Hexylamine

Toxicity to aquatic algae and cyanobacteria

Key value for chemical safety assessment

EC50 for freshwater algae:

1.98 mg/L

EC10 or NOEC for freshwater algae:

0.5 mg/L

Additional information

Derivation of ErC50 (72 h) using data from analogous compounds octylamine (CAS 111-86-0) and butylamine (CAS 109 -73 -9):

 

A read across study was performed using octylamine (CAS 111 -86 -4) as test substance. The test duration was 72 hours and the test organism was the green algae Scenedesmus subspicatus. The nominal test concentrations were: 0.005, 0.01, 0.02, 0.04, 0.08, 0.16, 0.31, 0.63, 1.25, 2.5 and 5 mg/L. The EC50 based on growth rate was determined to be 0.23 mg/L and the EC10 and NOEC were determined to be 0.07 mg/L and 0.01 mg/L, respectively.

 

In another read across study butylamine (CAS 109 -73 -9) was tested according to OECD 201 for its toxicity to the freshwater algae Desmodesmus subspicatus. The concentrations were 0, 4.6, 10, 22, 46, 100 mg/L and are analytically verified: Measured geometric mean: 0, 2.26, 8.5, 18.0, 32.5 and 77.5 mg/L. The 72 h test followed a static procedure. Based on growth rate, the ErC50 was determined to be 17 mg/L, the ErC10 was found to be 3.7 mg/L (Oxea Germany and BASF SE, 2013). The NOEC was determined to be 2.26 mg/L. Based on this result, the substance is supposed to be acutely harmful to aquatic algae.

 

As the toxicity of primary amines is related to the length of the hydrophobic carbon chains (the longer the chain the more toxic to aquatic organisms) the ErC50 for hexylamine (C6 -primary amine) was calculated as the geometric mean based on the ErC50 value of 0.23 mg/L for octylamine (C8 -primary amine) and the ErC50 value of 17 mg/L for butylamine (C4 -primary amine):

ErC50 (72 h): 1.98 mg/L (geometric mean).

 

The estimated ErC50 (72 h) value 1.98 (mg/L, geometric mean) was confirmed by applying the OECD-Toolbox: Two Toolbox calculations are available. The predicted EC50 values are in the same range (1 -10 mg/L) as the calculated ErC50 value: the first predicted EC50 value is 6.3 mg/L, the second one 4.71 mg/L.

 

Derivation of ErC10 (72 h) using data from analogous compounds octylamine (CAS 111-86 -4) and butylamine (CAS 109 -73 -9):

The ErC10 for hexylamine (C6 -primary amine) was calculated as the geometric mean based on the ErC10 value of 0.07 mg/L for octylamine (C8 -primary amine) and the ErC10 value of 3.7 mg/L for butylamine (C4 -primary amine):

ErC10 (72 h): 0.5 mg/L (geometric mean).

 

This ErC10-value of 0.5 mg/L was confirmed in the following trend analysis yielding an ErC10/NOEC-value of 0.34 mg/L:

The toxicity of primary amines is related to the length of the hydrophobic carbon chains: the longer (or greater the number of carbons) the chain the more toxic to aquatic organisms when the number of amines is constant.

Therefore, the EC10/NOEC was calculated using data from primary amines with varying chain length and usingthe function VARIATION of Excel.

The data of the following primary amines were used in the trend analysis:

Methylamine, CAS-# 74-89-5:

- TCC (ca. EC3; 8d) 4 mg/L;

- source :Bringmann, G. (1959). Gesundheits-Ingenieur 80(4): 114-120.

Ethylamine, CAS-# 75-04-7:

- TCC (ca. EC3; 8 d) 1.7 mg/L;

- source: Bringmann G & Kuehn R (1978).Vom Wasser 50: 45-60.

Butylamine, CAS-# 109-73-9:

- ErC10 (72 h) 3.7 mg/L;

- source : Muckle M. (2013). Determination of the 72h-EC50 of n-Butylamine in Desmodesmus subspicatus according to OECD 201 resp.EU C.3. Report-no 12070301G301. 2013-05-28.

Octylamine, CAS-# 111-86-4:

- ErC10 (72 h) 0.07 mg/L;

- source: BASF AG (1997).Determinition of the inhibitory effect of Octylamin on the cell multiplication of unicellular green algae. Study-no 96/0345. 1997-10-21.

 

Result:

Estimated EC10/NOEC is 0.34 mg/L based on data from primary amines with varying chain length using trend analysis (Excel function VARIATION)

 

Primary amine	C-Atome	EC10/NOEC
		Endpoint	(mg/L)	(estimated)
Methylamine, CAS-# 74-89-5	1	TTC (~EC3) (8 d)	4
Ethylamine, CAS-# 75-04-7	2	TTC (~EC3) (8 d)	1,7
Butylamine, CAS-# 109-73-9	4	ErC10 (72 h)	3,7
Octylamine, CAS-# 111-86-4	8	ErC10 (72 h)	0,07
Hexylamine, CAS-# 111-26-2	6	EC10/NOEC		0,34
estimated: Excel: function VARIATION