Hexadecyldimethylamine

Toxicity to soil macroorganisms except arthropods

Description of key information

ACUTE TOXICITY
In a reliable 14-day acute toxicity study (reliability category 1) with C12-14 DMA on Eisenia fetida, no signs of toxicity were observed at the nominal limit concentration of 1000 mg/kg soil dry weight. 
CHRONIC TOXICITY
In a reliable study (reliability category 1) assessing effects of the supporting substance HYEQS on mortality, biomass and the reproductive potential of the earthworm species Eisenia fetida, a NOEC (reproduction, 56 d) of 125 mg/kg soil dry weight was determined. No other adverse effects were observed. 

Key value for chemical safety assessment

Short-term EC50 or LC50 for soil macroorganisms:

1 000 mg/kg soil dw

Long-term EC10, LC10 or NOEC for soil macroorganisms:

125 mg/kg soil dw

Additional information

ACUTE TOXICITY

C12-14 DMA was tested for acute toxicity on Eisenia fetida in a reliable acute toxicity study (reliability category 1) according to OECD 207 performed compliant to GLP. The study was conducted with a limit test item concentration of 1000 mg/kg soil dry weight throughout 14 days. 40 test organisms with an individual weight between 0.3 - 0.6 g, divided into four replicates, were tested in regard to mortality, pathological symptoms, biomass and changes in the earthworm behaviour. No effects in regard to any of the investigated endpoints could be observed.

Consequently, DMA category members may be regarded as acutely non-toxic to terrestrial macroorganisms.

CHRONIC TOXICITY

Chronic toxicity of the supporting substance HYEQS to the earthworm species Eisenia fetida was assessed in a reliable (category 1) Earthworm Reproduction test performed according to OECD 222 (2004) and compliant to GLP over a period of 8 weeks.

HYEQS is of high similarity to C12-14 DMA in that it has essentially the same alkyl chain distribution and – like DMA category members - two methyl substituents at the amino group. The only difference is an additional hydroxyethyl substituent at the amino group rendering it a quaternary amine being permanently positively charged. This is however a minor difference as due to protonation at environmentally relevant pH values also DMA category members are predominantly positively charged at the amino group.

HYEQS was tested at five different application rates between 62.5 and 1000 mg/kg soil dry weight. Sexually mature earthworms were inserted into 6 control replicates and into 4 replicates per test item concentration (10 earthworms per replicate). The earthworms had an individual body weight ranging between 0.30 and 0.60 g at test initiation. HYEQS did not induce mortality or pathological symptoms to adult earthworms and the biomass increase of the adult earthworms was not statistically significantly reduced compared to the control after 28 days exposure. After eight weeks of exposure, the earthworm reproduction was statistically significantly reduced at 250 mg HYEQS /kg soil dry weight and higher compared to the control. All validity criteria of the OECD-guideline were met. Therefore,the following no-effect concentration for terrestrial macro-organisms is regarded as relevant for DMA category members: NOEC (56d; E. fetida; reproduction) = 125 mg/kg soil dry weight