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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reference:
Composition 0
Qualifier:
according to
Guideline:
EPA OTS 797.1300 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)
GLP compliance:
yes (incl. certificate)
Test material information:
Composition 1
Specific details on test material used for the study:
Chemical Name: (2-hydroxyethy1imino)diacetic acid, disodium salt
Synonym: Na2HEIDA
Appearance: clear liquid
Identrfication: 53053-35
Chemical Purity: 40% (wt./wt.)
Solubility: miscible in water
Dow Registry No.: 0018-5342
CAS NO: 135-37-5
Molecular Formula: C6HgNa2NO5
Molecular Weight: 221.12 g/mole
Molecular Structure: (Na' -02CCH2) 2NCH2CH20H
Analytical monitoring:
yes
Details on sampling:
On day 0, the bulk dose solution and the control daphnid water were sampled and analyzed. On day 2, the bulk dose solution, the triplicate test vessels at a
target concentration of 100 mg/L, and the triplicate control test vessels were sampled and analyzed. On each day, a 2 rnL aliquot. from each test vessel or bulk solution was collected and transferring to a 1 dram autosampler vial. The collected samples were then complexed with 0.2 mL of 0.05 M cupric acetate.
Each sample was mixed briefly before analysis by HPLC/UV.
On day 2, four additional 2 mL samples were collected from test vessel #4 at a target level of 100 mg a.i.1L. These additional samples were complexed along
with the other day 2 samples in order to determine method precision.
Vehicle:
no
Details on test solutions:
The laboratory water is of Midland Water Treal Lake Huron water supplied to The Dow Chemical Company by the City of Midland water treatment Plant. The water is obtained from the upper Saginaw Bay of Lake Huron off Whitestone Point and is limed and flocculated with ferric chloride. The water is
pumped to the laboratory prior to municipal treatment for human consumption. Before use in the laboratory, the water is sand-filtered, pH-adsusted with gaseous COz, carbon-filtered, and UVirradiated.
Daphnid water is prepared by adjusting laboratory water to a hardness of about 170 mg/L as CaC03 before autoclaving. After adjusting hardness, the water is autoclaved at 121°C and 18 psi for 30 minutes, cooled, and aerated for approximately 24 hours before use. Laboratory and daphnid water is monitored weekly for pH, alkalinity, conductivity and hardness, and twice yearly for total organic carbon (TOC), total suspended solids (TSS), selected inorganics and
organic compounds.
Test organisms (species):
Daphnia magna
Details on test organisms:
Instars (i.e. less than 24-hour old) from a laboratory-reared culture of Daphnia magnu Straus
were used for testing. This species is widely accepted and recommended for toxicity testing [1,2].
Rearing conditions were: illumination (cool-white fluorescent) 2045 + 323 lux; 16-hour light/8-
hour dark photoperiod; temperature 20 & 2°C. Daphnids were fed a mixed algal diet of
All.kistrodesmus con.volutus and Nitzschia frustulum 4 times weekly. The day before instars were
needed for testing, stock tanks containing adult daphnid (14 days old or greater) and instars were
filtered through a nylon mesh screen which passed all instars but retained the adult daphnids. The
nylon screen was then placed into another stock tank. The original solution with instars was
poured through a metal sieve into another stock tar?<. he instars collected on the sieve were
discarded and the original solution was poured back into the initial stock tank, along with the
corresponding insert. This procedure was repeated within 24 hours of the first screening. In this
manner, it was assured that the instars used for testing are those 24 hours old or less.
Test type:
static
Water media type:
freshwater
Limit test:
yes
Total exposure duration:
48 d
Hardness:
177 mg/l CaCo3
Test temperature:
20-21 C
pH:
7.6-7.9
Dissolved oxygen:
> 98.8 % of saturation
Conductivity:
480 µohm/cm
Nominal and measured concentrations:
Nominal concentration was 100 mg/l, measured concentrations of HEIDAA were ranging from 103 - 105 mg/l.
Details on test conditions:
Testing was conducted in 250 mL plastic cups. Test solution volume was 200 mL. All vessels
were loosely covered with watch glasses and were uniquely labeled for identification purposes.
During the test, a 16-h light/8-h dark photoperiod was provided using cool-white fluorescent
lighting and an automatic timer.
Reference substance (positive control):
no
Duration:
96 h
Dose descriptor:
LC50
Effect conc.:
> 105 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
act. ingr. (total fraction)
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
EC50
Effect conc.:
> 105 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
act. ingr. (total fraction)
Basis for effect:
mortality
Duration:
96 h
Dose descriptor:
NOEC
Effect conc.:
> 105 mg/L
Nominal / measured:
meas. (not specified)
Conc. based on:
act. ingr. (total fraction)
Basis for effect:
mortality
Details on results:
Preliminarv Study
A preliminary range-finding study (1211 1/96 - 12/13/96) was conducted to determine the test concentrations for the definitive study. The preliminary study was conducted in 250 mL plastic cups at concentrations of 0 (water control), 1, 10, 100, and 1000 mg a.i./L with 20 instars per dose level (2 replicates per dose level; 10 instars per replicate). Seventy percent mortahty was noted in the 1000 mg a.i./L dose level after 48 hours of exposure. The surviving instars at 1000
mg a.i./L were immobile. No other mortality or sublethal effects occurred at any other test concentration.
Definitive Studv
Based on the preliminary results, the definitive study (12/17/96 - 12/19/96) was conducted as a nominal 100 mg a.i./L limit test with 30 instars per test concentration and negative control (3 replicates per concentration; 10 instars per replicate). A bulk dosing solution (adjusted for 100% purity) was prepared at
a target concentration of 100 mg a.i./L by adding 201 pL of the test material to a 1 L volumetric flask and bringing up to volume with daphnid water. From thls
solution, 200 mL ahquots were added to each 100 mg a.i./L test vessel. The bulk dosing solution was stored in the incubator for the duration of the study. Instars were indiscriminately added to the test vessels within thirty minutes of test solution preparation and sampling. The instars were observed after 6 hours of exposure and then every 24 hours thereafter for mortality (no visible heartbeat) andor immobihty (no response within 15 seconds of gentle
agitation of the test vessel).
Validity criteria fulfilled:
yes
Conclusions:
The 96-hour LC50 and EC50 concentrations for HEIDA were greater than 105 mg a.i./L, the highest concentration tested. Mortality and sublethal effects were not noted in any test or control concentration. The no-observed-effect concentration (NOEC) for HEIDA with D. magna was
105 mg a.i./L.
Executive summary:

The 96-hour LC50 and EC50 concentrations for HEIDA were greater than 105 mg a.i./L, the highest concentration tested. Mortality and sublethal effects were not noted in any test or control concentration. The no-observed-effect concentration (NOEC) for HEIDA with D. magna was

105 mg a.i./L.

Description of key information

The 96-hour LC50 and EC50 concentrations for HEIDA were greater than 105 mg a.i./L, the highest concentration tested. Mortality and sublethal effects were not noted in any test or control concentration. The no-observed-effect concentration (NOEC) for HEIDA with D. magna was 105 mg a.i./L.

Key value for chemical safety assessment

EC50/LC50 for freshwater invertebrates:
105 mg/L

Additional information