N,N'-diphenylguanidine monohydrochloride

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

The test item (target substances, CAS 24245-27-0) is the salt of 1,3-diphenylguanidine and mono-hydrochloride. As read-across source substance the uncharged free base of 1,3-diphenylguanidine (CAS 102-06-7) is applied. This is considered appropriate since the target substance is expected to readily dissociate in contact with water such as surface water in the environment or the intestinal fluids or mucosal membranes of an organism. 1,3-diphenylguanidine is considered a weak base. Therefore, it is expected to be present as uncharged molecule at neutral and high pH solutions. However, acidic conditions will lead to protonation of the molecule and the charged ion is expected to be the main present form. Since transformation of the target to the source substance and vice versa is anticipated, kinetics and toxicological behaviour are well transferable from the source to the target substance. This applies for human health endpoints as well as for the aquatic environment.
Moreover, chloride ions are ubiquitously present in every-day nutrition and are part of numerous physiological processes. Therefore, this constituent does not require further assessment in regards to its toxicological behaviour. It is expected to be well regulated by endogenous physiological mechanisms of the organism.
Based on the considerations above, a read-across is considered appropriate and further tests, especially vertebrate studies, are not needed to adequately address this endpoint. Information Requirements are fulfilled according to REACH Annex XI Section 1.5.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

4.2 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Key result

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

3.2 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Description of key information

Based on experimental results obtained with the read-across substance (CAS 102 -06 -7) the LC50 for short-term toxicity with fish is considered to be 4.2 mg/L for the test item.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

4.2 mg/L

Additional information

Read-Across approach

There are no experimental data available regarding acute toxicity to fish with the test item. However, data are available with a structural analogue substance which are suitable and adequate to fulfill this endpoint. For Read-across justification please refer to the respective IUCLID Section.

Short-term toxicity to fish (CAS 102 -06 -7)

The acute toxicity of the read-across substance to fathead minnows (Pimephales promelas) was assessed using the methods outlined by the Committee on Methods for Toxicity Tests with Aquatic Organisms. Water quality parameters of temperature, dissolved oxygen, pH and ammonia were measured throughout the test and were within acceptable limits. As a quality check, the fathead minnows were challenged with areferencecompound, Antimycin A. The observed 96 hour LC₅₀and 95% confidence limits (C.I.) were within the 95% confidence limits reported in the literature (2), indicating that the fish were in good condition. The results of the four day static fish toxicity study using fathead minnows are summarized below.

1,3-diphenylguanidine 96-hour LC50 = 4.2 mg/L (3.2 -5.6 mg/L)

Antimycin A96-hour LC50 = 0.000028 mg/L (0.000023 -0.000034 mg/L)

Also, the results indicated a 96 hour, no observed effect concentration of 1.8 mg/L.