Alkaline earth metal and zinc hydroxy(substituted)acetate complexes and alkaline earth metal glyoxylate

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

fish, juvenile growth test

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

2004

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

test procedure in accordance with generally accepted scientific standards and described in sufficient detail

Reason / purpose for cross-reference:

reference to same study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 215 (Fish, Juvenile Growth Test)

Deviations:

not specified

GLP compliance:

not specified

Analytical monitoring:

yes

Details on sampling:

Samples of natural surface waters were taken at eight locations, five in The Netherlands, two in Belgium, and one in France. Samples for toxicity assays with different organisms were taken on various occasions. Two sampling techniques were used. The first technique consisted of taking a 50 L sample of natural water in acid-washed (0.14 N HNO3) polyethylene vessels. Upon arrival in the laboratory, the sample was filtered (0.45 mm; Gelman Science, Ann Arbor, MI, USA) and stored at 4 °C in the dark until use. This technique was used for all toxicity tests with D. magna and for two tests with P. subcapitata. The second technique consisted of concentrating in situ approximately 1000 L of water to a volume of approximately 20 L using reverse osmosis. This technique was used for all tests with rainbow trout and six tests with P. subcapitata. The technique was considered the most practical in order to obtain the large quantities of water needed for the chronic tests with rainbow trout. Upon arrival in the laboratory, the sample was stored at 4 °C in darkness. In order to use the sample for testing, the concentrated sample was diluted with deionized water to obtain the DOC concentration originally present in the natural surface water. As Ca and Mg were replaced with Na during the reverse osmosis process, the Ca and Mg concentrations of the diluted sample were readjusted to obtain the Ca and Mg levels measured in the original water sample using reagent-grade CaCl2 or MgCl2. It was previously demonstrated that this method yields very similar water chemistry in the reconstituted water as compared with the original water. Furthermore, tests with diluted reverse-osmosis concentrates and original water have been demonstrated to yield identical copper and zinc toxicity to D. magna and P. subcapitata.

Vehicle:

no

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

Juvenile Oncorhynchus mykiss were used for the test. Feeding at an amount of 4 % of fish wet weight/day was provided during the test (commercial fish food).

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

30 d

Test temperature:

15 °C

pH:

6.15 - 8.13

Dissolved oxygen:

> 90 % saturation

Details on test conditions:

TEST SYSTEM
- Test vessel: 5 L polyethylene aquaria
- fill volume: 3 L
- Aeration: yes
- Renewal rate of test solution (frequency/flow rate): 2 L/g/d
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 3

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: natural water (see sampling methods)
- Dissolved organic carbon: 2.84 - 22.9
- Chlorine: 10.4 - 158 mg/L
- Alkalinity: 1.7 - 68.5 CaCO3/L
- Intervals of water quality measurement: weekly, pH daily

OTHER TEST CONDITIONS
- Adjustment of pH: N-morpholinopropanesulfonic acid was added as a pH buffer
- Photoperiod: 12:12 (light:dark)
- Light intensity:

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
30-d NOEC, 30-day LC10, 30-d LC50

VEHICLE CONTROL PERFORMED: no

Reference substance (positive control):

no

Duration:

30 d

Dose descriptor:

LC50

Remarks:

pH 7.76, DOC 22.9 mg/L, Ca 32 mg/L

Effect conc.:

1 970 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Duration:

30 d

Dose descriptor:

LC50

Remarks:

pH 7.08, DOC 2.84 mg/L, Ca 8.05 mg/L

Effect conc.:

337 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Duration:

30 d

Dose descriptor:

NOEC

Remarks:

pH 7.76, DOC 22.9 mg/L, Ca 32 mg/L

Effect conc.:

771 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Duration:

30 d

Dose descriptor:

NOEC

Remarks:

pH 7.08, DOC 2.84 mg/L, Ca 8.05 mg/L

Effect conc.:

199 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element (dissolved fraction)

Basis for effect:

mortality

Details on results:

A large variation of physico-chemical characteristics important for zinc bioavailability was observed in the tested waters, i.e., DOC between 2.48 and 22.9 mg/L, pH between 5.7 and 8.4, Ca between 1.51 and 80.2 mg/L, Mg between 0.79 and 18.4 mg/L, and Na between 3.8 and 116 mg/L. For O. mykiss, chronic toxicity in natural waters varied about sixfold, as indicated by 30-d EC10s (between 185 and 902 mg Zn/L) and 30-d LC50s (between 0.337 and 1970 mg Zn/L). The 30-d NOECs ranged from 0.199 to 0.771 mg Zn/L.

