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For the assessment of the aquatic toxicity of C16 Alkylamidopropyltrimethylammonium Chloride short-term toxicity data with fish, aquatic invertebrates, algae and microorganisms are available.

The test item is known to sorb to organic and inorganic materials by different mechanisms. The sorption processes are mostly non-linear, means are concentration dependent. Due to these properties the test item is difficult to test in synthetic water (e.g. sorption to the test organisms and glass walls of the test vessels) and results from such tests depend from the test settings applied. Therefore, in the tests conducted with fish, aquatic invertebrates and algae natural river water was used which contains particulate as well as dissolved organic carbon to which the test item can sorb partially to reduce the difficulties encountered in tests with synthetic water (e.g. preventing that the test item settles onto surfaces). The sorbed fraction of the test item is difficult to extract from the test system which normally leads to low analytical recoveries at the end of the exposure. Nevertheless the test item is present in the test system and therefore available for exposure (dissolved in water and sorbed).

Additionally, the test vessels were pre-treated with the test solutions one day before the start of the respective exposure interval to saturate the glass walls with sorbed test item in the definitive test. This procedure was carried out to achieve stable exposure concentrations in the test vessels and to reduce losses of the test item by adsorption onto the glass walls.

 

Short term toxicity to fish

In a 96-h acute toxicity study according to OECD Guideline 236, adopted July 26, 2013, embryonic stages of zebrafish (Danio rerio) were exposed to

C16 Alkylamidopropyltrimethylammonium Chloride at nominal concentrations of 0 (control), 0.480, 0.864, 1.56, 2.80, 5.04 mg a.i./L, corresponding to measured (geom. mean) concentrations of 0, 0.0320, 0.0430, 0.0587, 0.0806, 4.55 mg/L under semi-static conditions.

The 96-h LC50 0.0455 mg a.i./L (95% c.l. 0.0431 – 0.0560 mg a.i./L) based on geometric mean measured concentrations

 

Short term toxicity to aquatic invertebtates 

The 48-hr-acute toxicity of C16 Alkylamidopropyltrimethylammonium Chloride to Daphnia magna  was studied under semi-static conditions according to OECD Guideline 202 (2004).  Daphnids were exposed to control and test chemical at nominal concentrations of 96.0, 192, 384, 768, 1536 µg a.i./L (corresponding to 26.6, 35.9, 61.4, 460, 1144 µg/L geom. mean measured concentrations) in natural river water for 48 h.

Mortality/immobilization was observed daily. 

The 48-hour EC50 was 61.4 µg a.i./L (95% confidence limits: 58.9 – 64.1 µg/L)

 

Toxicity to aquatic algae and cyanobacteria

In a 72 hour toxicity study according to OECD Guideline 201 (2011), the cultures of Desmodesmus subspicatus  CHODAT SAG 86.81 were exposed to C16 Alkylamidopropyltrimethylammonium Chloride at nominal concentrations of 0 (control), 0.493, 1.04, 2.17, 4.57, 9.60 mg a.i./L in natural river water, corresponding to geom. mean measured concentrations of 0 (control), 0.0210, 0.0347, 0.133, 2.33, 8.37 mg a.i./L under static conditions.

All test concentrations and the control were analytically verified by LC-MS/MS analysis at the start of the exposure (0 hours), 24, 48 hours and the end of the exposure (72 hours).

The measured concentrations of the test item at the start of the exposure were in the range of 82 to 100% of the nominal values. After 24 h, the measured concentrations of the test item were in the range of 22 to 76 % of the nominal values. After 48 h, the measured concentrations of the test item were in the range of < LOQ to 87 % of the nominal values and at the end of the exposure, the measured concentrations of the test item were in the range of< LOQto 96 % of the nominal values. Therefore, all values given are based on the geometric mean exposure concentrations.

The NOEC, EC10 and EC50 based on growth rate inhibition were 0.0202 mg a.i./L, 0.205 mg a.i./L (95% c.l. 0.131 – 0.881 mg a.i./L) and 0.407 mg a.i./L (95% c.l. 0.213 – 1.12 mg a.i./L), respectively.

The % growth inhibition in the treated algal culture as compared to the control ranged from 2% to 100%.

The NOEC, EC10 and EC50 based on yield were 0.0202 mg a.i./L, < 0.0202 mg a.i./L and 0.252 mg a.i./L (95% c.l. 0.103 – 0.892 mg a.i./L), respectively.

Microscopic evaluation of the cells at start and the end of the incubation period revealed no morphological abnormalities.

 

Toxicity to microorganisms

The toxicity of C16 Alkylamidopropyltrimethylammonium Chloride (95% a.i.) to microorganisms was investigated during a ready biodegradation study according to EU Method C.4-D (2008) and OECD guideline 301 F (1992), Manometric Respirometry Test over a period of 28 days and using an inoculum obtained from activated sludge from a predominantly domestic sewage treatment plant.

Inoculum blank, procedural/functional control with the reference substance Sodium benzoate and a toxicity control with 2000 mg/L test item and 100 mg/L reference item Sodium benzoate were performed.

The reference item degraded normally (91.6% by within 14 days). By the end of the test, the reference item was degraded to an average of 96.4%.

The biodegradation of the item mixture in the toxicity control was found to be 31.1% after 14 days of incubation. Thus, according to the test guidelines, the test item had no inhibitory effect on activated sludge microorganisms at the tested concentration of 2000 mg/L, as the biodegradation in the toxicity control was higher than 25% within 14 days of incubation.

 

Conclusion

The most sensitive organism to C16 Alkylamidopropyltrimethylammonium Chloride was Danio rerio. Thus, the lowest acute toxicity value is the 96 h LC50 to embryonic stages of Danio rerio of 45.5 µg/L. This value is used for the calculation of PNECs.

Based on these results and the substance being not rapidly biodegradable, C16 Alkylamidopropyltrimethylammonium Chloride has to be classified as Aquatic Acute 1 with an M factor of 10 and Aquatic Chronic 1 with an M factor of 10.