Tributylamine

Endpoint summary

Description of key information

Key values for acute aquatic toxicity

Algae: 72h-ErC50 (Pseudokirchneriella subcapitata; growth rate; geometric mean measured) 10.1 (95% CI: 9.38 -10.9) mg/L;

Daphnia: 48h-EC50 (Daphnia magna, immobilisation; measured) 8 mg/L (95% CI: 6.1-10.8 mg/L);

Fish: 28-days LC50 (Danio rerio, mortality; analytically verified) > 10 mg/L;

 

Key value for chronic aquatic toxicity

Algae: 72h-EC10 (Pseudokirchneriella subcapitata; growth rate; geometric mean measured) 4.64 (95% CI: 3.97 – 5.53) mg/L;

 

Toxicity to microorganisms

STP microorganisms: 2h-NOEC (Nitrosomonas sp., Nitrobacter sp., inhibition of nitrification rate) 100 mg/L;

Additional information

Short-term and long-term toxicity

Fish:

According to the key study for acute toxicity to fish, the 28-d LC50 for acute fish toxicity is greater than 10 mg/L (OECD 204; Danio rerio; analyt. verified; Hoechst 1991).

The supporting study delivered a 96-h LC50 of 16.3 mg/L (OECD 203; Oryzias latipes; nominal; NITE, 2002).

 

There are no valid long-term toxicity results for fish available. Fish are not the most sensitive organisms. Therefore and for reasons of animal welfare, a long-term toxicity study in fish is not provided.

Aquatic invertebrates:

In the reliable key study, the 48-h EC50 for acute effects of tributylamine on aquatic invertebrates was experimentally determined to be 8 mg/L (OECD 202; measured; Daphnia magna; Pedersen, 2003).

There are no valid long-term toxicity results for aquatic invertebrates available. As the chemical safety assessment does not indicate the need for further testing, no long-tern toxicity tests on aquatic invertebrates is provided.

 

Algae:

A valid OECD 201 (GLP; RL 1) study with Pseudokirchneriella subcapitata over 72 hours was performed (Herrmann, 2018) with analytical verification of test item concentrations.

The following ECx -values with 95% confidence intervals were determined (based on geometric mean measured test item concentrations):

ErC50: 10.1 (9.38 -10.9) mg/L

EyC50: 5.13 (4.14 -7.26) mg/L

ErC10: 4.64 (3.97 – 5.53) mg/L

The NOEC-values for inhibition of growth rate and yield after 72 hours were 1.65 mg/L and 0.154 mg/L, respectively.

 

Microorganisms:

The results from the nitrification inhibition study were selected as key value for the derivation of the PNEC stp. Tributylamine does not disturb nitrification: 2-h NOEC: 100 mg/L (Nitrosomonas sp., Nitrobacter sp.; nominal; no guideline followed; Hockenbury and Grady, 1977).

 

The second reliable study (key study) was a respiration inhibition test conducted with activated sludge (predominantly domestic). No guideline was followed. The substrate was glucose. The 7-d EC05 was 100 mg/L (read across from tributylammonium chloride; Yoshimura et al., 1980).

  

Overview on key and supporting ecotoxicity studies

Endpoint	Species	Value [mg/L]	Reliability	Remarks	Source
Fish
28-d LC50	Danio rerio	> 10	1 key study	nominal, analyt. verified	Hoechst AG (1991)
96-h LC50	Oryzias latipes	16.3	2 supp. study	nominal	NITE (2002)
96-h LC50	Leuciscus idus	> 100 - < 500	2 supp. study	pH-adjusted; nominal	BASF AG (1987)/ (BASF SE (2011)
Aquatic invertebrates
48-h EC50	Daphnia magna	8	2 key study	analytically verified concentrations; semi-static	Pedersen (2003)
Aquatic algae
72-h ErC10 (95% C.I.)	Pseudokirchneriella subcapitata	4.64 (3.97 – 5.53)	1 key study	geometric mean measured; growth rate	Herrmann (2018)
72-h ErC50 (95% C.I.)	Pseudokirchneriella subcapitata	10.1 (9.38 -10.9)	1 key study	geometric mean measured; growth rate
72-h EbC10	Desmodesmus subspicatus (reported as Scenedesmus subspicatus)	1.4	2 supp. study	test solutions neutralised; nominal; presumably biomass	Nusch (1987), cited in Amann et al. (1987/1988)
72-h EbC50	Desmodesmus subspicatus (reported as Scenedesmus subspicatus)	8.2	2 supp. study	test solutions neutralised; nominal; presumably biomass
Microorganisms
7-d EC05	Activated sludge, domestic	100	2 key study	Read-across to HCl salt of tributylamine used as test item; nominal	Yoshimura et al. (1980)
2-h NOEC	Nitrosomonas sp. and Nitrobacter sp.	100	2 key study	nominal	Hockenbury & Grady (1977)

 

It can be concluded that tributylamine is acutely toxic to aquatic organisms. TBA has been found to be stable in test solutions, based on TOC measurements in screening tests (without organisms) according to OECD 201 (>80% for 96 h) and OECD 202 (>80% for 48 h).