DOC

the percentage of Zn calculated to be bound to DOC in natural waters varied between 5 and 89 %. A general pattern is that, at lower Zn concentrations, more Zn tends to be complexed to DOC.

Alkalinity

ZnCO3 accounted in some cases for more than 10 % of the dissolved zinc, notably in those test waters with the highest levels of alkalinity and p

Conclusions:

For O. mykiss, chronic toxicity in natural waters varied about sixfold, as indicated by 30-d EC10s (between 185 and 902 mg Zn/L) and 30-d LC50s (between 0.337 and 1.970 mg Zn/L). The 30-d NOECs ranged from 0.199 to 0.771 mg Zn/L.

Executive summary:

Zinc toxicity to O. mykiss was evaluated in a series of experiments with spiked natural surface waters. The eight selected freshwater samples had varying levels of bioavailability modifying parameters: pH (5.7 – 8.4), dissolved organic carbon (DOC, 2.48 – 22.9 mg/L), Ca (1.5 – 80 mg/L), Mg (0.79 – 18 mg/L), and Na (3.8 – 120 mg/L). In those waters, chronic zinc toxicity (expressed as 50 % lethal concentrations [LC50]) varied up to 6-fold for the O. mykiss (30 -d LC50 between 0.337 and 1.970 mg Zn/L). The 30-d NOECs ranged from 0.199 to 0.771 mg Zn/L.

Reference 2

Endpoint:

fish life cycle toxicity

Type of information:

experimental study

Adequacy of study:

weight of evidence

Study period:

1974

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Guideline:

other: American Public Health Association, American Water Works Association and Water Pollution Control Federation: Standard methods for the examination of water and wastewater. 13th ed. Public Health Association, Washington, D. C. (1971).

Version / remarks:

Chronic flow-through bioassay

Deviations:

not specified

Principles of method if other than guideline:

The hard water chronic bioassay began with two-gram fingerlings and continued through sexual maturity as two-year-old fish. The soft water chronic bioassay began with eyed eggs and continued until, but not through, sexual maturity of the fish. Survival of fish from eggs and fry acclimated to sub-lethal concentrations was compared with survival of non-acclimated fish.

GLP compliance:

not specified

Specific details on test material used for the study:

Reagent-grade zinc sulphate

Analytical monitoring:

yes

Vehicle:

no

Details on test solutions:

Well water (hardness: 330 mg/L as CaCO3) was used for the hard water experiments and dechlorinated tap water (hardness: 25 mg/L as CaCO3) was used for the soft water experiments.

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Hardness:

26 +/- 3.7 mg/L as CaCO3 (soft water), 333 +/- 27.25 mg/L as CaCO3 (hard water)

Test temperature:

hard water: 16.2 +/- 0.79 °C, soft water: 12.7 +/- 3.4 °C

pH:

hard water: 7.81, soft water: 6.8

Dissolved oxygen:

6.8

Conductivity:

1383 +/- 117.56

Nominal and measured concentrations:

measured (in µg/L):
hard water: 2+/-0.1, 11+/-9, 36+/-17, 71+/-31, 140+/-51, 260+/-96, 547+/-134
soft water: 30+/-26, 170+/-70, 320+/-90, 640+/-170, 1055+/-260, 2200+/-530

Details on test conditions:

