Chloramide

Long-term toxicity to fish

Description of key information

The most sensible  parameter determined  in the only reliable long-term study performed according the OECD 210 on fish was the inhibition of the Mortality (post-hatch success) with an EC10 of 9.8 µg/L (monochloramine).

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

9.8 µg/L

Additional information

The long-term toxicity of monochloramine to vertebrates has been tested in one study.

This study constitutes a reliable key study for this endpoint.

In this study , the chronic toxicity toward fish, Zebrafish (Danio rerio), was assessed according to the OECD Guideline for Testing of Chemicals, No. 210 "Fish, Early-life Stage Toxicity Test". The study was compliant with the GLP. 

Newly fertilised eggs were exposed to seven concentrations levels for 30 days post-hatch under flow-through conditions.The test period (exposure of test organisms to the test solutions) was 35 days.

Two replicates per test concentration and control, with 30 fertilised eggs per test vessel, were tested at nominal concentrations of 0.40, 1.265, 4.00, 12.65, 40.0, 126.5 and 400 µg monochloramine/L

The five biological parameters investigated were the hatching success, the mortality (post-hatch success), the numbers of healthy fish, the length of the surviving fish and the dry weight of the surviving fish at the test end.

The analytical monitoring was performed from the measurement of TRC and FRC concentrations. TRC is the sum of the FRC (Free Residual Chlorine) and the CRC (Combined Residual Chlorine). CRC is composed of the 3 species of inorganic chloramines, mono-, di- and trichloramine). However according to the knowledge of the chemistry of chloramines and the test conditions (pH above of 8 and preparation of test solutions with a mass ratio Cl₂/N of 4.8), it is considered that monochloramine was the predominant species of inorganic chloramines (CRC).

The concentration of monochloramine was then determined from the TRC and FRC concentrations by multiplying the measured CRC concentrations (Total Residual Chlorine (TRC) minus Free Residual Chlorine (FRC)) provided as eq Cl₂/L by the factor of 0.725.

Chemical analysis of test concentrations was carried out on samples taken from: 12.65 (C4), 40.0 (C5), 126.5 (C6), 400 (C7), 1600 µg NH₂Cl/L (stock solution), 0.16 g NH₂Cl/L (test item solution) and control medium.

Samples of the test solutions were analysed to determine actual levels of test item in comparison to nominal test item concentrations. The determinations of actual concentrations showed a mean recovery of 37% at the highest test concentration. Since the difference between the nominal and the mean measured concentrations was >20%, all biological endpoints are expressed based both on nominal and mean measured test item concentrations.Only the results based on time-weighted mean are reported below as they were used preferentially for the toxicity assessment and the classification.

Under the experimental conditions of this study, a concentration-response relationship was observed. The following endpoints were determined for the test item based on measured concentrations:

Biological parameter	Endpoints [µgNH2Cl/L] based on
	measured concentrations
	EC50	EC10	NOEC
Hatching success	n.d.	n.d	≥148
Mortality (post-hatch success)	69,9	9,8	14,8
Numbers of healthy fish	n.d.	n.d	≥148
Length of the surviving fish	n.d.	31,5	46,8
Dry weight of the surviving fish	156,2	55,2	46,8

n.d. = not determined due to lacking concentration-response relationship

The five validity criteria of the OECD guideline 210 were fulfilled.

The most sensitive parameter was the inhibition of the mortality (post-hatch success) with an EC10 of 9.8 µg/L (monochloramine).

According to the guidance R10 of the ECHA “An EC10 for a long-term test which is obtained using an appropriate statistical method (usually regression analysis) will be used preferentially » than a NOEC. This notion is also supported by theOECD (OECD Environmental Health and Safety Publications Series on Testing and Assessment No. 54, 2006).

The following information is taken into account for chronic toxicity to fish for the derivation of PNEC:

Conclusion:

The study performed on Danio rerio was GLP compliant and carried out according the OECD Guideline 210. This study was judged valid without restrictions.

Values used for CSA.

35d-EC10 for freshwater fish: 9.8 µg/L