chronic category 3 as per the CLP criteria.