Sodium alkyl sulphate

Toxicity to aquatic plants other than algae

Description of key information

7d EC10  (Lemna minor, relative growth rate value) = 59.27 ppm OECD 221

Key value for chemical safety assessment

EC10 or NOEC for freshwater plants:

59.27 mg/L

Additional information

A growth inhibition test to Lemna minor (duckweed), following OECD 221 guideline, was conducted on Sodium dodecyl sulphate (SDS). The growth inhibiting and accumulation effects of sodium dodecyl sulphate (SDS) on were tested at 1, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 150, 200 and 300 ppm levels both in the full-strength and 1/10-diluted Jacob’s nutrient media under continuous illumination at 26-30°C for a 7-day experimental period. There were 3 replicates at each test concentration.

Fronds were healthy at the SDS concentrations of 1-70 ppm in the full-strength nutrient medium. At 80-100 ppm of SDS, most of the fronds turned white after the 4th day of incubation. After 7 days, the fronds appeared healthy at the SDS concentrations of 1-80 ppm in the 1/10-diluted growth media and at 90- 100 ppm of SDS, most of the fronds turned white and yellow.

Relative growth rate (RGR) experiments were continued up to 150, 200 and 300 ppm of SDS concentrations. At these levels, fronds became white completely on the 2ndday of incubation in both nutrient media.

The accumulation of SDS by Lemna minor L. (expressed on dry weight basis) increased with increasing concentrations of SDS between 1-90 ppm, both in full-strength and 1/10-diluted media. The pH of both full-strength and diluted media at 1-90 ppm of SDS levels increased during the test period and remained constant at higher SDS concentrations. This indicated that the biodegradation of SDS generated the alkaline intermediates in the medium.

The 7 d EC10 of Sodium dodecyl sulphate (SDS) to Lemna minor was 59.27 (49.19 - 71.34) ppm (full strength Jacob's medium) and 81.98 (77.28 - 86.98) (medium: 1/10 diluted Jacob's medium), based on relative growth rate in a static test. The result is based on nominal concentration.

This chronic toxicity to plants is classified as acceptable, and satisfies the guideline requirements for the OECD 221.