Chronic bioassays—The exposure system was similar to those used by BRUNGS (1969) and McKIM and BENOIT (1971). A modified proportional diluter (MOUNT and BRUNGS, 1967) delivered two liters of test solution to each aquarium every three minutes, resulting in a 95 % replacement time of 20 hours (SPRAGUE, 1969). The test aquaria were 265 L fiberglass tanks with acrylic plastic covers. All tanks were aerated throughout the experiments to maintain adequate dissolved oxygen levels. Fish were sacrificed periodically to adjust population density as crowding occurred In the tanks.
Hard water chronic bioassay—Chronic exposure of rainbow trout to zinc in hard water began 1 July 1969 by placing 30 2-g fingerlings into the exposure tanks. All aquaria were checked daily for dead fish. Total weight of the fish in each aquarium was obtained quarterly during the first year, and monthly thereafter, to evaluate the effects of zinc on growth. From these data, feeding rates were calculated for each test aquarium.
Soft water chronic bioassay—Chronic exposure of rainbow trout to zinc in soft water began 27 April 1972 with eyed eggs. The eggs, In plastic hatching trays, were incubated in the 265 L tanks. Water temperatures averaged 12.5 °C until hatching was complete six weeks later. To assess any growth effects caused by zinc, total weight of the fish was obtained monthly; for fish under 60 mm, a modification of the photographic technique of MARTIN (1967) was used with weight data from sacrificed fish. These data were also used to project daily feeding rates (HORAK, 1969).
Prior experiences at this laboratory indicated that it might be possible to acclimate rainbow trout to zinc in order to create some type of resistant mechanism within the fish. To explore this idea further, several hundred fish from the same batch of eggs used in the soft water chronic bloassay were marked with fluorescent pigment (PHINNEY et al., 1967). Two weeks after marking, the fish were added to the zinc exposure tanks. Dead fish were collected daily and examined under a black light for identification of marked fish.

Reference substance (positive control):

no

Duration:

22 mo

Dose descriptor:

other: MATC

Remarks:

hard water (330 mg CaCO3/L)

Effect conc.:

> 320 - < 640 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element

Basis for effect:

mortality

Duration:

22 mo

Dose descriptor:

other: MATC

Remarks:

Soft water (25 mg CaCO3/L)

Effect conc.:

> 140 - < 260 µg/L

Nominal / measured:

meas. (initial)

Conc. based on:

element

Basis for effect:

mortality

Details on results:

Hard water chronic bloassay—The MATC for rainbow trout exposed to zinc in a water hardness of 330 mg/L was between 640 µg/L zinc where there was 6.4 % zinc-caused mortality, and 320 µg/L where there were no zinc-caused mortalities. Many deaths occurred during the first two weeks, and again after four months of exposure in aquaria having zinc concentrations of 2200, 1050, and 640 µg/L zinc
Soft water chronic bioassay—The MATC for rainbow trout exposed to zinc in a water hardness of 25 mg/L occurred between 260 µg/L zinc, which caused appreciable mortality after the young fry were feeding normally, and 140 µg/L zinc, where there were no zinc-caused deaths. The zinc concentrations of this experiment caused no appreciable eyed-egg mortality. Although the mortality in the control is lower than in any of the other exposure aquaria, eggs of the same lot from which the experimental eggs were taken exhibited a 3.8 % mortality in the Bellvue Research Hatchery of the Colorado Division of Wildlife. The slightly higher mortality in all zinc exposure tanks therefore is not considered to be caused by zinc.
The reproductive aspects of the MATC were not examined during this experiment because of the small numbers of fish remaining at sexual maturity and inconsistent egg production by two-year-old trout.

After 21 months of exposure to zinc, 6 fish remained in each aquarium; aggressive behavior was observed in all tanks and eggs were found in several aquaria. The chronic toxicity of zinc to rainbow trout is also dependent upon the stage of the fish's life cycle during which exposure begins. Fish not exposed to zinc as eggs may be as much as four times more susceptible to zinc than fish exposed to zinc as eggs. It is possible therefore that an MATC for zinc in hard water may be higher than the one reported here if exposure had begun with eggs rather than fry.

