Hexamethylenediamine

Short-term toxicity to fish

Description of key information

The test substance is soluble and appears to be caustic in aqueous solution. This last feature was critical in the study design of available reports and data.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

1 825 mg/L

Additional information

The acute toxicity of hexamethylene diamine was tested on several different recommended species of fish. Four study reports were available and input as endpoint summary records. The two last Endpoint Summary Records could not be assigned for reliability but were formerly included in the IUCLID4 of the OECD SIDS (2000).

Only three study reports were sufficiently detailed and solid enough to be scientifically reliable according to Klimisch scoring (Klimisch et al., 1997). Although one of these, the study of Cellier (1998) which tested the substance on Danio rerio under semi-static conditions, but without pH adjustment, cannot be considered as valid. Due to the caustic effect of the substance, test solutions had to be pH adjusted to the recommended range (6.5-8.5) or lethality would occur due to the pH of the test solution. Munk (1992) conducted a finely detailed study where Leuciscus idus were tested under static conditions, once without pH adjustment, then with pH adjustment. In the first trial, without adjustment, fish died after 1 hour of exposure at pH = 11.0 and 215 mg/L. In contrast when pH was adjusted to 8.5 prior to the test, no mortalities were observed at 215 mg/L, the highest concentration tested in this study. Finally, Dupont (1985) tested the acute toxicity of the substance on Pimephales promelas after pH adjustment of test solutions at very high concentration up to 10 000 mg/L under static conditions. No mortalities were observed up to 1 000 mg/L. The 96h-LC50 of 1825 mg/L

(95%IC = 1237-2461 mg/L) using Probit analysis was calculated. Despite the lack of chemical analysis and the fact the study was performed under static conditions, this is considered the key study for Fish as this is the only study in which a LC50 was determined at reasonable conditions of pH. Moreover, test solutions of HMD have been shown to be completely stable under environmentally relevant conditions in a recent study on algae.