Chloramide

Long-term toxicity to aquatic invertebrates

Description of key information

The most sensible parameter determined  in the only reliable long-term study performed according the OECD 211 on Daphnia magna was the inhibition of the reproduction with an EC10 of 11.7 µg/L (monochloramine).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

11.7 µg/L

Additional information

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

This study constitutes a reliable key study for this endpoint.

In this study, the chronic toxicity toward the invertebrate Daphnia magna, was assessed according to the OECD Guideline for the Testing of Chemicals, No. 211, "Daphnia magna, Reproduction Test" adopted October, 2008.The study was compliant with the GLP. 

Neonate daphnids (parent animals; F₀females) aged less than 24 hours were exposed during 21 days at five concentrations levels, based on previous tests) under flow-through conditions.

Four replicates per test concentration and control, with five daphnids per test vessel, were tested at nominal concentration of 100, 31.6, 10.0, 3.16, 1.00 µg monochloramine/L.

The three biological parameters investigated were the reproduction as assessed by fecundity (total number of living offspring (F₁) per parental animal alive at the end of the test), the mortality/survival as assessed by immobility of parental (F₀)daphnids and the length of surviving parental daphnids.

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 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 were carried out 2-3 times per week in control and the highest concentration level (fresh and aged solutions).The lower concentration levels were not analyzed since only the highest nominal test concentration (100 µg/L) exceeded the Limit of Quantification of the analytical method.

Chemical analyses resulted in a time-weighted mean recovery of 52.9% of nominal concentrations throughout the test period. Therefore, the biological endpoints were calculated based both on nominal and time-weighted mean concentrations. Only the results based on time-weighted mean are reported below as they were used preferentially for the toxicity assessment and the classification.

A clear concentration-response relationship was observed for the end-points survival of first generation daphnids and reproduction.

NOEC, LOEC and EC_xvalues of the endpoints reproduction/fecundity (total number of living offspring per parent animal alive at the end of the test), mortality/immobility of parental daphnids, and length of parental daphnids based on statistical evaluation of biological results and time-weighted mean concentrations in µg monochloramine/L as follows :

	Endpoints [µg test item/l]
Parameter	EC10	EC20	EC50	NOEC	LOEC
Reproduction / fecundity	11.7	13.8	19.0	5.3	16.7
Mortality / immobility of parental daphnids	n.d.	n.d.	25.8	16.7	52.9
Length of parental daphnids	n.d.	n.d.	n.d.	5.3	16.7

n.d. :not determined

The two validity criteria of the OECD guideline 211 were fulfilled.

The most sensitive parameter was the inhibition of the reproduction with a 21d-EC10 of 11.7 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 the OECD (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 aquatic invertebrates for the derivation of PNEC:

Conclusion:

The study performed on Daphnia magna was GLP compliant and carried out according the OECD Guideline 211. This study was judged valid without restrictions.

Values used for CSA.

21d-EC10 for freshwater aquatic invertebrates:11.7 µg/L