Conclusions:

The chronic toxicity of zinc to rainbow trout also decreases as water hardness increases. The MATC obtained in hard water is with 320 - 640 µg Zn/L approximately two-and-one-half times the MATC obtained in soft water (140 - 260 µg Zn/L).

Executive summary:

Chronic flow-through bioassays, in which exposure data collected over at least one generation of the test organism were used to evaluate the effects of zinc on rainbow trout throughout its life cycle. The results of these bioassays are expressed as "maximum acceptable toxicant concentrations" (MATC's). Well water (hardness: 330 mg/L as CaCO3) was used for the hard water experiments and dechlorinated tap water (hardness: 25 mg/L as CaCO3). The chronic toxicity of zinc to rainbow trout decreases as water hardness increases. The MATC obtained in hard water is with 320 - 640 µg Zn/L approximately two-and-one-half times the MATC obtained in soft water (140 - 260 µg Zn/L). Obviously, fish which have been exposed to zinc as eggs are more resistant than fish which have not been exposed to zinc as eggs. Fish not exposed to zinc as eggs may be as much as four times more susceptible to zinc than fish exposed to zinc as eggs. It is possible therefore that an MATC for zinc in hard water may be higher than the one reported here if exposure had begun with eggs rather than fry.

Description of key information

Read-Across: WoE, Zn ion, O. mykiss, 30 d LC50: 2.04 to 11.94 mg/L; NOEC (30 d): 1.26 to 4.67 mg/L (converted to the target substance taking into account the Zn content of 16.5 %)

Read-Across: WoE, Zn ion,O. mykiss, MATC obtained in hard water of 1.94 - 3.88 mg/L and a MATC obtained in soft water of 0.85 - 1.58 mg/L (converted to the target substance taking into account the Zn content of 16.5 %)

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

1.26 mg/L

Additional information

Read-across - Zn ion

De Schamphelaere et al., 2005

Zinc toxicity to O. mykiss was evaluated in a series of experiments with spiked natural surface waters. The eight selected freshwater samples had varying levels of bioavailability modifying parameters: pH (5.7 – 8.4), dissolved organic carbon (DOC, 2.48 – 22.9 mg/L), Ca (1.5 – 80 mg/L), Mg (0.79 – 18 mg/L), and Na (3.8 – 120 mg/L). Chronic zinc toxicity (expressed as 50 % lethal concentrations [LC50]) varied up to 6-fold for the O. mykiss (30-d LC50 between 0.337 and 1.970 mg Zn/L). The 30-d NOECs ranged from 0.199 to 0.771 mg Zn/L.

This result is also relevant for the target substance, which contains 16.5 % zinc ions. Accounting to the Zn content of 16.5 %, this corresponds to a LC50 (30 d) ranging from 2.04 to 11.94 mg/L and a NOEC (30 d) ranging from 1.26 to 4.67 mg/L for O. mykiss

Sinley et al., 2005

The chronic toxicity of zinc to rainbow trout (O. mykiss) decreases as water hardness increases. The MATC obtained in hard water is with 320 - 640 µg Zn/L approximately two-and-one-half times the MATC obtained in soft water (140 - 260 µg Zn/L).

This result is also relevant for the target substance, which contains 16.5 % zinc ions. Accounting to the Zn content of 16.5%, this corresponds to a MATC obtained in hard water of 1.94 - 3.88 mg/L and a MATC obtained in soft water of 0.85 - 1.58 mg/L.

Conclusion

The study conducted by De Schamphelaere et al., 2005 is regarded as the most reliable. The study using zinc as test item is conducted according to OECD 215 and is well documented. On the contrary, Sinley et al (1974) using zinc sulphate as test item and the study is not in accordance with an OECD Guideline. Addtionally only MATC ("maximal acceptable toxicant concentration") values, but no NOECs are reported. MATC values would need to be recalculated to NOECs. For both studies the GLP compliance is not specified.

Taking all information into account the NOEC as obtained by De Schamphelaere et al., 2005 is set as key value for the chemical safety assessment.