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Ecotoxicological information

Long-term toxicity to fish

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Reference
Endpoint:
fish early-life stage toxicity
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Justification for type of information:
The available identification data for the Target and the Source substance support the read-across hypothesis. Adequate, reliable and available scientific information indicate that the Target and Source substance have, or are very likely to have, similar (eco)toxicological properties. There are no indications that constituents other than those identified for the substances or impurities may influence the validity of the read-across. There is no evidence that additional toxicological mechanisms, other than those identified in the read-across hypothesis, may be acting or have an adverse effect on the validity of the read-across.
Reason / purpose for cross-reference:
read-across source
Key result
Duration:
6 mo
Dose descriptor:
NOEC
Effect conc.:
ca. 500 g/L
Nominal / measured:
nominal
Conc. based on:
not specified
Basis for effect:
other: viability of the eggs
Details on results:
Estimate for the number of eggs: approximately 230000 eggs/m2 of field, equals approximately 83 billions of eggs in the channel (30 km length of embarkment protected with stones , width 6 m). The stones increased the number of eggs and the survival due to supply of lacunes which were protective against predators. No difference is reported between slags and natrual rock stone fields.
The oxygen concentration of egg layers on hard ground (independent on the nature of the stones - slag or natural rocks - was even in the lacune system of the stones, close to saturation (104 +/- 2 %).
The fertilization rate of eggs was independent from the nature of the stone fields and there was no difference between slag stone fields and the control fields of basalt, granite, and diabase (almost complete fertilization, at least 98.7 %)
The vitality of the eggs was determined from the heartbeat. Almost all larve in the eggs exhibited a normal development and the percentage of larvae with normal heartbeat was at least 98.3 %.
Living larvae were found up to 10 cm above normal water level in the lacune system of the stones (within the area regularily flooded by waves fron the heavy ship traffic of the channel)
Eggs which did not attach to solid ground formed thick aggregates (5-13 cm diameter) which drifted to the ground of the channel or into areas with soft ground (mud), or formed thick egg layers. The oxygen concentration inside such aggregate on mud ground (drainage channel) was significantly lower than on solid ground. The mud under the 4-16 cm thick (dead) egg layers in this area was black indicating oxygen depletion, and the oxygen concentrations were dramatically decreased e.g. in 6 cm depth to 38 % (from 104 % saturation). Under these conditions, less than half of the eggs were viable, and another week later after these findings, no live eggs were found. The majority of eggs was infested with mycels, and even empty eggs with infested larvae were found. Similar observations were made on other soft ground in the surroundings of Kiel (Hörn, Kiel Harbour).
Reported statistics and error estimates:
Almost complete fertilization and hatching, equal distribution of eggs. no detectable preference of natural rock in comparison to slag stones. For all parameters, maximum deviation was 1.7 %.
Validity criteria fulfilled:
yes
Conclusions:
Slag stones do not exhibit any hazardous effect on any stage of fish development e.g. fertilization of eggs, egg number, egg distribution, development of larvae.
Executive summary:

A field study was conducted in the Nord-Ostsee-Channel into elucidate the effects of stones of slag and natural rock on the reproduction of the herring, Clupea harengus. This channel is a significant spawning ground of herring, and every year approximately 15 millions of adult fish enter the channel for reproduction. The estimated number of eggs is approximately 230000 eggs/m2 of stone field, which equals approximately 83 billions of eggs in the channel (30 km length of embarkment protected with stones, width 6 m). The eggs are deposited above the stone fields, sink to the ground and attach to the stones and the filamentous algae growing on these stones.

From the egg distribution data, it was apparent that herring does not prefer to slag the natural rocks basalt, granite, and diabase as a spawning ground.

The oxygen concentration of egg layers on hard ground (independent on the nature of the stones - slag or natural rocks) was close to saturation level (104 +/- 2 % of saturation, approximately 8 mg/L, depending on e.g. temperature and salinity).

The fertilization rate of eggs was independent from the nature of the stone fields and there was no difference between slag stone fields and the control fields of basalt, granite, and diabase (almost complete fertilization, at least 98.7 %)

The viability of the eggs was determined from the heartbeat of the developping larvae. Almost all larve in the eggs deposited on hard ground had a normal heartbeat (at least 98.3 %). Concomitantly, no deviations from normal development were observed.

Description of key information

Slag stones do not exhibit any hazardous effect on any stage of early fish development e.g. fertilization of eggs, egg number, egg distribution, development of larvae.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish
Effect concentration:
500 g/L

Marine water fish

Marine water fish
Effect concentration:
50 g/L

Additional information

A field study was conducted in the Nord-Ostsee-Channel to elucidate the effects of stones of slag and natural rock on the reproduction of the herring, Clupea harengus. This channel is a significant spawning ground of herring, and every year approximately 15 millions of adult fish enter the channel for reproduction. The estimated number of eggs is approximately 230000 eggs/m2 of stone field, which equals approximately 83 billions of eggs in the channel (30 km length of embankment protected with stones, width 6 m). The eggs are deposited above the stone fields, sink to the ground and attach to the stones and the filamentous algae growing on these stones.

From the egg distribution data, it was apparent that herring does not prefer to slag the natural rocks basalt, granite, and diabase as a spawning ground.

The oxygen concentration of egg layers on hard ground (independent on the nature of the stones - slag or natural rocks) was close to saturation level (104 +/- 2 % of saturation, approximately 8 mg/L, depending on e.g. temperature and salinity).

The fertilization rate of eggs was independent from the nature of the stone fields and there was no difference between slag stone fields and the control fields of basalt, granite, and diabase (almost complete fertilization, at least 98.7 %)

The viability of the eggs was determined from the heartbeat of the developping larvae. Almost all larvae in the eggs deposited on hard ground had a normal heartbeat (at least 98.3 %). Concomitantly, no deviations from normal development were observed (Kils 1992).

From the observations of Kils, a (chronic) NOEC can be estimated. As the exchange rate of the brackish water is low in the channel, the hight of the water column (assumed to be 2.4 m in the slag fields) and the thickness of the slag layers (assumed to be 40 cm) were directly compared. Using a density of 3 for the slags, the estimated chronic NOEC (nominal) is approximately 12 kg/24 L = 500 g/L for weathered slags in brackish water.

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