Ladle skimming slag, Ladle furnace refining, slag, Ferrous slag

Long-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

fish early-life stage toxicity

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1990-1992

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Field study well documented. Study meets generally accepted scientific principles. Study acceptable for assessment

Principles of method if other than guideline:

Field study: 10 stations in the Nord-Ostsee-Kanal in the area and vicinity of the Schirnauer lake (channel km 70 to 75)

GLP compliance:

no

Remarks:

field study

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
basalt, diabase and granite as natural rock in stone fields
glass exposed to water in one of the stone fields (material not specified)
weathered plastic plates as substrate for attachment of eggs on mud ground
mud grounds of same waters

Analytical monitoring:

not required

Details on sampling:

Egg and population densities and distribution of the eggs were determined with the aid of a counting grid (net 1 cm). This grid was also used to determine the surface area of the stones

Vehicle:

no

Details on test solutions:

Not applicable, as slags are insoluble. Slags were used as a bank protection during the construction and enlargement phases of the channel.

Test organisms (species):

Clupea harengus

Details on test organisms:

Spawns of herring from the Baltic Sea, approximately 1500 t of biomass for the whole channel, which equalls approximately 15 millions of adult herrings. The estimated number of eggs found in the channel is 83 billions. That is in the same order of magnitude of the calculated number of eggs laid into the channel (188 billions, based on 25000 eggs/female)
the herrings spwan in a water depth of approximately 1 m , and hundreds of animals release thair sperma. the females lay their eggs solely on hard ground, and not deaper than 3 m. The eggs are released by the females in the water column and sink to the ground, attaching to any hard substrate or other eggs or filamentous algae. Some females even leave the water to and release their eggs outside the water. After spawning, the area is covered with a thick cover of eggs (some centimeters).
Females did not deposit eggs on soft ground, and not in areas with a water depth of more than 3 m. Eggs which did not attach to solid ground formed thick aggregates which drifted to the ground of the channel or into areas with soft ground (mud).

Test type:

other: Field study

Water media type:

brackish water

Limit test:

no

Total exposure duration:

6 mo

Remarks on exposure duration:

Observations starting from February until late summer boith in 1990 and 1991

Post exposure observation period:

The life span for herring is approximately 20 years. Adult herrings can propagate at the age of 3 years at the earliest. Herring depends on hard ground for spawning. As herring shoals return to their spawning grounds each year, it is likely that the fish returned to their spawning grounds in the following year, thus it is likely that fish returned for spawning to the areas they have been born suggesting that slags are without any efffect on

Hardness:

not measured

Test temperature:

ambient temperatures typical for surface waters in Nordic Central Europe

pH:

not measured

Dissolved oxygen:

in the interstitial (interlacunal) water of the stone banks typically 104 % of saturation

Salinity:

brackish water, salinity not measured

Nominal and measured concentrations:

not applicable

Details on test conditions:

The test area is located in the Nord-Ostsee-Kanal (Channel connecting the North Sea and the Baltic Sea), at channel km 70 to 75 in the Schirnauer Lake area and its vicinity. 3 test fields were situated on the northern banks of the channel, 7 test fields on the southern banks. Each test field (lenght 6 m) consisted of stone fields extending on the embarkment up to approximately 1 m above water level and approximately 5 m below water surface. The purpose of the slag and natural rock stones was the protection of the embarkment against wave action. The surface area of stones of 1 m2 of field was approximately 1.83 m2.
For comparison measurements were done on eggs collected from areas with "soft" (muddy) ground (drainage channel Entwässerungs-Siel Kiel-Holtenau). In these areas weathered plastic plates were used as a substrate for attachment of eggs.
For examination of swimming behaviour of the young free-living larvae, glass plates were incubated between the stones of the embrakments in the test fields. As being solid substrates, the eggs were attached to the glass. Shortly before hatching, a small net cage (40 mm diameter) was put over the glass surface and the swimming behaviour of the hatchlings was monitored.

Duration:

6 mo

Dose descriptor:

NOEC

Effect conc.:

ca. 500 g/L

Nominal / measured:

nominal

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).

Results with reference substance (positive control):

not applicable

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 %.

The channel with approximately 30 km of slag and natural stone fields is an excellent spawning ground for herring.

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

Aquatic toxicity studies are not available for Slag, pig iron ladle refining, non-granulated, water-cooled. Read-across to the assessment entity (analogue approach) to slags, steelmaking is applied for the assessment of Slag, Pig Iron ladle refining, non-granulated, water-cooled since the solved metal ion concentrations determine its fate and toxicity in the environment. Based on result of a leaching experiment performed with the target substance (i.e., Slag, pig iron ladle refining, non-granulated, water-cooled) and the source substance (i.e., slags steelmaking) solved metal ion concentrations of the target substance are similar to the solved metal concentrations of the source substance. Read-across is fully justified and discussed in detail in the RAAF document attached on IUCLID section 13.

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.