Chloramide

Short-term toxicity to fish

Description of key information

The most relevant 96h-LC50 was determined to be 0.064 mg/L (monochloramine) for the juvenile brook trout.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

0.064 mg/L

Additional information

A number of publications are available regarding the toxicity of chloramines on freshwater and marine fish.

Only the most relevant and the most useful studies for the hazard assessment under the Biocide regulation are reported in the summary below even if less relevant studies are also reported in the dataset (Johnson et al. 1977, Stangenberg et al. 1975, Brooks and Bartos et al 1984, Thomas et al. 1979 and Tompkins et al. 1979).

Freshwater

All the studies summarized below were selected and retained for the short-term toxicity assessment because the protocol design and the test conditions (particularly the pH and the ratio of Cl₂/N) were carried out in order to obtain predominantly monochloramine in the test solutions. Therefore, in all of these studies, the LC50s or TLms could be assigned to monochloramine.

Depending on studies, LC50 values are expressed either as monochloramine or as TRC (Total Residual Chlorine) or combined chloramines (CRC, Combined Residual Chlorine). Indeed, due to the difficulties to performed analytical monitoring on monochloramine specifically, TRC or combined chloramines were often used as surrogate of the monochloramine for the analytical monitoring. Thus, due care was taken on the expression of the results (i.e. expressed as mg eq Cl2/L for TRC or combined chloramines or as mg/L of monochloramine according the expression of the results reported in the studies). For the studies where the results expressed as TRC or CRC (mg eq Cl2/L), the results can be expressed in monochloramine by multiplying the concentration provided as mg eq Cl2/L by a factor of 0.725: Monochloramine (NH2Cl) [mg/L] = 0.725 * mg eq Cl2/L. This factor corresponds to the ratio between the molecular weight of CL2 and NH2Cl.

Many studies on fish were performed to simulate intermittent exposure occurring in natural waters receiving power plant cooling effluents or wastewater treatment plant effluents. Thus the available data concerning the short term toxicity to fish were mainly data referring to exposure of very short duration (pulse of monochloramine) and often on an intermittent regime (several short pulses doses for one or several days). No studies found in the literature search correspond to standard assessment endpoint used in REACH.In addition, in many studies, tests were performed on several species in order to determine the most sensitive one to monochloramine.

Heath (Heath et al 1978) exposed five fish species; rainbow trout (Salmo gairdneri),Coho salmon (Oncorhynchus kisutch), bluegill (Notemigonus crysoleucas),Carp (Cyprinus carpio) and Channel catfish (Ictalurus puctatus) to 45 min pulses of monochloramine three times a day for up to seven days in flow through tap water system at different temperatures.Channel catfish and Coho salmon were the most sensitive with an 96h-LC50 of 0.28 mg/L eq. Cl₂ at 24°C and 96h-LC50 of 0.64 mg/L eq. Cl₂ (TRC) at 12°C respectively.

Seegert and Brooks (1978) exposed ten riverine fish species; Emerald shiner (Notropis atherinoides), Spotfin shiner (Notropis spilopterus), common shiner (Notropis cornutus), channel catfish (Ictalurus punctatus), white sucker (Catastomus commersoni), sauger (Stizostedion candense), freshwater drum (Aptodinotus grumiens,) white bass (Morone chrypsops), bluegill (lepomis macrochitus),Carp (cyprinus carpio) at 10, 20 and 30 °C to determine their resistance to monochloramine. The exposure regime consisted to four periods of 40 minutes exposures administered at 5 hours intervals over 24 hours. The LC50s were determined at 48 hours post exposure. The LC 50 values showed an inverse relationship with the temperature and a species dependent variability. The resistant group freshwater drum, white bass, bluegill, Carp had LC50 values of 1.0 to 1.50 mg/L eq Cl₂. (TRC) For the sensitive group (the others fish species) LC50 values ranged from 0.35 mg/L eq Cl₂to 0.71 mg/L eq Cl₂(TRC).

Brooks and Bartos (1984 and 1982) exposed three species; Emerald shiner (Notropis atherinoides), channel catfish (Ictalurus punctatus) and Rainbow trout to four exposures regimes, typical to chlorination schedules of power plants. Fish were exposed to single 15 min, 30-min 120-min and 4 x 30-min periods. The LC50s were determined 48 hours after the last exposure.Emerald shiner was the most sensitive fish with a LC50 = 0.25 mg/L eq. Cl₂for an exposure of 4 x 30-min. and 120 min and the LC50 values for single exposure of 15-min and 30-min were 0.64 and 0.42 mg/L eq. Cl₂ (TRC) respectively. According to the protocol design and the test conditions, the monochloramine was the predominant inorganic chloramines so acute toxicity toward fish could be assigned to the monochloramine.

Elmore (Elmore et al 1980) exposed goldfish during 96 hours to pulses of monochloramine. Pulse was added when the monochloramine levels fell below nominal concentrations.This study allowed to determine a predicting model and this model predicted 24, 48, 72 and 96 h TLms (TLms Tolerance Limit median is similar to LC50) of 1.64, 1.15, 0.93 and 0.80 mg/L (monochloramine).

Larson (Larson et al1977) conducted acute toxicity tests with inorganic chloramines on brook trouts of different early-life stages (alevin, fry and juvenile). Tests were performed under continuous flow conditions. The goal of this study was to define whether acute toxicity was related to life stages of fish. Three groups of alevins, one of fry and two of juveniles were tested. The acute toxicity levels were not equivalent between the brooks trout stages studied. The lowest 96h-LC50 was 0.082mg/L eq. Cl₂ (TRC) for the fry brook trout (Salvenius fontinalis), the other 96h-LC50 were 0.088 mg/L eq. Cl₂(TRC) for the juvenile stage and 0.105 mg/L eq. Cl₂(TRC) for the alevin stage. In this study monochloramine was the predominant inorganic chloramines so acute toxicity toward fish could be assigned to the monochloramine.

