Sulphamidic acid

Toxicity to terrestrial plants

Description of key information

According to these results, the test item had a chronic inhibitory effect on emergence and post-emergence survival in Brassica rapa, and on growth in Avena sativa NOEC of 50 mg/kg soil dw). With respect to fertility, there was no inhibitory effect in the two tested plant species due to the test item (NOEC of 100 mg/kg soil dw).

Key value for chemical safety assessment

Long-term EC10, LC10 or NOEC for terrestrial plants:

50 mg/kg soil dw

Additional information

Sulfamic acid was investigated on the emergence, growth and fertility of terrestrial plant seedlings Avena sativa (oat) and Brassica rapa (turnip) according to the guideline DIN EN ISO 22030.

The seeds were placed in a natural sandy soil containing the test item at nominal concentrations of 6.25, 12.5, 25, 50 and 100 mg test item/kg dry soil. The test item was incorporated into the test soil at the beginning of the experiment. The effects on seedling emergence, growth and fertility were determined after the plants have built inflorescences (oat) or even seed pods (turnip). Additionally, growth was determined 14 days after emergence of 50 % of the control seedlings, representing the acute endpoint according to OECD 208. Five and four replicates were prepared for the control and per concentration, respectively.

There were significant effects on seedling emergence of Brassica rapa. The NOEC for emergence was 50 mg sulfamic acid per kg dry soil. Post-emergence survival was only affected significantly directly after emergence. Subsequently, no increased mortality due to the test item occurred. The NOEC for post-emergence survival was 50 mg sulfamic acid per kg dry soil. Seedling emergence and post-emergence survival of Avena sativa was not affected up to and including a concentration of 100 mg/kg dry soil, which was the highest concentration tested.

Growth measured as shoot length and biomass, was affected significantly by the test item sulfamic acid on growth day 14. However, effects on both endpoints of growth (shoot length and fresh weight) decreased with further time. The chronic NOEC for shoot length of Avena sativa at test end were 50 mg sulfamic acid per kg dry soil. The chronic NOEC for fresh weight of Avena sativa and both, shoot length and fresh weight of Brassica rapa at test end were ≥ 100 mg sulfamic acid per kg dry soil.

Fertility was not affected significantly by the test item. Number of flowers in Brassica rapa was significantly inhibited at day 14. This correlates with the early delay in growth. However, neither number or fresh weight of fertile seed pods in B. rapa nor inflorescences in A. sativa were inhibited at test end up to and including a concentration of 100 mg/kg dry soil, which was the highest concentration tested.

According to these results, the test item had a chronic inhibitory effect on emergence and post-emergence survival in Brassica rapa, and on growth in Avena sativa. With respect to fertility, there was no inhibitory effect in the two tested plant species due to the test item.

Relevant chronic NOEC for biological endpoints at test end

Test species	Emergence	Survival	Growth	Fertility
Brassica rapa	50 mg/kg	50 mg/kg	≥ 100 mg/kg	≥ 100 mg/kg
Avena sativa	≥ 100 mg/kg	≥ 100 mg/kg	50 mg/kg	≥ 100 mg/kg

Conclusion

The relevant chronic endpoints were seedling emergence in Brassica rapa and shooth length in Avena sativa with NOEC values of 50 mg sulfamic acid per kg dry soil and EC₁₀values of 56 and 51 mg sulfamic acid per kg dry soil, respectively.