In the study of Farrell (2001), the acute toxicity of monochloramine to juvenile chinook salmon (Oncorhynchus tskawytscha) was examined. Two types of exposure tests were performed with fasted chinook salmon: acute exposure less than 12 hours and sub-acute exposure more than 12 hours to 10 days.For the long term toxicity test (12 hours to 10 days), water was replaced in a test chamber every hour,. For the acute toxicity test (<12hours), the water was not changed.For exposures up to 10 days, the exponential equation describing the juvenile chinook salmon LC50 data for exposures between 10 and 10,000 minutes (7 days) was: LC50=7244*texp(-0.4525). The following LC50s were estimated using this equation: 0.144 mg/L at 96h, 0.270 mg/L at 24h and 0.112 mg/L (monochloramine) at 166.7h (7 days).

 

Concerning the short-term toxicity to fish, no acute fish tests performed according to standard test protocols were found in the collected and evaluated literature.

Almost all of these tests (except Farrell 2001 and Larson 1977) were designed with intermittent exposures or very short period exposure in order to mimic power plant cooling releases or wastewater releases. Therefore they are not relevant and adequate to determine a LC50 useful for the assessment of short term toxicity under the REACH regulation although their reliability is quite good because they are well described. The intermittent exposure regime could under or overestimate the toxicity compared to a continuous exposure (generally, the intermittent exposure regime is known to have a lower impact on animals, permitting a certain degree of recovery, than continuous exposure). Nevertheless, these data are useful as supportive data because they give an outline of monochloramine potential to produce acute toxic effects in fish.

Therefore, studies performed with constant exposure are considered as more relevant than ones with intermittent exposure and they were used preferentially for the short-term assessment under REACH regulation. The study performed with early life stages of fish (brook trout) has the most conservative LC50 with a LC50 of 0.088 mg/L eq. Cl₂ (TRC) for the juvenile stage (the juvenile stage was retained rather than the other earlier stage because it is more in adequacy with the standard assessment criteria of the short-term study). It was used as key study for this endpoint.

Marine water

Four short-term toxicity studies on fish have been reported for marine water.

Buckley (Buckley et al 1976) exposed Juvenile coho salmons (Oncorhynchus kisutch) to treated wastewater containing lethal levels of TRC (Total Residual Chlorine) with seawater diluent under continuous flow conditions. Testing consisted of a 96 hours exposure of duplicate groups to a continuous flow of effluent of 0% (control), 3%, 6%, 9% or 12% effluent (sea-water diluent). The 96-h TL50 was estimated to be 0.07 mg/L eq Cl₂of TRC (corresponding to 4% effluent). However no information was reported on the composition of these effluents. Therefore it is difficult to assign the toxicity observed to monochloramine.

The objective of Cappuzzo (Cappuzzo et al 1977) study was to differentiate the toxic effects of chloramines on three species of juvenile fish common scup, winter flounder and the killifish in continuous flow bioassays. Exposure concentrations ranged from 0.05 mg/L to 15.0 mg/L eq Cl_2.for chloramines solutions. Exposure regime was a single exposure of 30-min. Killifish were more susceptible than either of the two other species and its 48h-LC100 post exposure was 0.85 mg/L eq Cl_2.(TRC) of residual chloramines. The reliability is quite good but this study of Cappuzzo is not adequate to determine a LC50 useful for the assessment of short term toxicity since it was performed with a very short period exposure.

Bender (Bender et al 1977, results from Robert et al 1975) assessed the acute toxicity of chloramines toward different varieties of organisms, includingthree fish species pipe fish (Syngnathus fuscus),naked goby (Gobiosoma bosci)and silverside (Menidia menidia). The three fish species were exposed under continuous flow conditions during 96 hours.The lowest LC50 was calculated for Menidia menidia which was 0.04 mg/L eq Cl₂(TRC).

In this study, an amperometric titration method measuring the TRC was used. However this method does not distinguish chlorine compounds of bromide compounds. Therefore it was judged not relevant to assign the toxicity observed in this study to monochloramine.

 

In conclusion:

Fresh water:

Different studies are available although no study corresponds to a standard test protocol used for the risk assessment in REACH. Studies performed with constant exposure concentrations are used preferentially for the short-term assessment. The lowest LC50 found under the open literature is retained to be used for the risk assessment toward fish. The study of Larson et al 1977 is considered as the most relevant study. The lowest 96h-LC50, expressed as TRC, was determined as 0.088 mg/L eq. Cl₂ for the juvenile brook trout (Salvenius fontinalis). In this study, the predominant species of inorganic chloramines tested, according to the protocol design and the test conditions, should be the monochloramine. Therefore acute toxicity toward fish could be assigned to monochloramine and the concentration in TRC was considered as representative of the concentration of Monochloramine. The concentrations of monochloramine could be calculated by multiplying the TRC concentrations provided as eq Cl₂/L by the factor of 0.725. The 96h-LC50 expressed as monochloramine was 0.064 mg/L.

Marine water:

No key study was indentified for this marine water due to either not enough detail on composition of test solutions or a misfit analytical method or a too short exposure period.

Thus monochloramine is considered as very toxic to fish.